FAA Order 6050.32B

ORDER

6050.32B

SPECTRUM MANAGEMENT REGULATIONS
AND PROCEDURES MANUAL

November 17, 2005

DEPARTMENT OF TRANSPORTATION
FEDERAL AVIATION ADMINISTRATION

Distribution: A-WYZ-1; A-X(AF/AT)-2;
A-FOF-O (SUPV)

Initiated By: Tech Ops ATC Spectrum
Engineering Services (ASR-1)

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6050.32B

TABLE OF CONTENTS
Paragraph .................................................................................................................................................Page
CHAPTER 1. GENERAL
1.
Purpose.....................................................................................................................................
2.
Distribution ..............................................................................................................................
3.
Cancellation .............................................................................................................................
4.
Explanation of Changes ...........................................................................................................
5.
Forms .......................................................................................................................................
6. thru 199. Reserved ...............................................................................................................................

1
1
1
1
2
2

CHAPTER 2. THE RADIO FREQUENCY (RF) SPECTRUM
200.
RF Spectrum ............................................................................................................................
201.
Makeup of the Spectrum ..........................................................................................................
202.
Spectrum Limitation Considerations .......................................................................................
203. thru 299. Reserved ...........................................................................................................................

7
7
7
9

CHAPTER 3. HISTORY, AUTHORITIES AND RESPONSIBILITIES
300.
301.

General Considerations ............................................................................................................
International Organizations......................................................................................................
Figure 3-1. Partial Organizational Chart of the ITU ...............................................................
Figure 3-2a. ICAO Assembly Organization Chart..................................................................
Figure 3-2b. ICAO Secretariat Organization Chart ................................................................
302.
National Organizations - General ............................................................................................
Figure 3-3. Federal Communications Commission ................................................................
Figure 3-4. National Telecommunications and Information Administration..........................
Figure 3-5. Partial Organization Chart of the IRAC ...............................................................
Figure 3-6. AAG Controlled Bands ........................................................................................
Figure 3-7. Bands Under Coordination Control of FAA Field Coordinators .........................
Figure 3-8. Technical Operations ATC Spectrum Engineering Services ..............................
Figure 3-9. Summary of Frequency Bands Supporting Aviation............................................
303.
Technical Operations ATC Spectrum Engineering Services ...................................................
304.
Service Area Frequency Management Office (FMO)..............................................................
305. thru 399. Reserved ...........................................................................................................................

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25
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27
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30
30
31

CHAPTER 4. SPECTRUM MANAGEMENT EVALUATION CRITERIA
400.
General.....................................................................................................................................
401.
Criteria .....................................................................................................................................
402.
Subjects of Evaluation .............................................................................................................
403. thru 499. Reserved ...........................................................................................................................

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35

CHAPTER 5. FREQUENCY COORDINATION
500.
501.
502.

General..................................................................................................................................... 41
Headquarters ............................................................................................................................ 41
Field-Headquarters................................................................................................................... 41
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503.
504.

Field-External ........................................................................................................................
Field-Special ............................................................................................................................
Figure 5-1. Sample Memorandum To Aviation Event Sponsor..............................................
505.
Field-Internal............................................................................................................................
506.
Documents ...............................................................................................................................
507. thru 599. Reserved ...........................................................................................................................

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42
44
46
47
48

CHAPTER 6. TRANSMITTER AUTHORIZATION DOCUMENTS AND CALL LETTER
ASSIGNMENTS
600.
601.

Purpose.....................................................................................................................................
Facility Transmitting Authorization Document (FTA)............................................................
Figure 6-1. FAA Form 6050-1. Facility Transmitting Authorization (Reduced) ..................
Figure 6-2. TIOA Forms For Mobile/Portable/Handheld Transmitters..................................
602.
Requests For Frequency Action...............................................................................................
Figure 6-3. Sample of a Typical Service Area Frequency Request Form (Reduced) .............
603.
Call Letter Assignment ............................................................................................................
604.
Land Mobile Call Signs ...........................................................................................................
Figure 6-4. User Organization Identifiers ...............................................................................
605.
Station Identification Requirements.........................................................................................
606. thru 699. Reserved ...........................................................................................................................

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56
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57
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CHAPTER 7. HIGH FREQUENCY ASSIGNMENT PROCEDURES
700.

General.....................................................................................................................................
Figure 7-1. Ionospheric Layers Illustrated ..............................................................................
701.
International HF Requirements................................................................................................
702.
National HF Requirements.......................................................................................................
Figure 7-2. NRCS Frequencies ...............................................................................................
703.
HF Engineering........................................................................................................................
704.
Assigned vs. Window Frequency.............................................................................................
705.
Propagation and Circuit Reliability..........................................................................................
706.
Sunspot Numbers .....................................................................................................................
707.
Solar Flare/Storm Reporting Procedures .................................................................................
Figure 7-3. Smoothed Monthly Sunspot Numbers Jan 1749 - Apr 1996................................
708. thru 799. Reserved ...........................................................................................................................

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CHAPTER 8. AIRSPACE EVALUATION
800.
General.....................................................................................................................................
801.
Part 77 ......................................................................................................................................
802.
Title 49, Section 44718 ............................................................................................................
803.
Intranet Obstruction Evaluation/Airport Airspace Analysis (IOE/AAA) Web-based System
804.
Washington Headquarters Reviews .........................................................................................
805.
Electromagnetic Evaluation .....................................................................................................
806.
Airspace Analysis Model (AAM) ............................................................................................
807.
Determinations.........................................................................................................................
808.
Non-Broadcast Evaluations......................................................................................................
809. thru 899. Reserved ..........................................................................................................................
CHAPTER 9. VHF/UHF AIR/GROUND COMMUNICATIONS FREQUENCY ENGINEERING

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900.
Purpose.....................................................................................................................................
901.
Communications Frequency Allocations .................................................................................
902.
Basic Principles of Communications Frequency Engineering.................................................
903.
Special Issues To Be Considered .............................................................................................
904.
Automatic Terminal Information Service (ATIS) Voice Outlet Assignment Criteria.............
905.
AWOS/ASOS Frequency Assignment Criteria .......................................................................
906.
Backup Communications .........................................................................................................
907.
Temporary Assignments ..........................................................................................................
908. thru 999. Reserved ...........................................................................................................................

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86

CHAPTER 10. NAVIGATIONAL AID (NAVAID) FREQUENCY ENGINEERING
1000.
1001.

Purpose.....................................................................................................................................
NAVAID Frequency Allocation ..............................................................................................
Figure 10-1. NAVAID Band Use ...........................................................................................
1002.
Basic Principles of NAVAID Frequency Engineering ............................................................
1003.
NAVAID Frequency Engineering Methods.............................................................................
1004.
Equivalent Signal Ratio (ESR) ................................................................................................
1005.
Expanded Service Volume (ESV)............................................................................................
1006.
Special Issues To Be Considered .............................................................................................
1007. thru 1099. Reserved .......................................................................................................................

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94

CHAPTER 11. LOW/MEDIUM FREQUENCY (L/MF) GROUND NAVIGATIONAL AIDS
1100.
1101.
1102.

Purpose.....................................................................................................................................
General Considerations ............................................................................................................
Frequency Allocation For L/MF Facilities ..............................................................................
Figure 11-1. L/MF NAVAID Frequency Allocations.............................................................
1103.
Engineering Considerations For L/MF Frequency Selection...................................................
Figure 11-2. Estimated Ground Conductivity in the United States.........................................
1104.
Basic Tools...............................................................................................................................
Figure 11-3. Coverage and Interference Prediction Curves....................................................
1105.
Engineering Procedures ...........................................................................................................
1106.
Practical Example ....................................................................................................................
Figure 11-4. Geographic Separation Example ........................................................................
1107.
Airborne Measurements...........................................................................................................
1108. thru 1199. Reserved .......................................................................................................................

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100
101
102
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106
107
107
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108

CHAPTER 12. MICROWAVE DATA/COMMUNICATIONS LINKS FREQUENCY ENGINEERING
1200.
1201.
1202.
1203.
1204.

1205.
1206.

Purpose.....................................................................................................................................
Frequency Bands Available For Radio Links ..........................................................................
Figure 12-1. Bands Currently Used by FAA For Radio Links ................................................
International Coordination Requirements ................................................................................
Technical Standards For Links ................................................................................................
The General Procedure For Microwave Link Intersite Frequency Engineering ......................
Figure 12-2. Typical Parabolic Microwave Antenna Radiation Pattern .................................
Figure 12-3. Power Budget Study For a Microwave Link......................................................
Frequency Engineering For the 932-935 and 941-944 MHz Bands ........................................
Frequency Engineering For the 1710-1850 MHz Band ...........................................................

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1207.

Frequency Engineering For RCL in the 7125-8500 MHz Band ..............................................
Figure 12-4. Example of Tests 4 and 5 Prohibited Zones.......................................................
Figure 12-5. Standard RCL Frequency Family For 7125-8400 MHz.....................................
Figure 12-6. Sample of Frequency Selection, Test 4 and 5 ....................................................
1208.
Frequency Engineering For the LDRCL in the 7125-8500 MHz Band ...................................
1209.
Frequency Engineering For the 14.5000-14.7145 and 15.1365-15.3500 GHz Bands .............
Figure 12-7. Current TML Channelization Plan .....................................................................
1210.
Frequency Engineering for LDRCL For the 21.2-23.6 GHz Band..........................................
Figure 12-8. 21.2-23.6 GHz LDRCL Frequency Assignment Plan ........................................
1211.
Special Path Considerations.....................................................................................................
Figure 12-9. Space Diversity ..................................................................................................
Figure 12-10. Frequency Diversity .........................................................................................
Figure 12-11. Hybrid Frequency/Space Diversity ..................................................................
1212.
Paths With Passive Reflectors..................................................................................................
Figure 12-12. Periscope or Top Reflector Antenna System....................................................
Figure 12-13. Single Billboard Passive Antenna ....................................................................
Figure 12-14. Double Billboard Passive Antenna...................................................................
1213.
Mapping ...................................................................................................................................
1214. thru 1299. Reserved .......................................................................................................................

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CHAPTER 13. RADAR AND AIR TRAFFIC CONTROL RADAR BEACON SYSTEM (ATCRBS)
FREQUENCY ENGINEERING
1300.
1301.
1302.

Policy .......................................................................................................................................
General Assignment Procedures ..............................................................................................
PRR Assignment of ATCRBS .................................................................................................
Figure 13-1. Display Time Exposure For a Radial Flight Showing Ringaround....................
Figure 13-2. Display View of a Real and a False Target ........................................................
1303.
PRR Assignment Process.........................................................................................................
Figure 13-3. Radar and Associated Beacon Capabilities ........................................................
1304.
Frequency Assignment Process in the Radar Frequency Bands ..............................................
Figure 13-4. Radar Frequency-Distance Separation Criteria ..................................................
1305.
Frequency Assignments in the 1215-1390- MHz Band ...........................................................
Figure 13-5. ARSR-1/2 Staggered PRR and PRT Values (High)...........................................
Figure 13-6. ARSR-1/2 Staggered PRR and PRT Values (Low) ...........................................
Figure 13-7. ARSR-3 PRR Capabilities .................................................................................
Figure 13-8. ARSR-3 Average VIP PRTs ..............................................................................
Figure 13-9. ARSR-4 Crystal Oscillator, Stabilized Local Oscillator (STALO) and
Transmit Frequencies ..............................................................................................
1306.
Frequency Assignment Process in the 2700-3000 MHz Band.................................................
Figure 13-10. ASR-7E Primary Radar Frequency Pairs .........................................................
Figure 13-11. ASR-7 and Associated Beacon Staggered PRR and PRT ................................
Figure 13-12. ASR-8 and Associated Beacon Staggered PRR and PRT ................................
Figure 13-13. Typical ASR-8 Receiver Susceptibility Pass Band ..........................................
Figure 13-14. ASR-9 Radar and Beacon PRRs ......................................................................
1307.
Frequency Assignments in the 5600-5650 MHz Band ............................................................
1308.
Frequency Assignments in the 9000-9200 MHz Band ............................................................
1309.
Frequency Assignments in the 15.7-16.2 GHz Band ...............................................................
1310. thru 1399. Reserved .......................................................................................................................
CHAPTER 14. RADIO FREQUENCY INTERFERENCE

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1400.
1401.
1402.
1403.
1404.
1405.

Interference Problems ..............................................................................................................
Interference Reporting .............................................................................................................
Administrative Procedures.......................................................................................................
Internal Procedures ..................................................................................................................
Interference Locating Equipment.............................................................................................
Interference Locating Techniques............................................................................................
Figure 14-1. Image Frequency Relationships .........................................................................
1406.
Direction Finding (Below 1000 MHz).....................................................................................
1407.
Direction Finding (Above 1000 MHz).....................................................................................
Figure 14-2. Radar Interference DF Example.........................................................................
1408.
"Running Rabbit" Interference.................................................................................................
Figure 14-3. Running Rabbits Patterns ...................................................................................
1409.
Electronic Attack (EA).............................................................................................................
1410.
Power Line Interference...........................................................................................................
1411.
Digital Radio Systems..............................................................................................................
1412.
ELT Problems ..........................................................................................................................
1413.
Records of Unusual Previous Cases .......................................................................................
1414. thru 1499. Reserved .......................................................................................................................

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184
184
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184

CHAPTER 15. RADIO FREQUENCY INTERFERENCE MONITORING VANS (RFI VANS)
1500.

Introduction..............................................................................................................................
Figure 15-1. RFIM Functional Block Diagram.......................................................................
1501.
Control and Responsibility ......................................................................................................
1502.
RFI Van Use ............................................................................................................................
1503.
Instrumentation ........................................................................................................................
1504.
RFI Van System Operation ......................................................................................................
Figure 15-2. MCS Canned Measurements Startup Screen......................................................
1505.
Radar and ATCRBS Antenna Pattern Recording ...................................................................
Figure 15-3. Recording Setup and Sample tape......................................................................
Figure 15-4. Examples of Antenna Patterns On CCSA Printouts...........................................
1506.
High-Speed Recorder Calibration and Operation ....................................................................
1507.
Spectrum Analysis ...................................................................................................................
Figure 15-5. Photo of Spectrum From a Spectrum Analyzer..................................................
Figure 15-6. CCSA-Produced Radar Spectrum Plot...............................................................
Figure 15-7. A DC Bucking Voltage System For X-Y Plotters..............................................
Figure 15-8. Sample Spectrum Plot of a Rotating Radar........................................................
1508.
Frequency Measurements ........................................................................................................
1509.
Off-The-Air PRR Measurement...............................................................................................
Figure 15-9. Block Diagram of One Method of Measuring PRR ...........................................
Figure 15-10. Scope Displays For Correct and Incorrect Measurement.................................
1510. thru 1599. Reserved .......................................................................................................................

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200
202
202
203
204
205
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CHAPTER 16. IONIZED AND NONIONIZED RADIATION MEASUREMENTS
1600.
1601.
1602.
1603.

Purpose.....................................................................................................................................
General.....................................................................................................................................
Figure 16-1. Process for Obtaining a Radiation Hazard Measurement...................................
Importance of Measurements...................................................................................................
FMO Participation Limitation..................................................................................................

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1604.
1605.
1606.
1607.
1608.
1609.
1610.
1611.
1612.

Importance of Accuracy...........................................................................................................
Instrument Calibration .............................................................................................................
Availability ..............................................................................................................................
Ramifications ...........................................................................................................................
Measurement Philosophy.........................................................................................................
Measurement Considerations...................................................................................................
Measurement Standards and Procedures..................................................................................
Ionized Radiation Measurement Procedures............................................................................
Non-Ionized Radiation Measurement and Procedures.............................................................
Figure 16-2. Radars Used by FAA With Power Densities >MPE ..........................................
1613.
Measurement Considerations and Reference Data ..................................................................
Figure 16-3. Non-Ionizing MPE – Uncontrolled Environment ..............................................
Figure 16-4. Non-Ionizing MPE – Controlled Environment ..................................................
Figure 16-5. Ionizing TLV......................................................................................................
Figure 16-6a. Letter of Agreement Safety Program Responsibilities .....................................
Figure 16-6b. Letter of Agreement Safety Program Responsibilities.....................................
Figure 16-6c. Letter of Agreement Safety Program Responsibilities .....................................
Figure 16-6d. Letter of Agreement Safety Program Responsibilities.....................................
1614. thru 1699. Reserved. ......................................................................................................................

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232
232

CHAPTER 17. LAND MOBILE AND OTHER FM COMMUNICATIONS SYSTEMS
FREQUENCY ENGINEERING
1700.
1701.
1702.
1703.

General.....................................................................................................................................
Frequency Engineering ............................................................................................................
Systems Basics.........................................................................................................................
C3/NRCS .................................................................................................................................
Figure 17-1. C3/NRCS Communications Frequency Plan .....................................................
Figure 17-2. Example of a Repeater/Base/Portable/Mobile FM System ................................
1704.
RF Voice/Data Link Systems...................................................................................................
1705.
Miscellaneous Radio Links......................................................................................................
1706. Narrow Band Requirements...........................................................................................................
1707. thru 1799. Reserved .......................................................................................................................

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238

CHAPTER 18. ELECTRONIC ATTACK (EA) EVALUATIONS
1800.
1801.
1802.
1803.
1804.
1805.
1806.
1807.
1808.

Page vi

Purpose.....................................................................................................................................
Definitions................................................................................................................................
Applicable Regulations and Documents ..................................................................................
Responsibilities ........................................................................................................................
Analysis of EA Request ...........................................................................................................
Conclusions..............................................................................................................................
Operational Band and Channel Codes .....................................................................................
Figure 18-1. Frequency Band Designations.............................................................................
Frequency Band Correlation ....................................................................................................
Figure 18-2. Frequency Band Correlation ...............................................................................
EA Coordination Requirements by Frequency Band...............................................................
Figure 18-3a. Coordination Level Required by Channel and Frequency.................................
Figure 18-3b. Coordination Level Required by Channel and Frequency ................................
Figure 18-3c. Coordination Level Required by Channel and Frequency.................................

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6050.32B

Figure 18-3d. Coordination Level Required by Channel and Frequency.................................
Figure 18-3e. Coordination Level Required by Channel and Frequency.................................
Figure 18-3f. Coordination Level Required by Channel and Frequency.................................
Figure 18-3g. Coordination Level Required by Channel and Frequency.................................
Figure 18-3h. Coordination Level Required by Channel and Frequency ................................
Figure 18-3i. Coordination Level Required by Channel and Frequency.................................
1809. thru 1899. Reserved .......................................................................................................................

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CHAPTER 19. AUTOMATED ENGINEERING
1900.
Purpose ....................................................................................................................................
1901.
Automated Frequency Manager (AFM) ..................................................................................
1902.
AFM Agenda System...............................................................................................................
1903.
Airspace Analysis Model (AAM) ............................................................................................
1904.
RFI and RADHAZ Data Base..................................................................................................
1905.
Expanded Service Volume (ESV) Management System (ESVMS) ........................................
1906.
Radio Coverage Analysis System (RCAS) .............................................................................
1907.
Overview of the AFM ..............................................................................................................
1908.
AFM Agenda System...............................................................................................................
1909.
Airspace Analysis Model (AAM) ............................................................................................
1910.
RFI and RADHAZ Support .....................................................................................................
1911.
ESV ..........................................................................................................................................
1912. thru 1999. Reserved .......................................................................................................................

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267

APPENDIX 1. AIRSPACE EVALUATION
SECTION 1. BACKGROUND AND PROCEDURES
1.
2.
3.

4.
5.
6.

7.
8.
9.
10.

11.
12.

Introduction..............................................................................................................................
Background ..............................................................................................................................
FM Broadcast Tolerances ........................................................................................................
Figure 1. FM Channels and Center Frequencies.....................................................................
Figure 2. Spurious Emission Level of an FM Broadcast Transmitter
on 107.9 MHz ...........................................................................................................
TV Broadcast Tolerances.........................................................................................................
AM and Other Non-Broadcast Station Standards ....................................................................
Standard FPSVs For FAA Facilities ........................................................................................
Figure 3. TV Channels and Associated Frequencies ..............................................................
Figure 4. Idealized Standard TV Channel Spectrum ..............................................................
Evaluation Procedure Outline ..................................................................................................
Data Assembly .........................................................................................................................
Figure 5. Evaluation Procedure Outline Chart........................................................................
Intermod Study.........................................................................................................................
Ground Facilities......................................................................................................................
Figure 6. Typical FAA VHF and UHF RCF Ground Antenna Gain Vs. Frequency Plots .....
Figure 7. Example of Plot For Calculating Slant Range .........................................................
Airborne Receivers ..................................................................................................................
Samples ....................................................................................................................................
Figure 8. Relative Gain of Airborne COMM and NAV Antennas .........................................
Figure 9a. FAA Form 7460-1, Notice of Proposed Construction or Alteration......................
Figure 9b. Addenda to FAA Form 74670-1 Notice of Proposed Construction or

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Alteration ............................................................................................................... 17
Figures 10. thru 14. Reserved ................................................................................................. 17
13. thru 16. Reserved ............................................................................................................................... 17
SECTION 2. ENGINEERING PROCEDURES FOR OE CASES FOR FM BROADCAST AND
ILS/VOR
17.
18.

Purpose.....................................................................................................................................
OE Case Evaluation Procedure ................................................................................................
Figure 15. Sample OE Case Worksheet For FM.....................................................................
Figure 16. Sample PC CIRCLE Report ..................................................................................
Figure 17. Sample GROUND.WK1 Report............................................................................
19.
Example of AAM Program For FM/ILS..................................................................................
Figure 18. AAM Program Sample Search Plot.......................................................................
Figure 19a. AAM Program Sample RFI.PRT Printout ...........................................................
Figure 19b. AAM Program Sample RFI.PRT Printout (continued) .......................................
Figure 20. AAM Sample Plot of Predicted RFI - Horizontal - KHTN ...................................
Figure 21. AAM Sample Plot of Predicted RFI - Horizontal - PROP ....................................
Figure 22. AAM Sample Plot of Predicted RFI - Vertical - KHTN .......................................
Figure 23. AAM Sample Plot of Predicted RFI - Vertical - PROP ........................................
Figures 24. thru 30. Reserved ..................................................................................................
20. thru 24. Reserved ...............................................................................................................................

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24
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27
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29
30
31
32
33
34
35
35
35

SECTION 3. ENGINEERING PROCEDURES FOR OBSTRUCTION EVALUATION (OE)
CASES OF NON-FM BROADCAST
25.
26.
27.

Status........................................................................................................................................
Non-FM BC Study Procedures ................................................................................................
A Non-FM BC Example ..........................................................................................................
Figure 31. Sample Non-FM Worksheet ..................................................................................
Figure 32. Paragraph 26 a. (1) Example GROUND.WK1 Printout........................................
Figure 33. Paragraph 26 a. (3) Example IM Program Configuration .....................................
Figure 34. Paragraph 26 a. (4) Example of IM Program Printout...........................................

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45

APPENDIX 2. TECHNICAL DATA FOR VHF/UHF COMMUNICATIONS FREQUENCY
ENGINEERING

1.
2.

3.
4.

5.

Page viii

Figure 1. VHF Allocations - 118-137 MHz ............................................................................
VHF/UHF Frequency Engineering ..........................................................................................
FPSV ........................................................................................................................................
Figure 2. FPSVs ......................................................................................................................
Figure 3. High Altitude Enroute and Local Control FPSVs to Approximate Scale and As
Normally Shown Pictorially....................................................................................
Figure 4. Example of En Route Dimensions...........................................................................
Figure 5. Typical Terminal FPSV Dimensions.......................................................................
ATC Assignment Criteria ........................................................................................................
RLOS .......................................................................................................................................
Figure 6. Comparison of Distance to Horizon From the Same Altitude Between
Actual and Hypothetical 4/3 Earth Radius..............................................................
Intersite Frequency Engineering Procedures ...........................................................................
Figure 7. Cochannel Configuration For Undesired/Desired Distance Ratio...........................

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6050.32B

Intersite Cochannel Analysis By the Table Method ................................................................
Figure 8. Mileage Separation Tables For Usual FPSVs .........................................................
Adjacent Channel Considerations............................................................................................
Figure 9. Adjacent Channel Vertical Separation.....................................................................
Figure 10. 1st Adjacent Channel Separation Required ...........................................................
Intersite Cochannel Analysis ...................................................................................................
Figure 11. Cochannel Analysis by Calculation.......................................................................
Figure 12. Comparison of D/U and Distance Between Facilities With One Tailored
Service Volume.....................................................................................................
Cosite Interference Considerations ..........................................................................................
Limits of Coverage Charts .......................................................................................................
Figure 13. Limits of Coverage - VHF - Antenna Height = 10' ...............................................
Figure 14. Limits of Coverage - VHF - Antenna Height = 25' ...............................................
Figure 15. Limits of Coverage - VHF - Antenna Height = 50' ...............................................
Figure 16. Limits of Coverage - VHF - Antenna Height = 75' ...............................................
Figure 17. Limits of Coverage - VHF - Antenna Height = 100' .............................................
Figure 18. Limits of Coverage - VHF - Antenna Height = 150' .............................................
Figure 19. Limits of Coverage - UHF - Antenna Height = 10' ...............................................
Figure 20. Limits of Coverage - UHF - Antenna Height = 20' ...............................................
Figure 21. Limits of Coverage - UHF - Antenna Height = 30' ...............................................
Figure 22. Limits of Coverage - UHF - Antenna Height = 40' ...............................................
Figure 23. Limits of Coverage - UHF - Antenna Height = 50' ...............................................
Figure 24. Limits of Coverage - UHF - Antenna Height = 75' ...............................................

8
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10
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19
20
21
22
23
24

APPENDIX 3. NAVAID FREQUENCY ENGINEERING DATA AND PROCEDURES
SECTION 1. FREQUENCY/CHANNELIZATION CHART
Figure 1a.
Figure 1b.
Figure 1c.
Figure 1d.
Figure 1e.
Figure 1f.

Channel and Frequency Pairing With DME Pulse Time/Codes ............................
Channel and Frequency Pairing With DME Pulse Time/Codes (cont'd)...............
Channel and Frequency Pairing With DME Pulse Time/Codes (cont'd)...............
Channel and Frequency Pairing With DME Pulse Time/Codes (cont'd)...............
Channel and Frequency Pairing With DME Pulse Time/Codes (cont'd)...............
Channel and Frequency Pairing With DME Pulse Time/Codes (cont'd) ...............

1
2
3
4
5
6

SECTION 2. VOR AND DME/TACAN FREQUENCY ENGINEERING
1.
2.
3.
4.
5.
6.
7.

Frequency Engineering ............................................................................................................
Figure 2. FPSV's For VOR, DME/TACAN............................................................................
Frequency Engineering Procedures .........................................................................................
Intersite Analysis By the Table Method For VOR...................................................................
Intersite Analysis By the Table Method For DME/TACAN ...................................................
DME/TACAN Required Separation ........................................................................................
Use of the Larger Separation Requirement..............................................................................
Permissible Use of Tables........................................................................................................
Figure 3. VOR/VOR Cochannel Separations..........................................................................
Figure 4. VOR/VOR Interim 1st Adjacent Channel -50 kHz- Separations ............................
Figure 5. VOR/VOR Final 1st Adjacent Channel -50 kHz- Separations................................

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Figure 6. VOR/VOR 2nd Adjacent Channel -100 kHz- Separations......................................
Figure 7. VOR/LOC Interim 1st Adjacent Channel -50 kHz- separations .............................
Figure 8. VOR/LOC Final 1st Adjacent Channel -50 kHz- Separations ................................
Figure 9. DME/TACAN Cochannel Separations....................................................................
Figure 10. DME/TACAN 1st Adjacent Channel Separations ................................................
8.
Intersite Analysis By the Calculation Method .........................................................................
Figure 11. VOR, DME and TACAN Antenna Gain Figures ..................................................
9.
Sample of Cochannel Intersite Analysis By the Calculation Method......................................
Figure 12. VORTAC Cochannel Intersite Analysis Plot ........................................................
10.
Intersite Analysis of Adjacent Channels ..................................................................................
Figure 13. VORTAC 2nd Adjacent Channel Intersite Analysis .............................................
11.
Differences In Site Elevation ...................................................................................................
12. thru 13. Reserved ...............................................................................................................................
Figure 14. VOR Facility Separation Curves For ESR = +14 dB ............................................
Figure 15. VOR Facility Separation Curves For ESR = +17 dB ............................................
Figure 16. VOR Facility Separation Curves For ESR = +20 dB ............................................
Figure 17. VOR Facility Separation Curves For ESR = +23 dB ............................................
Figure 18. VOR Facility Separation Curves For ESR = +26 dB ............................................
Figure 19. VOR Facility Separation Curves For ESR = +29 dB ............................................
Figure 20. VOR Facility Separation Curves For ESR = +32 dB ............................................
Figure 21. ESR Ratio - VOR/VOR @ 1,000'..........................................................................
Figure 22. ESR Ratio - VOR/VOR @ 5,000'..........................................................................
Figure 23. ESR Ratio - VOR/VOR @ 10,000'........................................................................
Figure 24. ESR Ratio - VOR/VOR @ 15,000'........................................................................
Figure 25. ESR Ratio - VOR/VOR @ 18,000'........................................................................
Figure 26. ESR Ratio - VOR/VOR @ 20,000'........................................................................
Figure 27. ESR Ratio - VOR/VOR @ 30.000'........................................................................
Figure 28. ESR Ratio - VOR/VOR @ 40,000'........................................................................
Figure 29. ESR Ratio - VOR/VOR @ 50,000'........................................................................
Figure 30. ESR Ratio - VOR/LOC. VOR Is Desired @ 1,000' .............................................
Figure 31. ESR Ratio - VOR/LOC. VOR Is Desired @ 5,000' .............................................
Figure 32. ESR Ratio - VOR/LOC. VOR Is Desired @ 10,000' ...........................................
Figure 33. ESR Ratio - VOR/LOC. VOR Is Desired @ 15,000' .........................................
Figure 34. ESR Ratio - VOR/LOC. VOR Is Desired @ 18,000' ...........................................
Figure 35. ESR Ratio - VOR/LOC. VOR Is Desired @ 20,000' ...........................................
Figure 36. ESR Ratio - VOR/LOC. VOR Is Desired @ 30,000' ...........................................
Figure 37. ESR Ratio - VOR/LOC. VOR Is Desired @ 40,000' ...........................................
Figure 38. ESR Ratio - VOR/LOC. VOR Is Desired @ 50,000' ...........................................
Figure 39. DME/TACAN Facility Separation Curves For ESR = +2 dB ...............................
Figure 40. DME/TACAN Facility Separation Curves For ESR = +5 dB ...............................
Figure 41. DME/TACAN Facility Separation Curves For ESR = +8 dB ...............................
Figure 42. DME/TACAN Facility Separation Curves For ESR = +11 dB .............................
Figure 43. DME/TACAN Facility Separation Curves For ESR = +14 dB .............................
Figure 44. DME/TACAN Facility Separation Curves For ESR = +17 dB .............................
Figure 45. DME/TACAN Facility Separation Curves For ESR = +20 dB .............................
Figure 46 ESR Ratio - DME/TACAN to DME/TACAN @ 1,000' .......................................
Figure 47. ESR Ratio - DME/TACAN to DME/TACAN @ 18,000' .....................................
Figures 48 thru 60. Reserved ..................................................................................................

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SECTION 3. ILS AND DME FREQUENCY ENGINEERING
14.

Frequency Engineering For ILS and DME ..............................................................................
Figure 61. LOC Front Course FPSV.......................................................................................
Figure 62. LOC Back Course FPSVs......................................................................................
Figure 63. FPSV For ILS GS ..................................................................................................
Figure 64. FPSVs For DMEs Associated With ILS................................................................
15.
Frequency Engineering Procedures .........................................................................................
16.
Intersite Analysis By the Table Method For ILS LOCs ..........................................................
17.
Intersite Analysis By the Table Method For ILS-DME...........................................................
18.
ILS-DME Required Separation................................................................................................
19.
Use of The Larger Separation Requirement.............................................................................
20.
ILS Associated DME Adjacent Channel Undesired ................................................................
Figure 65. LOC Separation Distances Defined.......................................................................
Figure 66. LOC/LOC Cochannel Radii Separations...............................................................
Figure 67. LOC/LOC 1st Adjacent Channel - 50 kHz - Separations - Interim.......................
Figure 68. LOC/LOC 1st Adjacent Channel - 50 kHz - Separations - Final ..........................
Figure 69. LOC/VOR 1st Adjacent Channel - 50 kHz - Separations - Interim ......................
Figure 70. LOC/VOR 1st Adjacent Channel - 50 kHz - Separations - Final ..........................
Figure 71. LOC/VOR 2nd Adjacent Channel - 100 kHz - Separations ..................................
Figure 72. ILS-DME Cochannel Separations .........................................................................
Figure 73. ILS-DME 1st Adjacent Channel Separations ........................................................
21.
Intersite analysis of ILS by Calculation Method......................................................................
Figure 74. LOC Antenna Gains and Graph Reference ...........................................................
Figure 75. Critical Point Separation Distance.........................................................................
22.
Special Consideration For ILSs on Opposite Ends of a Runway.............................................
Figure 76. LOC Intersite Analysis By Calculation .................................................................
23.
LOC Calculation Example .......................................................................................................
Figure 77. DME and TACAN Antenna Gain Figures.............................................................
Figure 78. DME Intersite Analysis by Calculation.................................................................
24
DME Calculation Example ......................................................................................................
25.
ILS Markers .............................................................................................................................
26. thru 30. Reserved ................................................................................................................................
Figure 79.
Figure 80.
Figure 81.
Figure 82.
Figure 83.
Figure 84.
Figure 85.
Figure 86.
Figure 87.
Figure 88.
Figure 89.
Figure 90.
Figure 91.
Figure 92.
Figure 93.
Figure 94.
Figure 95.

LOC Facility Separation Curves For ESR = -52 dB..............................................
LOC Facility Separation Curves For ESR = -49 dB..............................................
LOC Facility Separation Curves For ESR = -46 dB..............................................
LOC Facility Separation Curves For ESR = -43 dB..............................................
LOC Facility Separation Curves For ESR = -40 dB..............................................
LOC Facility Separation Curves For ESR = -37 dB..............................................
LOC Facility Separation Curves For ESR = -34 dB..............................................
LOC Facility Separation Curves For ESR = -31 dB..............................................
LOC Facility Separation Curves For ESR = -28 dB..............................................
LOC Facility Separation Curves For ESR = -25 dB..............................................
LOC Facility Separation Curves For ESR = -22 dB..............................................
LOC Facility Separation Curves For ESR = -19 dB..............................................
LOC Facility Separation Curves For ESR = -16 dB..............................................
LOC Facility Separation Curves For ESR = -13 dB..............................................
LOC Facility Separation Curves For ESR = -10 dB..............................................
LOC Facility Separation Curves For ESR = -7 dB................................................
LOC Facility Separation Curves For ESR = -4 dB................................................

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Figure 96. LOC Facility Separation Curves For ESR = -1 dB................................................
Figure 97. LOC Facility Separation Curves For ESR = +2 dB...............................................
Figure 98. LOC Facility Separation Curves For ESR = +5 dB...............................................
Figure 99. LOC Facility Separation Curves For ESR = +8 dB...............................................
Figure 100. LOC Facility Separation Curves For ESR = +11 dB...........................................
Figure 101. LOC Facility Separation Curves For ESR = +14 dB...........................................
Figure 102. LOC Facility Separation Curves For ESR = +17 dB...........................................
Figure 103. LOC Facility Separation Curves For ESR = +20 dB...........................................
Figure 104. LOC Facility Separation Curves For ESR = +23 dB...........................................
Figure 105. LOC Facility Separation Curves For ESR = +26 dB...........................................
Figure 106. LOC Facility Separation Curves For ESR = +29 dB...........................................
Figure 107. LOC Facility Separation Curves For ESR = +32 dB...........................................
Figure 108. ESR ratio - LOC/VOR. LOC Is Desired Facility @ 1,000' ................................
Figure 109. ESR ratio - LOC/VOR. LOC Is Desired Facility @ 4,500' ................................
Figure 110. ESR ratio - LOC/VOR. LOC Is Desired Facility @ 6,250' ................................
Figure 111. LOC LPD (14-10) and (20-10) Antenna Radiation Patterns ...............................
Figure 112. LOC V Ring Antenna Radiation Pattern .............................................................
Figure 113. LOC Travelling Wave - 8 el Antenna Radiation Pattern.....................................
Figure 114. LOC Travelling Wave - 14 el Antenna Radiation Pattern...................................
Figure 115. LOC LPD 8 El Antenna Radiation Pattern..........................................................
Figure 116. LOC LPD 14 el Antenna Radiation Pattern ........................................................
Figure 117. LOC LPD GRN-29 Antenna Radiation Pattern...................................................
Figure 118. LOC Travelling Wave 14/6 Antenna Radiation Pattern.....................................
Figure 119. LOC Parabolic Narrow Antenna Radiation Pattern.............................................
Figure 120. LOC Parabolic Wide Antenna Radiation Pattern ................................................
Figure 121. LOC MRN-7 Dipole Antenna Radiation Pattern.................................................
Figure 122. LOC Redlich LPD (14-10) Antenna Radiation Pattern .......................................
Figure 123. LOC Mod. V Ring Antenna Radiation Pattern....................................................
Figure 124. LOC 1201 Dipole Antenna Radiation Pattern .....................................................
Figure 125. LOC 1203 Dipole Antenna Radiation Pattern .....................................................
Figure 126. LOC 1204 Dipole Antenna Radiation Pattern .....................................................
Figure 127. LOC 1261 Dipole Antenna Radiation Pattern .....................................................
Figure 128. LOC STAN37 Dipole Antenna Radiation Pattern...............................................
Figure 129. LOC Twin Tee Antenna Radiation Pattern .........................................................
Figure 130. LOC Standard 14 el V-Ring Antenna Radiation Pattern.....................................
Figure 131. DME Unidirectional Antenna Radiation Pattern .................................................
Figure 132. DME Bi-directional Antenna Radiation Pattern..................................................
Figures 133. thru 140. Reserved .............................................................................................

96
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98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
132

SECTION 4. CHECKING AN FAA PROPOSED ILS FREQUENCY WITH THE AAM
31.
ILS Frequency Study Procedure ..............................................................................................
32.
Step By Step Study Procedure .................................................................................................
33.
Study Results ...........................................................................................................................
34. thru 40. Reserved ..............................................................................................................................
Figure 141a. AAM Printout Page 1 ........................................................................................
Figure 141b. AAM Printout Page 2 .......................................................................................
Figure 142a. AAM Printout Page 1 .......................................................................................
Figure 142b. AAM Printout Page 2 ........................................................................................
Figure 142c. AAM Printout Page 3 ........................................................................................
Figure 142d. AAM Printout Page 4 ........................................................................................

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Figure 142e. AAM Printout Page 5 ........................................................................................ 147
Figure 142f. AAM Printout Page 6 ......................................................................................... 148
Figures 143. thru 154. Reserved ............................................................................................. 148
SECTION 5. NAVAID RECEIVER TEST FACILITIES FREQUENCY ENGINEERING
41.
42.
43.

Frequency Engineering For VOT Test Facilities .....................................................................
Frequency Engineering For Secondary Receiver Test Facilities .............................................
VOT Frequency Engineering By the Table Method ................................................................
Figure 155. Cochannel Separation of VOT and Operating VORs..........................................
Figure 156. LOC Radii Defined, Cochannel...........................................................................
Figure 157. Cochannel Separation of ILS and ILS-Test.........................................................
44.
VOT Frequency Engineering By the Calculation Method.......................................................
Figure 158. VOR Versus Cochannel VOT By Calculation ....................................................
45. thru 50. Reserved ................................................................................................................................
Figure 159. VOR/VOT Cochannel Facility Separation Curves +14 dbW..............................
Figure 160. VOR/VOT Cochannel Facility Separation Curves +17 dBW .............................
Figure 161. VOR/VOT Cochannel Facility Separation Curves +20 dBW .............................
Figures 162. thru 164. Reserved ..............................................................................................

151
151
152
152
152
153
153
153
154
155
156
157
157

SECTION 6. ESV FREQUENCY ENGINEERING
51.
52.

Frequency Engineering For ESV .............................................................................................
Minimum Power Available Requirements...............................................................................
Figure 165. Power Available Requirements For NAVAID Receivers ...................................
53.
An Example Of Power Availability .........................................................................................
Figure 166. Power Available - VOR........................................................................................
54.
The Interrelationship Of the VOR and DME/TACAN ESV ...................................................
55.
VOR/DME/TACAN ESV Determination Procedure...............................................................
Figure 167. Critical Point Measurement of an ESV ...............................................................
Figure 168. Example of VOR ESV By Calculation................................................................
56.
ILS-DME ESV Determination Procedure................................................................................
57.
ESV Special Considerations ....................................................................................................
Figure 169. Sample ESV Record Format................................................................................
58. thru 62. Reserved ...............................................................................................................................
Figure 170. Power Available Curves - 100 W - VOR 0-50 nmi.............................................
Figure 171. Power Available Curves - 100 W - VOR 0-220 nmi...........................................
Figure 172. Power Available Curves - 5 kW - TACAN 0-50 nmi..........................................
Figure 173. Power Available Curves - 5 kW - TACAN 0-220 nmi........................................
Figure 174. Power Available Curves - 100 W - Cardion DME 0-50 nmi...............................
Figure 175. Power Available Curves - 100 W - Cardion DME 0-220 nmi.............................
Figure 176. Power Available Curves - 100 W - Montek DME 0-50 nmi ...............................
Figure 177. Power Available Curves - 100 W - Montek DME 0-220 nmi .............................
Figure 178. Power Available Curves - 1 kW - Cardion DME 0-50 nmi.................................
Figure 179. Power Available Curves - 1 kW - Cardion DME 0-220- nmi .............................
Figure 180. Power Available Curves - 1 kW - Montek DME 0-50 nmi .................................
Figure 181. Power Available Curves - 1 kW - Montek DME 0-220 nmi ...............................
Figure 182. Power Available Curves - 100W - FA10153 DME 0-50 nmi .............................
Figure 183. Power Available Curves - 100W - FA10153 DME 0-220 nmi ...........................

165
165
165
165
166
166
166
167
167
168
168
169
169
170
171
172
173
174
175
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Figure 184. Power Available Curves - 100W - dBS5100A DME 0-50 nmi........................... 184
Figure 185. Power Available Curves - 100W - dBS5100A DME 0-220 nmi......................... 185
Figure 186. Reserved .............................................................................................................. 185
SECTION 7. MLS AND DME/P FREQUENCY ENGINEERING
63.

Frequency Engineering For MLS and DME/P.........................................................................
Figure 187. FPSV For MLS Approach Azimuth/Data Coverage ...........................................
Figure 188. FPSV For MLS Approach Elevation Coverage...................................................
Figure 189. FPSV For MLS Back Azimuth/Data Coverage...................................................
Figure 190. FPSV For MLS DME/P.......................................................................................
Figure 191. Interim MLS Cochannel and Adj. Channel Separation D/U Values ...................
Figure 192. DME/P Cochannel and Adjacent Channel Separation D/U Values.....................
64.
Frequency Engineering Procedures .........................................................................................
65.
MLS Intersite Analysis By Table Method ...............................................................................
Figure 193. Interim MLS Cochannel Separation Distance .....................................................
66.
DME/P Intersite Analysis By Table Method ...........................................................................
Figure 194. MLS DME/P Assignment Criteria.......................................................................
67. thru 70. Reserved. ...............................................................................................................................
Figures 195 thru 200 Reserved. ...............................................................................................

197
197
198
199
200
201
201
202
202
202
203
203
203
203

SECTION 8. LOCAL AREA AUGMENTATION SYSTEM FREQUENCY ENGINEERING
71.
72.
73.

Frequency Engineering ............................................................................................................
Figure 201. LAAS/LAAS/VOR Separation Criteria ..............................................................
Frequency Engineering Procedures .........................................................................................
Intersite Analysis by the Table Method for LAAS ..................................................................
Figure 202. LAAS/LAAS Cochannel Separations..................................................................
Figure 203. LAAS/VOR Interim 1st Adjacent Channel 50 kHz Separations..........................
Figure 204. LAAS/VOR Final 1st Adjacent Channel 50 kHz Separations .............................

211
211
212
212
212
213
213

APPENDIX 4. TECHNICAL DATA FOR VHF/UHF/SHF LINKS
Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Figure 6.
Figure 7.
Figure 8.
Figure 9.

Technical Parameters, ATT FR8 RCL ....................................................................
FR8 Interference Susceptibility Curves...................................................................
Technical Parameters, TML ....................................................................................
TML Interference Susceptibility Curves .................................................................
FAA Low Density RCL Path Design Criteria .........................................................
MDR 6X08 Specifications.......................................................................................
Nomograph For Free Space Propagation Loss ........................................................
Nomograph For Parabolic Antenna Gain ................................................................
Available Computer Analysis Models.....................................................................

1
2
3
4
5
6
7
8
9

APPENDIX 5. GLOSSARY (9 pages)........................................................................................................

1

APPENDIX 6. EMISSION DESIGNATORS (2 pages)............................................................................

1

APPENDIX 7. FORMULAS USED IN THIS ORDER (1 page) .............................................................

1

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APPENDIX 8. SOME PROCEDURES FOR RADAR ANTENNA VERTICAL PATTERN
MEASUREMENT BY SOLAR MEANS
1.
2.
3.

4.
5.

General.....................................................................................................................................
Two Methods of Solar Measurements .....................................................................................
Manual Measurement...............................................................................................................
Figure 1. Block Diagram of Manual Measurement ................................................................
Figure 2. Sample Recording With Calibration, Time and Amplitude Markings ....................
Figure 3. Sample Plot of Analyzed Recording........................................................................
Automated Measurement .........................................................................................................
Figure 4. Automated Radar Antenna Solar Measurement Block Diagram.............................
Documentation.........................................................................................................................

1
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6050.32B

CHAPTER 1. GENERAL
1. PURPOSE. This order establishes and describes the spectrum management function in the Federal Aviation
Administration (FAA) and delineates policies and procedures for the allocation and engineering of this scarce
resource.
2. DISTRIBUTION. This order is distributed to the director level in headquarters, the William J. Hughes
Technical Center, and the Mike Monroney Aeronautical Center; to division level in the Technical Operations,
Enroute and Oceanic, and Terminal Service Areas; and to all field offices with a supervisory distribution.
3. CANCELLATION. This order cancels and supersedes Order 6050.32A, dated May 1, 1998.
4. EXPLANATION OF CHANGES.
a. Many chapters and appendices have been updated and expanded to reflect, in particular, current FAA
policy and ensure appropriate guidance in addressing the broad range of issues related to aeronautical radio
frequency spectrum engineering and usage. A number of the more significant changes are highlighted in the
following items.
b. Chapter 8 has been updated with new guidance on Obstruction Evaluation notification requirements
and automation tools.
c. Chapter 9 has been updated to include guidance regarding the Sustaining Backup Emergency
Communications (BUEC) systems, as well as guidance on temporary frequency assignments for, in particular, Air
Shows and Fire Fighting.
d. Chapters 14 and 15 have been updated to reflect the current automation and analysis tools to better
detect, document, and resolve radio frequency interference (RFI) cases.
e. Chapter 16 has been expanded to address guidelines for radiation hazard measurements and related
procedures, as a result of the cancellation on April 22, 1999, of FAA Order 3910.3A, Radiation Health Hazards
and Protection, dated October 19, 1983.
f. Chapter 17 has been updated to reflect new frequency allotments, a new channel plan, additional
fixed communications systems, and new transmit emission standards.
g. Chapter 19 has been renamed to Automated Engineering (previously Automated Frequency Manager
(AFM)) and expanded to more broadly reflect the increased use of automation in satisfying spectrum engineering
and analysis functions.
h. Appendix 2 has been updated to reflect new policy changes to the engineering criteria and frequency
uses that have been developed for the Air-Ground VHF Communications frequency bands.
i. A new Appendix 3, Section 8 has been added to address Local Area Augmentation System (LAAS)
frequency engineering.

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5. FORMS. The following forms may be obtained from the FAA Depot through normal supply channels (see the
latest edition of Order 1330.3):
a. FAA Form 6050-1, Facility Transmitting Authorization, NSN 0052-00-688-6001;
unit of issue: sheet.
b. FAA Form 6050-2, Transmitter Identification and Operation Authorization,
NSN 0052-00-694-9000; unit of issue: sheet.
c. FAA Form 6050-4, Expanded Service Volume Request, NSN 0052-00-845-6000,
unit of issue: set.

6. thru 199. RESERVED.

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6050.32B

CHAPTER 2. THE RADIO FREQUENCY (RF) SPECTRUM
200. RF SPECTRUM. The RF or electromagnetic spectrum is a finite natural resource used by every country
in the world. The internationally used frequency unit is the "Hertz," named for an early pioneer in spectrum
research. The Hertz (Hz) is defined as one cycle per second (cps), with further prefixes from the Greek to indicate
multipliers. One thousand Hz is defined as 1 kiloHertz (kHz), one million Hz is 1 MegaHertz (MHz) and one
billion Hz is 1 GigaHertz (GHz), etc. The electromagnetic spectrum emissions of interest, which are called the
radio frequency bands, begin at 10 kHz and end at 300 GHz. Above 300 GHz are visible light, X-rays, gamma
rays and other electromagnetic phenomena.
201.

MAKEUP OF THE SPECTRUM.

a. By international agreement, the radio spectrum is divided into major bands in frequency decimal
multiples of three. The radio spectrum was originally defined in terms of metric system wavelengths. The three
multiple came into use because the speed of light and electromagnetic propagation is about 300 million meters per
second in free space. The length of a full wavelength is 3 x 108 meters per second (m/s) divided by the frequency
in Hz. Noting this frequency/wavelength relationship, a frequency of 3 MHz calculates to 100 meters for a full
wavelength.
b. These decade bands of frequencies have international defined names, using common terms. For
example, the band of frequencies from 30 kHz to 300 kHz is named Low Frequency (LF) and 300 kHz to 3 MHz
is designated Medium Frequency (MF). The bands continue from LF and MF to High (HF), Very High (VHF),
Ultra High (UHF) and Super High (SHF) with continuations above and below these ranges. The frequency band
names are divided by decimal breaks defined in wavelengths; e.g., 300 kHz is 1000 meters, 3,000 kHz is 100
meters, etc. The United States uses frequency in Hz as the unit for specific administrative tracking of spectrum
assignments.
202.

SPECTRUM LIMITATION CONSIDERATIONS.

a. Aeronautical safety systems shall be accommodated in aeronautical spectrum which is specifically
allocated for the service being satisfied and which is used exclusively by aeronautical safety systems. This
ensures protection from non-aeronautical users so that the high levels of integrity and availability required by civil
aviation can be met.
b. Congestion within the available spectrum is not the only factor limiting its use. First and primarily are the
international agreements and treaties to which the United States is a signatory. These matters are covered in detail
in chapter 3. Second is the necessary frequency bandwidth required to convey the transmitted information. Other
considerations are spectrum efficiency, propagation, capacity, equipment, economics and interference.
c. International agreements divide the spectrum into bands for either exclusive or shared use by a specific
service. The aeronautical service is just one of many defined services which have allocations in specific and
limited bands. The aeronautical mobile (R) and aeronautical radionavigation services are directly related to safety
of life and property in the air. Therefore, most such bands are allocated exclusively worldwide, where the
operations deal directly with operation of aircraft. Ancillary aeronautical services, such as fixed microwave
point-to-point systems, are shared with other users.
d. Aeronautical service frequency bands are distributed throughout the radio spectrum.

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e. Propagation characteristics play a major role in the limitations on use of the assigned spectrum. LF and
MF operate primarily on groundwave and can cover hundreds or thousands of miles day or night quite reliably.
HF uses the ionosphere to reflect signals for great distances around the earth, but are greatly affected by
day-to-night and seasonal changes. Beginning around the VHF band, "radio line-of-sight" (RLOS) propagation
conditions exist. RLOS extends the visual line-of-sight distance by virtue of the phenomenon that radio waves
"bend" near large objects such as the earth. See the Appendix 2 for details. At VHF frequencies and above, radio
signals travel in a straight line, modified by the bending of the path due to the RLOS effect. Large metallic or
electrically-conducting objects such as steel buildings will attenuate, retard or deflect the signal's path. Signal
reflection occurs under some conditions, but it is not considered as a reliable path except where the reflector is a
part of the planned path.
f. Technical equipment, particularly its changing style as the state-of-the-art progresses, places severe
restrictions on the spectrum engineer in engineering frequencies. For example, the original channel assignments
in the VHF communications band were every 200 kHz on the odd frequencies between 118.1 and 126.9 MHz,
e.g., 118.1, 118.3, etc. Congestion required narrowing the channels to 100 kHz so frequencies could then be
assigned on every decimal frequency, 118.1. 118.2, etc. While technically the number of channels doubled per
MHz, all could not be used simply. There were still thousands of 200 kHz channeled transceivers in use. It took
years of education and finally agency orders to permit the spectrum engineer full use of the 100 kHz channels.
Subsequent congestion brought further reduction to 50 kHz, then currently to 25 kHz channels, yet protection for
a "grandfather" period for older operating equipment always must be given.
g. Economics also has a very big impact on the spectrum engineer's ability to engineer frequencies. As
described in subparagraph e, even though revised frequency engineering allocations establishes additional
channels, they may not necessarily be able to be used. Whether airline or a private aircraft owner, the ability to
meet all the requirements for new equipment to meet technological advances is limited by the ability to pay for it.
h. Interference can be defined as any undesired signal or energy which prohibits or degrades the normal
reception of the desired signal. It can be divided into three broad categories; adjacent channel or cochannel radio
sources, man-made electrical noise, and natural solar and atmospheric noise.
(1) Adjacent channel or cochannel interference is caused by undesired radio transmissions which the
receiving device is unable to separate from the desired transmission. Adjacent channel interference is caused by
emitters using nearby channels and occurs because of the inability of the pass band of the victim receiver to
discriminate against near-frequency signals. Cochannel interference is caused by emitters using the same
frequency which are too close geographically. Proven radio frequency spectrum engineering criteria are used by
the spectrum engineer to establish an interference-free assigned frequency.
(2) Man-made interference is the most common and most insidious. The sources are limitless, from
"plastic welders," to electric motors of all types, to the incidental and spurious radiation of other transmitters. In
addition, there are cases of intentional interference, so-called "bogus" or "phantom" controllers, which FAA must
investigate (and prosecute) with the help of other agencies.
(3) Solar and atmospheric noise are outside human control. The sun emits an enormous amount of
energy throughout the spectrum, varying in day-to-day intensity and frequency. In frequencies through VHF,
solar radiation and atmospheric noise such as lightning and precipitation static are significant. From UHF and
above, noise generated internally in equipment is the controlling factor.

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(4) Intermodulation is defined as the presence of unwanted signals at the output of a less-than-ideal
amplifier resulting from modulation of the components of a complex waveform by each other in a nonlinear
system. When two or more signals are applied to a nonlinear device, a mixing or intermodulation action results
and signals are produced, having frequencies equal to the sums and differences of the original input signals,
among other signals. An otherwise linear device may be driven into nonlinear operation in the presence of strong
external signal levels. Although most cases occur in receivers, problems do occur when two or more transmitters
start radiating a mixed frequency created when a mix occurs in their final amplifiers, particularly when their
antennas are in close proximity. Detailed information will be found in Appendix 2.
(5) Desensitization is the deterioration of reception of a desired signal due to the proximity of a very
strong signal. The source of the problem could be of any frequency theoretically, but in practice, communications
frequencies usually are effected only by very strong signals below about 1 GHz. The strong signal drives the
receiver into non-linear function, desensitizing normal reception as well as generating many unwanted spurious
signals within the receiver.
203. thru 299. RESERVED.

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CHAPTER 3. HISTORY, AUTHORITIES, AND RESPONSIBILITIES
300.
GENERAL CONSIDERATIONS. The FAA, as one of the major users of the RF spectrum in the
United States, has an important national role in the management of frequencies. In turn, the nation has a major
responsibility to the rest of the world in the orderly development and application of the RF spectrum within the
international community. To acquaint the reader with the need for effective spectrum management within the
agency, this chapter presents an historical background of the development and current national and international
administrative authorities and responsibilities. Although it complicates the task, agency spectrum management is
bound by many international treaties, as well as the regulatory framework imposed by the dual spectrum control
entities in the United States: the Federal Communications Commission (FCC) and the National
Telecommunications and Information Administration (NTIA).
301.

INTERNATIONAL ORGANIZATIONS.

a. International Telecommunication Union (ITU).
(1) ITU. The ITU is an arm of the United Nations, with its headquarters in Geneva, Switzerland. It is the
fundamental authority for spectrum allocation and management. The ITU currently has a membership of nearly
190 nations, and 650 Sector Members (companies). The organization is one of the oldest international groups in
existence. In 1932, it became the successor to the International Telegraph Union that was created in 1865.
(2) ITU Authority. The ITU expresses its authority through the same channels as any other multilateral
treaty system. Regulations adopted by this international body must then be ratified further and signed by the
various administrations (nations) represented. These regulations are developed at conferences and through
negotiation where representatives of member nations formulate recommendations that are presented to the plenary
body in session for formal voting action leading to adoption. The adopted policies are then published and include
detailed regulations and policies in such areas as terminology, assignment and use of frequencies, band
allocations, frequency registration, technical specifications, measures against interference, administrative
provisions for stations and distress and safety procedures.
(3) Structure of the Union. An organizational diagram of the ITU, showing major functions of concern
to the FAA, is presented in figure 3-1. Some major activities and elements of the Union are as follows:
(a) Plenipotentiary Conference. Meeting at intervals of normally not less than 5 years, the
Plenipotentiary Conference determines the general policies for fulfilling the purposes of the Union. It reviews the
work of the Union and revises the Convention (organization definition) if considered necessary.
(b) World Radiocommunication Conference (WRC). A WRC is normally convened every three to
four years to consider specific radiocommunication matters. A WRC may revise the Radio Regulations, or deal
with any radiocommunication matter of worldwide character in accordance with its agenda. The Radio
Regulations constitute an international treaty on radiocommunication and cover the use of the radio frequency
spectrum by radiocommunication services.
(c) Council. The Council sets the final agenda for a WRC, normally two years before the conference
is held.

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FIGURE 3-1. PARTIAL ORGANIZATIONAL CHART OF THE ITU

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(d) Secretary General. The Secretary General is responsible to the Council for external relations,
public information and other directed functions. The office provides secretarial services for all conferences and
publishes the monthly journal services in several languages for distribution to member nations.
(e) Radiocommunication Sector. The Radiocommunication Sector is one of three major Sectors
directly under the authority of the Plenipotentiary Conference and the Council. Its primary functions are to
provide for international frequency registration, technical and administrative support to radiocommunication
study groups, to provide conference and assembly support and to provide seminars and training.
b. International Civil Aviation Organization (ICAO). ICAO is to the international scene as FAA is to the
national, except that it is only advisory, without authority to enforce its recommendations. Member nations,
including the United States, strive for strict adherence to ICAO standards. See figure 3-2. The following is a
summary of the ICAO goals:
(1) Ensure safe and orderly growth of international aviation throughout the world.
(2) Encourage the arts of aircraft design and operation for peaceful purposes.
(3) Encourage the development of airways, airports and air navigation facilities for international civil
aviation.
(4) Meet the needs of the people of the world for safe, regular, efficient and economical air transport.
(5) Prevent economic waste caused by unreasonable competition.
(6) Ensure that rights of contracting nations are respected fully and those nations given equal
opportunity.
(7) Promote safety of flight in international air navigation.
(8) Annexes to the ICAO Convention (the "Chicago Convention" which established ICAO) establish
international standards and recommended practices (SARPs) for aeronautical requirements such as licensing,
airworthiness, security, air traffic, search and rescue, communications, etc. "Standards" are necessary for the
safety or regularity of international aviation and "recommended practices" are desirable for the safety or regularity
of international aviation.

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FIGURE 3-2a. ICAO ASSEMBLY ORGANIZATION CHART

FIGURE 3-2b. ICAO SECRETARIAT ORGANIZATION CHART

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(9) ICAO operates and functions as follows:
(a) The Assembly is the sovereign body of ICAO and includes over 180 Contracting States. It meets
at least once every three years and handles broad policy issues. Each contracting State has one vote on an issue.
(b) The Council is the governing body of ICAO. It is a resident body comprised of 33
representatives from Member States elected by the Assembly for three-year terms. One of the primary duties of
the Council is to adopt SARP's and incorporate these as Annexes to the Convention to achieve international
uniformity/standardization and improve air safety, efficiency and regularity of flight. The U.S. has had a
representative member on the Council since the beginning of ICAO.
(c) The Air Navigation Commission (ANC) is comprised of 15 qualified technical experts from
Member States appointed by the Council. ANC is responsible for examining, coordination and planning all of
ICAO's work in the air navigation field and is the principal body concerned with developing SARPs. The ANC
forms panels and study groups consisting of outside technical experts to study specific issues and make
recommendations to the Council. A technical expert nominated by the U.S. has been a member of the
Commission since the beginning of ICAO. This expert has historically had an FAA background.
1. While Headquarters Monitors work on nearly all ICAO Panels, the two which routinely
address radio spectrum issues and on which Headquarters participates, are the Aeronautical Mobile
Communications Panel (AMCP) and the Global Navigation Satellite System Panel (GNSSP). Working Group F
of the AMCP addresses aeronautical radio spectrum issues in general, and develops the ICAO position for WRCs.
2. AMCP studies aeronautical mobile communications issues and develops SARPs for airground communications, satellite communications and associated systems. GNSSP is developing the SARPs for
the future Global Navigation Satellite System (GNSS).
(d) The Air Transport Committee normally does not address radio spectrum issues. It is
comprised of representatives from Member States who are appointed by the Council. Its work includes research
and recommendations such as policy guidance on airport and route facility economics and management. It
considers air transport issues in global conferences. The Air Transport Committee also forms panels and study
groups to process its work.
(e) The Secretariat serves as ICAO's permanent administrative body. The Secretariat staff
maintains ICAO documents and its bodies include the Air Navigation Bureau, the Aviation Security Branch and
the Technical Assistance Bureau. The Secretariat also administers the Seven Regional ICAO Offices which
develop and implement regional aviation initiatives.
302. NATIONAL ORGANIZATIONS - GENERAL. Each member nation of ITU is free to set up its own
procedures for authorizing the use of the spectrum within its nation, but consistent with the international table of
allocations approved by the last ITU conference. Exceptions may be taken to specific allocations, but a member
nation must notify ITU and be subject to conflicting use by other member nations following the allocations.
a. United States International Relations. In the United States, the State Department is responsible for the
international representation of the United States in ITU (as well as ICAO) forums, utilizing the full technical and
administrative support by all concerned United States agencies. The State Department acts as the ITU voting
member. The vote represents the consensus of an extensive NTIA/FCC preparatory process, or when a consensus
cannot be reached, the official position of the President. The State Department provides the liaison between the
United States and other governments when conflicts arise over application of the ITU Radio Regulations.

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b. United States Domestic Structure. The Communications Act of 1934, as amended, established a dual
system of control of the spectrum within the United States. The FCC administers all the spectrum assigned to and
operated by non-Federal agencies. The Act also specifies that all Federal agencies will have their spectrum needs
administered and authorized by a separate agency, currently the NTIA in the Department of Commerce (DOC).
Both agencies, FCC and NTIA, work together to formulate recommendations for national control of the spectrum,
as well as supply the Department of State with a consensual position for international conferences.
c. FCC.
(1) Jurisdiction. The FCC has jurisdiction over all non-Federal Government spectrum and spectrum
users in the United States. This includes not only broadcast, amateur, industrial, and civil aviation as it applies to
licensing the operators and equipment, but also State and municipal government entities as well.
(3) Organization. The Commission is composed of five commissioners, appointed by the President with
the advice and consent of the Senate. They serve 5-year staggered terms, so one term expires each year. There
can be no more than three commissioners from the same political party. One of the members is appointed by the
President to be Chair. A simplified block diagram of FCC organization is found in figure 3-3.

FIGURE 3-3. FEDERAL COMMUNICATIONS COMMISSION

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d. NTIA.
(1) Jurisdiction. NTIA has authority and responsibility for use of the Federal portion of the spectrum by
all Federal agencies, including the DOD and the FAA. It is empowered by the same Act as FCC, but has only the
Federal agencies' spectra to administer. NTIA and FCC work closely together, since a good portion of the radio
spectrum is shared between Federal and non-Federal users requiring joint action. A block diagram of NTIA is
shown in figure 3-4.
(2) Responsibilities. NTIA is responsible for administering that portion of the spectrum allocated to
Federal use. It is empowered to authorize Federal agencies, which demonstrate appropriate needs and satisfy
specific requirements, to use the spectrum. They can also withdraw that authorization or modify it if required.
NTIA is also bound by the ITU Radio Regulations. FAA's interface with NTIA is normally only at the
Washington level.

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FIGURE 3-4. NATIONAL TELECOMMUNICATIONS
AND INFORMATION ADMINISTRATION

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(3) Organization. The NTIA Administrator serves as the Special Assistant to the President for
Telecommunications. NTIA is currently located in Washington in the DOC. It has no field offices, but in effect
does have various "field representatives" in other agencies in the field. For instance, each FAA service area
Frequency Management Officer (FMO) is the NTIA's field coordinator for all radar beacons and all radars within
certain radar bands. This includes military and non-Federal radars and radar beacons.
(a) Interdepartment Radio Advisory Committee (IRAC). The IRAC, chaired by the NTIA
Deputy Associate Administrator for Domestic Spectrum Management, is one of the most important bodies which
interfaces with FAA frequency management. Authorization for all FAA frequencies, including our Land Mobile
networks comes through IRAC from NTIA. The IRAC is the working arm of NTIA, composed of 20 members,
each an agency of the Federal Government, including FAA. See figure 3-5. FAA participates and provides
technical expertise to all subcommittees of the IRAC.

FIGURE 3-5. PARTIAL ORGANIZATION CHART OF THE IRAC

(b) Spectrum Planning Subcommittee (SPS). The SPS carries out IRAC functions which relate to
planning for the use of the electromagnetic spectrum. This includes the apportionment of spectrum space for the
support of established or anticipated radio services, as well as the apportionment of spectrum space between or
among Government and non-Government activities.
(c) Technical Subcommittee (TSC). The TSC is a subcommittee of IRAC which examines the
technical aspects of the use of the electromagnetic spectrum.
(d) Radio Conference Subcommittee (RCS). The RCS advises the IRAC in those functions
relating to preparing for ITU radio conferences. This includes the development of recommended U.S. proposals
and positions.

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(e) Emergency Planning Subcommittee (EPS). In general, the EPS formulates, guides, and
reviews National Security Emergency Preparedness (NSEP) planning for Federal spectrum-dependent systems.
(f) Space Systems Subcommittee (SSS). The SSS, chaired by the NTIA, is responsible to the IRAC
for international registration of Government within the ITU forum.
(g) Frequency Assignment Subcommittee (FAS). The FAS is an IRAC subcommittee, which
operates to accomplish all the engineering and coordination for each agency's frequency requests. To facilitate its
work, FAS has specialized groups to assist with the enormous task of checking and coordinating every frequency
request. The following are the two most important groups to FAA:
1. Aeronautical Assignment Group (AAG). The AAG, chaired by the FAA, handles only
those frequencies which deal with aeronautical services, both Federal and non-Federal. In so doing, it can
tentatively "authorize" frequencies in that service directly to the FMO in the service area after assuring the request
meets all IRAC and FAA requirements. Aeronautical frequencies approved by AAG must be approved by the
FAS before they become final. The frequency bands under AAG control are shown in figure 3-6.
FIGURE 3-6. AAG CONTROLLED BANDS
190-285 kHz
285-435 kHz*
510-535 kHz*
74.8-75.2 MHz
108-121.9375 MHz inclusive
123.5875-128.8125 MHz inclusive
132.0125-136.0000 MHz inclusive
328.6-335.4 MHz
978-1020 MHz inclusive
1030 MHz
1031-1087 MHz inclusive
1090 MHz
1104-1146 MHz inclusive
1157-1213 MHz inclusive
5000-5250 MHz inclusive
*In these bands, only applications
for stations in the Aeronautical
Radionavigation Service shall be
sent to the AAG.

2. Military Assignment Group (MAG). The MAG does the same work as AAG, except for the
military fixed and mobile communications bands controlled by DOD, 225.000-328.600 MHz and
335.400-399.950 MHz only. FAA requests for use of those frequencies for A/G facilities must go through MAG
for initial approval.
(h) Field Coordinators. Because the IRAC lacks expertise in some areas, it needs field assistance in
its enormous task of coordinating some operations. As a result, the FAA and the DOD Area Frequency
Coordinators (AFC) are tasked with pre-coordination of some portions of the spectrum before the frequency
request is submitted to FAS or IRAC.

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1. FAA Field Coordinators have responsibility for coordinating certain radar frequency bands.
This entails the FMOs having to engineer each new radar or beacon request proposed for operation in their service
area, whether civilian test, military, other Federal agency use or FAA. Once the frequency or (in the case of radar
beacon) the Pulse Repetition Rate (PRR) has been engineered, it must be given to Technical Operations ATC
Spectrum Engineering Services for submission to IRAC through channels. Those bands are shown in figure 3-7.

FIGURE 3-7. BANDS UNDER COORDINATION CONTROL
OF FAA FIELD COORDINATORS
1030 MHz Airborne Radar Beacons (Interrogators)
1090 MHz Ground Transponders
1215-1400 MHz Radar (typically en route radar)
2700-2900 MHz Radar (typically terminal and weather radar)
9000-9200 MHz Radar (typically DOD precision approach radar)

2. DOD AFCs have a similar responsibility but for the telemetry bands 1435-1535 MHz and
2310-2390 MHz. FAA does not use these bands. DOD AFC responsibilities are covered in the NTIA Manual,
chapter 8.
(4) Spectrum chart. A wall size detailed graphic representation of the full spectrum is published by
NTIA and is available from Technical Operations ATC Spectrum Engineering Services upon request.
e. FAA. The spectrum management function in FAA is totally within the purview of Technical Operations
ATC Spectrum Engineering Services. The latest edition of Orders 1100.1, FAA Organization - Policies and
Standards, 1100.2, Organization - FAA Headquarters and 1100.5, FAA Organization - Field delineate the specific
functions of the office. Figure 3-8 provides a block diagram of Technical Operations ATC Spectrum Engineering
Services. Figure 3-9 lists the bands of frequencies with which FAA is concerned.

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FIGURE 3-8. TECHNICAL OPERATIONS ATC SPECTRUM ENGINEERING SERVICES

Office of ATC Spectrum Engineering
Services
Program Director

Chief Systems Engineer

Secretary

Management and
Program Analyst

Spectrum
Assignment and
Engineering Office

Page 28

Spectrum
Planning and
International
Office

Mike Monroney
Aeronautical
Center

William J. Hughes
Technical Center

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6050.32B

FIGURE 3-9. SUMMARY OF FREQUENCY BANDS SUPPORTING AVIATION

*
*
*
*
*
*

*

*
*
* **
* **
*
**

**

*

**

9 - 14 kHz OMEGA Navigation System
90 - 110 kHz LORAN C Navigation System
190 - 435 kHz Nondirectional Beacon
510 - 535 kHz Nondirectional Beacon
2100 - 28,000 kHz High Frequency Communications
74.8 - 75.2 MHz NAVAID (Marker Beacon)
108 - 112 MHz NAVAID (VOR, ILS Localizer)
112 - 118 MHz NAVAID (VOR, LASS and SCAT-I))
118 - 137 MHz VHF Air/Ground Communications
62 - 174 MHz Fixed, mobile Communications
225.0 - 328.6 MHz UHF Air/Ground Communications
328.6 - 335.4 MHz NAVAID (ILS Glide Slope)
335.4 - 399.9 MHz UHF Air/Ground Communications
406.0 - 406.1 MHz Satellite Emergency Position Indicating Radio Bcn
406.1 - 420.0 MHz Fixed, Mobile Communications
932 - 935 MHz Fixed Communications
941 - 944 MHz Fixed Communications
960 - 1215 MHz NAVAID (TACAN/DME, etc.)
978 MHz ADS-B (UAT)
1030 MHz Radar Beacon, TCAS, Mode S
1090 MHz Radar Beacon, TCAS, Mode S
1176.45 MHz Planned Global Positioning System (L5)
1227.6 MHz Global Positioning System (L2)
1215 - 1390 MHz Air Route Surveillance Radar
1544 - 1545 MHz Emergency Mobile Satellite Communications
1545 - 1559 MHz Aeronautical Mobile Satellite (R) (Downlink)
1559 - 1610 MHz GPS (L1), GLONASS
1645.5 - 1646.5 MHz Emergency Mobile Satellite Communications
1646.6 - 1660.5 MHz Aeronautical Mobile Satellite (R) (Uplink)
1710 - 1850 MHz Low Density Microwave Link
2700 - 2900 MHz Airport Surveillance Radar, Weather Radar
2900 - 3000 MHz Weather Radar
3700 - 4200 MHz ANICS (commercial satellite downlink)
4200 - 4400 MHz Airborne Radio altimeter
5000 - 5250 MHz NAVAID (Microwave Landing System)
5350 - 5470 MHz Airborne Radar and Associated Airborne Beacon
5600 - 5650 MHz Terminal Doppler Weather Radar
5925 - 6425 MHz ANICS (commercial satellite uplink)
7125 - 8500 MHz Radio Communications Link
8750 - 8850 MHz Airborne Doppler Radar
9000 - 9200 MHz Military Precision Approach Radar
9300 - 9500 MHz Airborne Radar and Associated Airborne Beacon
11.70 - 12.20 GHz FAATSAT (commercial satellite downlink)
13.25 - 13.40 GHz Airborne Doppler Radar
14.00 - 14.50 GHz FAATSAT (commercial satellite uplink)
14.50 - 15.35 GHz Television (Video) Microwave Link
15.70 - 16.20 GHz Airport Surface Detection Equipment (ASDE III)
21.20 - 23.60 GHz Microwave Link (Multi-use)
24.45 - 24.65 GHz Airport Surface Detection System (ASDE II)

* denotes AAG bands engineered by FAA; see NTIA Manual

** denotes those bands for which FAA is national coordinator; see NTIA Manual

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303. TECHNICAL OPERATIONS ATC SPECTRUM ENGINEERING SERVICES. The following are the
major assigned functions for Technical Operations ATC Spectrum Engineering Services:
a. Focal point within the FAA for all radio spectrum matters. Develops and executes FAA radio frequency
spectrum policy, plans and standards.
b. Engineers, obtains authorizations and protects those frequency assignments necessary to satisfy the
requirements of the National Airspace System (NAS).
c. Provides engineering support to service area and field facilities in the resolution and prevention of radio
frequency interference to NAS facilities.
d. Manages the classified frequency management data and associated secure computer facility at
Headquarters.
e. Performs engineering analysis of frequency assignment proposals by Government agencies, the FCC (for
non-Government aviation use), Canada, Mexico and other countries to determine the impact on the NAS, and to
preclude radio frequency interference to NAS facilities and services.
f. Represents the agency on the IRAC and other Government and industry spectrum management
committees and working groups and Federal advisory committees which address spectrum issues.
g. Serves as the manager of aeronautical frequencies in the United States. Manages and engineers those
aeronautical frequencies identified for AAG management and chairs that group. In addition, the NTIA has
delegated band coordinator responsibilities to the FAA for radar (1215-1390, 2700-2900 and 9000-9200 MHz
bands) and the radar beacon (1030/1090 MHz) systems.
h. Assists in developing the United States' position and inputs for use in various international meetings.
Represents the United States at those ITU and ICAO meetings that require frequency management technical
expertise and which address or impact civil aviation matters.
I. Maintains the FAA radio frequency portion of the Federal Government's recovery communications
(RCOM) mobilization plans.
j. Conducts engineering studies relating to incorporation of future communications, navigation and
surveillance (CNS) systems within assigned portions of the radio spectrum in accordance with the NAS Capital
Investment Plan (CIP) and FAA Research, Engineering and Development Plan.
k. Executes the electromagnetic radiation hazard measurement program, both ionizing and non-ionizing, for
all FAA equipment and systems.
l. Administers the electromagnetic compatibility portion of the agency's airspace case program.
304. SERVICE AREA FREQUENCY MANAGEMENT OFFICE (FMO). The following are the major
functions assigned to the service area frequency management office:
a. Serves as the focal point within the service area for all frequency matters.
b. Investigates and resolves Radio Frequency Interference (RFI) problems.

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c. Validates and forwards frequency requirements with specific recommended frequencies
to Technical Operations ATC Spectrum Engineering Services.
d. Performs electromagnetic compatibility studies.
e. Performs radiation hazard measurements.
f. Controls and maintains the service area RFI Monitoring Van(s) (RFIM Van).
305. thru 399. RESERVED.

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CHAPTER 4. SPECTRUM MANAGEMENT EVALUATION CRITERIA

400. GENERAL. This chapter provides the evaluation criteria to measure the field level spectrum
management function effectiveness.
401. CRITERIA. The service area spectrum management function evaluations shall be conducted in
accordance with the latest edition of Order 1800.14, Airway Facilities Evaluation Program.
402. SUBJECTS OF EVALUATION. The FAA service area spectrum management office
performance shall be measured against the following evaluation criteria.
a. Compliance With Standards and Guidelines. Service area spectrum management personnel
shall be familiar with and strictly apply as appropriate, ITU, ICAO, FCC, NTIA and FAA published
regulations governing frequency matters.
b. Efficiency and Economy.
(1) Personnel functions shall be defined by workload description statements, which accurately
define the work performed by the FMO, that accompany the generic position descriptions.
(2) Cross-training shall be accomplished to provide essential coverage of specialized areas.
(3) Economy of personnel and material shall be pursued actively in all operational phases.
c. Spectrum Engineering.
(1) Frequencies shall be engineered properly (prior to formal assignment) with respect to
radiation, propagation, emission and power factors, including engineering consideration of protection
from potential interference.
(2) The FMO shall be the focal point and provide guidance and expertise in frequency matters to
all service area elements.
(3) Guidance shall be provided to the service area’s planning elements in advance of
programming actions concerning the spectrum bands to be used, radiated power and emission
characteristics of the new facilities and any limitations which appear because of legal or technical
restrictions. Likewise, timely spectrum engineering guidance shall be provided to non-Federal entities,
other Federal agencies and DOD elements desiring to establish aeronautical systems.
(4) Service area radiating systems shall be evaluated periodically, consistent with established
review plans, for compliance with emission and performance standards, with deviations and
recommendations reported for correction.
(5) The FMO will coordinate with DOD organizations within their service areas as necessary, to
ensure that electronic attack activity (including chaff operations, electronic jamming, etc.), does not
impact the NAS.
(6) Airspace cases will be analyzed in such a manner as to ensure that non-Federal users do not
cause interference to critical aeronautical facilities.
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(7) The FMO shall conduct electromagnetic compatibility studies, as necessary, to determine the
effect of proposed systems on current NAS systems.
(8) The FMO should participate in the site selection and installation planning for all new NAS
facilities and systems.
(9) The FMO should visit service area centers and TRACONs periodically in order to review
requirements for radio spectrum to support NAS operations.
d. Interference resolution.
(1) Frequency interference problems to the NAS from any source shall receive priority
attention and be corrected in minimum time.
(2) Close working relationships shall be established with other agency elements in Technical
Operations Services, Enroute and Oceanic Services, Terminal Services, Flight Standards (FS), and
Airports, as well as local FCC and DOD frequency personnel, to assure rapid correction of interference
problems.
(3) Every effort shall be made to terminate or correct an interfering device in lieu of a frequency
change to solve a problem.
(4) Appropriate data on incidents shall be entered into the RFI data base and engineering
reports shall be prepared, describing problems, their resolution and recommendations regarding action to
be taken to preclude recurrence. Copies of the reports shall be furnished to all entities involved and
Technical Operations ATC Spectrum Engineering Services.
(5) FMO offices shall have operable mobile and portable electronic interference detection
equipment in addition to an RFIM van. Calibration shall be maintained for all critical equipment.
e. Frequency assignment records.
(1) The Government Master File (GMF) shall be kept current.
(2) Frequency utilization shall be reviewed periodically, consistent with established review
plans. The reports on the reviews shall include followup actions taken.
(3) Frequency Transmitting Authorizations (FTA) for all FAA transmitters shall be issued by
the FMO to the appropriate FAA authority for posting. When visiting a facility, the FMO should review
the FTA for posting and accuracy.
(4) Procedures shall be established that use the available automated capabilities to determine
quickly the status of all frequency assignment actions.
(5) Filing procedures shall be established to assure rapid retrieval of correspondence and record
information.
f. Planning.
(1) Arrangements shall be made to assure that FMOs receive information regarding frequency
requirements for new facilities as soon as known, to assure the availability of frequencies.
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(2) FMO staff members shall maintain awareness of new system developments and techniques
to provide information to planning offices.
(3) Frequency assignment shall be obtained in time to enable installation personnel to order
necessary crystals, filters, etc., prior to scheduled installations.
(4) Maintain an awareness of the current status of projects to ensure that frequency records are
kept updated.
g. Coordination.
(1) Channels of communication shall be established and maintained with appropriate military
representatives and offices, FCC district and monitoring offices, other Federal spectrum users,
interference resolution organizations and representatives of non-Federal aviation industry spectrum users.
(2) Other FAA entities, such as Enroute and Oceanic Services, Terminal Services, FS, and nonFed Coordinator shall be apprised of FMO functions and capabilities.
(3) Coordination requirements for frequency matters in ITU, IRAC, ICAO and FCC regulations
and procedures shall be adhered to.
(4) Procedures shall be established and maintained to assure close coordination with adjacent
service areas.
h. Radiation Hazard Survey. The FMO is the single point-of-contact in the service area for
performing designated radiation hazard measurements, both ionizing and non-ionizing, and is responsible
for the definitive measurements of radiation levels. (See Chapter 16).
(1) FMOs shall conduct radiation hazard measurements and prepare reports as required.
(2) Technical Operations ATC Facilities, Environmental, Energy Conservation, and
Occupational Safety and Health (EEOSH) Services has overall program management responsibility for
environmental hazards, including radiation hazards.
(3) In addition, the following functions are assigned to FMOs through Order 3900.19B:
(a) Coordinate and consult with the Industrial Hygiene Program Manager in providing
advice and information on matters pertaining to radiation health hazards in FAA operations.
(b) Coordinate with the Industrial Hygiene Program Manager, the Industrial Investigations
Program Manager and the Safety and Health Managers in responding promptly to reports of radiation
health hazards.
(c) Perform radiation health hazards surveys on new and modified facilities that house
equipment, systems or substances capable of producing external ionizing or non-ionizing radiation fields,
and others as required.
403. thru 499. RESERVED.
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CHAPTER 5. FREQUENCY COORDINATION
500. GENERAL.
a. Any frequency assignment MUST be coordinated before it can be processed and authorized. The very
nature of radio signal radiation makes it a candidate for interference to another frequency, thus all interested
parties must be in agreement before a reliable frequency can be assured. There are five major areas of
coordination within the FAA spectrum management function. They are headquarters, field-headquarters,
field-external, field-special and field-internal. Each has its own requirements and peculiarities, thus requires
separate explanation.
b. As a general policy, only one frequency will be assigned for each individual requirement. For example,
only one VHF A/G communications (COMM) frequency will be assigned for each Air Route Traffic Control
Center (ARTCC) sector. Frequencies designated as "back-up" or "spare" are not authorized.
501. HEADQUARTERS. All coordination with other Federal agencies, except as discussed in paragraphs 503
through 505, and any with foreign governments, is accomplished only by Technical Operations ATC Spectrum
Engineering Services. Numerous coordination procedures have been developed for various frequency usages and
are listed in the NTIA Manual of Regulations and Procedures for Federal Radio Frequency Management (NTIA
Manual) in paragraph 8.3. This includes the east coast National Radio Quiet Zone (NRQZ).
502. FIELD-HEADQUARTERS. For new programs and systems, Technical Operations ATC Spectrum
Engineering Services engineers may do the initial planning, engineering frequency applications. All routine
aeronautical COMM, NAV and radar frequencies are engineered in the field and then forwarded to Technical
Operations ATC Spectrum Engineering Services prior to being forwarded to Frequency Assignment
Subcommittee for approval and eventual inclusion in the Government Master File.
503. FIELD-EXTERNAL. In general, the FMO is urged to form a close working relationship with the field
representatives of agencies with whom the FMO will work. A partial list of such agencies and the FMO's
responsibilities are as follows:
a. Inter-service area Work Force Support. Service areas can better adjust to peak workload conditions by
establishing a seamless environment so that service areas can provide support to each other to accomplish
functions as peaks occur. This inter-service area support would be provided at the request of the service areas
needing the support. Headquarters may, in some cases, provide funding for this support.
b. FCC Field Office. The FMO should become well acquainted with the Engineer in Charge of any FCC
Field Office(s) in the FMO's service area. Interference dealing with a non-Federal transmitter will be coordinated
with the local FCC. All communications with the local FCC representatives shall go through the regional FMO.
c. DOD AFC. DOD has established AFCs within designated areas of the United States and possessions.
These AFCs represent DOD in their respective areas and have coordination authority over all the military services
in their areas. If any DOD AFC has area encompassing any of the FMO's service area, it is imperative that the
FMO become well acquainted with the AFC, since all military frequency coordination with FAA within the
AFC's area of responsibility will be with the DOD AFC. See NTIA Manual, Chapter 8 and Annex D, for areas of
responsibility, contacts, and telephone numbers.
d. Military AFCs. The three main military departments, Army, Navy and Air Force, have their own service
coordinators. Each service has a specific area of influence and each area is spelled out in the NTIA Manual,

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Annex D. Just as with the DOD AFCs, it is important that the FMO become acquainted with these officials
whose control areas are within the various service areas.
e. United States Forest Service (USFS) and Bureau of Land Management (BLM). The person who has
frequency coordination responsibility in USFS and the BLM in each service area is one that each FMO should
know. In those service areas where forest fires are a problem, requests will be coming in at odd times for VHF
COMM frequencies to use for the duration of a fire for communication with water-drop aircraft. Knowing the
contact in advance is a great time saver.
f. Search and Rescue (SAR) Groups. There are a large number of SAR groups in the country. Most are
state or municipal governments, but a few are citizens groups who are interested in volunteering in searches for
lost or downed aircraft. They are the ones who will request temporary frequency authorizations for Emergency
Locator Transmitter (ELT) tests.
g. Local Aviation Groups. Local aviation groups are a source of information and frequently come to the
FMO for assistance with new frequency requirements. For instance, an airport owner wanting a new Aeronautical
Advisory Station (Unicom) frequency will come to the FMO. In addition, these groups have a lot of general
information that can benefit the FMO. Included in this category are AOPA, ATA, Civil Air Patrol (CAP) and
similar organizations.
h. Other Federal Agencies. It is to the advantage of the FMO to be involved with other Federal agencies in
the service area that use the radio spectrum. A good working relationship with other agencies is to the benefit of
all. When another Federal agency causes interference to FAA frequencies, contact with the local agency’s
technical personnel will bring much faster resolution to the problem than trying to resolve the problem at the
national level.
504. FIELD-SPECIAL. The FMO may receive special requests not covered by the normal processes. In such
cases, the FMO must take particular care in fulfilling them and should consider all parameters before acting or
referring to headquarters. When action is taken, Technical Operations ATC Spectrum Engineering Services shall
be notified promptly if the FMO has taken or is contemplating taking action. Some of these actions are:
a. ELT Tests. Various SAR groups wish to train their pilots at periodic intervals. To do so, they use an
ELT, hidden by one of their group in some relatively remote area to test how long it takes for the pilots to locate it
from the air, using whatever direction-finding equipment or techniques they have at their disposal. Refer to
subparagraphs (1) and (2) below for the procedure on how to accommodate these requests.
(1) The ELT test frequency is 121.775 MHz, as specified in Advisory Circular 91-44. Training
SHALL NOT be conducted on 121.5 MHz or 243.0 MHz.
(2) When a group wishes to conduct ELT training, they shall contact the FMO and provide the
following information:
(a) Date and time of the test.
(b) Site coordinates.
(c) Organization name and the name of a responsible person in the organization.
(d) A telephone number will be attended during the entire ELT test so that in the event of
emergency or unacceptable interference, the test can be terminated quickly.

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b. Forest Firefighting Frequencies. USFS and BLM have interagency agreements with FAA for temporary
use of A/G COMM frequencies to communicate with water-dropping aircraft during a forest fire. Some states
also have firefighting aircraft and may contact FAA. The detailed procedure is left to the individual FMO. It is
not uncommon for the firefighting agency to call the FAA duty officer Sunday midnight (or other inconvenient
hours) requesting FAA permission to use a VHF COMM frequency. In addition, it is FAA's responsibility to
publish the firefighting director's contact frequency in the NOTAM that establishes the temporary flight
restrictions (TFR) for firefighting operations. This is to allow media aircraft access to the area to collect news
information.
(1) The fire services have proved beyond a doubt that the first 15 minutes of a fire determines whether it
can be controlled promptly. The FMO should have a list of available frequencies at ready access, which means
that the FMO and staff engineers will have them at home, too. The requesting agency should be advised at the
time of authorization to call the FMO or the duty officer as soon as the frequency is no longer needed.
(2) The FMO shall forward a completed frequency assignment to Technical Operations ATC Spectrum
Engineering Services, and may notify Technical Operations ATC Spectrum Engineering Services by phone of any
frequency use that has been authorized.
c. Fly-ins. Various groups request Terminal Services to provide a temporary control tower for special
events of usually one to three days duration. To do that, Terminal Services must be provided with frequencies for
the temporary tower or other requirements. On occasion, this might be a UHF frequency, if military aircraft are
involved. Mostly, however, the request from Terminal Services will ask for a local control and a ground control
frequency. The frequency 123.1 MHz may be used for a tempo control tower when coordinated with SAR, if air
safety considerations are met.
(1) Initial contact between the aviation event sponsor and the FAA is normally with either the Flight
Standards District Office (FSDO) or Area Director of Terminal Operations for the geographic service area of
concern at least 45 days prior to the event. If temporary use of frequencies for control of the event's air traffic is
needed, or if the assigned frequencies at the air show's location will be used differently than presently authorized,
the Area Director of Terminal Operations for the geographic service area of concern or Flight Standards Field
Office (FSFO), as appropriate, will contact the service area FMO for advice, or the sponsor may contact the
service area FMO directly.
(2) The aviation event sponsor may have proposed frequencies desired for use, for example, either
FCC-controlled frequencies in the 122.8-123.0 MHz band for non-FAA use (UNICOM), (MULTICOM) or
specific FAA air traffic control frequencies. The FMO will advise the aviation event sponsor whether the
proposed frequencies are acceptable and whether the frequencies being proposed are too congested to allow
proper control of the aviation event. If the sponsor has no recommended frequencies or has chosen frequencies
which are not acceptable to the FAA, then the FMO will advise the FSFO with a service area coordination
number [for an example, see subparagraph (3)] and temporary frequencies, as needed.
(3) A coordination number (for example, GL T030043) will be provided to the event sponsor for each
frequency which is coordinated for the event use. The FMO will enter the temporary frequencies into the
automated frequency management system to document their use. The frequency assignment will include both
start and stop dates for the new assignment.
(4) The FMO will forward a memorandum to the aviation event sponsor noting the coordination and
frequencies to be proposed to the FCC for use. A courtesy copy of this document will be provided to Technical
Operations ATC Spectrum Engineering Services. An example of such a memorandum is shown in Figure 5-1.

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FIGURE 5-1. SAMPLE MEMORANDUM TO AVIATION EVENT SPONSOR

Subject: Coordination of Frequencies for Special
Aeronautical Events
From:

Service Area Frequency Management Office

To:

Aviation Special Event Sponsor

As coordinated on (date), this office has no objections to your use of the following
frequency for use at (name) air show. The following applies:
Frequency Coordinated:
Power/Emission:
Description of Antenna:
Location of Transmitter (include geographical coordinates):
Class of Station:
Dates/Times to be Used:
FAA Service Area Coordination Number:
In order to obtain Special Temporary Authority to use this frequency, you must submit
a request to the Federal Communications Commission (FCC) via the FCC internet
address (currently http://wireless.fcc.gov/), and follow the directions under
“online filing”, in order for them to review your application. Please cite the above
FAA Service Area Coordination Number on your application documents to expedite FCC
processing.
Please contact (name) at FAA (Service Area) Frequency Management Office,
(telephone), if you have further questions.
(Signature)
cc: Area Director of Terminal Operations; Service Area Non-Fed Coordinator;
HQ FAA/Technical Operations ATC Spectrum Engineering Services

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(5) After coordination with the FAA service area FMO, the sponsor will be expected to submit all
required forms and fees to the FCC for a special temporary authority (STA) for use of the coordinated frequencies
as required by the FCC rules. The sponsor may do this either by letter, telegram, fax or e-mail.
(6) Upon receipt of the memorandum from the service area, Technical Operations ATC Spectrum
Engineering Services will coordinate with the FCC and, in addition, will forward a memorandum to the FCC
Licensing Division, Gettysburg, Pennsylvania, noting the FAA service area coordination number and stating that
FAA has no objection to the temporary use of the frequencies for the aviation event.
(7) In most cases, the FCC will issue the STA to the sponsor no later than 15 days prior to the event
provided that all required forms and fees are received at their office within 30 days of the event.
d. Non-Federal Requirements.
(1) FCC licenses all non-Federal NAVAID and air-to-ground (A/G) COMM facilities. The owner or
sponsor of the facility must obtain airspace and frequency approval by FAA while processing the application for a
transmitting license through FCC. The following is the order of priority for assigning frequencies to non-Federal
facilities after airspace approval has been granted.
(a) Public use airport tower or NAVAID providing Instrument Flight Rules (IFR) service.
(b) Private use airport tower or NAVAID providing IFR service.
(c) Public or private use Visual Flight Rules (VFR) or en route advisory service.
(2) FAA must advise sponsors in subparagraph (c) above that frequency assignments can be taken away
from the facility with a one year notice to satisfy a more critical requirement. The sponsor must also be advised
that, if frequency changes are required to assign a channel to the facility, the sponsor must reimburse FAA for the
cost of the changes.
(3) Non-Federal NAVAIDs must be in the NAS. If it is to be private, the applicant shall be advised that
a proposed frequency will be engineered if possible. However, since it is not in the NAS, it is subject to
withdrawal for a NAS facility, if the frequency is required at a later date. Lastly, the applicant must be advised in
writing that if a frequency is engineered, it will be reserved for only one year. After that, it will be withdrawn if
not used. Extensions can be given only upon a showing of definite progress in procuring FCC license and
equipment delivery. Flight Standards has to concur with the request. If the NAVAID is a Compass Locator
(COMLO), the power limit is 25 watts (W). If a VOR or ILS, the power and service volume will be of terminal
class.
(4) If a COMM frequency, it also is reserved for only one year. The power limit shall be 10 W.
(5) Equipment shall be FCC type-approved and the applicant shall be so advised.
(6) Licenses for Non-Federal radio navigation aids.
(a) Proponent actions:
1. The proponent fills out an FAA Form 7460-1 and submits it to the appropriate service area
Non-Fed Coordinator.

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2. At the same time, the proponent submits an FCC Form 406 (Application for License) to the
FCC Licensing Division at Gettysburg, Pennsylvania.
(b) Service area actions:
1. Upon receipt of the FAA Form 7460-1 from the proponent, the FAA service area Non-Fed
Coordinator will forward the request to Air Traffic Organization System Operations Services.
2. Air Traffic Organization System Operations Services will initiate an airspace case (as
needed) and register the proponent with Aeronautical Information Management (AIM) in System Operations
Airspace and AIM.
3. Air Traffic Organization System Operations Services returns the FAA Form 7460-1 to the
service area Non-Fed Coordinator who then submits the form to the service area FMO.
4. The Service Area FMO engineers the appropriate frequency, prepares a temporary frequency
application and forwards it to FAA Headquarters. At the same time, the FMO also extracts the applicable
information from the FAA Form 7460-1 to prepare a memorandum to the FCC indicating the status of the
proponent's request.
(c) FCC actions:
1. The FCC Licensing Division receives the FCC memorandum, logs it for tracking purposes
and forwards it to FCC Headquarters.
2. FCC Headquarters processes the memorandum and forwards it to FAA Headquarters.
(d) FAA Headquarters actions;
1. FAA engineers and selects a frequency to satisfy the requirement (based on the temporary
frequency assigned by the service area FMO) and forwards the application to NTIA for approval.
2. FAA electronically forwards a copy of the FCC memorandum, with the coordinated
frequency, to FCC Headquarters.
3. When the frequency application is approved by NTIA, the FCC Licensing Division issues
the license to the proponent.
e. Electronic Attack (EA) Missions. EA missions are military exercises whereby electromagnetic signals
are radiated intentionally to cause interference to other military units being tested for EA defense. See chapter 18
for a detailed discussion.
f. Unusual Request. Unusual requests will be received from time to time, and there is no way to cover them
all here. When not covered by specific instructions herein or by headquarters directive, all requests for unusual
needs should be telephoned or faxed to Technical Operations ATC Spectrum Engineering Services.
505. FIELD-INTERNAL. All of the foregoing paragraphs in this chapter have dealt mostly with coordination
outside the service area office. But coordination within the service area office is as essential as outside. The style
of frequency coordination will vary with the service area because of the various configurations of the spectrum
management functions. At least the following shall be included:

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6050.32B

a. Air Traffic. Except for a few land mobile system needs, all frequencies engineered are to meet an air
traffic service need. Thus the FMO must coordinate closely with Enroute and Oceanic Services, and Terminal
Services, personnel as appropriate. This is not only to meet the current need, but also to be aware of service
planning so that efficient spectrum usage in the future may be taken into account.
b. Flight Standards. The same logic applies here, particularly as it relates to NAVAIDs. But if FS needs to
change a route or vector, an Expanded Service Volume (ESV) or even a new NAVAID may be required.
Frequent meetings with FS personnel are recommended.
c. New requirements for COMM, NAVAID, and radar facilities. Attendance at program review meetings
within the Service Area office and at System Management Offices (SMO) by the FMO is essential to provide as
much advance notice as possible of new facilities and programs to permit advanced planning.

d. Adjacent Service Areas. FMOs should coordinate frequently with their counterparts in adjacent service
areas. This is particularly important when a planned facility's interference range infringes upon an adjacent
service area’s territory. When a frequency request is filed with Technical Operations ATC Spectrum Engineering
Services, it is assumed that the FMO has coordinated with any affected adjacent service areas.
506. DOCUMENTATION. The FMO is required to have many sources of documentation in order to effectively
coordinate. At least the orders and documents listed in subparagraphs a.- u. below, as applicable, shall be
maintained by the FMO.
a. NTIA Manual Of Regulations and Procedures For Federal Radio Frequency Management.
b. FCC Rules and Regulations.
c. ICAO Annex 10.
d. Government Master File on CD-ROM
e. FCC Aeronautical Frequency List (see CFR 47, Part 87 -- Aviation Services).
f. The Daily National Automated Performance Reporting System (NAPRS) data report.
g. Aeronautical Information Manual.
h. ITU Radio Regulations.
i. Military Joint ECM Regulation, CJCSI, Performing Electronic Warfare in the United States and Canada.
j. The latest edition of Order 7610.4, Special Military Operations.
k. The latest edition of Order 7400.2, Procedures for Handling Airspace Matters.
m Federal Aviation Act of 1958, revised April 1981.
n. The latest edition of the Federal Aviation Regulations, Part 77.
o. The latest edition of Order 7350.6, Locations Identifier Handbook.

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p. The latest edition of Order 1380.40, Airway Facilities SMO Level Staffing Standard System.
q. Sectional Aeronautical Charts.
r. VFR Terminal Area Charts.
s. Airport Facility Directory.
t. U. S. Terminal Procedures.
u. DOD Flight Information publications.

507. thru 599. RESERVED.

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6050.32B

CHAPTER 6. TRANSMITTING AUTHORIZATION DOCUMENTS
AND CALL LETTER ASSIGNMENTS
600.
PURPOSE. This chapter describes the procedures for issuing and posting transmitter authorization
documents and the guidelines for assigning call signs to all transmitters.
601.
FACILITY TRANSMITTING AUTHORIZATION DOCUMENT (FTA). All transmitters
authorized must have appropriate documentation posted for identification and certification purposes. In FAA,
there are two basic forms, a certificate style and a metallic label.
a. For all fixed, base, and land transmitters, the certificate is used. Currently, it is FAA Form 6050-1,
Facility Transmitting Authorization. See figure 6-1.
(1) Each facility shall have its own document and its unique document number for file purposes. The
number shall consist of two letters identifying the service area, followed by a number. The letters and numbers
will remain for that site as long as the site exists. Whenever there are modifications to any assignment at that
facility, a new document shall be issued, with an added letter starting with "A." When the assignments are
subsequently modified, documents will contain sequential sub-letters, "B," "C," etc. until "Z." After "Z," the
letter will start again at "A." The original document shall be posted at the site.
(2) The Automated Frequency Management program (AFM) now in use for frequency
request/authorization will generate one FTA for each facility. This program will contain a database of all FTA's
issued.
(3) Emission designators for major FAA systems can be found in the appendix.
b. For all mobile transmitters, the identification label, FAA Form 6050-2, Transmitter Identification and
Operation Authorization (TIOA), shall be used. For hand held transceivers, either the Form 6050-2 or a smaller
equivalent may be used. The call letters of the unit will by typed or inked on it before applying to the transmitter.
Because the metallic labels stick very firmly, any changes in call letters should be accomplished by placing the
replacement label directly over the old one. The procedure for assignment of call letters will be covered later. If
the unit is transferred to a different organization or shipped to the FAA Depot for exchange and repair, a new
identification label will be issued. A sample of both TIOA forms is shown in figure 6-2.

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FIGURE 6-1. FAA FORM 6050-1, FACILITY TRANSMITTING AUTHORIZATION (REDUCED)

FIGURE 6-2. TIOA FORM FOR MOBILE/PORTABLE/HANDHELD TRANSMITTERS

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602. REQUESTS FOR FREQUENCY ACTION. Frequency requests from entities within the service area
should be standardized for record purposes. This will assure the FMO receives all the information needed with
the request. A sample service area form is shown in figure 6-3.

FIGURE 6-3. SAMPLE OF TYPICAL SERVICE AREA FREQUENCY REQUEST FORM (REDUCED)

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603.
CALL LETTER ASSIGNMENT. All transmitters that are in use shall be identified by assigned call
letters to meet international requirements, to help users know with whom they are communicating and to identify
signals in case of interference.
a. Most NAVAIDS are identified in accordance with Order 7350.6, Location Identifier Handbook.
b. Communications facilities are voice identified by facility; e.g., "Denver Tower," "Kansas City Center,"
etc.
c. HF, VHF, and UHF non-aeronautical service voice transmitters are identified by standardized
alpha-numeric call signs. They are the systems described in Chapter 17, Land Mobile and Other FM
Communications Systems Frequency Engineering.
(1) HF call signs will be issued by Technical Operations ATC Spectrum Engineering Services in
accordance with the standard operating procedure "Procedure for Assigning Call Signs," a policy letter to the
service areas.
(2) VHF/UHF Land Mobile call systems shall be managed and issued by the FMO in accordance with
paragraphs 604 and 605.
LAND MOBILE CALL SIGNS. Land mobile call signs shall be formulated and assigned in accordance
604.
with subparagraphs a. through e., below.
a. FM Repeater stations call signs shall consist of the prefix "FAA" followed by the repeater's three- or
four-character facility identifier, as shown in the Facility Master File (FMF).
b. FM Base, Mobile, and Portable transmitters call signs shall consist of the most commonly recognized
area identifier where the station is located, followed by a user identifier issued according to figure 6-4.
c. Stations located at a service area office use the service area identifier. Special organizations will be
identified as follows:

Page 56

Washington Headquarters

AHQ

Metropolitan Wash. Airports

MWA

FAA William J. Hughes
Technical Center

ACT

Mike Monroney
Aeronautical Center

AAC

11/17/05

Chapter 6 - continued

6050.32B

FIGURE 6-4. USER ORGANIZATION IDENTIFIERS

Organization

Identifier

Washington headquarters, FAA William J. Huges
Technical Center, Mike Monroney
Aeronautical Center, Regional Administrator,
Regional Communications Control Center

001-099

Flight Standards

100-199

Civil Aviation Security

200-299

Aircraft Certification

300-399

Technical Operations Divisions

400-499

Technical Operations SMOs

500-999

d. An alphabetic character following the user identifier will identify the station type thus:
B - Base station
M - Mobile station
P - Portable (e.g., handheld)
X - Other (e.g., portable repeater)
e. For example: DCA 618M would identify a Technical Operations SMO mobile radio at Washington
National Airport.
605.
STATION IDENTIFICATION REQUIREMENTS. Technically, mobile units communicating with
each other or a base station in simplex need not identify if the associated base station identifies. But since much
of mobile communication is through a repeater, and identification must be used during that time, it should become
standard to use the assigned call sign during every communication. The NTIA Manual paragraph 6.5.2 states,
"Each station shall transmit its assigned call sign on each frequency in use at the beginning and end of operation,
and at least once an hour. More frequent identification may be made if delay to traffic will not result." Fixed,
Land and Mobile (including hand-held) stations must identify this way. Repeater transmitters are presently
identified by the voice identification of the stations being repeated. In the future, repeaters will have automatic
Morse code or digital identifiers installed which will contain the call assigned by the FMO as described in this
chapter.
606. thru 699. RESERVED.

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6050.32B

CHAPTER 7. HIGH FREQUENCY ASSIGNMENT PROCEDURES
700.

GENERAL.

a. HF by definition covers from 3 to 30 MHz. It is that portion of the spectrum that has the potential for
providing communications worldwide. For this reason, HF is often referred to as a “poor man’s satellite.” The
availability of signal reception anywhere in the world depends on many conditions. The time of day, time of year,
time of the 11-year sunspot cycle, and the frequency itself are all determining factors. Up to 30 MHz, the higher
the frequency, the further a signal can be received in daytime. But at night, most signals above 15 MHz are
RLOS or ground wave propagation. This is due to the nature of the signal as it reflects off one of the various
layers of ionosphere from about 50 to around 200 miles above the earth. These reflective layers, known originally
as the Kennelly-Heaviside Layers for their discoverers, are now generally referred to as “ionospheric layers.”
There are five identified layers that are a consideration in HF radio propagation. See Figure 7-1. Through
improvements in technology, many of the factors that need to be considered have been automated (including the
development and use of automated HF data link) and HF is becoming a much more reliable means of
communication. Due to the increase in reliability and the high cost of satellite service, the demand for HF is
increasing.
b. At night, lacking the sun's heating of the various ionospheric layers, most layers will not reflect the higher
frequencies. It is common for HF systems to have "day" and "night" frequency pairs or "families of frequencies"
spread throughout the HF frequency band so that communications can be established during a variety of
propagation conditions. Headquarters has assigned families of five or more frequencies throughout the HF band
for use by FAA. One circuit might use an 8 MHz frequency at nighttime and a 16 MHz frequency during the
daytime to cover the United States.
(1) The D layer averages 45-55 miles above the earth. Its density, thus its ability to reflect radio signals,
varies with the sun's height during the day. The rise and fall of the D layer (sunrise to sunset) determines the
lowest usable frequency (LUF) that will support propagation between two selected fixed points at a given time.
This layer is most significant below 5 MHz. This layer permits long-distance reception of AM Broadcast stations
at night.
(2) The E layer averages 65-75 miles above the earth. This layer affects mid-range HF frequencies in
daylight hours.
(3) The Es layer, usually called the sporadic-E layer, drifts erratically and unpredictably about 70 miles
above the earth. It is significant only for frequencies of around 20 MHz and higher.
(4) The F1 layer averages 90-120 miles above the earth. It is also dependent upon the sun for its
existence. The F1 layer disintegrates and melds with the F2 layer after sunset.
(5) The F2 layer averages 200 miles above the earth and is the most important layer for long range
propagation. It permits reflection of signals that can be received for thousands of miles.
c. The term maximum usable frequency (MUF) refers to the highest frequency that will permit
satisfactory propagation of radio signals between two fixed points at a given time. MUF varies diurnally,
seasonally and with the sunspot cycle. The HF frequencies that propagate best are between LUF (lowest usable
frequency) and MUF, although the frequency for optimum transmission (FOT) is about 20 percent below MUF.
See subparagraphs a. and b., above.

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d. A more detailed description of the ionospheric layers can be found in the ARRL Handbook for The Radio
Amateur.

FIGURE 7-1. IONOSPHERIC LAYERS ILLUSTRATED

Courtesy ARRL Handbook

701. INTERNATIONAL HF REQUIREMENTS. The HF services available to support the NAS
international requirements are the Aeronautical Mobile (R) and Fixed services. The HF Aeronautical Mobile (R)
service provides A/G communications for flights operating in international airspace beyond the VHF range of air
traffic control (ATC) ground stations. The A/G communications in support of the ATC function is provided by
Aeronautical Radio, Inc. (ARINC), under contract to FAA. The ground-to-air communications service is a
broadcast service, providing meteorological information to enroute aircraft (VOLMET), and is provided by FAA.
Frequency assignments are in accordance with ITU Appendix 27, Frequency Allotment Plan for the Aeronautical
Mobile (R) Service and Related Information, from those allotted to Major World Air Route Areas (MWARA),
Regional and Domestic Air Route Area (RDARA), and VOLMET, respectively. Aeronautical HF
communication is not permitted over the continental U.S. when VHF communications are available, except in
times of emergency.

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702. NATIONAL HF REQUIREMENTS. Additional HF services are required to satisfy national (domestic)
requirements.
a. HF Aeronautical Mobile (R) service provides A/G communications in the State of Alaska via FAA
FSSs. Frequency assignments are made in accordance with ITU, Appendix 27 from those allotted to RDARA and
the Annex to the NTIA manual.
b. HF Fixed service provides point-to-point (PTP) communications primarily in support of the National
Radio Communications System (NRCS), known internally as Command and Control Communications (C3).
Frequency assignments in this service are made in accordance with the NTIA Manual, Table of Frequency
Allocations. See figure 7-2 for authorized NRCS frequencies. Refer to the individual station's FTA for details of
the assignment.

FIGURE 7-2. NRCS FREQUENCIES

CHNL FREQ
(kHz)

NOTES

00
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17

USB (East. U.S.)
LSB (West. U.S.)
USB; LSB
USB
USB (West. U.S.)
LSB (East. U.S.)
USB; LSB
USB (East. U.S.)
LSB (West. U.S.)
USB (East U.S.)
LSB (West. U.S.)
USB; LSB
USB (East. U.S.)
LSB (West. U.S.)
USB (West. U.S.)
LSB (East. U.S.)
USB; LSB
USB (East. U.S.)

4055.0
4055.0
4625.0
5860.0
6870.0
6870.0
7475.0
7611.0
7611.0
8125.0
8125.0
9914.0
11637.0
11637.0
13457.0
13457.0
13630.0
15851.0
NOTES:
1.
2.
3.
4.

CHNL

18
19
20
21
22
23
24
none
none
25
26
27
28
none
none
none
none

FREQ
(kHz)
15851.0
16348.0
19410.0
19410.0
20852.0
24550.0
24550.0
3428.0
5571.0
8912.0
11288.0
13312.0
17964.0
2866.0
3449.0
8855.0
11375.0

NOTES

LSB (West. U.S.)
USB; LSB
USB (East. U.S.)
LSB (West. U.S.)
USB; LSB
USB (West. U.S.)
LSB (East. U.S.)
USB: A/G FIFO use
USB; A/G FIFO use
USB; A/G FIFO use
USB; A/G FIFO use
USB; A/G FIFO use
USB; A/G FIFO use
USB; A/G Alaska only
USB; A/G Alaska only
USB; A/G Alaska only
USB; A/G Alaska only

USB - upper sideband operation
LSB - lower sideband operation
Eastern U.S. is defined as East of the Mississippi River
Western U.S. is defined as West of the Mississippi River

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703. HF ENGINEERING. For new HF requirements, Technical Operations ATC Spectrum Engineering
Services normally does the HF engineering. Service areas may be asked to provide the following information to
process the frequency assignment.
a. Station Class (STC)
b. Emission (EMS)
c. Power (PWR)
d. Transmit/Receive State (XSC/RSC)
e. Transmit/Receive Antenna Location (XAL/RAL)
f. Transmit/Receive Antenna Latitude (XLA/RLA)
g. Transmit/Receive Antenna Longitude (XLG/RLG)
h. Transmit/Receive Antenna Dimensions (XAD/RAD - gain only)
i. Transmit Azimuth (XAZ)
j. Authorized Area of Operation (*RAD)
k. Number of Stations and System Name/Identifier (*NRM)
l. FACID Sort
704. ASSIGNED VS. WINDOW FREQUENCY. The Frequency Transmit Authorization (FTA) that is issued
by the service area should contain the window frequency (the frequency that is dialed into the radio) for each HF
frequency assignment that is to support a single side band operation. The assigned frequency is required to reflect
the center of the occupied bandwidth, but for a single sideband assignment, this is not the frequency that the radio
is tuned to. For an Upper Side Band (USB) assignment, the window frequency is equal to the assigned frequency
minus one-half of the assigned bandwidth (e.g. the window frequency for an USB frequency assignment of
5572.4 kHz with a 2.8 kHz bandwidth is 5572.4 – 1.4 = 5571 kHz. Therefore, when the radio is tuned to 5571
kHz the transmitted information is contained between 5571 kHz and 5573.8 kHz with the center of the bandwidth
-5572.4 kHz - being the assigned frequency. For a Lower Side Band (LSB) frequency assignment, the window
frequency would be the assigned frequency plus one-half of the assigned bandwidth.
705. PROPAGATION AND CIRCUIT RELIABILITY. There are several computer models that will
reasonably predict HF radio signal propagation via ionospheric sky wave paths. These models have many
parameters, but are mainly predicated on sunspot activity.
706. SUNSPOT NUMBERS. Sunspot numbers are the number of sunspots observed over a specific period of
the approximate 11-year cycle. The National Institute of Standards and Technology (NIST) observation group
determines the level of effect. The HF MUF varies due to many factors (see paragraph 700), including sunspot
activity. The more sunspot activity, the more the ionosphere is ionized, the denser the layer and the higher the
MUF. The reverse is true as sunspot activity decreases. A plotted graph of observed sunspots for 1749-1996 is
shown in figure 7-3.

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707. SOLAR FLARE/STORM REPORTING PROCEDURES. The NIST provides solar flare alerts to
FAA through Technical Operations ATC Spectrum Engineering Services, who in turn, passes them to FMOs.
Although the heaviest effect is upon HF, VHF as well as hard-wired data circuits are affected due to the increased
earth magnetic currents. The usual VHF effect on communications is a squelch break, followed by a "hissing"
noise.

FIGURE 7-3. MONTHLY SUNSPOT NUMBERS JAN 1749 - APR 1996

708. thru 799. RESERVED.

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(2) Any changes or modifications to radio frequency systems, when specified in the original FAA
determination, including:
(a) Change in the authorized frequency.
(b) Addition of new frequencies.
(c) Increase in effective radiated power (ERP) equal to or greater than 3 decibels (db).
(d) Modification of radiating elements such as:
1. Antenna mounting location(s) if increased 100 feet or more, irrespective of whether the overall
height is increased.
2. Changes in antenna specifications (including gain, beam-width, polarization, pattern).
3. Change in antenna azimuth/bearing (if directional antenna).
802. Title 49, Section 44718. By regulation or order when necessary, the Secretary of Transportation shall
require a person to give adequate public notice, in the form and way the Secretary prescribes, of the construction
of any structure or landfill that may result in an obstruction of the navigable airspace or an interference with air
navigation facilities and equipment or navigable airspace. An aeronautical study shall be conducted to determine
the extent of the adverse impact, if any, on the safe and efficient use of such airspace, facilities or equipment. It
also provides for aeronautical studies regarding an existing object. The service area FMO shall evaluate these
cases for hazardous electromagnetic effect in the same manner described in paragraph 801a. Aeronautical studies
will be handled directly with the proponent by System Operations Services, who will keep Technical Operations
ATC Spectrum Engineering Services informed of all action.

803. INTRANET OBSTRUCTION EVALUATION/AIRPORT AIRSPACE ANALYSIS (iOE/AAA)
WEB-BASED SYSTEM. The iOE/AAA is a national, web-enabled application that allows data sharing, and
communication between and among FAA service areas and employees. The iOE/AAA system replaces the
previous procedure in determining the potential effects of various types of man-made structures in the NAS.
Commercial and/or government entities submit construction plans to the FAA regarding new or existing
structures obstructions. Obstruction Evaluation Services personnel will then input the data into the iOE/AAA
system to evaluate the potential effects to the NAS, based on criteria indicated in FAA Order 7400.2 (“Procedures
for Handling Airspace Matters”). FMOs shall use the iOE/AAA system to track each case study which is routed
to them through the system, and will provide an EMI and obstruction analysis response in a timely manner.
804. WASHINGTON HEADQUARTERS REVIEWS. The sponsor of any proposed construction or
alteration, or any person who stated a substantive aeronautical comment on a proposal in an aeronautical study,
may petition the Administrator for a discretionary review of a determination, revision or extension of a
determination issued by the service area Obstacle Evaluation Services organization. The authority to grant a
review is delegated to System Operations Services. Such petitions are processed and coordinated by the Airspace
and Rules Division within System Operations Services. Once granted, discretionary review is conducted by the
various Washington Headquarters services in the same manner as the original service area evaluation. Based
upon review, analysis and evaluation of the service area’s report of the aeronautical study, briefs, and related
submissions by any interested party, the Airspace and Rules Division within System Operations Services prepares
a notice affirming, revising, or reversing the original determination for the signature of the Vice-President for
System Operations Services.

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805. ELECTROMAGNETIC EVALUATION. The electromagnetic evaluation of a proposed construction or
alteration to any man-made structure or facility must be detailed and consistent. Particular attention should be
given to high power AM, FM, and TV broadcast proponents, as well as, several other frequency bands,
administered by the FCC, that are adjacent to or co-channel with FAA authorized frequencies.
a. The evaluation should begin by gathering all pertinent data required. Through the use of various
programs and on-line databases available in the AFM, a listing of all ground aeronautical receivers and
transmitters and all commercial broadcast transmitters should be compiled. This list must include frequency,
geographic coordinates, emitter effective radiated power (ERP), and elevations. Consideration must be given to
overall terrain height, antenna height, and the proximity of any existing commercial transmitters.
b. When plotting the chart, locations of Instrument Landing System (ILS) Frequency Protected Service
Volumes (FPSV), ESVs, Markers, VHF Omnidirectional Radio Range (VOR), air-to-ground communications
(COMM) and surveillance facilities should be noted. In some cases, facilities within a 30 nautical mile (nmi)
radius or more of the proposed site may need to be accounted for.
c. An intermodulation (IM) study utilizing the frequencies compiled is the next step. The study should
include at least third order calculations. If hazardous intermodulation products result, the Venn diagram
procedure detailed in Appendix 1of this order must be used to determine where it exists for all situations except
those involving FM broadcast stations to ILS localizers and VORs. The predicted area of intermodulation must
fall in the FPSV for a hazard to exist.
d. Brute force for COMM facilities is also calculated using the Venn diagram method. If an aircraft enters
this area, the broadband radio frequency (RF) section of the receiver will be driven into non-linearity regardless of
transmitted frequency and desensitization will result.
e. The Airspace Analysis Model (AAM) will be used to evaluate the effects of FM broadcast signals on ILS
localizer, VOR and COMM signals received by airborne receivers, as well as by ground receivers in the case of
COMM. This includes intermodulation, receiver front-end overload and adjacent channel interference.
f. Signal levels at the input of FAA ground receivers should be calculated for both out-of-band and in-band
(spurious) signals.
g. A very important part of this entire evaluation is a vertical profile plot of the proposed site and affected
facilities. In many cases, it will be necessary for the FMO to obtain the antenna radiation patterns (horizontal and
vertical) from the proponent. All calculations are based on an isotropic radiator. Use of the actual antenna
radiation pattern provides a more realistic evaluation.
h. The complete and detailed procedure along with several examples of an airspace evaluation is contained
in Appendix 3 of this order.
806. The AAM was designed to assist the FMO in determining the effects of various radio frequency emitters on
aircraft navigation and communications facilities. The model determines the effects of FM broadcast stations on
ILS localizer and VOR signals. It allows the selection of a proponent FM station to provide a complete
compatibility analysis between the proponent and any selected localizer within 30 nmi of the proponent. It is
available for download at the Technical Operations ATC Spectrum Engineering Services website.
a. The AAM computes the boundaries of a three-dimensional service volume for the specified facility. It
then generates a test grid inside the service volume at specified horizontal and vertical increments. The field
strength for the proponent station is computed at each point on this grid and compared to threshold criteria that
have been shown in bench measurements to cause brute force interference in typical receivers. All possible

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2- and 3-frequency third order IM products involving the proponent and other FM transmitters are computed and
the combined field strength of the stations contributing to each product is compared to other threshold criteria.
b. The output of the AAM is a series of plot files of predicted interference points within the designated
service volumes. The files may be plotted to a terminal screen, a printer or a plotter. The AAM will also indicate
if no interference potential exists. A complete technical description of the AAM is available when the AAM is
downloaded for use.
807. DETERMINATIONS. After the engineering evaluation has been performed, it is necessary to determine
whether the predicted interference (if any) is a hazard to air navigation.
a. In a 1985 letter from the Chairman of the FCC to the Administrator of the FAA, it was agreed that in
certain situations where there is insufficient scientific information upon which to make a conclusive
determination, that certain limiting conditions would be added directly to new or modified station authorizations.
These limiting conditions that are set forth in the "conditional statement" are as follows:
Upon receipt of notification from the Federal Communications Commission that harmful interference is
being caused by the licensee's (permittee's) transmitter, the licensee (permittee) shall either immediately
reduce the power to the point of no interference, cease operation or take such immediate corrective action
as is necessary to eliminate the harmful interference. This condition expires after 1 year of interferencefree operation.
b. This includes the following situations:
(1) VHF-TV broadcast proponents that appear to be a hazard based on the current electromagnetic
interference prediction data and methods.
(2) FM broadcast proponents proposing to relocate and/or modify an existing FM station resulting in an
equal or lesser interference problem than presently exists. This can include a change in location, power,
frequency, antenna height or antenna type.
(3) Interference is predicted in an area inside the service volume where an aircraft cannot possibly fly
due to terrain, physical obstructions, and/or effects of EMI.
808. NON-BROADCAST EVALUATIONS. There are special considerations given to certain non-broadcast
transmitters. These procedures are covered under a joint public notice issued by FAA and FCC and a joint agency
policy for Technical Operations Services and Air Traffic Organization System Operations Services. The public
notice is quoted verbatim as subparagraph a, below. The agency policy is summarized in subparagraph b, below.
a. Joint FAA/FCC public notice:
The Federal Aviation Administration (FAA) and the Federal Communications Commission
(FCC) have reached an agreement to simplify the handling of electromagnetic interference (EMI)
issues with respect to AM broadcast stations, fixed microwave transmitters, and cellular
radiotelephone fixed transmitters. The FAA's concern in this area arises from the possibility that
such transmitters might be installed too close to remotely controlled aeronautical receivers so as to
disrupt air traffic control communications and navigational aids.
It has been agreed that the FAA will not issue a hazard determination to those applicants for
licenses involving cellular fixed transmitters, fixed microwave transmitter, or AM broadcast
transmitters that invite potential EMI, nor, will the FAA request the applicants to use filtering

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6050.32B

beyond what is normally required by FCC rules. Rather, the FAA will include the following
language in a Determination of No Hazard, assuming that physical obstruction is not an issue.
FAA facilities critical to aviation safety are located (distance) from your proposed
transmitter site. You may cause harmful interference to these facilities if your equipment
meets only minimum FCC standards for spurious emissions. Before you begin any
transmission from your facility, contact (name and phone number of local FAA contact)
to arrange procedures to verify that no interference is caused.
FCC requirements in:
47 CFR 73.44 (c)
47 CFR 22.907 (c)
47 CFR 21.106 (c)
47 CFR 74.23 (a)
47 CFR 94.71 (d)

(in the case of AM broadcast stations)
(in the case of fixed cellular transmitters)
(in the case of common carrier fixed microwave transmitters)
(in the case of broadcast auxiliary transmitters)
(in the case of operational fixed service transmitters)

indicate that the licensees may need to employ extra filtering or take other measures if
their transmissions disrupt other services. The commission requires its licensees to
cooperate fully with other Federal agencies (users in other services) in this case the FAA,
to eliminate any harmful interference covered by the above requirements.
This agreement does not affect the requirement of an FCC applicant to notify the FAA of
proposed construction or modification of towers under existing FAA and FCC rules. Facilities
located near airports raise concerns about possible interference to aircraft and will be handled
under existing procedures.
This agreement should speed the authorization of service for licensees in the above categories.
Both agencies agree that this special case of potential interference to ground based receivers from
transmitters at widely differing frequencies can be adequately handled by requiring the licensee
(applicant) to shut down if EMI is present due to the use of the transmitter.
b. The policy for use of the new statement for AM broadcast, cellular, PCS, and microwave transmitters
which are a potential for electromagnetic interference (EMI) is as follows:
(1) The FMO shall not recommend that a Determination of Hazard be issued when an AM broadcast,
cellular, PCS, or microwave transmitter evaluation indicates the possibility of EMI to an FAA facility.
(2) The current procedures for determining whether the proposed facility will exceed the limits of
-4 dBm for out-of-band or -104 dBm for in-band shall be used for evaluation.
(3) If no problem is predicted, the FMO shall so notify the service area Obstacle Evaluation Services
entity involved.
(4) If a problem is predicted, instead of either recommending a hazard be written or telling the
proponent that additional attenuation will be required, Obstacle Evaluation Services will be provided with the
name of the service area FMO whom the proponent must contact to arrange procedures to verify that no
interference is caused. This initial verification is done during the CP phase of the FCC licensing process. FCC
rules require that during this period, all interference must be eliminated before the applicant can receive a
transmitting license.

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(5) Upon notification by the proponent of the intent to turn on a new transmitter, the service area FMO
will contact the System Management Office that is responsible for the facility where the problem has been
predicted. The following is the required procedure:
(a) The System Management Office will coordinate the turn-on for testing of the new facility with
the proponent to ensure that all FAA personnel are aware of the existence of the new potential for interference and
make whatever arrangements they feel are necessary to adequately monitor any suspected EMI to FAA
equipment.
(b) These arrangements can include having a technician at the site to monitor the equipment,
advising Obstacle Evaluation Services of the potential for interference and to be aware of it, or even simply noting
the new facility in case interference is reported in normal day-to-day operations.
(c) If interference is detected, the System Management Office will immediately notify the proponent,
who will shut down the interfering transmitter. The System Management Office will also notify the service area
FMO who in turn will contact the local FCC office.
(d) The FCC will, at this point, use their own existing procedures to bring the proponent into
compliance with the applicable FCC requirements.
(e) Only in the rarest situations would a proposal be submitted for one of these services at a location
that could endanger FAA facilities. Such a condition (such as a high power AM BC transmitter located in close
proximity to an airport or navigational aid) would be so obvious to the reviewing official that it would be
accorded special attention beyond the requirements of the notice.
809. thru 899. RESERVED.

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CHAPTER 9. VHF/UHF AIR/GROUND COMMUNICATIONS
FREQUENCY ENGINEERING
900. PURPOSE. The purpose of this chapter is to present an overview of the frequency engineering necessary
for A/G communications in the VHF and UHF bands. The detailed frequency engineering for this function is
found in Appendix 2.
901. COMMUNICATIONS FREQUENCY ALLOCATIONS. All voice communications for ATC utilizes
AM in the bands:
118.000 - 136.975 MHz*
225.000 - 328.600 MHz#
335.400 - 400.000 MHz#
* Portions are not available to FAA. See Appendix 2.
# Only some frequencies are usable by FAA air traffic control communications
(pilot-to-controller) with military aircraft.
902. BASIC PRINCIPLES OF COMMUNICATIONS FREQUENCY ENGINEERING. Due to the fixed
number of frequencies available for communications facilities, each communications frequency is reused as often
as possible throughout the country. Communications frequency engineering provides an interference-free
environment for each facility within its FPSV. There are several different functions for communications and each
has its own FPSV, defined in the appendix. Communications frequency engineering involves three analysis
disciplines: intersite (cochannel), adjacent channel and cosite.
a. Intersite analysis is necessary to prevent radio frequency interference (RFI) between facilities providing
service on the same frequency at different geographic locations. The basic factors considered in intersite analysis
are the Radio Line of Sight (RLOS) and the ratio between Desired (D) and Undesired (U) signal levels (D/U), as
seen at the airborne receiver input. As discussed in Appendix 2, the ratio of the desired and undesired signals can
be calculated using path loss between the desired signal source and the undesired signal source at the critical point
on the FPSVs associated with the two facilities being analyzed. All cochannel communications frequency
assignments shall be engineered to meet a D/U distance ratio of 5:1 (a signal D/U ratio of 14 dB), and all
cochannel broadcast transmitters shall be beyond RLOS to any point within the FPSV.
b. Adjacent channel analysis is necessary to prevent RFI resulting from the close location of two FPSVs
with frequency separations of only 25 kHz. Since some frequency separation does exist, path loss is not as critical
as in the intersite analysis above. The basic method is to separate FPSVs so that they do not overlap, plus a small
additional protective distance (see the appendix for a complete discussion). For adjacent channels separated by 25
kHz, the FPSVs shall be geographically separated by a minimum of 0.6 nmi horizontally or 7,000 feet vertically.
For adjacent channels separated by 50 kHz or more, no geographic separation shall be required between the
FPSVs.
c. Cosite analysis is necessary to prevent RFI resulting from the interaction of transmitter and receivers at or
near the same site, which may be far removed in frequency. These sources can be FAA equipment in the same
building, or high power or broad-spectrum emissions such as AM/FM/TV broadcast stations from a few miles
away. Cosite RFI includes intermodulation, spurious emission, cross-modulation, harmonic, image, and overload
interference. A discussion of cosite interference is found in Appendix 2.
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SPECIAL ISSUES TO BE CONSIDERED.

a. Ground transmitter power is normally at a level of 10 watts (W). The need for higher power must be
justified in the FMO’s application for a frequency approval.
b. UHF coverage is less than VHF, even for the same power. When the service radius exceeds 100 nmi,
power available (limits of coverage) curves must be checked carefully.
c. Aircraft transmitter power differs between aircraft. For practical frequency engineering, all aircraft are
assumed to have the same output Effective Isotropic Radiated Power (EIRP) as that of the ground transmitter.
d. FM and TV broadcast interference, primarily from receiver overload (desensitization) is an increasing
concern. The FMO shall carefully check the proximity for the presence of such transmitters during frequency
engineering process. This is discussed in detail in the appendix.
e. Slant range is the actual distance between the ground transmitter and an aircraft at any critical point, with
the radial distance and the altitude of the aircraft each forming a leg of a triangle. The hypotenuse is the actual
distance, or slant range. However, because of the shape of most FPSVs, there is negligible difference between the
slant range and the ground radial distance, so the service radius is always considered as a ground radial.
f. Antenna coverage is affected by lobing of antenna radiation. Within limits, the lower the VHF or UHF
antenna with respect to ground level, the better the overall coverage. This is very evident in Appendix 2.
g. At some "problem" sites, e.g., where there is limited real estate for adequate antenna separation or other
constraints, FMOs may be required to consider multicouplers and/or combiners to prevent frequency interference.
The following policy addresses the use of multicouplers and/or combiners.
(1) Technical Operations ATC Spectrum Engineering Services will manage the overall program for
requirements and budgetary purposes.
(2) FMOs will validate the requirements for multicoupler/combiners at sites within their service areas in
coordination with the concerned Regional Associate Program Managers (RAPM).
(3) FMOs must carefully specify requirements for multicouplers and combiners. Whereas multicouplers
are somewhat flexible in their potential for retuning to meet changing requirements, the combiner can tune only
within a very narrow range of operating frequencies.
(4) FMOs shall note use of multicouplers/combiners in the GMF remarks section using the appropriate
format.
904. AUTOMATIC TERMINAL INFORMATION SERVICE (ATIS) VOICE OUTLET ASSIGNMENT
CRITERIA. The following criteria will be used to the maximum extent possible in selecting ATIS voice outlets:
a. Priority for selecting a frequency to support ATIS broadcasts:
(1) VOR or VOR with tactical air navigation capability (VORTAC), except if they are Doppler-type,
provided the VOR or VORTAC is located within three nautical miles of the airport. This only applies to those
VORs that do not currently provide other broadcast signals such as Enroute Flight Advisory System (EFAS).
(2) VOR test facility (VOT) for departure ATIS only.

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(3) A 25 kHz discrete VHF air-ground frequency (for service to the military, any 25 kHz discrete UHF
air-ground communications channel in the band 225-400 MHz).
b. Power output of an ATIS operating on a discrete VHF or UHF channel should not exceed 10 W.
c. Service volume of an ATIS operating on a discrete VHF or UHF channel must be consistent with the
Terminal Radar Approach Control (TRACON) airspace, and is normally limited to 60 nmi and 25,000 feet above
ground level (AGL). The concerned service area air traffic organization must approve requirements in excess of
this value.
d. Frequency protection ratio (D/U) for an ATIS operating on a discrete VHF or UHF channel shall be a
minimum of:
(1) 14 dB from an aircraft at the edge of the ATIS service volume to another cochannel ATIS, Automated
Weather Observing System (AWOS) or Automated Surface Observation System (ASOS).
(2) Beyond RLOS separation from a potential interferer at the edge of an FPSV to the transmitter site of
the ATIS.
NOTE: The minimum separation is inclusive, i.e., both (1) and (2) must be met.
e. If the proposed ATIS facility does not conform to subparagraphs (1) through (4) above, the FAA may
not assign the system a broadcast frequency.
905. AWOS/ASOS FREQUENCY ASSIGNMENT CRITERIA. (These criteria also apply to other weather
broadcast services under different names.) The following criteria shall be used to the maximum extent possible in
selecting AWOS/ASOS voice outlets:
a. Priority for selecting a frequency to support AWOS/ASOS broadcasts:
(1) At airports with towers, use the existing ATIS voice outlet, if available. If the tower operates
part-time, the AWOS/ASOS shall operate independently of the ATIS during non-operational hours.
(2) At airports without ATIS, use a non-Doppler VOR or VORTAC site if it is within 3 nmi of the
AWOS/ASOS facility. This only applies to those VORs that do not currently use the facility for other broadcast
signals such as EFAS.
(3) If no ATIS or VOR is available, the AWOS/ASOS facility shall be assigned an available 25 kHz
air/ground frequency, with first consideration given to (a) or (b) below.
(a) 120.000 MHz is available for AWOS/ASOS requirements at non-air traffic control tower
locations, and at air traffic control tower locations if the AWOS/ASOS transmit antenna is located at least 2,000
feet from the tower cab.
(b) The frequencies 121.425, 121.450, 121.550, and 121.575 MHz (i.e., guard band frequencies for
121.500 MHz) are available for FAA AWOS/ASOS installations, subject to stringent emission mask
requirements. These frequencies shall not be used to satisfy non-FAA requirements unless coordination is
undertaken with Technical Operations ATC Spectrum Engineering Services to ensure that special action is taken
to implement sufficiently stringent emission masks, as part of the transmitter specifications, and on-going
maintenance procedures to satisfy the special requirements of using these frequencies.

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b. If a Nondirectional Beacon (NDB) is available and desired, the AWOS/ASOS may be broadcast over
the NDB, when the AWOS/ASOS facility will be within 3 nmi of the NDB. This does not apply to twofrequency NDBs that are not capable of voice transmission. The NDB frequency must be in the 325-415 kHz
range to support voice.
c. Power output of an AWOS/ASOS operating on a discrete VHF channel should not exceed 2.5 W.
d. Service volume of an AWOS/ASOS operating on a discrete VHF shall not be less than 15 nmi and 5,000
feet AGL and is normally limited to 25 nmi and 10,000 feet AGL. Requirements in excess of this value must be
approved by the concerned service area air traffic organization. Under no circumstances shall the radius of the
service volume exceed the terminal control area.
e. Frequency protection ratio (D/U) for an AWOS/ASOS operating on a discrete VHF channel shall be a
minimum of:
(1) 14 dB from an aircraft at the edge of the AWOS/ASOS service volume to another co-channel ATIS,
AWOS or ASOS.
(2) Beyond RLOS separation from a potential interferer at the edge of an FPSV to the transmitter site of
the AWOS/ASOS. NOTE: The minimum separation is inclusive, i.e., both (1) and (2) must be met.
f. If the proposed AWOS/ASOS facility does not conform to the criteria in subparagraphs a. through e.
above, the FAA may not assign the system a broadcast frequency.
906. BACKUP COMMUNICATIONS. In many cases, backup communications facilities are maintained to
preclude a total loss of services at air traffic control facilities. In the enroute environment the Backup Emergency
Communications system (BUEC) has been in place for many years. In the large TRACON environment there are
now many facilities with Emergency Communications Systems (ECS) that function much like the enroute BUEC
systems. Many airports also separate their primary and secondary radios to eliminate single points of failure in
their communications system. Additionally, most towers have portable battery operated radios for emergencies.
a. The enroute BUEC radio system is changing from a system that used a few strategically located tunable
radios to provide backup service for the enroute facilities to a system that has a dedicated fixed tuned radio for
each enroute sector. This new Sustaining BUEC system is being implemented within the Sustaining BUEC
program.
(1) The tunable BUEC system has been scheduled for de-commissioning and removal by early 2006. It
was typically located at enroute radar sites because of the access to the FAA microwave backbone as an
alternative means of connecting to the ARTCCs. These tunable BUEC radios were not easily colocated with most
fixed tuned FAA radios, because they were more susceptible to cosite RFI than the fixed tuned FAA radios.
(2) The Sustaining BUEC system provides a dedicated backup radio tuned to the ATC sector frequency
for each primary transmitter supporting a sector. The FMOs shall ensure that the site selected for the location of
the Sustaining BUEC radio provides the necessary coverage for the sector or portions of the sector that the
primary facility covers, and must satisfy the full frequency engineering criteria for a Remote Control Air/Ground
(RCAG) frequency assignment. A Sustaining BUEC shall not be colocated in the same facility as the primary
radio. Any exceptions to these requirements must be justified by waivers jointly approved by Technical
Operations, and Enroute and Oceanic Services.

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b. The large TRACON ECS system is much like the Sustaining BUEC system. The FMOs shall ensure that
the site selected for the location of the ECS radio provides the necessary coverage for the airspace that the
primary facility covers and must satisfy the full frequency engineering criteria for a Remote Transmitter/Receiver
(RTR) frequency assignment. An ECS radio shall not be colocated in the same facility as the primary radio. Any
exceptions to these requirements must be justified by waivers jointly approved by Technical Operations and
Terminal Services.
c. When the main and standby radios are located in separate facilities on an airport, both radios shall have
their own GMF assignment. The two assignments shall be select keyed with each other and labeled as the main or
standby radio in the “Remarks” section of the GMF record.
d. The portable battery operated emergency radios used in towers are not normally listed in the GMF.
e. Dedicated back up or emergency frequencies (excluding 121.500 and 243.000 MHz) shall not be
allowed at any location.
907. TEMPORARY ASSIGNMENTS. Requests to provide temporary frequency assignments for air shows,
fire fighting, military exercises, and other events are a normal part of the FMO duties. Each of these situations is
different and requires the FMO to understand the function of each temporary frequency requested.
a. Air Shows are common events typically occurring during the summer months. The aircraft coordination
at air shows fall into one of three basic categories: FAA controllers in temporary towers, military controllers in
temporary towers, and non-Fed air boss’ coordinating aerial activities. In all cases, the FMO shall review the
frequency requests to ensure the radius, flight level, function, and numbers of frequencies are consistent with the
delegated airspace, types of aircraft, and size of the facility. Military aircraft shall use UHF frequencies unless
there is only a single VHF frequency for the air show. Separate VHF frequencies for military aircraft shall not be
issued. Extra or spare frequencies shall not be issued. The Search and Rescue frequency 123.100 MHz may be
issued as an air show frequency with the understanding that the air show may be preempted if a Search and
Rescue operation occurs in the vicinity of the air show.
(1) For the case with FAA controllers in temporary towers, the FMO shall engineer the appropriate
frequencies and enter them into the AFM using an air show temporary (AS T) prefix for the serial number. The
temporary assignment shall contain the start and stop date for the air show (a day or two may be added to the
beginning and/or end of the scheduled air show duration to accommodate practice days and/or arrival and
departure coordination if requested). All temporary air show assignments shall be deleted from the AFM once the
air show dates are past.
(2) For the case of military controllers in temporary towers, the FMO shall follow the procedure for
FAA controllers but shall not release the frequencies to the requestor. The FMO shall instruct the requestor that
frequencies have been reserved for the air show and tell the requestor that they must obtain a temporary
assignment for the air show frequencies through the appropriate DOD National Frequency Management Office.
Once Technical Operations ATC Spectrum Engineering Services has received a temporary frequency request for
the air show from the appropriate DOD National Frequency Management Office, the frequencies will be released.
(3) For the case of non-Fed air boss’ coordinating the aerial activities, these requestors should normally
be referred to the FCC. The FCC will typically authorize the use of an FCC controlled frequency for the air show.
However, there are cases where the FCC frequencies are too congested for use by a non-Fed air boss, and it is
prudent to allow an ATC frequency to be used for the air show. As in the case of the military controllers, the
FMO shall not release the frequency to the requestor. The requestor must obtain a temporary license from the
FCC for the air show. The FAA will give the frequency to the FCC when the temporary request is processed.

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For some special events (e.g., Oshkosh or Sun-N-Fun) permanent frequencies may be assigned and placed in the
GMF. These assignments require the prior concurrence of Director of Technical Operations ATC Spectrum
Engineering Services and must be clearly labeled as frequencies for the special event. The FMO should be aware
of these permanent frequencies and use them to meet other temporary requirements whenever possible.
b. Fire Fighting frequencies are assigned to assist various agencies involved in aerial fire fighting activities.
All fire fighting frequencies are coordinated through the National Interagency Fire Center (NIFC). Requests from
individual agencies, states, or local governments should be referred to NIFC. In the more fire prone (i.e. Western)
portions of the United States, fire fighting sectors have been established to coordinate fire fighting activities.
A fire fighting frequency is typically assigned to each of these sectors to allow immediate response to any
reported fire. The frequencies for these sectors should be reused as often as possible realizing that fire fighting
aircraft typically operate within 1000 feet of the ground. This frequency is typically assigned for the entire fire
season (April-October). The FMOs may set aside a second frequency for each of these sectors to be available for
quick release if fire activity escalates in a particular area. As fire activity increases, additional project fire
frequencies may be engineered for specific fire efforts. Once these project fires are contained these frequencies
should be released back to the FAA. In addition, tanker base frequencies are also issued for the fire season. All
fire fighting frequencies shall be placed into the AFM using the fire fighting temporary prefix (FFT) and shall
have a current year serial number. All other fire fighting assignments shall be deleted from AFM.
c. Military exercises often involve requests for VHF and UHF air/ground frequencies. The FMO must
carefully evaluate the request presented from the military and should discuss the exercise with the concerned
service area air traffic organization. Most military exercises are normally to support military training and do not
justify the use of VHF air/ground frequencies; however, in some of these cases, a single VHF air/ground
frequency may be issued for the exercise. In a few cases, the military exercise involves the delegation of airspace
to the military to provide ATC services to everyone in that airspace. If the delegated airspace is open to the flying
public, then paired VHF air/ground frequencies are required for each UHF frequency. The use of contracted civil
aircraft and COTS training aircraft that do not have UHF radios does not justify the use of 118.000-137.000 MHz
frequencies in military exercises. The FMO shall engineer the military exercise frequencies and enter them into
AFM using the appropriate military temporary prefix (AR T, AF T, N T) but shall not release the frequencies to
the requestor. The FMO shall instruct the requestor that frequencies have been reserved and tell the requestor that
they must obtain a temporary assignment for the exercise through the appropriate DOD National Frequency
Management Office. Once Technical Operations ATC Spectrum Engineering Services has received a temporary
frequency request from the appropriate DOD National Frequency Management Office, the frequencies will be
released.
d. Other temporary assignments may arise as seasonal activities or search and rescue training. For search
and rescue training, the frequency 122.900 MHz is specified in the FCC rules for use by the Civil Air Patrol and
state or local agencies engaged in search and rescue training. These groups should not use 123.100 MHz for
training. For guidance on other temporary VHF and UHF air/ground communications requests contact the
Technical Operations ATC Spectrum Engineering Services National VHF and/or UHF frequency band manager.
908 thru 999. RESERVED.

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CHAPTER 10. NAVIGATIONAL AID (NAVAID) FREQUENCY ENGINEERING
1000. PURPOSE. The purpose of this chapter is to present an overview of the frequency engineering necessary
for ILS [including Transponder Landing System (TLS)], VOR, VHF Omnidirectional Radio Range Test (VOT),
Area VOT (AVOT), Distance Measuring Equipment, Normal (DME/N), Precision Distance Measuring Equipment,
Precision (DME/P), Tactical Air Navigation (TACAN), Microwave Landing System (MLS), Local Area
Augmentation System (LAAS), Wide Area Augmentation System (WAAS), Automatic Dependant Surveillance Broadcast (ADS-B) and the Global Positioning System (GPS). The detailed frequency engineering for these
NAVAID facilities is discussed in Appendix 3.
1001. NAVAID FREQUENCY ALLOCATION. NAVAID facilities are dependent upon the use of the RF
spectrum. A summary of the present international and national frequency allocations for NAVAID is shown in
figure 10-1.
FIGURE 10-1. NAVAID BAND USE

FACILITY TYPE
ILS LOCALIZER

FREQUENCY BAND (MHZ)
(LOC)

108.1 - 111.95

LAAS

112.0 - 117.975

ILS GLIDESLOPE (GS)

328.6 - 335.40

ILS MARKER BEACON
ADS-B

75
978.0

VOR, VOT, AVOT

108.00 - 117.975

DME/N, DME/P, TACAN

960.0 - 1215.0

MLS

5031.0 - 5090.7

GPS L5

1176.45

GPS L1

1575.42

1002. BASIC PRINCIPLES OF NAVAID FREQUENCY ENGINEERING. Due to the fixed number of
frequencies available for NAVAID facilities, each NAVAID frequency is reused as often as possible throughout the
country. NAVAID frequency engineering provides an interference-free assigned environment for each NAVAID
facility within its FPSV. Each type of NAVAID has its own characteristic FPSV, and each is defined in Appendix
3. NAVAID frequency engineering involves two frequency analyses: intersite and cosite.
a. Intersite Analysis is necessary to prevent RFI between facilities on the same and adjacent frequencies
providing service in different or adjacent areas. The basic factor considered in intersite analysis is the D/U ratio, as
seen at the airborne NAVAID receiver input. All NAVAID frequency assignments must meet certain D/U ratio
values (see Appendix 3). For example, a VOR assignment must meet 23 dB ratio for cochannel D/U within its
FPSV. The 23 dB ratio is based upon the ICAO standard of required 20 dB D/U ratio, with the addition of a 3 dB
factor to allow for the facility power decreasing 3 dB before its monitor shuts it down. The required D/U ratios for
each type of VHF/UHF/SHF NAVAID for cochannel and adjacent channels are provided in Appendix 3.

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b. Cosite Analysis is necessary to prevent RFI resulting from the interaction of transmitters and receivers at or
near the same site. Cosite RFI includes intermodulation products, cross-modulation, receiver desensitization
(overload), adjacent channel signals, harmonics and AM/FM/TV interference.

1003. NAVAID FREQUENCY ENGINEERING METHODS. The cosite analysis procedure is discussed in
Appendix 3. It will not be repeated in this chapter. As for intersite analysis, there are two basic methods for
determining whether a proposed frequency meets the required D/U ratio criteria.
a. Method 1: Use of Reference Tables. A series of reference tables will be found in Appendix 3, which
shows conservative worst-case separation distances required for each NAVAID type. If the proposed new facility
meets all the separation requirements of appropriate reference tables, no further search is necessary, and the
frequency application may be prepared. This method is discussed in detail in Appendix 3.
b. Method 2: Calculation of Required Separation. In frequency-congested areas, it is necessary to use a
more accurate and detailed method of determining the required separation distance. The calculation method takes
the following equipment parameters into consideration and the required D/U ratio is adjusted accordingly:
(1) Transmitter power.
(2) Antenna gain.
(3) Antenna directivity.
(4) Antenna orientation.
1004. EQUIVALENT SIGNAL RATIO (ESR). The adjusted D/U ratio is called ESR. A series of curves based
on this ESR will be found in Appendix 3, showing the required separation distance. The detailed procedure for
calculating the ESR and using the curves is discussed in Appendix 3.
1005. EXPANDED SERVICE VOLUME (ESV). An ESV is a special volume of airspace outside of the
normally specified FPSV. Each ESV is engineered using the same criteria as for the FPSV. In addition to meeting
the required D/U ratio criteria, each ESV shall also meet certain minimum signal strength requirements as
prescribed in Appendix 3. Since ESVs are not registered in the NTIA GMF, Technical Operations ATC Spectrum
Engineering Services maintains a separate data base within the AFM for all ESVs used in the NAS. The detailed
procedures for engineering ESVs and updating the ESV data base are discussed in Appendix 3.
1006. SPECIAL ISSUES TO BE CONSIDERED.
a. NAVAID 50 kHz Assignments. Since some general aviation aircraft may not yet be equipped with
50 kHz (200-channel) navigation receivers, every effort shall be made to find a 100 kHz assignment for a NAVAID
facility before assigning a 50 kHz channel.
b. Paired NAVAID Assignments. To minimize a potential safety hazard, frequency protection shall be
provided for all services associated with a facility, even if only one service is installed. When an ILS LOC is
assigned, the associated DME frequency shall be frequency protected even if no DME is installed. The same holds
true for VOR/DME/TACAN and MLS/DME/P and MLS/DME/N.
c. Localizer Receiver Desensitization Due to In-Band Localizer Signals. Interference between localizers
serving different runways at the same airport is possible depending on the configuration of the runways and the
distance between the two systems. When an aircraft on approach passes through a strong radiation field of a

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localizer serving a reverse or an adjacent runway, the ILS siting criteria (FAA Order 6750.16) requires that a
positive interlock device be installed to prevent both systems from transmitting simultaneously. FMOs may be
asked to evaluate waivers to this siting policy at airports where more efficient use of runways is required.
The FMO must analyze the specific situation and geometry so that airborne ILS avionics are not desensitized due to
other localizers at the airport. The following policy is provided:
(1) An undesired localizer signal level of -33 dBm will not be exceeded within the FPSV of a
collocated ILS.
(2) Calculations will be done using the free space formula.
d. VOR/DME/TACAN Collocation Assignments. Some VOR/DME/TACAN facilities that were in place in
1980 were engineered under criteria slightly different than that shown in Appendix 3. As such, any installations,
which have passed flight inspection satisfactorily in the past, shall be considered as conforming to these criteria.
However, any new facility frequency engineered shall adhere to the criteria presented in
Appendix 3.
(1) The greater distance separation of the individual frequency paired VOR/DME/TACAN shall be used.
In facilities of equal power, the criteria charts and graphs will show that the DME/TACAN required separation is
greater than that of any paired VOR for most conditions.
(2) In all cases, the GREATER requirement shall be used as minimum separation for the frequency pair,
regardless of whether both paired facilities are installed.
e. DME at ILS Locations. ILS/DMEs generally require separation distances far beyond that provided for the
LOCs due to the DME's separation criteria and omnidirectional antenna pattern. Therefore, it is important to ensure
that when engineering an ILS LOC frequency, its associated DME meets the required separation, even if no DME
is installed. In frequency congested areas, the frequency protection for the DME may not be possible without using
50 kHz NAVAID frequencies. If the DME is not actually installed, the DME frequency protection may be waived
through the normal NAS Change Proposal (NCP) process.
f. DME/P and DME/N at MLS Locations. The conditions are the same as with DME at ILS locations.
g. Potential FM/TV Interference. Because of an abundance of FM and TV high power transmitters around
the country, an approach or an airway may place an aircraft over or very near one of these transmitters. Their
overwhelming power, frequently on the order of a megawatt or more ERP, can cause severe overloading of the
front end of aircraft receivers, and thus the loss or deterioration of NAVAID reception. A routine item to be
checked for problems in a frequency study shall include the verification of nearby FM or TV transmitters. Of
particular concern are the FM transmitters near the upper end of the FM broadcast band because it is immediately
adjacent to the 108.0-117.975 MHz NAVAID band. All new ILS and VOR proposals will be evaluated using the
AAM to determine the potential for any interference from FM and TV Broadcast stations. See Appendix 1 for
further discussion of FM/TV interference.
h. Collocated NAVAIDS. At some sites, a VOR/DME/TACAN or ILS/DME paired facilities may not be
actually collocated. To meet ICAO and FAA standards, such paired facilities must be installed within the
distances specified in the Appendix 3, or else the two facilities may not be frequency paired. An ILS/DME may be
collocated with either the LOC or the GS transmitters.

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i. Terrain Shielding. A transmitter's signal strength in space can be affected by the shielding of terrain,
buildings, vegetation, etc. This can have an impact on the D/U signal ratios in space. If shielding is severe, it may
be possible to provide the required D/U signal ratios with less than the recommended station separation.
The use of terrain shielding, as a way to decrease the separation requirement, should be treated on a case-by-case
basis through sound engineering judgment. This facility must be flight checked with satisfactory results and
documented through the normal NCP process.
j. LAAS spectrum support will be referred to Technical Operations ATC Spectrum Engineering Services for
engineering and assignment action.
k. ADS-B currently uses the Universal Access Transceiver (UAT) and transmits on 978.0 MHz. The UAT
transmits ADS-B data air-to-air for cockpit display and air-to-ground for use by ATC. The UAT may receive
ground-to-air Flight Information Service (FIS) and Traffic Information Service (TIS) data for cockpit display.
l. WAAS transmits on GPS frequency L1 from geosynchronous satellites that cover the continental U.S.
(excluding Alaska).
m. GPS frequency L5 is expected to be implemented starting with the Wide Area Augmentation System
(WAAS) geostationary satellites by 2007, with the GPS constellation implementation to follow in the 2010-2015
time frame. Since L5 transmits on 1176.45 MHz, it was previously considered that some TACAN/DME frequency
changes might need to be made to accommodate L5. However, after considerable study it has been concluded that
no TACAN/DME frequency changes will be required in the NAS to provide satisfactory L5 operation.

1007. thru 1099. RESERVED.

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CHAPTER 11. LOW/MEDIUM FREQUENCY (L/MF) GROUND NAVIGATIONAL AIDS
1100. PURPOSE. The purpose of this chapter is to describe the necessary techniques and actions required to
provide a frequency for a low/medium frequency (L/MF) NAVAID. L/MF includes Compass Locator (COMLO)
and Nondirectional Beacon (NDB), also known as a "Homer."
a. The COMLO is an NDB, usually of low power, strategically located on an ILS approach path to provide
L/MF azimuth guidance to an airport, in addition to the more precise guidance of the ILS LOC. COMLOs are
normally collocated with ILS Outer Markers (OM) and Middle Markers (MM), and referred to as "LOM" and
"LMM," respectively. The LOM transmits, in Morse code, the first two letters of the associated ILS identifier.
The LMM transmits the last two letters of the associated ILS identifier. For example, COMLOs installed with the
Los Angeles, CA (LAX) ILS would be "LA" for the LOM and "AX" for the LMM. To the extent possible, the
frequencies of the LOM and LMM shall not be separated less than 15 kHz nor more than 25 kHz.
b. The NDB is a free-standing nondirectional radio beacon designed to provide navigational service over a
specified radial distance from the facility. It can have power from 10 W to 1000 W, typically 25 W, depending on
the need. It should be noted that due to very heavy congestion in this band, the FMO shall do everything possible,
by coordinating with the concerned service area air traffic organization and FS, to engineer the lowest possible
emitted power to cover the requirement. The Aeronautical Information Management (AIM) in System Operations
Airspace and AIM is responsible for the coordination of requests for three-letter location identifiers.
Coordination with this organization is accomplished by each service area through the concerned air traffic
organization.
1101. GENERAL CONSIDERATIONS.
a. NDB and COMLO are treated the same for frequency assignment purposes. For simplicity, only the term
NDB will be used hereafter when it is intended to refer to both.
b. An NDB frequency selection model is available on the AFM for engineering NDB requirements.
c. A required signal level of 70 microvolts per meter (uv/m), which is also 37 dB above one microvolt per
meter (dBuv/m), is the standard set for the signal required at all points on the outer limits of the NDB FPSV. If
the NDB transmitter power decreases by 3 dB, the resultant signal would be equivalent to 50 uv/m at all points on
the outer limits of the NDB FPSV. At this point, the remote NDB alarm is triggered.
d. The D/U signal level standard for an NDB is 15 dB. This provides an assured 12 dB protection of the
FPSV when the desired signal decreases 3 dB from the normal operating power. At this point, the system should
alarm.
e. Channelization of the band is 1 kHz. First adjacent channel is 1 kHz removed, second adjacent is 2 kHz
removed, etc.
f. The mode of radiation is considered to be ground wave, while acknowledging that, particularly at night,
sky wave does enter into propagation mode.
g. The FPSV is considered to be a cylindrical volume of airspace, centered on the NDB, with no upper
altitude limit. Since the ground wave is the principal radiation factor, the signal level in any given direction is a
function of the antenna efficiency, the ground system associated with the antenna and the ground conductivity
medium through which the signal passes to get to the point under consideration.

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h. NDB FPSV's are classified as follows:
(1)

LOM/LMM

15 nmi radius

(2)

MH (less than 50 W)

25 nmi radius

(3)

H (50 w or more, but
less than 2,000 W)

50 nmi radius

HH (2,000 W or more)

75 nmi radius

(4)

i. An NDB's primary function is as a NAVAID, However, voice modulation is permitted in addition to the
required Morse code identifier only on a secondary basis, and then only when it causes no interference to any
other facility as a result of the additional voice modulation.
j. An NDB for non-Federal use, which requires a frequency request through FCC, has the same priority as
an FAA or other Federal agency facility, provided that the proposed NDB has an FAA approved procedure on it.
Any other non-Federal use is on a secondary basis, assignable only if:
(1) The facility could be accommodated without moving or otherwise affecting FAA facilities in
any way.
(2) FAA concurrence with use of the frequency is contingent upon the frequency being withdrawn upon
notice by FAA in writing at any time it is needed for a facility which has a procedure and is in the NAS.
k. Permissible power is that normal power level which just meets the level required to assure 70 uv/m at the
circumference of the FPSV. In some unique instances, due principally to poor ground conductivity, it may be
impossible to meet the signal level requirement at some azimuths. In this case, an option, if FS and the concerned
air traffic organization concur, could be to commission with restrictions.
l. There is little difference in the signal level between ground and any altitude normally flown by aircraft
within the FPSV specified. As a general rule, the signal level measured at any altitude is considered to be the
same as found at ground level and all other altitudes at that azimuth.
m. A dual carrier NDB has an upper sideband (only) with full carrier. It radiates a Continuous Wave (CW)
carrier on the assigned frequency. The identification signal is provided by an on/off keying of a second carrier,
transmitted at a frequency equal to the first carrier frequency plus the frequency of the modulation tone. For
example, at a carrier frequency of 200 kHz, the second carrier would be at 200.4 kHz (for a 400 Hz identifier) and
at 201.02 kHz (for a 1020 Hz identifier). For purposes of registering in the GMF, the emission designator would
be 500HXXA and the center frequency would be 200.2 kHz (for a 400 Hz identifier) and 1.112XXA emission
designator and 200.51 kHz center frequency (for a 1020 Hz identifier).
1102. FREQUENCY ALLOCATION FOR L/MF FACILITIES. The frequencies allocated for L/MF use are
shown in figure 11-1.

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FIGURE 11-1. L/MF NAVAID FREQUENCY ALLOCATIONS

Frequency
(kHz)
190 - 200

Limitations & Comments
AR Primary

200 - 275

AR Primary; AM Secondary

275 - 285

AR Primary; AM Secondary; MR Secondary

285 - 325

MR Primary; AR Secondary

325 - 335

AR Primary; AM Secondary; MR Secondary

335 - 405

AR Primary; AM Secondary

405 - 415

R Primary; AM Secondary

415 - 435

MM Primary; AR Primary

510 - 525

AR Primary; MM Primary

525 - 535

AR Primary; M Primary

KEY
AR - Aeronautical Radionavigation (FAA & Non-Fed. NDB's)
MR - Maritime Radionavigation
R - Radionavigation
MM - Maritime Mobile
M - Mobile
(For detailed definitions, see NTIA Manual, Chapter 6.)

a. NDB voice is not permitted in the bands 190-199.9, 285-324.9, and 415-535 kHz.
b. The band 525-535 kHz use by Mobile Service is limited to the Travelers' Information Service (TIS),
operating on 530 kHz. Voice modulation of NDB's is not permitted in this band.
AR stations are authorized for off-shore use only, on a non-interference basis to TIS.
c. Maritime radiobeacons in the 285-325 kHz band segment will not be used for aeronautical operations. In
addition, FMO's will avoid use of the 285-325 kHz band segment for aeronautical radiobeacons because of the
incompatibility between aeronautical NDB receivers and the maritime NDB's which transmit DGPS signals for
use by maritime users.

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1103. ENGINEERING CONSIDERATIONS FOR L/MF FREQUENCY SELECTION. It is unfortunate,
but frequency engineering for L/MF facilities is not a straight-forward technical operation. There are several
reasons for this.
a. L/MF propagation is not an omnidirectional straight line decay of signal situation. Since ground wave is
involved to a considerable degree with the conductivity of the ground in each azimuth direction, there can be wide
variations of signal strength in different directions from a single antenna.
(1) An antenna near a body of water, particularly ocean water, will have greatly increased radiation in
the azimuths covered by the ocean, while inland azimuths will retard radiation due to signal losses caused by
poorer conducting earth. As an example, an NDB on the northern Florida east coast will have very efficient
radiation into the Atlantic Ocean. But because the ground conductivity is very poor there, signals radiated to the
west would be much reduced.
(2) A specific example would be that at 50 nmi to the west, a signal of 20 uv/m would be measured from
a 25 W NDB. The same signal measured eastward to sea (assuming the NDB to be on or very close to the beach)
would produce 70 uv/m, or an approximately 11 dB stronger signal.
(3) Night-effect can occur because an NDB radiates both a ground wave and a sky wave. The ground
wave is usable for navigation within the operational service volume. The sky wave is radiated up into space and
reflected back to earth by the ionosphere. This reflection results in the presence of an attenuated sky wave at
varying distances from the NDB ground station. The distance and the amount of attenuation are determined by
the height and density of the ionosphere and the angles at which the radiated sky wave strikes the ionosphere.
Sky wave field strength is subject to changes in the ionosphere. This is similar to the conditions for HF described
in chapter 7. These changes occur as a function of the time of day, time of year and phase of the solar cycle. At
night, the reflective property of the ionosphere increases for L/MF and the lower HF bands resulting in a sky
wave field strength that can be substantially larger than during the day.
b. A ground system consisting of four copper wires, equally spaced radially about the base of the antenna,
would give a smaller signal at any given point as compared to the same antenna with 30 equally-spaced copper
radials.
c. There are no "standard" antennas, so whatever antenna is installed will affect the radiation efficiency.
The most common antennas used are the symmetrical "T" and the top loaded vertical or "Top Hat."
d. Ground conductivity charts are only approximate, and the various curves used are an average of
empirical data.
e. With all those limitations, it can be seen that the process which will be described is only an estimate of
the level of signal to be expected at the periphery of the FPSV.

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FIGURE 11-2. ESTIMATED GROUND CONDUCTIVITY IN THE UNITED STATES

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1104. BASIC TOOLS. The basic tools used in engineering frequencies for L/MF are the ground conductivity
map and the prediction curves.
a. The Ground Conductivity Map. Refer to figure 11-2. The conterminous U.S. (CONUS) is divided up
into small "jig-saw" segments with numbers in each piece. Those numbers are the numerical value of
"millimho/m" (mm/m) and represent units of reluctance, the unit used to represent average electrical conductive
quality of the ground in the area. A value of 1 to 4 is poor; 8 is good; 15 and 30 are so good that they are
practically indistinguishable from sea water. Sea water, the reference at 4,000, is the ideal. These values will be
more meaningful when they are compared with the other tool, the coverage and interference prediction curves.
b. Prediction Curves. Refer to figure 11-3. These curves are designed to give the user a predicted level of
signal at a given distance from the transmitter. The three shaded curves are for "poor" ground at 1 to 4 mm/m,
"good" ground at 8 mm/m and sea water at 4000 mm/m. Conductivity values between 1 and 4000 must be
interpolated.
(1) There is a frequency factor in the curves. The frequency range covered is over 2:1. Conductivity
varies with frequency so that the left side of each curve is 400 kHz and the right side is 200 kHz. Frequencies in
between must be interpolated.
(2) The curves are normalized to 300 kHz and so have an antenna efficiency factor which is shown
between 200 kHz and 400 kHz. The antenna radiation correction factor for frequencies in between must be
interpolated.
(3) There are corrections for receiver intermediate frequency (IF) selectivity. While newer receivers
will have quite sharp IF selectivity, until such time as the large majority of airborne receivers are of that group,
the receiver correction values shown on the chart shall be used.
(4) Typical facility types, as related to average radiation level from usual antennas, are shown as a series
of parallel straight lines. Where the line intersects the 0 dB abscissa, the indicated μv/m value (good only on the
"0 dB" line) is that predicted at 1 nmi.
(5) The vertical scale for the abscissas is the dB value below signal voltage level at 1 nmi. For instance,
the 25 W NDB line shows an expected level of 3700 uv/m at 1 nmi. Its intersection with the 70 uv/m service
radius at the -34.5 dB abscissa, when followed to the inverse distance line, indicates that a level of 70 uv/m would
occur over perfectly-conducting ground at 50 nmi. In propagation, field voltage decays inversely as the distance.
Power varies inversely as the square of the distance. A signal voltage at 2 nmi is 6 dB less than that signal level at
1 nmi. The "inverse distance" line runs from 1 mv/m to 1000 mv/m. The distance and voltage are inversely
proportional and their ratio is 1000:1. It can be seen that dB = 20 log (E1/E2) = 20 log 1000 = 20 X 3 = 60 dB.
The inverse distance line is from 0 to –60 dB.

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FIGURE 11-3. COVERAGE AND INTERFERENCE PREDICTION CURVES

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1105. ENGINEERING PROCEDURES.
a. Conductivity. Required facility geographical separation (S) is calculated by using figures 11-2 and 11-3.
Figure 11-2 shows the ground conductivity in mm/m which determines which curves to use in figure 11-3.
b. Separation Distance (S). (S) is the minimum distance required between facilities to prevent interference
and is defined as:

(S )= dD + dU

where dD

= distance from the desired facility to the edge of its service volume

dU = distance from the undesired facility to the edge of the desired service volume
c. Calculation of Required Separation Distance.
(1) Find the facility service volume dD in nmi on the bottom of figure 11-3. Move up to intersect the
appropriate ground conductivity curve from figure 11-2, interpolating for frequency. Note the attenuation value
in dB at the left of figure 11-3.
(2) Add the antenna radiation correction factor shown in figure 11-3 to the dB value in
subparagraph 1.
(3) Algebraically add the correction factor to subparagraph 2 for difference in facility power. For
example, if the undesired facility is 50 W and the desired facility is 25 W, add -3 dB.
(4) Add the receiver correction value to subparagraph 3 when the undesired station is within ±6 kHz of
the desired station. The "Undesired receiver correction with voice" shall be used first. If a frequency cannot be
engineered using that value, the "Undesired receiver correction without voice" may be used only if the desired
station does not have transmit voice.
(5) Algebraically add -15 dB to the value obtained in subpara. 4; this gives the D/U ratio of 15 dB
required.
(6) Use the dB attenuation value obtained in subparagraph 5 and find this level at the left of figure 11-3.
Move across to intersect the appropriate conductivity curves. This intersection determines dU in nmi from the
bottom scale.
(7) Add dD and dU to obtain the required separation (S) distance necessary for the desired facility to have
a minimum of 15 D/U.
(8) Determine the required (S) for the undesired facility in the same manner (now the undesired is the
desired and vice versa).

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1106. PRACTICAL EXAMPLE. See figure 11-4.

FIGURE 11-4. GEOGRAPHIC SEPARATION EXAMPLE

a. Station A, the desired station, is on 400 kHz, power 25 W, FPSV 25 nmi, with conductivity of 2 mm/m.
b. Station B, the undesired station, is on 400 kHz, power 50 W, FPSV 25 nmi,
also 2 mm/m.
c. Calculating Station A Distances.
(1) Find the facility dD of 25 nmi FPSV at the bottom of figure 11-3. Move up and intersect the 400 kHz
2 mm/m curve. Note the attenuation value of -37.5 dB at the side of the graph.
(2) Algebraically add -3 dB radiation correction factor to the value of subparagraph 1: -37.5 + (- 3) =
-40.5 dB.
(3) Determine the dB power difference: PD/PU = 25/50. 10 log ½ = -3 dB. Add that value to the value
of subparagraph 2: -40.5 - 3 = -43.5 dB.
(4) Determine the receiver correction value. In this example, the stations are on the same frequency,
receiver correction is 0 dB, so the value remains -43.5 dB.
(5) Algebraically add -15 dB to the value obtained in subparagraph 4: -43.5 + (- 15) = -58.5 dB.
(6) Find the value -58.5 dB at the left of figure 11-3 and move across to intersect the 400 kHz curve for 2
mm/m. From the scale at the bottom of the graph, note the value is 90 nmi.
(7) Add dD + dU = 25 + 90 = 115 nmi, the required separation for (S).

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d. Calculating Station B Distances.
(1) Find the facility FPSV dD of 25 NM at the bottom of figure 11-3. Move up and intersect the 400 kHz
2mm/m curve. Note the attenuation value of -37.5 dB. See subparagraph c(1).
(2) Algebraically add -3 dB antenna radiation correction factor to value of subparagraph 1:
-37.5 + (- 3) = -40.5 dB.
(3) Determine the dB power difference: PD/PU = 50/25. 10 log 2 = +3 dB. Add that +3 db to the value
of subparagraph. 2: -40.5 + 3 = -37.5 dB.
(4) Determine the receiver correction factor to be 0 dB, so the value remains at -37.5 dB.
(5) Algebraically add -15 dB to the value in subparagraph 4: -37.5 + (-15) = -52.5 dB.
(6) Find the value -52.5 dB on the side of figure 11-3 and move across to intersect the 400 kHz 2 mm/m
curve. Note the value is 65 nmi.
(7) Add dD + dU = 25 + 65 = 90 nmi, the required (S).
(8) Compare the required separations for each calculation. Note that the larger requirement is 115 nmi,
and the larger is always used.
1107. AIRBORNE MEASUREMENTS.
a. The same kind of measurements (for the proposed facility) could be made from a flight inspection
aircraft. The problem is in the receiving antenna in the aircraft. A calibrated loop remains as a calibrated entity
only as long as its surroundings are nominal, or at least not changing. With a loop on an aircraft, any change of
aircraft position with respect to the plane of the loop which has to be maximized with respect to the signal source
will nullify its calibration. The cost of using a flight inspection aircraft is prohibitive to be used as a "study"
vehicle.
b. A FAA Study covering a comparison of airborne and ground measurement was completed in 1980. A
thorough report of that study is available for FMO consideration in Report No. FAA-R-6050.2, Low Frequency
Beacon Signal Strength Determination, dated January 1980.
1108.-1199. RESERVED.

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CHAPTER 12. MICROWAVE DATA/COMMUNICATIONS LINKS
FREQUENCY ENGINEERING
1200. PURPOSE. This chapter and its associated appendix provide the criteria for the engineering of
frequencies for each of the type of links indicated in the title. It does not supersede or replace existing
maintenance or installation instructions, but rather provides only that technical data required to provide the
frequency engineering necessary for each facility. Coordination between the frequency engineer and the
installation staff is essential to assure system viability.
1201. FREQUENCY BANDS AVAILABLE FOR RADIO LINKS. Radio frequency link engineering
involves two frequency analyses, cosite and intersite. The following bands are available for links as indicated.
FIGURE 12-1. BANDS CURRENTLY USED BY FAA FOR RADIO LINKS

162-174 MHz

Land Mobile*

Very congested band

406.1-420 MHz

Land Mobile*

Very congested band

932-935 MHz

Fixed Station

LDRCL

941-944 MHz

Fixed Station

LDRCL

1710-1850 MHz

Fixed Station**

LDRCL

7125-8500 MHz

Fixed Station

Radio Communications Link (RCL)

14.4-15.35 GHz

Fixed Station

TV Microwave Link (TML)

21.2-23.6 GHz

Fixed Station

Microwave links

* Specific frequencies are allotted for fixed operations such as Low Level
Windshear systems (LLWAS), RMM, MALSR, etc. (See chapter 17.)
** New requirements for radio links will not be satisfied in the 1710-1850 band.

a. The band 7125-8500 MHz is broken up by segments allocated to space communications. Only the
subbands 7125-7250, 7300-7900, and 8025-8500 MHz are available for fixed PTP links.
NOTE: The FR8 RCL will not operate in the 8400 to 8500 MHz band.
b. The band 14.5-15.35 GHz is broken into three sections. The portion 14.7145-15.1365 GHz is allocated to
other services on a primary basis. This subband must be avoided in planning Television Microwave Link (TML)
systems.

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c. Because of the wide variety of microwave equipment used by FAA, detailed engineering criteria are not
provided for all such systems. Detailed engineering criteria are provided for the FR8 because of its extensive use.
In general, when doing spectrum engineering for microwave systems, the intersite engineering should be done
first, since it is straightforward. When analyzing the cosite situation, care must be taken that image frequencies of
the system are considered. The appropriate manufacturer's equipment specifications should be consulted and the
general procedures of paragraph 1204 followed.
1202. INTERNATIONAL COORDINATION REQUIREMENTS. When systems are to be designed for use
within 100 nmi of the Canadian or Mexican borders, Technical Operations ATC Spectrum Engineering Services
should be notified very early in the project. There are international agreements with Canada and Mexico that
require coordination. Early coordination can prevent having to vacate a planned frequency group when it is found
to conflict with their operations.
1203. TECHNICAL STANDARDS FOR LINKS. See Chapter 5 of the NTIA manual. Technical data for FAS
applications for U/SHF systems are found in appendix 4.
1204. THE GENERAL PROCEDURE FOR MICROWAVE LINK INTERSITE FREQUENCY
ENGINEERING is basically an orderly step-by-step compilation of all the parameters of all potentially
competing systems. It simply consists of carefully examining every parameter that would affect the overall RF
path from a transmitter output to a receiver input. Essentially, the frequency is unimportant to the procedure
because the procedure is the same for 900 MHz as it is for 21 GHz. While Technical Operations ATC Facilities
sets the physical path, the frequency engineer must check the spectrum compatibility both as a potential interferer
to other established systems (culprit) and as a potential receiver of RFI from other systems (victim). See figure
12-3. The following is a general discussion of the detailed procedure followed by a simple format that is intended
to assist in assuring that all parameters are considered as well as providing a study record of each system analysis.
a. While the actual site path will be engineered by Technical Operations ATC Facilities, the frequency
engineer must be sufficiently familiar with certain of the engineering parameters to assure that the frequencies
engineered will work with the system.
b. Cosite considerations. Of particular importance are other microwave systems. For instance, the second
harmonic of much of the 7125-8500 MHz band falls into the 14.50-15.35 GHz band. FAA is not always able to
site its equipment on an exclusive FAA site, thus any other users' equipment must be considered.
c. Intersite and near parallel path considerations. The site shall be frequency engineered by checking the
GMF carefully for the full bandwidth of FAA's equipment and add to that the bandwidth of any other user's
equipment operating in the area. The parameters for determining the signal level at a victim receiver include the
proximity of frequency, receiver band pass characteristics, and the geographical location of the victim receiver.
Determination of the required azimuth separation from other users is also a matter of parameters as described in
paragraph d.
d. From the transmitter end, there are several parameters to be considered.
(1) Transmitter output power, specified in dBm, normally a positive value.
(2) Wave guide (feed line) power loss, in dB, always a negative value.
(3) Antenna gain in dB is always a positive value. However, the value for any given azimuth can vary
considerably from other azimuths. At microwave frequencies for links, high gain directional antennas are
required. The main beam peak gain is often in the range of 30 dB to 40 dB. However, only a few degrees off the
azimuth of the main beam, the gain is reduced considerably, to as much as -20 to -30 dB. It is essential that the
radiation pattern specified by the antenna manufacturer be available for determining the gain in a particular
azimuth.

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(4) Parabolic antenna gain calculations are approximated by a simple formula. Parabolic antennas are
considered to be between 55 percent and 65 percent efficient. This general formula is for nonstandard size
reflectors and for frequencies not commonly used for RCL and TML. A nomograph for parabolic antenna gains
is found in appendix 4. Assuming the nominal 55 percent value, the gain would be:

GdB = 20 log D + 20 log f + 7.5
Where:
GdB

=

gain over isotropic, in dBi

f

=

frequency in GHz

D

=

parabolic reflector diameter, in feet

Assuming a 6 foot diameter reflector at 7.700 GHz,
G

=

15.56 + 17.73 + 7.5

=

40.79 dBi, or approximately 41 dBi

(a) The forward gain of a high directional antenna is usually specified by the manufacturer in
decibels above an isotropic antenna (dBi) or decibels above a dipole antenna (dBd), with dBd representing a value
of 2.1 dB above dBi.
(b) The radiation pattern plot is usually shown in the manufacturer's instruction book or
specification sheet. This plot may be polar or linear, but both are shown with the main beam at 0 dB and all side
lobes shown as values less than the main beam reference gain value.
(c) The actual gain of the antenna at any given azimuth other than the primary main beam is that
value shown on the plot for the selected azimuth subtracted from the rated main beam gain. For instance, a
certain parabolic antenna is rated by the manufacturer at 43 dBd gain. The plot normally shows the main beam at
0 degrees, which represents the 43 dBd gain value. See figure 12-2. Use the HH plot, the upper solid line curve.
Looking at the plot at 15 degrees (the azimuth of the victim receiver), it is noted that at that azimuth, a minor lobe
has a value of -37 dBd. Thus, the gain in the direction of 15 degrees from the azimuth of the main beam would be
a value of 43 - 37 = 6 dBd. That value of 6 dBd is what is used as the "main beam" gain for subparagraph (3)
above.

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FIGURE 12-2. TYPICAL PARABOLIC MICROWAVE ANTENNA RADIATION PATTERN

e. It is necessary to calculate propagation loss as a parameter in assuring that the transmitter (Tx) power,
the antenna gain, minus the free space loss, plus the receiver (Rx) sensitivity all add up to a usable path. This
calculation is needed to determine the level of suspected signal in the vicinity of any competing user on the
frequency engineered, for compatibility. Free space propagation loss is not obtainable on the earth, due to

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atmospheric losses, reflections, etc. But using the basic free space propagation loss formula is as good an
approximation as can be gained without actually putting a signal on the air and measuring it at the receiving
location. That free space loss formula is:

Lfs (dB) = 37.8 + 20 log f + 20 log d
where: Lfs = free space loss, in dB
f = frequency, in MHz
d = distance in nmi
(for statute miles, the constant 37.8 changes to 36.6)
Assuming a 30 nmi path at 7700 MHz,
Lfs = 37.8 + 77.7 + 29.5
= 145 dB
f. A nomograph for space loss is found in appendix 4.
g. From the receiver end, there are other parameters to be considered.
(1) The receiver minimum signal level required for satisfactory operation. This value should have
already been determined by Technical Operations ATC Facilities in their siting study to assure adequate signal at
the receiver at all times. This level is always a negative dBm value and is specified by the manufacturer.
(2) The receiver system interference susceptibility level is specified by the manufacturer in the system
instruction manual or specification sheet. This value is usually in the form of a graph curve with dBm level on
the y axis and frequency on the x axis. See Appendix 4 for typical curves. This value in dBm is the value that
must ultimately be checked against the culprit's signal level at the victim receiver input terminals to determine
whether RFI is anticipated.
(3) The receiving antenna gain in dB at the azimuth of the culprit incoming signal. That gain is
determined in the same manner as for the transmitting antenna in subparagraph a. (3), above.
(4) The receiving wave guide (feed line) loss, always a negative value, in dB. This is determined from
the wave guide or feed line manufacturer's specification sheet.
h. The path fade margin is the one variable in the parameters. It is the loss of signal level at the receiver
from variable propagation losses, such as atmospheric moisture, air particle content, etc. The manufacturer of the
system will specify the path margin normally required to assure adequate signal from the desired source to the
desired receiver. While there is some variance among manufacturers and with frequency (higher bands are more
subject to these path fade problems), a manufacturer frequently will specify a 10 dB fade margin. That is, under
normal conditions, to assure that the minimum required signal is received by the desired receiver from the desired
transmitter during path fade conditions, an additional level of protection is engineered into the siting of the units
of the system. In this frequency compatibility study, however, a 15 dB D/U protection value shall be used which
includes the path fade and other parameters not absolute. See figure 12-3.

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FIGURE 12-3. POWER BUDGET STUDY FOR A MICROWAVE LINK

1. Undesired transmitter power

(+) _______ dBm

2. Undesiredt transmitter wave guide or feed line loss

(–) _______ dB

3. Undesired transmitter antenna gain in the direction of
the desired receiver. [1204 d.]
a. Main beam gain of the antenna

(+) _______ dB

b. Off-azimuth loss in the direction of the desired

(–) _______ dB

c. Total undesired antenna gain in the direction of
desired (sum of a. and b. above)

(±) _______ dB

4. Free space propagation loss. [1204 e.]

(–) _______ dB

5. Desired receiver antenna gain in the direction of
the undesired transmitter. [1204 g.]
a. Main beam gain of the antenna

(+) _______ dB

b. Off-azimuth loss in the direction of the undesired

(–) _______ dB

c. Total desired antenna gain in the direction of
undesired (sum of a. and b. above)

(±) _______ dB

6. Desired receiver wave guide or feed line loss

(–) _______ dB
________________

7. Undesired signal level at desired receiver input (TOTAL)

(±) _______ dBm

8. Desired receiver RFI susceptibility level. [1204 g.]

(–) _______ dBm

9. Difference between 7. and 8.

(±) _______ dB

The value of item 9 must be -15 dB or less (more negative) for interference-free operation
of the link. A 15 dB safety margin, over and above all other calculations, should be
provided for the receiver, to assure a positive D/U ratio under all conditions, including path
fades.

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i. Desired versus Undesired. When engineering a link frequency for FAA, the FAA transmitter is the
"undesired" culprit. All other receivers in place within RLOS (or at least 40 nmi) and within frequency range
must be checked as the "desired" or victim. When checking the FAA receiver situation, any other system
transmitter within the same bounds is the culprit. For both situations, FAA as a victim and a culprit, adequate
protection must be shown before the frequency(ies) can be submitted to Technical Operations ATC Spectrum
Engineering Services for approval. If another agency is proposing a new system and an FAA system is within
interference bounds, the other agency must assure protection. In some bands, that agency is required to
coordinate with the FAA to verify protection assurance. Even in the bands not requiring FAS coordination
notices, verify before approving or coordinating the proposal.
j. The most practical method to accomplish the study is to use these tools:
(1) A topographical or sectional map permits plotting and verification of the systems accurately by
coordinates. It is then easy to draw a straight line between the two systems and measure the azimuth deviation
from the respective antennas' azimuths heading for their own system.
(2) The AFM CIRCLE program will permit quick and easy access to all systems within the frequency
and distance ranges desired for the study.
(3) The AFM bearing/distance program will also provide quick and accurate azimuths and distances
between culprit and victim sites.
(4) Note that the final selection of the frequency(ies) may depend on terrain factors which are not easily
quantified but which may be apparent from a site survey or analysis of a topographical map.
(5) Use the format of figure 12-3 to determine the power budget and the D/U ratio.
k. Many FAA microwave systems use digital radios. It should be noted that nominally up to 10 dB of
additional margin may be required for digital receivers as compared to an equivalent analog receiver.
1205. FREQUENCY ENGINEERING FOR THE 932-935 AND 941-944 MHZ BANDS.
Engineering of LDRCL in these bands is straightforward. The channeling plans for these bands and other
constraints on their use are found in NTIA Manual, Chapters 4 and 5. Cosite and intersite engineering will utilize
procedures found in paragraph 1204, as well as criteria in NTIA Manual, Chapters 4 and 5.
1206. FREQUENCY ENGINEERING FOR THE 1710-1850 MHZ BAND. As directed by Title VI of the
Omnibus Budget Reconciliation Act of 1993 (OBRA-93), Title III of the Balanced Budget Act of 1997 (BBA97), and the Strom Thurmond National Defense Authorization Act for Fiscal year 1999 (NDAA-99), the 17101755 MHz portion of this band will be auctioned and transferred to the private sector. Therefore, there will be no
further FAA assignments in the 1710-1755 MHz band. No standard frequency plan exists for this band. Refer to
Paragraph 1204 for a general analysis of microwave link engineering.
a. Cosite frequency engineering.
(1) Transmitter-to-transmitter (Tx/Tx) frequency separation shall be at least 30 MHz.
(2) Transmitter-to-receiver (Tx/Rx) frequency separation shall be at least 40 MHz.
(3) Receiver-to-receiver (Rx/Rx) frequency separation shall be at least 15 MHz.

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b. Intersite frequency engineering. To assure that other microwave systems in the area do not cause
interference (or in order to determine that FAA systems will not cause interference to other agencies' systems), the
following procedure shall be used.
(1) Using the AFM CIRCLE program, determine all microwave systems within at least 60 nmi of the
proposed site.
(2) Using the AFM bearing/distance program, and taking into account the beam widths of the
respective transmit and receive antennas, determine all microwave systems which could be an interference source
or victim of the proposed site.
(3) Using the procedure given in figure 12-3, determine whether potential interferers or victims should
be further analyzed.
1207. FREQUENCY ENGINEERING FOR RCL IN THE 7125-8500 MHZ BAND. This process consists of
two separate criteria. The first considers the FR8 equipment requirements. Note that the FR8 equipment is
limited to 7125-8400 MHz. The second concerns microwave link general engineering and is discussed in
paragraph 1204.
a. Cosite frequency engineering.
(1) The FR8 equipment frequency selection criteria consists of seven tests. These test apply to the Tx's
and Rx's using a common wave guide and antenna configuration.
Test 1. Space bands - must be located outside of bands 7250-7300 and 7900-8025 MHz.
Test 2. Rx local oscillator (LO) - must be within the band 7125-8400 MHz.
Test 3. Tx/Tx and Rx/Rx separation - a minimum of 60 MHz.
Test 4. Tx/Rx separation - Tx frequency must have at least 80 MHz separation from the Rx input
frequency. If the Rx is at 8200, then a Tx is not permitted between 8120-8280, based on this test.
Test 5. Image frequency protection - For a 1 W Tx, the Tx output frequency must have at least 30
MHz separation from the image frequency; i.e., if the Rx is at 8200 and the Rx LO at 8270, then the Rx
image frequency is 8340. The Tx must then not be within the 8310-8370 range, based on this test. For a
low side Rx LO at 8130, the Rx image frequency is 8060. A Tx is not permitted within the 8030-8090
range, based on this test. For a 5 W Tx, the Tx output frequency must have at least 45 MHz separation
from the Rx image frequency. If an enhanced Rx RF input is installed, both 1 W and 5 W Tx's output
frequency must have at least 15 MHz separation from the Rx image frequency.
See figure 12-4.
Test 6. The transmitter local oscillator (Tx LO) must be >30 MHz from other Rx(s) within
the hop.
NOTE: TX LO = RX LO, i.e. TX = 8270, TX LO = 8270; no other RX permitted between 8240-8300.
Test 7. For a 1 W Tx, a third-order intermodulation products frequency is not permitted within 15
MHz of the Rx input frequencies. For a 5 W Tx, a third-order intermodulation products frequency is not
permitted within 30 MHz of the Rx input frequencies.

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FIGURE 12-4. EXAMPLE OF TESTS 4 AND 5 PROHIBITED ZONES

(2) Once the 7 tests in subparagraph (1) above have been satisfied for the Tx's and Rx's on a common
antenna, the back-to-back coupling must be considered. Back-to-back coupling is the fraction of power received
by a second antenna located on the same tower but facing in a different direction from the Tx antenna and using a
separate wave guide. The following specifications assume an angular azimuth separation of at least 15 degrees.
(a) For a 1 W Tx with a standard antenna, the Tx output frequencies must be separated from other
cosite Rx frequencies by at least 40 MHz.
(b) For a 5 W Tx with a standard antenna, 45 MHz.
(c) For a 1 W or 5 W Tx with a high performance antenna, 25 MHz.
b. Intersite frequency engineering. Use the same procedure as described in paragraph 1204.
(1). The antenna front-to-back ratio must also be considered. That ratio is defined as the ratio of the
power transmitted by the front side of the antenna to the power transmitted by the back. For a 1 W or 5 W Tx
with a standard antenna, the transmitted frequencies must be separated from other cosite frequencies by at least 30
MHz; with a high performance antenna, 10 MHz.
(2) The standard RCL frequency family is shown in figures 12-5 and 12-6.
(3) The preferred LO frequency is indicated following the operating frequency. The "+" indicates the
LO is on the high side of the operating frequency, the "—", the low side.

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FIGURE 12-5. STANDARD RCL FREQUENCY FAMILY FOR 7125-8400 MHz

Direction A
7340 —*

Direction B

A.

7160 +

7430 +

7605 —

B.

7205 + 7385 —*

7475 +*

7650 —

C.

7185 + 7365 +

7695 —**

7630 +

D.
D.

7230 + 7135 +
7230 + 7320 —*

7495 —
7495 +*

7580 +
7580 —

E.
E.

7685 — 7805 +
7685 — 7805 +

8170 +
8170 +

8290 —
8045 +

F.
F.

7745 + 7865 —
7745 + 7865 —

8230 —
8230 —

8350 —
8105 +

G.
G.

7725 + 7845 —
7725 + 7845 —

8210 +
8210 +

8330 —
8085 +

H.

7785 + 8270 —

8145 —

8390 +

J.
J.

7765 + 7885 —
7765 + 7885 —

8250 —
8250 —

8370 —
8125 +

K.
K.

7705 + 7825 +
7705 + 7825 +

8190 +
8190 +

8310 8065 +

Notes:

(1) * Indicates a "flopped" LO. This option was not initially
manufactured for this LO, but it can be ordered.
(2) ** Indicates a new frequency, not previously assigned to the
RML standard family.
(3) Direction A or B is a set of Tx's and Rx's in one direction of a hop.
(4) Before using the above sets of frequencies together within
the same link or on parallel links, they must be checked for
back-to-back and front-to-back separations.
(5) The table does not assume or imply exclusive FAA use.
(6) See figure 12-6 for examples of selection and tests. Frequencies
are taken from the standard chart. Test 4 results show Tx
frequencies do not fall on critical frequencies. Test 5 results show
Tx frequencies fall outside image band plus separation band.
(7) The symbols "+" or "—" indicate that the preferred LO is located
on the high or low side of the operating frequency, respectively.

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FIGURE 12-6. SAMPLE OF FREQUENCY SELECTION, TEST 4 AND 5

-------->
-------->
<-------<--------

Tx
Tx
Rx
Rx

7160 +
7340 —
7430 +
7605 —

-----------Test 4 ---------Rx 1 = 7430
Rx 2 = 7605
-80
+80
7350
7685
(image is on the opposite side)

----------Test 5----------Tx 1 = 7430 + Rx 2 = 7605 —
(Image band 140 MHz) +140
-140
(30 MHz reqd sep.) + 30
-30
7600
7435

c. Hybrid frequency/space diversity. See paragraph 1211.
1208. FREQUENCY ENGINEERING FOR LDRCL IN THE 7125-8500 MHZ BAND. This considers the
ALCATEL MDR-6000 equipment requirements.
a. Cosite frequency engineering.
(1) The ALCATEL equipment frequency selection criteria consists of 6 tests. These tests apply to the
Tx's and Rx's using a common wave guide and antenna configuration.
Test 1. Space bands - must be located outside of bands 7250-7300 and 7900-8025 MHz.
Test 2. Rx local oscillator (LO) - must be within the band 7125-8500 MHz.
Test 3. Tx-to-Tx frequency separation must be 46 MHz or greater.
Test 4. Rx-to-Rx frequency separation must be 46 MHz or greater.
Test 5. Tx-to-Rx frequency separation. The Tx frequency must have at least 115 MHz separation
from the Rx input frequency.
Test 6. A third-order intermodulation product is not permitted within 15 MHz of the Rx input
frequency.
(2) Once the 6 tests in subparagraph (1) above have been satisfied for the Tx's and Rx's on a common
antenna, the back-to-back coupling must be considered. Back-to-back coupling is the fraction of power received
by a second antenna located on the same tower but facing in a different direction from the Tx antenna and using a
separate wave guide. The following specifications assume an angular azimuth separation of at least 15 degrees.
(a) It is recommended that the Tx output frequencies must be separated from the other cosite
frequencies by at least 33 MHz.

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b. Intersite frequency engineering. Use the same procedure as described in paragraph 1204.
c. Hybrid frequency/space diversity. See paragraph 1211.
1209. FREQUENCY ENGINEERING FOR THE 14.5000-14.7145 AND 15.1365-15.3500 GHZ BANDS.
a. Cosite frequency engineering is unnecessary. FAA only uses this band for one-way links to support
Digital Bright Radar Indicator Tower Equipment (DBRITE).
b. Intersite frequency engineering. This frequency band and associated equipment are normally limited to
a 20 mile one-way path with not more than two repeaters. See paragraph 1204.
c. The frequency family plans are shown in figures 12-7.
d. The TML equipment frequency coverage limitation prohibits use of the TML equipment between
15.25-15.35 GHz.

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FIGURE 12-7. CURRENT TML CHANNELIZATION PLAN
MHz

MHz

MHz

14501.25*
14503.75
14506.25
14508.75
14511.25
14513.75
14516.25
14518.75
14521.25
14523.75
14526.25
14528.75
14531.25
14533.75
14536.25
14538.75
14541.25
14543.75
14546.25
14548.75
14551.25
14553.75
14556.25
14558.75
14561.25
14563.75
14566.25
14568.75
14571.25
14573.75
14576.25
14578.75
14581.25
14583.75
14586.25
14588.75
14591.25
14593.75
14596.25
14598.75
14601.25
14603.75

15141.25*
15143.75
15146.25
15148.75
15151.25
15153.75
15156.25
15158.75
15161.25
15163.75
15166.25
15168.75
15171.25
15173.75
15176.25
15178.75
15181.25
15183.75
15186.25
15188.75
15191.25
14193.75
15196.25
15198.75
15201.25
15203.75
15206.25
15208.75
15211.25
15213.75
15216.25
15218.75
15221.25
15223.75
15226.25
15228.75
15231.25
15233.75
15236.25
15238.75
15241.25
15243.75

14606.25
14608.75
14611.25
14613.75
14616.25
14618.75
14621.25
14623.75
14626.25
14628.75
14631.25
14633.75
14636.25
14638.75
14641.25
14643.75
14646.25
14648.75
14651.25
14653.75
14656.25
14658.75
14661.25
14663.75
14666.25
14668.75
14671.25
14673.75
14676.25
14678.75
14681.25
14683.75
14686.25
14688.75
14691.25
14693.75
14696.25
14698.75
14701.25
14703.75
14706.25
14708.75*

MHz
15246.25
15248.75
15251.25**
15253.75**
15256.25**
15258.75**
15261.25**
15263.75**
15266.25**
15268.75**
15271.25**
15273.75**
14276.25**
15278.75**
15281.25**
15283.75**
15286.25**
15288.75**
15291.25**
15293.75**
15296.25**
15298.75**
15301.25**
15303.75**
15306.25**
15308.75**
15311.25**
15313.75**
15316.25**
15318.75**
15321.25**
15323.75**
15326.25**
15328.75**
15331.25**
15323.75**
15336.25**
15338.75**
15341,25**
15343.75**
15346.25**
15348.75**

* These frequencies cannot be used for bandwidths greater than 2.5 MHz.
Total number of channels is 168.
** Due to TML equipment limitations, these frequencies are not usable.
From the radar end, use a 14 GHz frequency. If a repeater is necessary,
use the paired 15 GHz frequency for the repeater. If another repeater is
required, use another 14 GHz frequency; do not exceed two repeaters.

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1210. FREQUENCY ENGINEERING FOR LDRCL IN THE 21.2-23.6 GHZ BAND. This band has a very
short propagation characteristic and can be optimally engineered by assuring that cochannel operations are not
within 10 nmi. The frequency plan for LDRCL in this band is shown in figure 12-8.
a. Cosite frequency engineering. For cosite operation, ensure a Tx-Rx frequency separation of at least
1.2 GHz and a Tx-Tx frequency separation of at least 50 MHz.
b. Intersite frequency engineering. See paragraph 1204, except limit search to RLOS.

FIGURE 12-8. 21.2-23.6 GHZ LDRCL FREQUENCY ASSIGNMENT PLAN
Freq 1
(GHz)
21.225
21.275
21.325
21.375
21.425
21.475
21.525
21.575
21.625
21.675
21.725
21.775
21.825
21.875
21.925
21.975
22.025
22.075
22.125
22.175
22.225
22.275
22.325
22.375

Paired with

Freq 2
(GHz)
22.425
22.475
22.525
22.575
22.625
22.675
22.725
22.775
22.825
22.875
22.925
22.975
23.025
23.075
23.125
23.175
23.225
23.275
23.325
23.375
23.425
23.475
23.525
23.575

1211. SPECIAL PATH CONSIDERATIONS. Although the problem occurs most often on the southern
portions of the east and west coast of the contiguous United States and Hawaii, varying path propagation can
present real difficulties. There are two ways to alleviate the problem. One is space diversity and the other is
frequency diversity. Because space diversity takes no additional frequencies, it is preferable. See figure 12-9.
In addition, for digital systems, a hybrid combination of both space and frequency diversity can be provided.
See subparagraph c.

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FIGURE 12-9. SPACE DIVERSITY

a. Space diversity is an effective method to counter multipath fading. It relies on the height dependence of
the maxima and minima of the multipath interference patterns. By using the combined or switched output of two
antennas separated vertically by many wavelengths, significant improvement can be achieved.
(1) If the antennas have sufficient separation, fades on one path will be accompanied by an enhanced
signal on the other path. Vertical antenna separation of 30 to 35 feet for RCL and 25 to 35 feet for TML should
be adequate. Best performance will be obtained if the second antenna is placed directly above the original clear
path antenna. However, tower height restrictions or costs may prohibit this option.
(2) Satisfactory performance can usually be obtained when the spacing between antennas is split above
and below the original clear path. In this case, it will be necessary to check for problems due to nearby obstacles
close to the lower antenna path to assure a still clear path.
(3) To have space diversity in one direction of the link, the spaced antennas are associated with the Tx's.
For more severe fading problems, spaced antennas are placed at both ends of the link.
FIGURE 12-10. FREQUENCY DIVERSITY

b. The RCL and LDRCL use frequency diversity. A diagram of such a system is shown in figure 12-10.

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c. A hybrid system of combined frequency/space diversity for digital systems for the 7125-8500 MHz
band also can be provided.
(1) In a hybrid diversity configuration, one antenna is installed at one end of the path (Site A) and two
antennas are installed at the other end of the path (Site B). Two different frequencies are transmitted from the
common antenna at Site A and they are received on the two different antennas at Site B. As a result, the direction
of transmission from A to B is similar to normal space diversity. In the reverse direction, one frequency is
transmitted from the top and the other from the bottom antenna. Both frequencies are received at the common
antenna Site A and switched to the appropriate receiver.
(2) In both directions of transmission, there is a physical separation between the propagation paths.
There is a true space diversity improvement in both directions. Since the different paths also operate at different
frequencies, there is also frequency diversity improvement.
(3) Cosite frequency engineering for the digital hybrid system is different from analog engineering.
(a) Transmitter to transmitter (Tx/Tx) frequency separation shall be equal to or greater than
50 MHz.
(b) Receiver to receiver (Rx/Rx) frequency separation shall be equal to or greater than 50 MHz.
(c) Transmitter to receiver (Tx/Rx) frequency separation shall be equal to or greater than 115 MHz.

FIGURE 12-11. HYBRID FREQUENCY/SPACE DIVERSITY

1212. PATHS WITH PASSIVE REFLECTORS. Reflectors are a way to direct the beam path to where it is
needed while avoiding obstructions, or where considerable height is needed to avoid a long wave guide run.

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a. A periscope antenna is shown in figure 12-12. A parabolic antenna is positioned to beam upwards to
illuminate a passive reflector at the top of the tower. This avoids problems and costs associated with long runs of
wave guide with minimal change in net gain. When properly designed, only first Fresnel zone energy is reflected,
thus avoiding phase cancellation from the out-of-phase second zone energy. The design produces a sharper beam
with 2 or 3 dB gain.

FIGURE 12-12. PERISCOPE OR TOP REFLECTOR ANTENNA SYSTEM

FIGURE 12-13. SINGLE BILLBOARD PASSIVE ANTENNA

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FIGURE 12-14. DOUBLE BILLBOARD PASSIVE ANTENNA

b. Billboard passive repeaters are used for links where terrain, foliage or man-made obstacles prevent a
direct RLOS between desired sites. Figure 12-13 depicts single and figure 12-14 depicts double billboard
configurations. Here again, both the original and reflected paths must be considered, both for satellite conflict
and for the possibility of line-of-sight interference to another user on the same path. That is, not only the
billboard reflected path must be checked, but also the azimuth "direct" path of the transmitted signal as it points at
the billboard reflector. In Figure 12-13, that is the Tx/Rx azimuths between the billboard tower and the
foreground tower as well as the azimuths through the mountains path.
1213. MAPPING.
a. Link systems can become very complex, particularly if there are repeaters, or if any reflectors are used.
Research for any new FAA systems must first look at other FAA and other systems to assure compatibility. It is
necessary to establish some form of maps on which to plot all regional systems.
b. The format is not specified, but some form of map records for all regional link system shall be
maintained. Aeronautical sectional or local maps are excellent, because they have accurate coordinates on them,
and make plotting of sites easy.
1214. thru 1299. RESERVED.

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CHAPTER 13. RADAR AND AIR TRAFFIC CONTROL
RADAR BEACON SYSTEM (ATCRB S) FREQUENCY ENGINEERING
1300. POLICY. Technical Operations ATC Spectrum Engineering Services completes all initial frequency
engineering for new radar systems. The regional FMO completes subsequent frequency changes as a result of
RFI or relocations, modifications, five/ten year reviews, and coordination of other agencies requests to transmit in
the radar frequency bands.
a. FAA is designated by NTIA as the national coordinator for 1030/1090 MHz and the 1215-1390 MHz,
2700-2900 MHz and 9000-9200 MHz bands. As national coordinator, all users must coordinate with the FAA for
systems in these bands. Upon coordinating with a field user of these systems, the service area FMO will enter a
coordination record into the automated frequency management (AFM) system pending database to "reserve" the
frequency for the user. These coordinated requirements will be forwarded to Technical Operations ATC
Spectrum Engineering Services by setting the status of the record to “MN”. Technical Operations ATC Spectrum
Engineering Services will review these records, make any necessary changes to the proposed operation, and then
set the record to a status of “MA” to indicate the concurrence of Technical Operations ATC Spectrum
Engineering Services. Once the record is set to “MA” status, the regional FMO can then pass on to the field user
the FAA’s concurrence along with any necessary changes or restrictions to the proposed operation. The
coordinated record will be purged from the pending database once the assignment has been registered in the
Government Master File.
b. FAA, as Chair of the AAG, is also responsible for the proper engineering and management of the
1030/1090 MHz pair. Upon coordination with users for new requirements on these frequencies, the FMO will
enter a coordination record, as is done for the above radar bands, in order to reserve the frequency and the PRR.
(1) All Mode-S systems require a Site Identification (ID), or II code assigned. Using the properly
assigned Site ID code is critical to prevent aircraft from being locked out from responding to other interrogations.
Requests to use Mode-S will be forwarded to Technical Operations ATC Spectrum Engineering Services, who
will engineer a Site ID.
(2) All Mode-4 requests will be forwarded to Technical Operations ATC Spectrum Engineering Services
for support. The DOD uses Mode-4 when interrogating on 1030 MHz to determine if an aircraft is friendly. This
mode of operation, however, suppresses civil transponders preventing civil aircraft from responding to legitimate
interrogations by air traffic control. Caution must be exercised before approving any use of 1030 MHz by the
military to ensure that the military will not be operating in Mode-4. Mode-4 operations are often indicated by a
pulse duration of 0.5 microseconds as opposed to the standard ATCRBS 0.8 microseconds. If the use of Mode-4
is required, the request should be forwarded to Technical Operations ATC Spectrum Engineering Services.
c. Next Generation (NEXRAD) (WSR-88D) and Terminal Doppler Weather Radar (TDWR) systems
operate in the 2700-3000 MHz and 5600-5650 MHz band respectively. All new frequencies to support these
systems will be engineered by Technical Operations ATC Spectrum Engineering Services. The service area FMO
will still do five-year reviews and any necessary modifications to these frequency assignments.
d. Airport Surface Detection Equipment (ASDE) models X and 3 operate in the 9.0-9.2 GHz and
15.7-16.2 GHz band respectively. Technical Operations ATC Spectrum Engineering Services will engineer all
new frequencies to support these systems. The service area FMO will still do five-year reviews and any necessary
modifications to these frequency assignments.

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1301. GENERAL ASSIGNMENT PROCEDURES.
a. The selection of a frequency for an Air Route Surveillance Radar (ARSR) that operates in the 12151390 MHz band, or Airport Surveillance Radar (ASR) that operates in the 2700-2900 MHz band, is similar to the
problem of squeezing a COMM or NAVAID facility into an already crowded spectrum. The major difference is
the large bandwidths and power required. For instance, an ARSR-1 or ARSR-2 has an emitted spectrum that
extends considerably beyond the –20 dB bandwidth that is defined in the emission designator. Although the
spectrum beyond the –20 dB bandwidth is over 40 dB suppressed and meets the NTIA standard, that broad
spectrum can be a problem to adjacent channel users.
b. Radar receivers also have a decided effect on the assignment process. Even though a receiver may seem
to have a band pass that is extremely wide by COMM or NAVAID standards, the narrowest band pass possible is
implemented to detect the weak return signals required for radar reception. If it is an established radar system, it
must be protected by any assignment of a new facility.
c. Most radars have two separate transmitters and receivers, although some radars operate only one transmit
and receive (T/R) channel at a time. The other channel is normally tuned to another frequency and is used as a
backup or an alternate system. For interference protection and to realize the benefits of frequency diversity, it is
desirable to separate the two frequencies as far as possible within the band. While as much frequency separation
as possible is the goal, in most areas of the country, frequency congestion is so severe that the two channels must
be assigned frequencies with only a few MHz of frequency separation. Since the unused channel is kept "hot,"
some frequency separation is necessary to prevent interference to the operating channel.
d. Diplex radars operate both channels simultaneously, although their actual transmitting time is usually
separated in time so that the transmitted pulse of one is off while the transmitted pulse of the other is firing.
The difficulty for the FMO is that a minimum frequency separation between the two channels is required (see
paragraphs 1304-1308 for individual radar's minimum frequency separation).
e. The pulse repetition rate (PRR) is the number of pulses of energy per second (pps) transmitted by the
system and normally is the trigger for the associated ATCRBS interrogator.
f. The pulse repetition time (PRT) is that time in microseconds (usec) between the start of any two
consecutive radar pulses. In numerical terms, PRT = 1/PRR and PRR = 1/PRT.
g. Radar Beacon Systems have changed over time from the original concept of simple detecting and
ranging. The addition of a nondirectional but lower power simultaneously transmitting set of pulses has been
used to reduce false targets caused by various sources. The system is called Side Lobe Suppression (SLS), and a
later version, Improved SLS (ISLS). With the implementation of Specialized ATCRBS with discrete address
capability (Mode S) and other monopulse radars, "sum and difference" patterns on the directional antenna are
being used to enhance accuracy.
h. Other devices such as a Beacon False Target Eliminator (BFTE) and a "defruiter" to eliminate
electronically undesired responses called False Returns Unsynchronized In Time (FRUIT) have had varying
degrees of success. Newer versions that include Mode-S capability allow beacon systems to access a single
aircraft through selective addressing.
i. The FMO also should be aware of airborne radar and altimeter frequency bands, such as 42004400 MHz, 5350-5470 MHz, 9300-9500 MHz and 13.25-13.45 GHz. From time to time, the FMO may be asked
to assist in elimination of RFI for such systems.

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1302. PRR ASSIGNMENT OF ATCRBS.
a. The ATCRBS is the heart of the entire NAS surveillance system. Unfortunately, ATCRBS operates
through a single pair of frequencies: 1030 MHz (ground-to-air) and 1090 MHz (air-to-ground). The only method
for discriminating between each ATCRBS facility is by the PRR (noting that ATCRBS PRR is really
interrogations per second and not pulses per second). It is only through the use of different PRRs that all these
systems can operate simultaneously. Since all the military IFF systems also operate on the same frequency pair,
the critical task of engineering individual PRRs can be readily understood.
b. The best current method to keep PRRs from interfering with one another is to use a staggered PRR. It
works on the basis of a crystal controlled clock generating a fixed time base. Prearranged programming selects a
PRT in sequence, followed by another but different period, and so on for 4, 5, 6 or 7 periods before repeating the
whole sequence. Each such stagger system has several stagger groups. By staggering PRRs, the chance of hitting
the exact time of an emitted pulse of another 1030 MHz interrogator is enormously decreased. The stagger
sequence for ARSRs and ASRs and their associated ATCRBS are shown in various figures in later paragraphs
and tables.
c. The necessity for separating PRRs is that should two interrogators transmit at the same PRR and both
illuminate the same aircraft simultaneously, both radars will receive both reflections and produce a real and a false
target, separated by the time and azimuth difference between the two reflections.
d. ATCRBS is normally associated with FAA ASR and ARSR radars, but at times, ATCRBS is a standalone system. ATCRBS also has been called Secondary Radar (SECRA), Secondary Surveillance Radar (SSR),
Radar Beacon (Beacon), interrogator (ground), transponder (aircraft) and the military versions Identification,
Friend or Foe (IFF) and the DOD Selective Identification Feature (SIF) modified IFF. In ATC functions, the
ATCRBS is sometimes tied to a primary radar and its PRR is equal to or a submultiple of the primary's PRR. In
the case of staggered PRR, there is a basic clock relationship between the primary radar and the interrogator.
e. There are a number of problems which may be considered as "interference" in the broad sense. The
FMO must be aware of them and their consequences as part of the PRR selection process and interference
reporting.
(1) Ringaround is an aircraft transponder being interrogated by antenna side lobes causing elongated
targets on the radar scope, as shown in figure 13-1. The effect is reduced or eliminated by sidelobe suppression
(SLS).
(2) False targets can be caused by either synchronous airborne replies to another beacon or reflections of
the main beam energy. Aircraft transponders can reply to more than one interrogator and thus the beacon ground
system can receive signals with various PRRs. A defruiter will eliminate nonsynchronous PRR FRUIT, but it will
not reject synchronous PRR replies, so that false targets may appear on the display. This problem can best be
controlled by geographical separation of similar PRR beacon systems. False targets are also caused by reflections
of the main beam signal off large metal objects (e.g., a hangar), such that an aircraft outside the main beam is
interrogated (see figure 13-2). SLS and interrogator power reduction will help reduce this phenomenon. (See
Orders 6310.6, Primary/Secondary Terminal Radar Siting Handbook; 6340.15, Primary/Secondary En Route
Radar Siting Handbook; 6360.12, ATCRBS Performance Handbook.)
(3) "Second time around" signals are those which show up on the scope even though they are beyond
the distance of the actual target. It is caused by the interrogator signal going beyond its intended range and being
received during the "next" receive pulse period of the radar, thus showing in the designed range, but actually
being at a much greater distance. Various stagger and other fixes have eliminated most of this problem, but it
does occur on occasions.

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(4) Broken or serrated targets can be caused by synchronous PRR and by overinterrogation, causing
reduction in sensitivity such that only the strongest interrogation will be answered. It is best controlled by low
PRR assignments, proper PRR separation, and interrogator power reduction.
(5) Defective responses can plague the FMO which are not actual interference from another source.
The ability to diagnose the difference is an art that comes from training and experience. Technical Operations
ATC Spectrum Engineering Services can supply data. A good information source is the radar engineering group
in the service area office.

FIGURE 13-1. DISPLAY TIME EXPOSURE FOR A RADIAL FLIGHT
SHOWING RINGAROUND

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FIGURE 13-2. DISPLAY VIEW OF A REAL AND A FALSE TARGET

f. From the radar engineer's perspective, the highest possible PRR is desirable so that the hits-per-scan can
be high. That function is an important parameter in radar operation. But from the FMO's view, the lowest PRR is
ideal, to keep the ATCRBS spectrum as free from congestion as possible.
g. Care must be taken to separate assigned PRRs by a sufficient amount to assure noninterference. This is
really a function of time and thus is a pulse period variant. But in the 350-370 pps non-stagger range of the
ARSR-1 and -2, a PRR difference of 5 pps is sufficient. The standard PRRs for these radars are 350, 355, 360,
365 and 370 pps. Non-stagger radar beacons associated with ASR types normally use a PRR from 323-400 pps,
e.g., ASR-8.
h. The same frequency pair (1030/1090 MHz) is also used by DOD IFF/SIF. But many of their older
radars have PRRs that come out in odd numbers and decimals, due to the multivibrator oscillators used to
generate the PRR. There is another problem with that type of radar. Besides drifting some because it is not
crystal controlled, such military radars operate on harmonics of the oscillator. As a result, PRR can be transmitted
at a much higher or lower rate than authorized, if the Nth harmonic is inadvertently tuned up. This has happened
in the past. Hopefully, this will gradually diminish as old radars are phased out and newer stable and staggered
PRRs are introduced in the new equipment.
1303. PRR ASSIGNMENT PROCESS. There is a series of procedures and precautions involved in making a
new or modified PRR assignment.
a. The FAA is designated by the NTIA as the national coordinator for the 1030/1090 MHz frequency pair.
This includes DOD as well as non-Federal users. Non-Federal users include contractors developing and testing
radars for the Federal Government. All non-Federal assignments and any DOD assignment that is not being used
exclusively for air traffic control are considered experimental.
b. New PRR requests require careful review of the location, equipment type, and PRR parameters requested.
This will consist primarily of consulting the geographic/PRR list retained in the FMO's office, following the steps

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outlined in paragraph “d” below, and utilizing these guidelines:
(1) When a PRR is engineered for a non-FAA requestor, the requestor shall be advised of the FMO's
recommended PRR. The requestor's IRAC or FCC application must show that coordination has been effected
with the FMO.
(2) When a PRR is engineered for an FAA facility, an IRAC application will be filed in the usual
manner.
(3) If a suitable PRR is not found, the FMO shall notify the requestor of the problem, advising the
requestor that it will be necessary to adjust parameters so that another search may be made. To the extent
possible, the FMO should offer suggestions about what parameters can be changed to allow a PRR to be assigned.
Advise Technical Operations ATC Spectrum Engineering Services if no PRR can be found.
c. The national standard maximum PRR is 450 pps and must not be exceeded.
d. Interrogator PRR Engineering procedures:
(1) Beacon paired with a primary radar:
(a) The first step in engineering a beacon PRR is to determine what PRRs the beacon system is
capable of accepting. If the beacon uses a staggered PRR, get the stagger sequences that the system is capable of.
(b) The second step is to find the average PRT if the system is staggered. If the system has only a
single fixed PRR, then skip this step; otherwise, you have to calculate the average PRR. If the stagger rates are
expressed as PRRs (i.e a four time stagger of 223/320/267/350), then each PRR will need to be converted to a
PRT (1/PRR), the PRTs added up, divided by the number of PRRs in the stagger sequence, take the reciprocal of
the quotient, and then multiply by (1 X 106). For example, using the four time stagger sequence provided in the
example above:

1/223 = .0044843, or 4484.3 usec
1/320 = .0031250, or 3125.0 usec
1/267 = .0037453, or 3745.3 usec
1/350 = .0028571, or 2857.1 usec
4484.3 + 3125.0 + 3745.3 + 2857.1 = 14211.7 usec
14211.7 / 4 = 3352.925 usec
1 / 3352.925 = .000298247 (1 X 106) = 298.247 average Pulses Per Second
Note: The average PRR is not calculated by just adding the PRRs and dividing by the stagger rate.
(c) The third step is to determine whether the new interrogator is an ARSR-4 (250 nmi), en route (200
nmi), or a terminal (60 nmi) facility.
(1) ARSR-4 facilities shall be assigned PRTs that differ by at least 25 usec from any other ARSR-4
facility within 500 nmi, from any other en route facility within 400 nmi, and any terminal facility within 350 nmi.

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6050.32B

(2) En route radars shall be assigned PRTs that differ by at least 25 usec from any other en route
facility’s PRT within 360 nmi, and terminal facilities within 300 nmi. At least 25 usec of PRT separation needs to
be maintained between the enroute radar and any ARSR-4 within 400 nmi.
(3) Terminal radars shall be assigned PRTs that differ by at least 25 usec from any other terminal
facility’s PRT within 200 nmi, en route facilities within 300 nmi, and ARSR-4 facilities within 350 nmi..
NOTE: For radar systems that use a staggered PRR, use the PRT of the average PRR as calculated in the
second step above. It is this PRT that you base the 25 usec of separation on - not each PRT in the stagger
sequence.
(4) A stand-alone beacon uses the same procedure. Just base the 25 usec separation criteria on the
range of the beacon.
e. ATCRBS or IFF/SIF interrogator power must be reduced to the lowest possible level. The higher the
power, the more aircraft are interrogated and generate replies, cluttering the ATCRBS environment. In practice, it
has been found that 60 to 100 W is sufficient for most 60 nmi terminal systems. The maximum permissible
power that can be used by en route radars such as the ARSR series is 52.5 dBW (approximately 1,500W).
However, with the advent of the FAA William J. Hughes Technical Center (FAATC) Dipole Feed (NADIF)
antenna and later other models, a power of only 250 W will still provide good system coverage while reducing
overinterrogation of the system. DOD IFF/SIF systems frequently try to use 500 to 1,000 W. The FMO must
ensure that only the minimum power needed to do the job is all that is used, whether it is associated with ARSR,
ASR, DOD radar or stand-alone. A minimum signal level of –74 dBm is all that is needed to interrogate an
aircraft transponder.
f. Special care must be taken when dealing with some DOD radars whose antennas have very broad beam
widths. Some systems, particularly older models or those used in training have small antennas for portability.
This helps them in rapidly moving the equipment around, but unfortunately the result of the smaller antenna is a
much broader beam width. Instead of 1Ε or 2Ε maximum beam width of FAA ATCRBS antennas, some of the
older military portable units have as much as 8Ε beam width. This multiplies the number and duration of
interrogations of aircraft, adding unnecessary congestion. NTIA does not yet have antenna beam width standards
(see NTIA Manual).
g. DOD training maneuvers may present the FMO with interference problems. While the FMO does not
have the authority to specify beam widths, NTIA requires that the FMO be advised when maneuvers are to be
held in an FMO's service area. An alert is thus received to the possibility of ATCRBS interference through
overinterrogation. The FMO will coordinate the DOD training radar usage, e.g., power, PRR, etc., and seek the
advice of Technical Operations ATC Spectrum Engineering Services as needed. If the DOD is requesting to use
Mode-4, then forward the request to Technical Operations ATC Spectrum Engineering Services for support. In
the event of an actual problem of this kind, the FMO shall immediately contact the appropriate DOD AFC
and Technical Operations ATC Spectrum Engineering Services.
h. Radar Beacon Performance Monitors (RBPM), which are also called “parrots”, are often associated with
ATCBI systems. These systems operate on 1090 MHz and require an assignment. The purpose is to provide a
known fixed return to the beacon system for calibration. Mode-S systems usually have two parrots associated
with the system. Often these systems are located very close to the ATCBI and require only minimal power.
Assignments to support a parrot should include the delay characteristics in microseconds and nautical miles if a
delay line is inserted in the system. The beacon code used and the altitude setting of the parrot should also be in
the assignment. Altitude settings must be maintained to either 60,000 feet or above, or below sea level to prevent
interference to TCAS.

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FIGURE 13-3. RADAR AND ASSOCIATED BEACON CAPABILITIES

RADAR

PRR CAPABILITIES

ASSOCIATED BEACON PRR

AN/CPN-4
AN/FPN-47
AN/FPS-7
AN/FPS-18
AN/FPS-20, -20A
AN/FPS-64, -65,
-66, -67
AN/GPS-4
AN/GPN-12
AN/GPN-20
AN/GPN-30
AN/MPN-13, -14
AN/MPS-11
AN/TPS-43

1500
See ASR-5
244
1200
350, 355, 360, 365, 370
340, 345, 350, 355
360, 365, 370
360
See ASR-7
See ASR-8
See ASR-11
1100
360
227, 250, 278
(3X stagger)
245, 250, 258
(6X stagger: 245.1,
235.3, 227.3, 278.6,
263.9, 258.4)
See figures 13-5, -6
See figures 13-7, -8
See figure 13-9
810, 900, 1125, 1140,
155, 1170, 1185
See figures 13-10, -11
See figure 13-12
See figure 13-14
722,788,935,1005
(4X stagger)

300
See ASR-5
Same as primary radar
300
Same as primary radar
Same as primary radar

AN/TPS-43E

ARSR-1, -2
ARSR-3
ARSR-4
ASR-4, -5, -6
ASR-7
ASR-8
ASR-9
ASR-11

Same as primary radar
See ASR-7
See ASR-8
See ASR-11
275 (4:1 countdown from primary)
Same as primary radar
Same as primary radar
Same as primary radar

Same as primary
Same as primary
Same as primary
3:1 countdown from primary
See figures 13-10, -11
See figure 13-12
See figure 13-14
Assign fixed PRR of at least 200 PPS
(PRR is independent from primary.
Assign PRR’s as close to 200 PPS as
possible.)

1304. FREQUENCY ASSIGNMENT PROCESS IN THE RADAR FREQUENCY BANDS: The below
engineering criteria is the “rule-of-thumb” frequency and distance separation to use when supporting radar
systems between 1215-1390 MHz, 2700-3000 MHz, 5600-5650 MHz, 9000-9200 MHz, and 15.7-16.2 GHz:

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6050.32B

FIGURE 13-4. RADAR FREQUENCY-DISTANCE SEPARATION CRITERIA

Distance
in NMI

1 – 2.5
2.5 – 5
5 – 10
10 – 50
50 – 100
100 –150
Over 150

Required
Frequency
Separation
in MHz
30
25
23
20
10
5
0

a. These are general criteria that were developed years ago based on testing. Since they were developed,
there have been many changes in the way radar systems perform. Time has proven, however, that with few
exceptions, these criteria work to protect cochannel and adjacent channel radar systems from interference. If a
frequency cannot be found using these criteria, forward the requirement to Technical Operations ATC Spectrum
Engineering Services and a more in depth analysis will be performed.
b. One source of interference that is sometimes encountered, but protection cannot be granted from, is the
propagation affect of ducting. Ducting sometimes affects radar systems that have 600 nmi of separation. There is
not enough spectrum to reduce the frequency reuse rate to 600 nmi. If ducting between two systems is a
consistent problem, frequency reassignments will be considered.
1305. FREQUENCY ASSIGNMENTS IN THE 1215-1390 MHZ BAND. This band is used by the FAA to
support en route radar facilities for air traffic control and assignments must be confined to the 1240-1370 MHz
frequency band. This sub-band of the 1215-1390 MHz is allocated for aeronautical radionavigation and,
generally speaking, receives better protection from interference. When making assignments in this band, the
second harmonic may fall in the 2700-2900 MHz terminal radar band and so must be given consideration. If a
frequency is required to support an en route radar facility and cannot be accommodated in the 1240-1370 MHz
band, forward the requirement to Technical Operations ATC Spectrum Engineering Services.
a. The band 1240-1370 MHz. The majority of radars in this band are the FAA ARSR-1, -2, -3 and -4 and
FPS series. The ARSR-1, -2 and FPS series radars have two channels each which may be assigned frequencies
within 5-10 MHz since only one channel transmits at a time. The ARSR-3 is a diplex radar and requires two
frequencies substantially separated (about 25 MHz) within the band. The ARSR-4 is a diplex radar which
requires two frequencies, but the choice of frequencies are limited to those in the ARSR-4 crystal sets. When one
frequency is selected, the second frequency is automatically paired 82.85 MHz away.
(1) The ARSR-1, -2, and FPS series are very high power and long range radars. To the extent the terrain
permits, they are sited on a clear, high point of terrain. This, of course, extends their RLOS to other long range
radars. In the plains area, this is not as much a problem as in the West or East.
(a) Frequency separation between these radars is usually satisfactory at 5 MHz for 100 nmi and
10 MHz for 50 nmi. See figure 13-4. These long range radars (200 nmi range) are usually not sited closer than
about 100 nmi, unless terrain factors require closer siting. In these few cases, it will be necessary to give a wider
frequency separation.

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(b) Band pass filters may have to be used on some older ARSRs to reduce the emitted spectrum to
prevent interference to other nearby radars, or even to the ARSRs associated ATCRBS. Contact Technical
Operations ATC Spectrum Engineering Services for details.
(c) ARSR-1/2 staggered PRR's. Figures 13-5 and 13-6 provide the average PRRs and stagger PRTs
for the ARSR-1/2 radars. The ARSR-1/2 normally uses the high (noted as "H" in the figure) rate PRR sequences,
while the low rate (noted as "L" in the figure) sequences are available as a modification to the ARSR-1/2. Both
low and high rates are available for the FPS type radars.

FIGURE 13-5. ARSR-1/2 STAGGERED PRR AND PRT VALUES (HIGH)

Num HIGH/
LOW

Avg
PRR
(Hz)

00
01
02
03
04
05
06
07
08
09

Page 146

H
H
H
H
H
H
H
H
H
H

352.61
354.48
356.38
359.29
360.23
362.19
364.17
366.17
368.19
370.23

Pulse Repetition Time (PRT) in μs
AVG
PRT1 PRT2 PRT3 PRT4 PRT5 PRT
2647
2633
2619
2605
2591
2577
2563
2549
2535
2521

2836
2821
2806
2791
2776
2761
2746
2731
2716
2701

2761
2595
2731
2716
2702
2699
2673
2658
2643
2629

2609
3310
2582
2568
2654
2540
2526
2513
2499
2485

3327
3310
3292
3275
3257
3239
3222
3204
3187
3169

2836
2821
2806
2791
2776
2761
2746
2731
2716
2701

11/17/05

Chapter 13 - continued

6050.32B

FIGURE 13-6. ARSR-1/2 STAGGERED PRR AND PRT VALUES (LOW)

Num High/
Low

Avg
PRR
(Hz)

00
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46

L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L

279.88
281.06
282.33
283.53
284.82
286.12
287.36
288.68
289.94
291.29
292.65
293.94
295.33
296.65
298.06
299.49
300.84
302.30
303.67
305.16
306.65
308.07
309.60
311.04
312.60
314.17
315.66
318.78
320.41
322.06
323.62
325.31
326.90
328.62
330.36
332.01
333.78
335.46
337.27
339.10
340.83
342.70
344.47
346.38
348.31
350.14

Pulse Repetition Time (PRT) in us

PRT1 PRT2 PRT3 PRT4 PRT5 PRT
3115
3102
3088
3075
3051
3046
3034
3020
3008
2993
2979
2966
2952
2939
2925
2911
2898
2884
2871
2857
2843
2830
2816
2803
2789
2775
2762
2735
2721
2707
2694
2680
2667
2653
2639
2626
2612
2599
2585
2571
2558
2544
2531
2517
2503
2489

3939
3923
3905
3889
3871
3853
3837
3819
3803
3785
3767
3751
3733
3717
3699
3681
3665
3647
3631
3613
3595
3579
3561
3545
3527
3509
3493
3459
3441
3423
3407
3389
3373
3355
3337
3321
3303
3287
3269
3251
3235
3217
3201
3183
3165
3149

3207
3193
3179
3165
3151
3137
3123
3109
3095
3081
3067
3053
3039
3025
3011
2997
2983
2969
2955
2941
2927
2913
2899
2885
2871
2857
2843
2815
2801
2787
2773
2759
2745
2731
2717
2703
2689
2675
2661
2647
2633
2618
2605
2591
2577
2563

3481
3467
3451
3437
3421
3405
3391
3375
3361
3345
3329
3315
3299
3285
3269
3253
3239
3223
3209
3193
3177
3163
3147
3133
3117
3101
3087
3057
3041
3025
3011
2995
2981
2965
2949
2935
2919
2905
2889
2873
2859
2843
2829
2813
2797
2783

4123
4105
4087
4069
4051
4033
4015
3997
3979
3961
3943
3925
3907
3889
3871
3853
3835
3817
3799
3781
3763
3745
3727
3709
3691
3673
3655
3619
3601
3583
3565
3547
3529
3511
3493
3475
3457
3439
3421
3403
3385
3367
3349
3331
3313
3295

3573
3557
3542
3527
3511
3495
3480
3464
3449
3433
3417
3402
3386
3371
3355
3339
3324
3308
3293
3277
3261
3246
3230
3215
3199
3183
3168
3136
3121
3105
3090
3074
3059
3043
3027
3012
2996
2981
2965
2949
2934
2918
2903
2887
2871
2856

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Chapter 13 – continued

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(2) The ARSR-3 is a simplex radar requiring a pair of frequencies, one for each channel. Although they
are time sequenced to operate from different time zeros, the two assigned frequencies should be separated at a
minimum of 25 MHz. This could entail shifting other radars in the area to other frequencies in the band.
Technical Operations ATC Spectrum Engineering Services engineers the frequency pairs.
(a) The ARSR-3 associated beacon uses an identical staggered or nonstaggered trigger used by the
ARSR-3 itself. Four fixed pulse repetition rates are available from a front panel selection. However, the PRT is
expressed in nmi with the basic rate designated as "A." For example: A = 238 nmi = 238 X 12.355 usec =
2,940.5 usec. Note that theoretically it would take a radar signal 12.355 usecs to go out 1 nmi, hit a target and
return the 1 nmi. If a value for "A" is chosen between 222 and 261 nmi, the four fixed intervals are selected
automatically by the following trigger sequence:
A + 16, A, A - 8 and A - 16. For example: A = 238 nmi; the four fixed PRRs would be equivalent to
254, 238, 230 and 222 nmi.
(b) The staggered trigger sequence selected depends on the nmi range selected for "A." There are
three stagger sequences available, known as Variable Interpulse Periods (VIP). They are VIP-8, VIP-7, and
VIP-5 (see figures 13-7 and 13-8). If "A" is between 235 and 261 nmi, the sequence is VIP-8; if between 228 and
235 nmi, VIP-7; if between 222 and 228 nmi, VIP-5. The VIP number indicates the number of different pulse
intervals.

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FIGURE 13-7. ARSR-3 PRR CAPABILITIES

ARSR-3 OPERATIONAL PRR MODES
1. Stagger trigger (Normal selection)
2. Nonstagger trigger (Special)

STAGGER/NONSTAGGER TRIGGER PRR

Stagger Trigger PRR (three trigger sequences, determined by value of "A" in nmi)
VIP-8 - "A" = any nmi integer between 235 and 261
Sequence: A-32 nmi, A+24 nmi, A-16 nmi, A+8 nmi, A-8 nmi,
A+16 nmi, A-24 nmi, A+32 nmi. (eight different PRTs)

VIP-7 - "A" = any nmi integer between 228 and 235
Sequence: A-24 nmi, A+24 nmi, A-16 nmi, A+8 nmi, A-8 nmi,
A-8 nmi, A±0 nmi, A-24 nmi, A+40 nmi. (nine different PRTs)

VIP-5 - "A" = any nmi integer between 222 and 228
Sequence: A-16 nmi, A+8 nmi, A+16 nmi, A+24 nmi, A-16 nmi,
A-8 nmi, A-16 nmi, A+40 nmi. (eight different PRTs)
Non-stagger PRR (four trigger sequences, determined by value of "A" in nmi)

"A" = any nmi integer between 222 and 261
Sequence: A+16 nmi, A ±0 nmi, A-8 nmi, A-16 nmi.

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FIGURE 13-8. ARSR-3 AVERAGE VIP PRTS

NMI

AVG PRT AVG PRR
(usec)
(pps)

NMI

AVG PRT AVG PRR
(usec)
(pps)

VIP-8

235
236
237
238
239
240
241
242
243
244
245
246
247
248

2904.43
2916.79
2929.15
2941.51
2953.87
2966.23
2978.59
2990.95
3003.31
3015.67
3028.03
3040.39
3052.75
3065.11

344
343
341
340
339
337
336
334
333
332
330
329
328
326

249
250
251
252
253
254
255
256
257
258
259
260
261

3077.47
3089.83
3102.19
3114.55
3126.91
3139.27
3151.63
3163.99
3176.35
3188.71
3201.07
3213.43
3225.79

325
324
322
321
320
319
317
316
315
314
312
311
310

233
234
235

2866.38
2827.74
2891.10

349
347
346

226
227
228

2792.25
2804.61
2816.97

358
357
355

VIP-7

228
229
230
231

2816.94
2829.30
2841.66
2854.02

355
353
352
350

VIP-5

222
223
224
225

Page 150

2742.81
2755.17
2767.53
2779.89

365
363
361
360

11/17/05

Chapter 13 - continued

6050.32B

(3) The ARSR-4 is a diplex radar with two separate frequencies within the band which are paired using
the pairing scheme in figure 13-9. Although the ARSR-4 can operate and frequency hop throughout the 12151400 MHz band, day-to-day frequency assignments/operations are confined to two frequencies in the spectrum
allocated for aeronautical radio navigation between 1240-1370 MHz.

FIGURE 13-9. ARSR-4 CRYSTAL OSCILLATOR, STABILIZED LOCAL OSCILLATOR (STALO)
AND TRANSMIT FREQUENCIES

ODD GROUP CRYSTALS (MHz)
XTAL OSC.

STALO

NO.

FREQ.

LOWER

UPPER

LOWER

HIGHER

01 45.5929

1458.97

1215.58

1298.94

1255.94

1308.79

03 45.7548

1464.15

1220.76

1303.62

1231.12

1313.97

05 46.2402

1479.69

1236.29

1319.15

1246.65

1329.51

07 46.4021

1484.87

1241.47

1324.33

1251.83

1334.69

09 46.8876

1500.40

1257.01

1339.87

1267.37

1350.22

11 47.0494

1505.58

1262.19

1345.04

1272.54

1355.40

13 47.5349

1521.12

1277.72

1360.58

1288.08

1370.94

15 47.6967

1526.29

1282.90

1365.76

1293.26

1376.12

17 48.1822

1541.83

1298.44

1381.29

1308.79

1391.65

19 48.3440

1547.01

1303.62

1386.47

1313.97

1396.83

FREQ.

SET 1

SET 2

EVEN GROUP CRYSTALS (MHz)
02 45.6738

1461.56

1218.17

1301.03

1228.53

1311.38

04 45.8357

1466.74

1223.35

1306.21

1233.71

1316.56

06 46.3212

1482.28

1238.88

1321.74

1249.24

1332.10

08 46.4830

1487.46

1244.06

1326.92

1254.42

1337.28

10 49.9685

1502.99

1259.60

1342.46

1269.96

1352.81

12 47.1303

1508.17

1264.78

1347.63

1275.13

1357.99

14 47.6158

1523.71

1280.31

1363.17

1290.67

1373.53

16 47.7776

1528.88

1285.49

1368.35

1295.85

1378.71

18 48.2631

1544.42

1301.03

1383.88

1311.38

1394.24

20 48.4250

1549.60

1306.21

1389.06

1316.56

1399.42

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6050.32B

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b. The bands 1215-1240 and 1370-1390 MHz. Radars assigned in these bands will be primarily for DOD
use. In these cases, the FMO has the same responsibility under NTIA directive to provide just as adequate
interference protection to DOD/DOD radars as provided for DOD/FAA adjacent systems. The FMO should work
very closely with the appropriate DOD AFC to provide the best separation possible commensurate with good
spectrum utilization and conservation.
1306. FREQUENCY ASSIGNMENTS IN THE 2700-3000 MHZ BAND. This band is not exclusive to FAA.
The 2900-3000 MHz portion is used by NWS solely for the NEXRAD weather radar. The FAA is designated by
NTIA as the field coordinator for the 2700-2900 MHz portion of the band which is for aeronautical
radionavigation services, meteorological aids and the DOD area surveillance radars. Because of this field
coordination authority, the FMO selects and recommends frequencies in the 2700-2900 MHz band for all
agencies which have a requirement to use this band. Subsequently, the agency, not the FAA, is required to
process their frequency request through NTIA for formal assignment with the proper FAA coordination note.
a. FAA 2700-3000 MHz assignments.
(1) In general, if a radar frequency being considered is not within RLOS to any other radar within
±10 MHz, the assignment should be acceptable. Reflections from mountainous terrain could cause interference,
so two radars within reflection range should be separated 5 to 10 MHz to prevent problems. Consideration should
also be given to the second harmonic of enroute radars operating in the 1240-1370 MHz band. If one of the radars
is not crystal controlled, periodic frequency checks should be made of to prevent gradual drift onto the other
radar's frequency.
(2) A diplex radar is designed to take advantage of the differences in propagation between two separated
frequencies, and thus it is desirable to separate the two frequencies as much as possible.

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(a) The ASR-7 is a diplex radar but only on the channels shown in figure 13-10.

FIGURE 13-10. ASR-7E PRIMARY RADAR FREQUENCY PAIRS
Channel A (MHz)
2705
2710
2710
2715
2720
2720
2725
2730
2740
2750
2755
2760
2760
2765
2770
2770
2780
2790
2800
2810
2820
2820
2820
2830
2830

Channel B (MHz)
2855
2770
2795
2820
2780
2785
2860
2790
2800
2810
2850
2820
2850
2880
2830
2850
2840
2850
2860
2870
2750
2880
2890
2890
2895

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(b) The PRR/PRT stagger sequences are shown in Figure 13-11.

FIGURE 13-11. ASR-7 AND ASSOCIATED BEACON STAGGERED PRR AND PRT

EQP SET PRR PRT PRR PRT PRR PRT PRR PRT PRR PRT PRR PRT PRR PRT PRR PRT
RDR

P 1200

BCN

P

554

RDR Q 1188
BCN Q

548

RDR R 1176
BCN R

436 2296

862 1109

879 1086

2236 542 1846

346

963

940 1064 706 1417

2889 443
972

343 2916
982

519

1431

1883 514

921 1085 692

1445

---

---

1902 509

991

912 1095 684

1459

336 2973

430 2325 521

1920 545

938

996 1001

902 1106 677

1473

415 2411

333 3003

426 2348 516

1939 449

Notes: PRR in pps
PRT in usec
RDR = radar
BCN = beacon interrogator
Primary ASR-7 is 6X stagger; associated beacon is 8X stagger

AVERAGE PRR's
Set
P
Q
R
S
T
U

Page 154

---

931 1074 699

2303 526

Bcn Avg
445
441
438
432
428
424

Radar Avg
1002
992
982
973
964
954

---

---

---

525 1906 320 3129

438 2281 531

339 2946 434

929 1008

2258 536 1865

---

2388

896 1064

505 1981

350 2859 447

920 1019

887 1075

510 1961 419

875 1114

1053 713 1403

911 1029

427 2342

515 1943 423 2365

866 1126

953 950

902 1039

870 1098

520 1924

858 1138

527 1897

893 1050

525 1905 431 2319

850 1150

532 1878

RDR U 1140
BCN U

1825

853 1120

530 1886

841 1161

537 1861

RDR T 1152
BCN T

1806

543 1842

RDR S 1164
BCN S

833 1173

---

---

---

---

---

1926 316 3160
---

---

---

1943 313 3192
---

---

---

1964 310 3223
---

---

---

1982 307 3254
---

---

---

2002 304 3286

11/17/05

Chapter 13 - continued

6050.32B

(c) The ASR-8 dual channel radar presents special problems in providing paired frequencies for it.
The emitted spectrum of the transmitter is about ±10 MHz, about the same as the ASR-7. Associated PRR/PRT
stagger sequences are shown in figure 13-12. But the big problem is the receiver band pass. Each receiver is
approximately ±40 MHz wide. In addition, there is a manufacturer's limitation that the individual channels must
be separated by an amount greater than 60 MHz. See figure 13-13. To fit ASR-8 diplex frequencies into an
already congested environment presents the FMO with a very difficult task. Because changing a frequency in an
ASR-8 requires replacing a whole transmitter package that includes oscillators and diplexer, a frequency change
will be considered only as a last resort for an RFI problem remedy. Any ASR-8 frequency problem should be
referred to Technical Operations ATC Spectrum Engineering Services.

FIGURE 13-12. ASR-8 AND ASSOCIATED BEACON STAGGERED PRR AND PRT

PRR
DESIGNATION

AVG
RADAR
PRR

BEACON PRR
3:1 CNTDWN
PPS / ΦSEC

RADAR 4X
STAGGER SEQUENCE
PRT (ΦSEC)

BASIC

1040

347 / 2883

830

1177

876

961

0.5

1035

345 / 2898

835

1182

881

966

1.0

1030

343 / 2913

840

1187

886

971

1.5

1025

342 / 2928

845

1192

891

976

2.0

1020

340 / 2940

849

1197

896

980

2.5

1015

338 / 2958

855

1202

901

986

3.0

1010

337 / 2970

859

1206

905

990

3.5

1005

335 / 2985

864

1211

910

995

4.0

1000

333 / 3000

868

1216

915

1000

4.5

995

332 / 3015

874

1221

920

1005

5.0

991

330 / 3027

878

1225

924

1009

5.5

986

328 / 3042

882

1229

929

1014

6.0

981

327 / 3057

887

1234

934

1019

6.5

977

325 / 3072

892

1239

939

1024

7.0

973

324 / 3084

897

1244

943

1028

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6050.32B

Chapter 13 – continued

11/17/05

FIGURE 13-13. TYPICAL ASR-8 RECEIVER SUSCEPTIBILITY PASS BAND

(d) The ASR-9 radar is a single channel/dual frequency terminal radar. Only one channel, manually
selectable by the operator, is on the air at any one time. Available crystals allow tuning throughout the band in 1
MHz increments between 2703-2987 MHz. PRR stagger sequences are shown in figure 13-14. While it is
possible to have the ASR-9 channels as little as 10 MHz apart, it is advantageous to separate the channels by
at least 50 MHz in order to allow frequency diversity to mitigate radio interference and anomalous propagation.

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Chapter 13 - continued

6050.32B

FIGURE 13-14. ASR-9 RADAR AND BEACON PRRS

BEACON PRR, NORMAL MODE
Staggered PRR (per CPI pair)

00
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15

440
434
434
431
428
425
422
419
417
414
411
408
406
403
400
398

440
434
434
431
428
425
422
419
417
414
411
408
406
403
400
398

514
506
506
503
499
496
493
489
486
483
479
476
473
470
467
464

514
506
506
503
499
496
493
489
486
483
479
476
473
470
467
464

342
338
338
335
333
331
328
326
324
322
320
318
315
313
311
309

514
506
506
503
499
496
493
489
486
483
479
476
473
470
467
464

Average PRR (per CPI pair)
BCN RADAR
330
326
326
323
321
319
317
315
312
310
308
306
304
302
300
298

429
423
423
420
417
414
411
408
406
403
400
397
395
392
390
387

1172
1156
1156
1148
1140
1132
1124
1116
1109
1101
1094
1087
1080
1073
1066
1059

BEACON PRR, VIP MODE
Staggered PRR, (per CPI pair)
16
17
18
19
20
21
22
23
24
25
26
27
28

436
433
430
427
424
421
418
415
413
410
407
404
402

433
430
427
424
421
419
416
413
410
407
405
402
400

513
510
506
503
499
494
492
489
486
482
479
476
473

512
508
505
501
498
496
491
487
484
481
478
475
471

340
337
335
333
330
328
326
324
322
319
317
315
313

511
507
504
500
497
493
490
487
483
480
477
474
471

Average PRR, (per CPI pair)
329
327
325
322
320
318
316
314
312
309
307
305
303

426
423
420
417
414
411
408
406
403
400
398
395
392

1164
1156
1147
1140
1131
1124
1116
1108
1101
1094
1087
1080
1072

(e) The ASR-11 radar is a diplex radar that requires two frequency pairs for operation. The two
frequency pairs may be selected from anywhere within the 2702.6 – 2897.5 MHz tuning range, but must be
separated by at least 30 MHz. Each pair consists of two frequencies that are +/- 0.5 MHz offset from the main
carrier. The carrier frequency is what is assigned so each ASR-11 will only have two frequency assignments even
though it operates on four frequencies. An assignment of 2730 MHz, for example, with result in actual operations
being on 2729.5 MHz and 2730.5 MHz, but only an assignment on 2730 MHz is needed. The second assigned
frequency in this example must be at least 30 MHz from 2730 MHz. This assignment process is permitted by
NTIA because of the EMC emission level provisions and the purity of the transmissions. The ASR-11 uses a four
times stagger that is not adjustable. The average PRF for all ASR-11s is 856 PPS. The associated monopulse

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beacon system is independent of the ASR-11 and accepts a fixed PRF assignment between 200 and 450 PPS.
Due to the increased accuracy that is realized by a monopulse beacon, however, PRR assignments will be as close
to 200 PPS as possible to reduce the amount of FRUIT produced by 1030 MHz interrogations.
b. Non-FAA 2700-2900 MHz assignments.
(1) NWS Radars. Some of the older style weather radars operated by the NWS such as WSR-57 and
WSR-74 still operate in this band. They are tunable but have rather poor spectra. Generally speaking, separation
from FAA ASR series, except ASR-8, needs to be about 20 MHz within RLOS. In the case of the ASR-8, a clear
band ±40 MHz for each channel frequency is required. Because of the relatively unstable operating parameters of
those older radars, they need to be checked on a case-by-case basis. Joint DOD/FAA/NWS NEXRAD, also
known as WSR-88D, is replacing the entire NWS inventory. NEXRAD installations must be coordinated
carefully between FAA/NWS, particularly, the site locations.
(2) DOD Radars. Most of the DOD permanent requirements in this band will be for radars that are the
DOD equivalents of FAA radars, such as the AN/GPN12 (ASR-7), AN/GPN20/GPN27 (ASR-8), and AN/GPN30 (ASR-11). Assuming these are in ATC use around military bases, the FMO shall give the same protection and
availability as FAA and NWS radars. Should the request be for tactical or training purposes, that function is
secondary to all others and may be accommodated only if there is space without crowding or moving any of the
ATC or NWS radars.
(3) Non-FAA/non-NWS/non-DOD Radars. This group will consist primarily of non-federal radars and
usually will be experimental systems to develop air traffic control radar, tactical systems, or radar systems for
foreign sale. These requirements will be secondary and handled on a case-by-case basis, in coordination with
Technical Operations ATC Spectrum Engineering Services.
1307. FREQUENCY ASSIGNMENTS IN THE 5600-5650 MHZ BAND. TDWR presently is the only radar
that FAA operates in this band. The band is shared with various weather radars operated by the DOD, NWS, and
commercial weather radar systems usually associated with local new television stations. TDWRs are normally
sited off the airport in order to provide better surveillance in the area of that airport. Therefore, in some cases,
TDWRs are located adjacent to public facilities, and FMOs need to take special care that pre-commissioning
radiation measurements are known and documented. When engineering an operating frequency for the TDWR,
a circle search using the GMF and taking into account assigned frequencies as low as 5.4 GHz must be made in
order to ensure compatibility with existing radars in the band 5.600-5.650 GHz as well as wide band radars
operated by other agencies in the spectrum below 5.6 GHz. In addition, when siting TDWRs, in the vicinity of
ASRs, the second harmonic relationship between 2.700-2.900 GHz band and the 5.600-5.650 GHz band must be
considered.
1308. FREQUENCY ASSIGNMENTS IN THE 9000-9200 MHZ BAND. FAA operates the ASDE-X radar
system in this band. Although the ASDE-X system can operate on up to four frequencies in the band, minimum
performance standards can be met on two frequencies. The band is also used by the military for Precision
Approach Radar (PAR). When making assignments for an ASDE-X system, a distance of 18 nmi between the
ASDE-X and PAR is usually sufficient. If the proposed separation between systems is less then 18 nmi, then
forward the requirement to Technical Operations ATC Spectrum Engineering Services for a more in-depth
analysis. For PAR and other military operations in this band, the FMO engineers and recommends a frequency
for the DOD requestor, just as with the other bands in this chapter. However, since the FMO normally is not
familiar with these DOD radars, it is best to coordinate with the appropriate DOD AFC and use the DOD's
expertise in this area as FAA's recommendation. Should any user of this band contact the FMO reporting
interference, the FMO shall take the lead in resolution of the problem as the NTIA designated field coordinator
for this band.

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6050.32B

1309. FREQUENCY ASSIGNMENTS IN THE 15.7-16.2 GHZ BAND. This band is used by FAA for
ASDE-3 but is shared with and subject to coordination with DOD as coequal. Non-Federal users are permitted in
this band on a noninterference basis to ASDE-3. For all ASDE-3 frequency assignments, the FMO shall
coordinate with Technical Operations ATC Spectrum Engineering Services.
1310. thru 1399. RESERVED.

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6050.32B

CHAPTER 14. RADIO FREQUENCY INTERFERENCE
1400. INTERFERENCE PROBLEMS. Effective reporting and timely awareness of a Radio Frequency
Interference (RFI) problem is essential before a resolution approach can take place. To resolve RFI, the
Frequency Management Officer (FMO) must be resourceful and have a wealth of analytical experience and good
technical references. This chapter is a good reference and it outlines the general procedures to follow in the
resolution of RFI to National Airspace System (NAS) services. For all reported events of RFI it is critical that the
service area FMO do a thorough desktop analysis of the situation to determine the approach to a potential solution
and the resources that will be required. An additional reference guide for applying radio interference
investigation techniques is the Radio Frequency Interference (RFI) Detection, Analysis and Resolution
textbook, prepared for Technical Operations ATC Spectrum Engineering Services. This pamphlet is supplied to
Technical Operations Services specialists and service area FMOs during the Radio Frequency Interference
Resolution training course (Course # 45018) and further copies are available upon request.
1401. INTERFERENCE REPORTING. Whether the RFI problem is resolved locally or not, the RFI event
must be reported to Technical Operations ATC Spectrum Engineering Services. On a regular basis, Technical
Operations ATC Spectrum Engineering Services receives inquiries, congressional and otherwise, concerning
ongoing interference problems affecting NAS services. Headquarters must be in a position to promptly reply on
the status of any problem at any time. Order 6050.22C prescribes policies and procedures for reporting and
investigating intentional interference (phantom controllers incidents). The following general guidelines shall be
used for RFI reporting:
a. Use of the Maintenance Management System (MMS): System Management Office (SMO) or Systems
Operations Center (SOC) specialists are required to perform MMS log entries. FAA Form 6050-3, Frequency
Interference Report is no longer required.
b. Facility service event associated with the RFI: The National Airspace Performance Reporting System
(NAPRS) Interrupt Report (LIR) or Administrative Report (LAD) log entry shall be used.
c. Facility service interruption associated with the RFI: The NAPRS LIR Line/Frequency (LLF) log
entry shall be used. For NO service interruption the LAD log entry shall be used.
d. For the LIR/LLF and LAD:
(1) Enter 84 in the CODE CAT field (LIR/LLF). Enter 07 in the CODE CAT field (LAD)
(2) Enter the duration of the RFI in the OPEN/START and ENTRY/CLOSE fields.
(3) Enter the affected frequencies and channels in the appropriate data fields.
(4) Enter a brief description of the interference and information regarding any actions started or
completed in the COMMENTS field. Additional comments may be added by supporting organizations, e.g.,
SMO, service area FMO, etc.
e. Separate logs: If required, separate or associated logs should be created for each RFI incident and linked
to the parent log via the RELATED LOG ID field referencing the record or log ID number of the parent log.
f. MMS Report format: This information is available in detail in FAA Order 6000.48, General
Maintenance Handbook for Automated Logging.
g. Use of the Spectrum Management Data Base (SMDb): Radio Frequency Interference events not logged
in the MMS system by SMO or SOC field specialists must be logged in the National Airspace System (NAS) RFI
or Global Positioning System (GPS) RFI modules of the SMDb system. The SMDb is available over the FAA
intranet secured network at http://asr.faa.gov/. Authorized users navigate via the FAA intranet to the Technical
Page 167

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Operations ATC Spectrum Engineering Services website link, the SMDb NAS RFI and GPS RFI reporting tools
become available. A system User Identification (USER ID) and password is required for access to these secured
areas of the database. No USER ID is required to access the online HELP link, which provides the SMDb System
User Manual for detailed instructions on how to create and record a particular RFI event.
h. Service Area FMO upward reporting. The nature and particularly the impact and importance of an RFI
problem must be carefully weighed. If there is a reasonable chance that the RFI might be of immediate interest to
headquarters, Technical Operations ATC Spectrum Engineering Services shall be advised immediately. The
following types of RFI incidents require the Technical Operations ATC Spectrum Engineering Services liaison at
the FAA National Operations Control Center (NOCC) in Herndon, VA, to be contacted with the following
information:
(1) Problems with equipment design or design deficiency.
(2) Problems dealing with major or hub airports.
(3) Problems indicating FAA and FCC/NTIA frequency standards are in conflict.
(4) Any interference receiving media attention.
(5) Any interference connected with an accident or incident.
(6) Any interference, which might arouse political or aviation community interest.
(7) Any interference causing a facility to be shut down or restricted.
(8) Any interference to high frequency (HF) assignments.
(9) Any interference attributable to testing, either by another entity or through FAA procedures (e.g.,
maintenance or others).
1402. ADMINISTRATIVE PROCEDURES. Determining the source or cause of interference to NAS services
determines the administrative procedures required for quick resolution.
a. Unknown source: An in-depth desk analysis is the first step in determining the source of RFI. RFI
sources begin as an unknown source until positive correlation can be made with a commercial, civil government
or military establishment. While reports are being obtained, the FMO shall use any available automation analysis
tools to reduce the area from where a culprit source may be radiating the RFI. Technical Operations ATC
Spectrum Engineering Services makes available the Radio Coverage Analysis System (RCAS), Airspace Analysis
Model (AAM), Space Loss Calculator (SLC), and Aircraft Situation Display (ASD) automation tools. These
tools combined with effective reporting data bases will assist in narrowing the potential geographical location of
the RFI source and provide valuable information for a possible airborne mission. In addition, the FMO shall
contact the Technical Operations ATC Spectrum Engineering Services liaison at the NOCC for additional
expertise in conducting the desk analysis. The Technical Operations ATC Spectrum Engineering Services
Liaison may establish teleconferences with concerned air traffic organization personnel to obtain additional RFI
reports from facilities or pilots.
b. Non-Government source: The Federal Communications Commission (FCC) is the government agency
that has regulatory oversight on non-government sources. The appropriate local FCC Field Office shall be
contacted by the FAA service area FMO for proper coordination. When a private proponent has been determined
as the source, careful judgment must be exercised in approaching the owner of the establishment or equipment.
The FCC should be contacted first for awareness and coordination. The FCC may exercise administrative or
other legal procedures depending on their history records on the proponent. In addition, the Technical Operations
ATC Spectrum Engineering Services liaison to the NOCC shall be contacted in the event that the FCC national

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6050.32B

Communications Crises Control Center (CCCC) support is necessary. For situations regarding intentional
interference the guidelines in Order 6050.22 shall be followed.
c. Government source: RFI incidents caused by another government organization shall be resolved and
coordinated locally to the extent possible with the government agency's technical representative responsible for
the operation of the offending equipment. If unsuccessful notify the Technical Operations ATC Spectrum
Engineering Services liaison at the NOCC with all necessary details related to the identified RFI problem and let
the national liaison coordinate resolution at the FAA headquarters level. Service area FMO personnel are
encouraged to participate in local state government frequency management meetings and forums to establish good
working agreements.
d. Airborne RFI investigation support: The service area FMO will be the focal point authorized to
make requests for airborne RFI investigation support. The FMO shall coordinate the airborne RFI investigation
through the national Technical Operations ATC Spectrum Engineering Services liaison at the NOCC. A simple
electronic mail message describing the nature of the pilots-only reported RFI should be sent by service area FMOs
to the Technical Operations ATC Spectrum Engineering Services NOCC liaison to quickly initiate the
coordination process. The electronic mail request shall be followed with a formal memo to the Directors of
Technical Operations ATC Spectrum Engineering Services and Technical Operations Aviation System Standards.
The Technical Operations ATC Spectrum Engineering Services intranet website also has an electronic airborne
support request form that will allow the service area FMO to initiate coordination for scheduling an aircraft from
any location where he/she has access to the FAA network. This tool may be used as an alternative to electronic
mail for requesting airborne RFI investigation support.
(1) Technical Operations ATC Spectrum Engineering Services NOCC Liaison: The specialist at this
office will gather all pertinent RFI problem data from the service area FMO, SOC, SMO, or concerned air traffic
organization facility. After sufficient data to initiate an RFI investigation flight pattern is obtained, coordination
with the Flight Inspection Central Operations (FICO) office is performed via telephone. The FICO will determine
the earliest dates, crews and aircraft that will support the airborne RFI mission. This telephone request will be
followed up by electronic message with any further details that will aid the flight crew in performing the airborne
search.
(2) Non-FAA aircraft: Airborne RFI investigations for the restoration of NAS navigation,
communication or surveillance services can only be performed under an approved FAA flight program. The
Navigational Aids Signal Evaluator Radio Frequency Interference (NASE/RFI) is the Technical Operations
Aviation Systems Standards primary approved flight program for airborne RFI investigations. The FAA research
and development flight program managed by the William J. Hughes Technical Center is the second alternative.
RFI airborne investigations outside an FAA approved flight program require special exceptions and approval
from Technical Operations ATC Spectrum Engineering Services. Technical Operations ATC Spectrum
Engineering Services may specifically authorize the Ohio University Avionics Engineering Center flight program
to execute an airborne RFI investigation when none of the FAA flight program aircraft are available.
e. Costs Expenditures: In all RFI investigation cases, accurate records should be kept on the costs and
funds expended to investigate the RFI event including man-hours and when applicable, aircraft hourly rate costs.
These costs shall be logged in the SMDb costs entry fields.
f. RFI Suppression Devices: These types of devices are implemented when frequency management
engineering criteria for equipment electromagnetic compatibility at FAA facilities is difficult to attain. These
conditions exist when a transmitter is in close physical proximity or in close frequency proximity to a victim
receiver. The following FAA policy addresses the use of RFI suppression devices such as multicouplers,
combiners, isolators, etc. to resolve cosite problems:
(1) Technical Operations ATC Spectrum Engineering Services will manage the overall program for
requirements and budgetary purposes.

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(2) FMOs shall validate the requirements for multicoupler and combiners within their service area in
coordination with the Regional Associate Program Managers (RAPM).
(3) FMOs must carefully specify requirements for combiners. Combiners have a very narrow range of
operating frequencies. Multicouplers are flexible in their potential for retuning to meet changing requirements.
(4) FMOs shall note the use of multicouplers or combiners in the GMF remarks section using the
appropriate format.
1403. INTERNAL PROCEDURES. RFI resolution techniques may vary from service area to service area,
depending on the service area organizational structure, policies and the FMO's available RFI mitigation assets.
The following procedures are recommended as general guidelines that may be adjusted to meet specific service
area needs:
a. SMO frequency coordinators: Identify focal points and agreements at the SMO level. Technical
Systems Offices (TSO) personnel at the SMO level have been designated as RFI focal points and are good
resources.
b. SMO interference liaisons: Designate key service area air traffic organization and Technical Operations
Services management personnel to coordinate regular meetings and to assure Air Traffic personnel reports any
interference to the SMO frequency coordinators focal point promptly.
c. Service area air traffic organization/Technical Operations Services Outreach: Establish periodic
teleconferences or briefings with service area air traffic organization and Technical Operations Services branches
within the service area offices toward increasing RFI impact awareness. The Technical Operations ATC
Spectrum Engineering Services liaison at the NOCC provides a daily status of RFI events being tracked in the
NAS during the morning national operations teleconference. FMO and SMO participation on this national
teleconference is highly encouraged.
d. Prompt Notification: Establish a chain of contacts at the SMO and FMO, when an RFI problem has been
found to be a defective FAA transmitter. The SMO shall request FMO assistance in certifying the RFI cause.
Confirming ON/OFF tests shall be performed; remedial filter recommendations, suggestions and engineering
observations using FMO interference locating and measuring equipment shall be completed.
e. Seamless Service Area Support: During difficult and critical RFI events requiring additional resources
or when FMO personnel shortages impact the service area’s ability to resolve RFI, a request for "Seamless
Service Area Support" shall be coordinated. The FMO is the focal point to coordinate "Seamless Support." RFI
events impacting NAS services shall be given the highest priority and support coordinated with the Technical
Operations ATC Spectrum Engineering Services liaison office at the NOCC. The Technical Operations ATC
Spectrum Engineering Services management staff will give final "Seamless Support" approval.
1404. INTERFERENCE LOCATING EQUIPMENT. Service area FMOs have several types of direction
finding equipment utilizing proven signal monitoring technologies. The equipment is used to assist the FMO’s
skills to resolve RFI. The FAA Radio Frequency Interference (RFI) Detection, Analysis and Resolution textbook
is a detailed reference source of information on equipment and techniques. Basic general guidelines for resources
and equipment are as follows:
a. Telephone Lists: Comprehensive lists of contacts are important namely; FCC, other Federal Agencies,
other State Agencies, DOD Area Frequency Coordinator (DOD AFC), and private frequency management
organizations. Calls to these contacts with a description of the nature of interference assists in the resolution.

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b. Audio Recording: RFI audible characteristic is very important in identifying interference sources. The
sound of the RFI may provide clues to the source identity. Careful listening to the signal or reviewing audio
recordings from air traffic facilities can reveal such things as:
(1) Service: Police, Taxi Dispatch, Amateur Radio, Paging, Cellular, etc.
(2) Emission: Pulse modulation (i.e., radar and other pulse type emissions are recognizable by their
characteristic "buzz."), Phase Modulation, Frequency Modulation, etc.
(3) Nature: Drifting signals, frequency sweep (i.e., industrial heating device), video field change (i.e.,
characteristic "hum" change), rhythmic ticking (i.e., timing circuits) musical sound (i.e., varying telemetry signal),
etc.
c. Spectrum Analyzer: The spectrum analyzer (SA) is an instrument that should be used by properly trained
Technical Operations Services specialists. Short duration or "burst" type signals, complex waveforms signals,
and signals that drift within a wideband spectrum are some of the measurement benefits the SA provides to the
Technical Operations Services specialists. Locating intermittent RFI is particularly time consuming and use of
the SA may provide the necessary clues for RFI resolution.
(1) Overload Caution: The SA has a wideband front end. When high-level signals are present at the RF
front end it can generate internal spurious signals, which may appear as if they were real signals. In addition,
false signal levels are displayed due to front end overloading condition. The standard procedure to avoid this
problem should always be to use a tunable filter or in-line attenuation pads with the SA. In line attenuator pads or
filters may reduce the overall sensitivity of the SA, but will permit on-frequency use while rejecting strong offfrequency sources.
(2) No Filter Procedure: The following procedure may prevent the SA overload condition in the presence
of high-level signals. Set the SA to monitor the RF signal of interest and note any adjacent signal levels. Insert
10 dB of external attenuation. If all signals presented on the screen are reduced by 10 dB, then the front end is not
being overloaded (Note: make sure a wide enough spectrum bandwidth is being measured). If some shown
signals drop more than 10 dB, then the front end is being overloaded, and another 10 dB attenuation is required.
When a level of additional insertion occurs where every signal drops equally, the integrity of the front end of the
SA is assured. (Note: Attenuation reduces the sensitivity of the SA).
d. Receiver: This type of equipment provides the highest flexibility for investigating RFI in the NAS. Field
strength meter receivers are manufactured with great shielding and bonding for great sensitivity and selectivity.
These are costly units and used for specialty applications. Inexpensive general purpose portable receivers may be
sufficient for some RFI investigations. In addition, 360, 720 or 760 channel VHF aeronautical transceivers can be
reasonably effective in the VHF spectrum under some power line RFI investigations. For best results during RFI
investigations, it is recommended that a receiver be used that permits the use of an external antenna, has RF gain
control, is shielded, and has a carrier level meter.
e. Antennas: Specific types of antennas connected to a receiver for direction-finding (DF) work will provide
the Technical Operations Services specialist with a better probability to quickly locate the RFI source. A Loop,
Yagi, Log Periodic, or even a simple Dipole, which can be used for DF, will work appropriately if used according
to direction finding techniques. Further details are provided in paragraph 1406 b.

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f. Direction Finders: There are DFs configured for fixed remote site operation and those configured for
portable mobile operation. The fixed DF configuration is automated and is available for local or remote operation
24 hours and 7 days a week. Portable DFs are available in manual and automated modes. These are used from a
fixed location or while in motion.
(1) Fixed DF: Fixed DF facilities are presently limited to high-traffic density areas where RFI has the
potential to severely impact NAS services, causing delays and safety risks. They are strategically located to attain
triangulation within a geographical area that is within Radio Line of Sight (RLOS) to each of the fixed DF sites.
The expansion of fixed DF sites is expected throughout the NAS in the near future.
(2) Portable DF: Service area FMOs are the focal point that coordinate the use of portable DFs which
can be used in a vehicle while in motion in the manual or automated mode. Technical Operations ATC Spectrum
Engineering Services also manages a national handheld and portable direction finder program, which utilizes
general purpose receivers and processors specially designed for RFI investigation work. Service area FMOs are
also the focal point for coordinating the use of these nationally available portable and handheld DF systems with
the Technical Operations ATC Spectrum Engineering Services liaison office at the NOCC.
g. RFIM Van: Some RFI events require the use of a vehicle as an efficient tool when used by a proficient
operator, especially if the RFI source is suspected to be at some distance from the victim equipment. The ability
to take bearings quickly in an automated mode, while traveling, assists in rapid DF triangulation that leads to
source location. Service area FMOs are the focal point for coordinating the use of the RFIM van. Further
information concerning RFIM vans will be found in Chapter 15.
1405. INTERFERENCE LOCATING TECHNIQUES. The techniques for locating an RFI source vary,
depending on the nature of the RFI and the personnel seeking resolution. A rule of thumb is that no condition is
to be assumed. All possibilities must be considered. Engineers in the radio frequency field have developed some
basic techniques over the years. The following paragraphs provide general guidance, listed by the type of system
receiving interference.
a. Ground Communications interference: This is RFI to FAA equipment use for Air/Ground voice
communications in the terminal and en route environments. This equipment experiences the most RFI, which can
be classified into three basic types: internal, local, and external.
(1) Internal interference is RFI generated within the receiver, normally harmonic or spurious emissions
generated by internal crystal oscillators or synthesizers used in the superheterodyne circuitry. This RFI manifests
as unmodulated carriers on specific frequencies, appearing constantly. FMOs should examine this possibility
prior to seeking for external sources. Aging crystals, oscillator tuning, and change on receiver voltage during
routine maintenance can initiate a spurious signal. It is recommended that the antenna be removed from the
receiver and the input terminal be grounded. If the signal remains, the source is internal and the receiver should
be repaired.
(2) Local interference is RFI caused by other signal sources in the same rack, same room, or same
building. Signals generated by another transmitter or receiver can cause a receiver response on the assigned
frequency. Service area FMOs should carefully assess, when receiving a complaint, if the interference "just"
started. It could have been present since installation of the victim receiver or the source transmitter or receiver,
but only recently became noticeable. The problem may be masked by normal squelch setting and then become
noticeable only when the squelch level is lowered or increased traffic on the frequency causes the squelch to be
opened more frequently.

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(a) Intermods: The potential for intermodulation when engineering the frequencies for a site shall be
avoided. Lower order (third or fifth order) intermods may exist below squelch until frequent use of the site
frequencies unveils its presence. Intermod is easily recognized by its makeup of a mix of two or more facility
frequencies other than the victim frequency. Intermods are covered in Appendices 1 and 2.
(b) Some Resolutions:
1. Antenna relocation (vertical or horizontal separation).
2. Receiver or transmitter relocation (to another site).
3. Cavity or crystal filter installation (victim receiver input).
4. Cavity and/or ferrite isolator installation (transmitter outputs).
5. Frequency change (last alternative - may introduce new problems).
(3) External interference is RFI caused by a myriad of sources, including such devices as heater
thermostats, broken power pole insulators, doorbell transformers, computers, industrial devices using RF energy
(i.e., “plastic welders") and almost any conceivable RF source. The problems divide into six major categories: cochannel, adjacent channel, brute force, intermod, image and audio rectification.
(a) Cochannel interference is RFI generated when a signal is within the receiver band pass of the
assigned frequency. The victim receiver receives a signal at its detector that is processed as a desired signal. The
FMO shall carefully identify the signal (voice, pulse, etc). Careful listening of the interference directly or from
AT tapes, shall be performed.
(b) Adjacent Channel interference is RFI caused by signals much broader and stronger than those in
the cochannel case. The receiver band pass is a product of its RF and IF band pass circuits, but they are limited in
their curve shape due to the Automatic Gain Control (AGC) function of the receiver. Sometimes the channel
assigned above or below the victim frequency causes the problem.
(c) Brute Force interference, also known as front-end overload is an exceedingly strong signal which
might be anywhere in the radio spectrum. For example, a 50 kilowatt FM broadcast transmitter in the 88 to
108 MHz band a few hundred feet from an FAA receiver can completely overload the receiver. The result is
desensitization of the receiver and usually the passing of the FM signal through the receiver. Brute force can also
be in-band and near-frequency (i.e., a receiver tuned to 125.575 MHz could be overloaded by a transmitter on
125.60 MHz in the vicinity, assuming its antenna were in proximity). Relocating the transmitter or receiver
antenna to achieve 1,000 feet or more separation can cure brute force problems. Installation of a cavity or crystal
filter is a good solution as well.
Note: This type of problem normally occurs within the same building, or nearby buildings. To minimize brute
force (overload) potential, the FAA cosite standard for frequency separation is 0.5 MHz for VHF (118-137 MHz)
and 1.0 MHz for UHF (225-400 MHz) for transmitter and receiver antennas within 80 feet of each other.
(d) Intermodulation (IM) interference normally occurs in a receiver, caused by a combination of
external strong signals (2 or more) which algebraically mix to produce the victim frequency, usually in the first
mixer or first amplifier. The receiver responds to the mixed frequency as if it were an "on frequency" signal.
Intermods may also occasionally be created within transmitters where they are in close proximity. A spectrum
analyzer could be of valuable assistance in determining the interfering signal level.

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1. IM definition: IM is expressed with formulas where the mathematical relationship of various
frequencies results in the operating frequency of to the victim equipment. For example:
2nd Harmonic IM = 2Fc; (Fc = Center Frequency)
2 x (121.5 MHz) = 243.0 MHz
3rd Harmonic IM = 3Fc; (Fc = Center Frequency)
3 x (121.5 MHz) = 364.5 MHz
Sum/Difference 2 Frequency Third Order IM = 2F1 ± F2
2 x (119.8 MHz) - 118.1 MHz = 121.5 MHz
2 x (119.8 MHz) + 118.1 MHz = 357.7 MHz
Sum/Difference 3 Frequency Third Order IM = F1 + F2 ± F3
118.1 + 124.7 + 121.3 = 364.1 MHz
118.1 + 124.7 - 121.3 = 121.5 MHz
2. Receiver IM Resolution: One potential solution is to install a band-reject (notch) filter at the
input of the victim receiver, tuned to one of the undesired frequencies that generates the IM inside the receiver.
This reduces one of the undesired signals below the level at which it drives the victim receiver front end into nonlinear operation. A second potential solution would be to use a bandpass filter at the victim receiver, tuned to the
victim frequency. This is effective, however, only if the culprit frequencies which cause the intermod, are well
removed from the victim frequency. The frequency separation requirement is a function of the bandpass filter
selectivity curve.
3. Transmitter IM Resolution: Potential solutions are to use bandpass or band-reject filters at the
antenna input of the culprit transmitter. Proximity of strong signal causes unwanted mixing in the amplifier or
mixer stage of the transmitter. The transmitter final amplifier is driven by these external signals into non-linear
operation, generating and radiating the undesired IM (or spurious) signal on the victim frequency. Since a
transmitter is actually radiating the IM (or spurious) signal, nothing can be done at the receiver to resolve the
problem, only stopping the undesired strong signals from entering the culprit transmitter yields resolution.
(e) Image interference: This is caused by a strong external signal which mixes with the local oscillator
(LO) in the victim receiver to produce the intermediate frequency (IF) which then is processed by the receiver just
as if it were a desired "on frequency" signal.
1. Case example: A Flight Service Station (FSS) receiver is tuned to 121.5 MHz. Its Local
Oscillator (LO) is 20.6 MHz above the desired frequency (i.e., 121.5 + 20.6 = 142.1 MHz). If a sufficiently
strong signal appears at the victim receiver input from a culprit frequency of 162.7 MHz, this signal will get
through the first amplifier of the receiver and mix with the 142.1 MHz LO to produce the intermediate frequency
(IF) of 20.6 MHz. See figure 14-1 for a graphical illustration. For aviation frequencies, an LO on the low side
(i.e., 121.5 – 20.6 = 100.9 MHz) is avoided because the "image" frequency would be 80.3 MHz, close to TV
channel 5 video carrier.

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FIGURE 14-1. IMAGE FREQUENCY RELATIONSHIPS

2. FAA A/G Radios: The commonly used VHF/UHF receivers are the ITT GRR-23, GRR-24 and
the Motorola CM200V/U units. The GRR LO's are 20.6 MHz above the desired frequency, except for 322 MHz
and higher, where they are below. All CM200 series LO's are 45.0 MHz above the desired receive frequency.
The CM200 also has a second IF at 456 kHz.
3. Image RFI Resolution is to filter out the undesired signal from entering the victim receiver by
reducing its level below that to which the receiver will respond. The amount of rejection required will depend on
the filter selectivity curve. Other alternatives are to lower the power of the culprit transmitter, install a directional
antenna to discriminates against the victim-culprit azimuth or to move one of the sites further away.
(f) Audio Rectification is interference whereby an audio amplifier is driven into detection mode by the
strength of the culprit signal, usually a nearby high power AM broadcast station. At some strength level, any
signal can cause a contact (i.e., a transistor input junction, a poor ground connection, etc.) to act as a diode and
rectify the signal, then reradiate the detected signal. The signal may be distorted because it is the increase in
intensity from the amplitude modulation that drives the device into detection mode. In these cases, an amplifier
may act as a radio receiver. The problem usually is at the input stage where the amplification is the greatest and
the rest of the amplifiers merely amplify it.
1. Resolution: One potential solution is to bypass the input circuit with a small (0.005 Microfarad)
capacitor between the circuit board ground and the closest possible point of input to the amplifier stage, with the
shortest possible leads. Also useful is a ferrite bead on the input line wire. If the strong signal is entering the
amplifier cabinet by the power line or remote speaker lines, it is recommended to wrap the line through a ferrite
ring, which will act as a radio frequency choke. Sometimes merely plugging in the power cord to another outlet
circuit will change the level enough to eliminate the rectification. Each case may be unique, however applying
these techniques in a logically progressive manner may yield the solution.

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b. Airborne Communications interference is RFI to aircraft receivers which can be difficult to
investigate and locate. Because of RLOS, the RFI source affecting a flying aircraft may be located a hundred
miles or more from the area where aircraft are being affected. The following procedure is recommended for
investigation and location of such RFI sources.
(1) Obtain the following data from the service area air traffic facility:
(a) Date and time the RFI reports started
(b) Aircraft Location (altitude, latitude, longitude, airline, aircraft type)
(c) RFI Occurrence (constant, intermittent, morning, night, weekends)
(d) RFI Description (music, voice, squelch breaks, tones)
(2) Constant RFI: If the RFI is fairly constant but only one airline reports the problem, suspect their
equipment and contact their maintenance department with the information you have obtained from the service
area air traffic facility. If several airlines and private pilots have reported the problem then the following is
recommended:
(a) RFI reports data: Coordinate with the service area air traffic facility to request reports from
aircraft at various altitudes in the affected area to monitor the frequency for RFI (targets of opportunity).
(b) RFI data analysis: Analyze the data provided by the service area air traffic facility and plot on a
high or low aeronautical sectional map the extreme points at which multiple RFI reports have been received.
(c) Area Reduction: To the extent possible, use the RLOS generated by each aircraft data point and
the Venn diagram techniques to identify an area of less than 50 nmi radius having the majority of RFI complaints.
Conduct the following checklist in an attempt to reduce the size of the geographical area to be searched on the
ground:
1. Altitude – reports 6,000 ft below local ground level
2. Area – 50 nmi east, west, north to south radials centered on the RFI area
3. AGC level – note on a chart the points where the signal is the strongest
4. Triangulation – estimate a grid where the source may be located
5. Repeat steps 1, 2,3 and 4 above – with reports at 2000 ft, 3000 ft, etc.
6. Reduce area – 20 nmi east-west, north-south. Fine tune estimated area
7. Proceed with the ground search of the area identified in 4 and 6 above.
(3) Intermittent RFI: If the RFI is intermittent the problem becomes a greater challenge and may require
further assistance at the national level. If several airlines and private pilots have reported the problem, the
following is recommended:
(a) Procedures: The same techniques described under Constant RFI above are applicable when
intermittent RFI is reported. Coordination for an FAA flight check is the same as for Constant RFI. However, the
Technical Operations ATC Spectrum Engineering Services liaison at the NOCC may coordinate collaborative
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assistance for additional PIREPS reports from a special RFI working group of the Air Lines Pilots Association
(ALPA) named "aeroRFI." Additional assistance may be coordinated with the Air Transport Association (ATA),
the National Business Aircraft Association (NBAA), and the Aircraft Owners and Pilots Association (AOPA).
These organizations can provide VHF A/G data link message reports to the Technical Operations ATC Spectrum
Engineering Services NOCC liaison for further analyzing the geographical area of the RFI.
c. NAVAID interference: This type of RFI is more difficult to identify and is generally first noted by pilots.
Unless the RFI source is a strong signal, there is a possibility that it may not be detected on the ground, except in
the immediate vicinity of the source. It may be necessary for the FMO to arrange airborne RFI support with the
Technical Operations ATC Spectrum Engineering Services liaison at the NOCC for such investigation.
(1) Ground VOR RFI: This problem is mostly local and may be reported principally on an airport. In
this case, it would be worth trying a ground search with the RFIM van on and around the airport first, or using a
handheld DF system.
(2) Airborne VOR and LOC RFI: This problem is frequently from FM broadcast stations, especially if
they are in the upper part of the 88 to108 MHz band, creating brute force and intermod problems in the airborne
receiver when the aircraft nears the FM transmitter site. Unless the FM station is clearly identified by the
reporting pilot, it will be necessary for the FMO or flight inspection crew to observe reception of the signal in the
air. The following steps are recommended:
(a) Flight Check: The FMO should join the flight inspection crew to make a definite determination
whether a reported interference is really a problem or a problem in the reporting aircraft equipment.
(b) Air Traffic Check: Request the appropriate ATCT, TRACON or ARTCC personnel to query
aircraft of opportunity to determine whether they notice a reported problem, before investigating a report.
(c) Confirm Reports: The FMO must confirm additional reports from aircraft utilizing the NAVAID
service. The FMO shall seek for reports issued by other FI crews on the affected NAVAID.
(3) TACAN RFI: This type of RFI can be caused in two ways. Airborne reception can be affected by a
source of interference somewhere on the ground. The ground based TACAN receiver can also receive
interference from any source nearby on the ground or from any airborne source within RLOS. The FMO should
work closely with the SMO frequency coordinator or SMO technicians if necessary so that the FMO can
determine whether to work with the interrogator or the transponder frequency. Once the local geographical area is
known, the FMO should proceed to locate the RFI source, using many of the techniques described in this chapter
for interference to air/ground communications systems.
d. Radar Interference: This type of RFI requires collaboration with the concerned service area air traffic
organization to identify. It is generally first noted by controllers. Interference to primary and its associated
beacon present a particular problem in locating an RFI source.
(1) Primary radar RFI: Primary radar interference is normally another radar, although occasionally it is
a harmonic from a lower frequency transmitter. The FMO should coordinate with SMO technicians to determine
the azimuth the interference indicates on the air traffic controller’s scope. If the source is another radar, the
interference may appear as dotted spirals named "running rabbits," which appear to "run" as the radar rotates. If
the FMO has good records from the radar coordination program, the source might be identified by the PRR.
There is a method to determine this from the radar scope presentation and it is detailed in paragraph 1408.

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(2) Radar Beacon (ATCRBS or IFF) RFI: This type of interference is the most difficult of all because
all interrogators and transponders work on the same frequency (1030/1090 MHz) and are separated only by PRR.
Interference is usually from another interrogator, which could be several hundred miles away. Interference will
normally show up as intermittent false targets. This is because two different interrogators can illuminate an
aircraft at nearly identical times, resulting in both radars "painting" both replies offset in time.
(a) Aircraft Location: It will be necessary to coordinate with the concerned service area air traffic
organization to determine in what general area the aircraft are located which are producing the false targets. Once
the area is known, monitoring of 1090 MHz should be done, looking for aircraft replies on the same PRR (±3 pps)
as the victim radar. From there, it becomes trial and error plus deduction. Attempt to determine the direction of
the victim aircraft. The area of search will have to be widened until an interrogator on 1030 MHz can be heard
that matches the PRR of the victim. It is then located by DF procedures, as described in paragraph 1407.
(b) Beacon RFI: Since another interrogator almost always causes beacon interference, the FMO must
exercise patience and diligence to locate it. The use of telephone contacts, particularly with DOD spectrum
coordinators and appropriate on/off tests, are clearly indicated before a ground search is begun. Here is where the
FMO's PRR coordination records, contacts set up in advance with DOD, other spectrum coordinators, and the
telephone are usually the most valuable tools.
(3) Reflections: Awareness of reflections from metallic objects such as buildings, fences and the like can
cause interference by putting the source radar signal into areas not intended. See paragraph 1302 and figure 13-1.
1406. DIRECTION FINDING (BELOW 1000 MHz). After initial investigation procedures by means of
telephone points of contact and record searching the next step to locate the potential source of RFI is to use DF
equipment and techniques. There are three principal techniques, automatic DF, directional antenna DF, and
proximity DF ("hot and cold" method). These techniques may be applied equally when used in an RFIM van, a
standard vehicle mounted auto-readout or hand carried portable unit. Further details on these techniques could be
found in the Radio Frequency Interference (RFI) Detection, Analysis and Resolution pamphlet referenced in
paragraph 1400. This pamphlet could be obtained from Technical Operations ATC Spectrum Engineering
Services in Washington, DC.
a. Automatic DF: Equipment and techniques of this type uses a set of ground plane vertical aerials,
switched at a rapid rate, with a representative display of the incoming signal by compass rose showing a line of
bearing strobe or numerical digital azimuth readout. Some automated systems make use of a computer, which
allows for electronic data storage for later retrieval and analysis of the data. With automatic DF systems, the
FMO follows the direction indicated by the line of bearing (LOB) on the display until the source is located.
Caution needs to be exercised when using these automatic DF systems since many false bearings may appear on
the display due to signal reflections. It is recommended that the FMO continue to obtain LOBs while mobile to
get out of zones that caused the reflections.
(1) RFID System: This is a portable unit that operates under the concept of a single channel Watson-Watt
system that modulates the carrier with AM sidebands carrying the DF information. The RFID utilizes a series of
multi-element adcock antennas for DF directional information where most of the processing is performed. In
addition, the system is fully controlled by a laptop computer making it capable of unattended operation.
(2) PIMDS System: Like the RFID, this unit also operates under the concept of a single channel WatsonWatt system. The unit has RF combining circuits including the Sum/Diff Hybrids, and circuits that create the N-S,
E-W, and Sense antenna patterns from the array inputs. In this unit, modulators and Gain/Phase equalization
circuits modulate the N-S and E-W signals with low frequency tones, combining them with the sense signal.
The gain and phase vs. sense values are equalized over the frequency range to provide very accurate lines of
bearing readings. This system is self-sustaining and does not require a laptop computer to operate. However, the
computer can be added and unattended data collection can be performed.
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b. Directional Antenna DF: This type of equipment and techniques are frequently used because of the great
availability of the equipment and its relatively low cost. The antenna is connected to a general-purpose
monitoring receiver, which should include tuning in the aeronautical navigation and communications radio
spectrum. For better results the equipment should have a signal strength meter. If a meter is not available, the
aural signal intensity variance heard over the monitoring receiver speaker can be used. When a loop or dipole
antenna is utilized, a signal null with respect to the source is of interest, because the null is much narrower
(sharper) than the maximum signal reading. For a Yagi, Horn, or other high gain type antenna, the maximum
signal reading is of interest. This is because of the radiation pattern of these particular types of antennas. The
maximum lobe signal reading provides an unambiguous direction. However, the nulls in these kinds of antennas
are varied and not diametrically opposed, so they may create confusion in determining the actual bearing.
Technical Operations ATC Spectrum Engineering Services manages the K95-100 series handheld system. This
system is the most widely used by AF specialists and is available through the FAA Logistics Center.
(1) Loop Antenna: Electrically one half wave or less, the minimum signal is perpendicular to the plane
of the loop. That is, when the loop is rotated, the signal meter or audio level will vary so that looking through the
loop when the signal is nulled (i.e., at minimum level), it will indicate the bearing direction of the signal being
received. A loop bearing is bi-directional. Since the loop null is symmetrical (when used within its design
parameters), the source can be either in front or behind the loop. The procedure to determine the true direction to
the source, after the first bearing has been taken, is to move at a right angle between one hundred and a thousand
feet from the first bearing. Take another bearing. If the source is less than two miles away, the second bearing
will cross the first bearing and thus establish a true direction ahead or behind. A third right angle measurement
may be required if the source is at a considerable distance. Next, travel to the general area where the bearings
intersect and take a third or fourth bearing. When this bearing is plotted, it should create a triangle with the first
two. The source should be in or near the area enclosed by the triangle. Continuing triangulation will narrow the
search area.
(2) Dipole Antenna: The handling process is similar to the one described for the Loop antenna but the
indication is reversed. A dipole minimum or null is off the ends of the dipole, along its parallel plane. In effect,
the dipole null is in the direction of (points to) the source. Because it is not electrostatically shielded like a loop,
a dipole is subject to many more reflections. Caution must be exercise in following the bearings. Making
frequent stops for additional bearing is recommended. Like the loop, the dipole is bi-directional. If it is not
adjusted to resonant length it may not have symmetrical nulls. It is recommended that a chart showing the
resonant length with respect to frequency be carried so that the dipole can be adjusted accordingly.
(3) Monopole (Whip) Antenna: The procedure is the same as the dipole. A whip is normally attached to
the receiver antenna input connector. The receiver or antenna is rotated so that the plane of the whip is horizontal.
It is then used just as a less effective dipole. A whip can be used satisfactorily, if the signal is reasonably strong,
or the receiver is very sensitive. In addition, a certain amount of directivity can be obtained by holding the
receiver and antenna in front of the operator. As the operator rotates about on his/her vertical axis, one null may
be more noticeable ("deeper") than the other. If this is the case, body mass is absorbing some of the VHF signal
when it is behind the operator, so the "deeper" null could indicate the signal source is behind the operator.
(4) Yagi Antenna: A corner reflector or other multi-element type antenna is unidirectional. A signal
strength meter on the receiver or other level readout must be used. The maximum received signal is of interest
and used to determine a bearing to the source. The broad radiation pattern (“nose”) of the beam can be centered
when a meter is used or other type of signal level readout. Nulls are asymmetrical, thus unusable. There are three
advantages to a Yagi, corner reflector or beam antenna; (a) each produces gain, (b) each is unidirectional, and (c)
each is polarized. Polarization allows for rotating the antenna on its directional axis to determine the signal
source polarity or minimize reception of cross-polarity undesired signals.

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(5) Log Periodic: The procedure is the same as the Yagi antenna. This is also a multi-element type
antenna that provides unidirectional characteristics. The same procedures used for the Yagi antenna for
determining the bearing to the source apply to the Log Periodic.
(6) All Antennas: The antennas mentioned in this paragraph are effective. All should be operated away
from metal or other RF reflective surfaces to prevent any reflections from giving erroneous or ambiguous
bearings. It is recommended that 15 to 20 feet separation be maintained for a vehicle and up to 500 feet from a
building. The loop is least affected due to its electrostatic shield. However, unless it is resonant at the frequency,
it will provide some signal reduction over a dipole. Its static field shielding makes it superior for close proximity
work. It is frequently beneficial to start with a dipole or Yagi until sufficient signal is received to use a loop.
c. Proximity DF ("Hot and Cold"): This technique is useful but a very time consuming and limited
procedure. The technique consists of carrying a monitoring receiver either physically or in a vehicle, tuned to the
frequency experiencing the interference. By trial and error, an area of maximum signal detected can be identified
by observing the signal strength meter on the receiver as the unit is moved about. If the receiver has no meter or a
meter is not available with suitable RF gain control, the alternative is to detune the receiver intentionally in the
presence of a strong signal, which will give the appearance of a weaker signal to the receiver. By careful position
selection or choice of moving from location to location, selective detuning, and other intuitive judgment the
source could be located.
1407. DIRECTION FINDING (ABOVE 1000 MHz). Microwave DF techniques are normally in the TACAN,
Radar, MLS or RCL radio spectrum bands. There is no fine line at 1000 MHz. However, dipole and loop
antennas become progressively ineffective for DF work above about 600 MHz and Yagis above 1,000 MHz. Log
Periodic (LP) are more effective and Horn antennas start around 1000 MHz (1 GHz). These or helical equivalents
are normally used, and because of antenna pattern configuration, the maximum signal is used for DF work. The
new and future aeronautical navigation satellite service such as the Global Positioning System (GPS) will operate
in the L band spectrum making the Log Periodic and Horn antennas the instruments of choice for DF work.
a. TACAN Type Signal: For this type of signal or other steady state emission, the source is located by
triangulation as described in paragraph 1406. A Horn or Helical antenna is unidirectional, so even the first
bearing taken indicates the initial unidirectional approach (allowing for reflections). A Horn is polarized (either
vertically or horizontally), so it must be rotated on its directional axis to determine the polarization of the
incoming signal. A Helical is not polarization sensitive, except where the source is reverse helical. In this case,
the received signal is greatly attenuated by the reverse polarization of the receiving antenna.
b. Rotating Radar Type Signals: If the RFI signal is a rotating radar, the DF procedure is more complex.
Because the DF receiver is illuminated for only milliseconds every 4 to 12 seconds on the average, some means is
required to denote small differences in received signal as the Horn direction is changed. If a field strength meter
is used, the direct peak detection hold function should be used, since each illumination peak will be held for a few
seconds. This allows visual noting and will permit signal level differences as small as 1 dB to be seen. If a
general-purpose receiver is used, a high-speed recorder such as the TechniRite Model 711 attached to the
Y output or detected signal will permit the same observation in real time.
(1) Horn/Helical Antennas: The horn or helical antennas should be positioned every 10° to 15° at a time
and the received level noted. It is recommended to measure two or three passes at each azimuth before shifting
the antenna. This will allow peculiar propagation such as beam fly-through by passing aircraft to be averaged out.
Peak azimuth readings should not be assumed as the bearing. A complete 360° check should be performed. The
first peak measured may be a reflection or a minor lobe of the receive antenna. The real peak should stand out
significantly. Another aid in discriminating between direct and reflected signals is that at microwave frequencies,
reflected signals off flat surfaces shift polarity 90°, but reflections off rough surfaces such as mountains, may
change anywhere between 0° and 90°.
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FIGURE 14-2. RADAR INTERFERENCE DF EXAMPLE

(2) Radar RFI Example: A radar interference signal might be chased for miles in a continuing direction,
only to find it to change abruptly concurrent with a marked increase in received signal strength. An actual
example is shown in figure 14-2. The original bearings (1) through (4) in figure 14-2 all showed the same general
area source and for 30 nmi converged on a point. This was because at the lower elevations, the only signal that
the victim radar and the DF equipped vehicle could receive was that reflected from the mountain. But upon
arrival near the converging point, the bearing suddenly shifted and the level greatly increased. The DF equipped
vehicle’s receiver was now high enough to see over the hills that blocked direct reception of the interferer site.
The victim radar received its interference by reflection from the large 10,000 foot mountain.

1408. "RUNNING RABBIT" INTERFERENCE. Paragraph 1405 mentions the type of interference that
occurs when two search radars of fixed PRR's are operated in proximity. The dotted line spirals, running out from
or into the center of the radarscope display indicate this type of radar interference. It most likely would happen
near a military base or training area where transient troop groups make frequent changes of radars. There is a
formula which will allow the FMO to determine the PRR of the interferer radar, since the FAA PRR will be
known.
a. Parameters: The first parameter needed is to determine whether the "rabbits," which actually are
presentations of the difference in PRRs, are faster or slower than the FAA victim radar. The second parameter is
the number of "rabbits" per radar sweep. The patterns for each condition are shown in figure 14-3. Shown below
is the calculation for an interferer's PRR.

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FIGURE 14-3. RUNNING RABBITS PATTERNS

b. When the PRR's are fairly close,
ƒi = ƒv ± RS
where;
ƒi
ƒv
R
S

= PRR of interferer radar in pps
= PRR of victim radar in pps
= Azimuth scan rate of victim radar in r/s
= Spirals/revolutions on victim radar scope presentations

c. For Example:
ƒi = ƒv ± RS
Victim radar PRR = 360 pps
Victim radar azimuth scan rate = 15 r/min = 0.25 r/s
Victim radarscope presentation shows 6.0 spirals/revolution
thus;
ƒi = ƒv ± (6.0 x 0.25)
ƒi = ƒv ± 1.5
fi = 361.5, if the rabbits are as in presentation a of figure 14-3.
fi = 358.5, if the rabbits are as in presentation b of figure 14-3.

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1409. ELECTRONIC ATTACK (EA): DOD conducts frequent flights radiating for EA missions, covering
very large geographic areas. In addition, the DOD conducts periodic GPS jamming test emissions. These
emissions can be sources of serious RFI problems. The procedures are covered in chapter 18.
1410. POWER LINE INTERFERENCE. This type interference is difficult to locate. When power line
generates ("carries") interference, it acts as a Beverage antenna and can conduct the RFI for miles along its lines
as standing waves. (A Beverage antenna is one straight wire fed at one end that is many wavelengths long,
usually 7 or more wavelengths. This configuration results in the antenna main radiation lobe being approximately
in the same direction as the wire.) A motor arcing at a farm or factory can be the cause of the RFI. Arcing
insulators on the power line are also potential causes. This type of problem is best solved by using a mobile
system like the RFIM van or other suitable equipped vehicle and "cruising" the line coming into the facility, and
other lines nearby.
a. Electric Motor Type: If it sounds like an electric motor, it could be from next door to several miles away,
depending on how strong the brush arcing is and the amount of current drawn by the motor. Driving the RFI
vehicle along the line feeding the facility will show a gradually increasing/decreasing average signal. Some
frequent small increases in noise may be experienced as each power pole is passed. Using hot-and-cold DF
techniques may lead into the area or the building with the source, which should be located within a reasonable
period of time. When found, it should be brought to the attention of the operator, then of the utility company
which supplies the service. Quick resolution may be accomplished when the FMO makes the operator aware of
the impact to the safety of the flying public due to this RFI. Only fixing the problem at its source, probably with
power line filters or additional or better grounding at the motor, can cure electric motor RF noise. In all cases, the
FCC should be notified.
b. Intermittent Arcing: If it sounds like intermittent arcing, it probably is a cracked or broken insulator on a
pole’s crossarm. The utility company should be notified, stressing the aviation safety of life and property risks.
The utility company may have an "interference" group, but if so, generally they are understaffed so that resolution
may take a long time. The service area FMO should make an effort to locate the problem. If the FMO can locate
it and report the pole to the utility company, resolution should be prompt. Since an arcing insulator can lead to a
pole fire, a utility company normally will take immediate action. Use of the RFIM van or other suitably equipped
vehicle to travel along the line is recommended. In the general area of the defective insulator, there will be a
marked increase in RF noise. By carrying the portable receiver, the FMO can check the poles with the highest RF
noise radiation. Standing next to the pole, a moderate blow with good-sized hammer will send sufficient
vibrations up the pole to rattle the insulators. If the pole struck is the offender, the noise in the receiver will
increase momentarily. On occasions, the arcing might even stop for a while until some other vibration sets it off.
Once it has been located, note the location and the pole number so that it can be reported to the appropriate utility
company.
c. Ultrasonic Detectors: If available, an ultrasonic detector is a component of the RFI equipment
complement. It is another tool that can be used with great efficiency in locating the arcing spot. After narrowing
the area with a vehicle, the ultrasonic detector is pointed at individual cross-arms and insulators from the ground
position. Since the detector uses a parabolic reflector, the ultrasonic source can be pinpointed by aural and level
meter means via a bore sight, sometimes down to the specific insulator. When located, it should be reported
promptly to the utility company with awareness notification to the FCC. Insulator arcing may occur at any time,
but frequently starts after a long dry period when dust and dirt accumulate on the surfaces. The first rain, if heavy
enough to clean the insulators thoroughly, may clear up the problem for a time. A light first rain after a long dry
spell can make matters worse by washing dirt into a crack, setting up an even better arcing path.

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1411. DIGITAL RADIO SYSTEMS. Commercial digital radio systems, especially microwave links, are being
implemented across the country. Because of the decreased resistance of some digital radio receivers to certain
types of RFI, FMOs need to be aware that there may be increasing numbers of complaints from commercial
vendors concerning RFI to their systems. FMOs receiving such complaints need to first evaluate the accused
(FAA) interference source to assure that it is operating within specifications. If the FAA system is within
parameters, then the FMO may help the commercial vendor in whatever manner possible, as long as no expense is
incurred to the FAA. Special attention shall be taken on the Wide Area Augmentation System (WAAS) and
Local Area Augmentation Systems (LAAS). These systems are satellite based navigation digital systems
operating at very low-level signals. If the victim is a federal agency, including any of the military armed forces,
plan to work with that agency in the same manner, but notify Technical Operations ATC Spectrum Engineering
Services early on in the case for possible headquarters support.
1412. ELT PROBLEMS. Since their introduction, ELT's have caused a considerable amount of interference by
false activations. Since they are on the emergency frequencies 121.5/243.0 MHz, they must be located and shut
down quickly to keep the channels clear for legitimate ELT use by downed aircraft. Air traffic control facilities
will be the first to know if a false activation occurs, since it mostly occurs on an airport. If it is very strong, the
concerned service area air traffic organization should not only notify the Search and Rescue (SAR) personnel, the
nearest ARTCC, and the service area duty officer, but also the appropriate SMO and the FMO. Most SMO
offices have been supplied with hand carried ELT locators. They or other hand-held DF receivers can be used to
locate the offending ELT. The hand-held K95-100 series DF supplied to service area FMOs and SMOs is an
effective system for ELT location. Sometimes an accidentally triggered ELT may be in the trunk of a personal
car, taken home by the pilot, or (as has happened) been set off by rough handling in shipping. An accidentally
triggered ELT may be found at nearly any location, even far away from airports.
a. Procedure: The ELT must be silenced as quickly as possible. The FCC can be called for assistance, but
this should be as a last resort and only if the FAA personnel cannot locate it themselves. Once found, it must be
reported to the duty officer and the appropriate service area air traffic organization manager whose facility first
reported it. By national agreement, all ELTs heard are assumed to be a downed aircraft until proven otherwise.
b. Aircraft ELT: If the ELT is located in an aircraft, do not enter it. The local General Aviation District
Office (GADO) or Air Carrier District Office (ACDO) and the service area duty officer shall be notified as to the
aircraft identification. It is their job to contact SAR and the owner of the aircraft to shut it down.
1413. RECORDS OF UNUSUAL PREVIOUS CASES. While all cases must be reported (see paragraph
1401), unusual or unique case records can provide a wealth of material which can be used to save time in
resolving similar cases. All FMOs are requested to submit brief narrative descriptions of unusual resolved
problems to Technical Operations ATC Spectrum Engineering Services so that they can be disseminated to other
service area FMOs. The SMDb shall be used as much as possible to record these unusual events. In addition,
audio tape recordings should be made of new or unusual cases and forwarded to Technical Operations ATC
Spectrum Engineering Services for inclusion in the national RFI sounds bank. This sound bank can be found
within the NAS RFI or GPS RFI modules of the SMDb for easy electronic file download. If the source has a
particularly unusual video presentation on an oscilloscope or spectrum analyzer, a video tape of the RFI sent to
Technical Operations ATC Spectrum Engineering Services would be useful and can be included electronically as
part of the SMDb logged event.
1414. thru 1499. RESERVED

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CHAPTER 15. RADIO FREQUENCY INTERFERENCE MONITORING VANS (RFI VANS)
1500. INTRODUCTION. The term "RFI Van" is the name historically used to identify the vehicles with
specialized equipment, which are used for the location and resolution of radio frequency interference problems
affecting the National Airspace System (NAS). The most recent generation of RFI Vans is known as the Radio
Frequency Interference Monitoring System (RFIMs). The RFIMs are operated with or without engineering
personnel to perform a certain set of measurements. The RFI Van vehicles have varied from passenger
automobiles with basic RFI equipment, to Step Van vehicles, to large trucks with measurement electronic
equipment housing power generating system to power it. In this order, the terms "RFI Van" or "Van"
encompasses all those vehicles past, present and future including the new generation under the Transportable
Interference Monitoring Detection System (TIMDS) program.
a. The RFI Van: This is an engineering tool with advanced automation used for the management of the
radio spectrum. The RFI Van performs many functions in the Communications Navigation and Surveillance
(CNS) area. In addition, Radio Frequency Interference resolution is an important part of its function. Figure 15-1
shows a block diagram of the equipment functionality used in the current RFIM.
FIGURE 15-1. RFIM FUNCTIONAL BLOCK DIAGRAM

b. RFI Van Spectrum Monitoring: The spectrum used by the FAA has an increasing requirement to be
continuously monitored. As more FAA facilities are added to the NAS, and transmitters from other services
surround these facilities, the already congested spectrum becomes more crowded. Careful RF engineering must
be performed to effectively use the portion of radio spectrum allotted to the FAA. The service area Frequency
Management Officer (FMO) uses the capabilities of the RFI Van to monitor the spectrum environment in the
service area and engineer its use effectively.
c. RFI Van National Program: Technical Operations ATC Spectrum Engineering Services established the
Radio Frequency Interference Monitoring (RFIM) System to specify a standard RFI Van configuration for all
FAA service areas. This program standardized the style and configuration of the vehicle, equipment and software
for the RFI vans based on service area FMO office requirements. In addition, a comprehensive safety
modifications program has been implemented for each service area RFI Van. The operation, control and
maintenance is currently the responsibility of the service area FMO.

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1501. CONTROL AND RESPONSIBILITY. The service area Frequency Management Office has full
responsibility for the operation and maintenance of the RFI Van assigned to their service area. The FMO
schedules calibration of all RFI Van systems on a yearly basis. The FAA William J. Hughes Technical Center has
established a national RFI Van modification and test facility in Atlantic City, New Jersey. Improvements, safety
modifications, and software changes are coordinated through the RFI Van Engineering Change Proposal (ECP)
process.
a. FMO RFI Van Planning: The Frequency Management Office plans and schedules the use of the RFI
Van for providing electromagnetic radiation measurement and interference detection and location services to
organizations having a need for it. System Management Office (SMO), Systems Operations Centers (SOC) or
Operations Control Centers (OCC) specialists are required to coordinate with the service area FMO.
b. FMO RFI Van Familiarization: The FMO is the FAA representative thoroughly familiar with the
technical equipment in the RFI Van, the practical applications of it, and possesses good knowledge of any facility
equipment in need of test and measurement for which the RFI Van will be useful.
c. FMO RFI Van Coordination: The FMO operates the equipment in the RFI Van, records and analyzes
measurement data, evaluates results, and prepares necessary documentation and reports. In addition, the FMO
works closely with service area air traffic organization, SMO, and other concerned personnel to uncover, locate,
and eliminate harmful interference. The FMO is the focal point for coordination with the FCC and other
appropriate agencies in resolving harmful interference problems consistent with agency interests.
1502. RFI VAN USE. The RFI Van is outfitted with state of the art measurement equipment and automation
tools, which can be used for radio frequency interference location and resolution. A variety of electromagnetic
radio spectrum measurements can be accomplished. Some of these uses are:
a. Antenna Radiation Patterns: The RFI Van system will measure and plot antenna radiation patterns
while the facility under test operates normally.
b. Interference Detection: The RFI Van Direction Finding equipment provides Lines of Bearing (LOB) in
the direction of an electromagnetic signal source.
c. Spectral Signature Measurements: The RFI Van Spectrum Analyzer equipment allows Fast Fourier
Transform (FFT) measurements while the facility under test operates normally.
d. Frequency Measurements: RFI Van Frequency Counter equipment performs frequency tolerance
measurements on facility transmitting equipment without disruption its operation for later adjustments.
e. Electromagnetic Surveys: The RFI Van automated software tools allow for electromagnetic
compatibility and field strength measurements for facility coverage without disruption.
f. Radiation Hazard Measurements: Non-Ionizing radiation (i.e., thermal radiation) measurements can be
performed for facility compliance with Occupational and Safety Hazards Administration (OSHA) standards.
1503. INSTRUMENTATION. The RFI Van is outfitted with a standard set of equipment and instrumentation
to assure the capability of accomplishing the uses and functions listed in paragraph 1502. Additional equipment
may be added temporarily at the option of the individual service areas for specific tasks that will require other
specialized equipment. However, the core equipment is the following:
a. Field Strength Meter: The FAA operates in certain portions of the radio spectrum, so it is essential that
FMS equipment be properly calibrated for measuring the spectrum in which FAA operates. The RFI Van FMS
measure frequencies from Low Frequency (LF) Non-Directional Beacons (NDB's) through Airport

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Surveillance Radars (ASR) and Radio Communication Links (RCL). The Airport Surveillance Detection System
(ASDE), Television Microwave Links (TML) and other new facilities can be measured as well. The four field
strength measurement ranges are:
(1) 100 kHz to 30 MHz.
(2) 30 MHz to 1000 MHz (1GHz).
(3) 1 GHz to 10 GHz.
(4) 10 GHz and above.
b. Spectrum Analyzer (SA): The RFI Van spectrum analyzer has a measurement frequency range from
Very Low Frequency (VLF) 9 kHz to Super High Frequency (SHF) 26 GHz. The spectrum analyzer has X and Y
outputs to record received signal spectra on a standard X-Y Plotter. In addition, computer interfaces allow for a
standard commercial printer or plotter to be used. The Spectrum Analyzer also comes with the capability to add
optional external mixer devices that increases the measuring range to millimeter wave. Like the field strength
meter, the SA also must be calibrated so that it can be used in finite field strength and power density
measurements.
c. RF Signal Generator: The RFI Van is equipped with a signal generator for generating test signals to be
performed on site bench measurements of interest. The Signal Generator is capable of generating signals from
500 kHz to 1 GHz.
d. Frequency Counter: The RFI Van is equipped with a frequency counter with a range up to 1.5 GHz.
This equipment is usable for any counting function, however, it is particularly useful for measuring radar/beacon
pulse repetition rates (PRRs) in conjunction with the field strength meter. In addition, it permits direct off-the-air
measurements of high-level signals.
e. Step Attenuator: The RFI Van has accurate external step attenuators for increasing measurement
equipment input attenuation with a range from 0 to 120 dB in 1 dB or 10 dB steps from 500 kHz through 26 GHz.
External Step Attenuator purposes are twofold.
(1) It can be used for dB step calibration of the X-Y Plotter and antenna pattern recordings.
(2) It can be used to insert basic attenuation before the field strength meter or SA to prevent its overload
and operation at its greatest sensitivity, inhibiting AGC action, thus permitting linear readouts.
f. Antennas, Rotator and Mast: The RFI Van is equipped with a set of antennas to cover the radio
spectrum capable of being measured by the field strength meters and SAs as mentioned in subsections a and b
above. Generally, this will be loop antennas for the L/MF frequency range, frequency adjustable Dipoles, Log
Periodic or Biconical antennas for 30 to 1000 MHz, and Horn or Helical antennas for 1 GHz and above. Yagi
antennas for specific ranges are very effective. An antenna rotator mounted on the roof of the van allows rotating
the installed antenna from inside the vehicle for the proper direction or polarization. The RFI Van is also
equipped with a pneumatic mast that rises up to 40 feet.
g. Tunable Filters: The RFI Van is equipped with filters (i.e., band pass, notch, etc.) for at least the range
100 MHz to 3 GHz. The filters are interfaced or connected in front of the field strength meter or SA to eliminate
instrument self spurious signal generated from the presence of very strong environmental signals other than the
frequency being measured.

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h. Oscilloscope: The RFI Van is equipped with a scope for measuring rapid events, particularly rotating
radar. It is also used for analyzing detected signals from receivers, field strength meters or SAs.
i. Audio Tape Recorders: The RFI Van is equipped with audio tape recorders for recording the sound of
received signals. The unit is particularly useful in recording interference signals for evidence and later resolution.
The RFI Van computer workstation may also be used for this purpose if a sound card interface is available.
j. Aviation VHF Transceiver: The RFI Van is equipped with an air-ground aviation transceiver for
communicating with Air Traffic Control Towers (ATCT) and Flight Service Station (FSS) on airports and with
Flight Inspection (FI) aircraft during interference locating procedures.
k. Land Mobile VHF Transceiver: The RFI Van is equipped with a Frequency Modulated (FM) narrow
band transceiver for communicating with SMO personnel at sites under investigation, in some circumstances with
FI aircraft, and sometimes with the home base via the NRCS (C3) network.
l. Direction Finder: The RFI Van is equipped with a direction finder system capable of providing a line of
bearing (LOB) in the direction of the source signal. This equipment is extremely useful when detecting and
locating signals causing interference to FAA systems.
m. Printer and X-Y Plotter: The RFI Van is equipped with a commercially available Laser Jet quality
printer. An optional X-Y Plotter may be used by the FMO conducting the measurements.
n. DC Inverter: The RFI Van is equipped with a commercially available direct current (DC) to 115 volts
(V) alternating current (AC) inverter for powering low-drain ac powered equipment and charging NiCad batteries
for accessory equipment in the van. The RFI Van vehicle battery supplies the DC source and is charged or
"floated" by the van engine alternator.
o. Engine Generator: The RFI Van is equipped with a commercially available gasoline (or diesel) driven
generator for 117 V AC of 1.5 to 3.5 kW capacity. This unit is used for supplying ac power to the larger drain
units and used when the van is parked with its engine turned off and not charging the RFI Van battery.
p. Ancillary Items: Service area Frequency Management Offices may from time to time use a number of
ancillary items as follows:
(1) Step-recovery diode for extending the frequency meter and generator output to at least 3 GHz for
accurate radar and beacon frequency measurements.
(2) Broadband amplifiers for at least 100-1,000 MHz, to permit increased signal level to drive the step
recovery diode for microwave measurements above 1 GHz.
(3) Ultrasonic narrow beam detector for locating specific defective insulators or crossarms on power
poles which cause arcing and resultant broadband interference.
(4) A Citizens Band (CB) transceiver for receiving road advisories when the RFI van is on long trips.
(FMOs are reminded that CB may only be used for receiving information, and not transmitting, unless there is a
road emergency involved.)
(5) Family Radio Service (FRS) FM Transceiver for intercommunicating with the RFI Van personnel or
during interference location coordination.
(6) Extra Step Attenuator for additional signal attenuation when in close proximity of high emitters.

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(7) Altimeter and Compass for altitude and azimuth determination with respect to the measured site.
(8) A radar beacon transponder mounted in the van, used only to work with a service area air traffic
organization and Flight Standards to positively locate the van on a radar scope when working on radar
measurements or interference problems.
(9) Global Positioning System receiver for determination of precise position in latitude and longitude at
the location of conducting measurements.
(10) A cellular telephone for contacting other agencies such as the Federal Communications Commission
or Law Enforcement as deemed necessary.
1504. RFI VAN SYSTEM OPERATION. Operating the various systems in the RFI Van requires knowledge,
training, and skill. While there are several independent systems, they all merge into one total monitoring and
measuring system. The FMO must remember that measurements and follow-on documentation is very important
for the various agency and service area programs. The FMO's work may be presented as evidence in court. Thus,
all measurements and documentation resulting must be handled within the highest professional standards.
a. The RFI Van measurement control system (MCS): The MCS is an easy-to-use program for computer
controlled field frequency measurement. A selection of canned measurements is available which requires a
minimum of user input. The canned measurements are the simplest way to take RF measurements, and those
canned measurements include most of the measurements required by the FAA. The MCS can perform an RF path
calibration and use the results to adjust measurement values to account for the changes in system gain at higher
frequencies. FMOs may also manually set up the instruments, and then use the MCS software to capture the
instrument settings and data on the computer hard drive. The MCS has been written in LabVIEW® 5.0 under the
Windows 95® operating system with many menu driven functions. Technical Operations ATC Spectrum
Engineering Services has developed a comprehensive training course for the use of this automated tool. The
following paragraphs will deal mostly with instruction and examples of each system operation from a general
perspective. See Figure 15-2.
FIGURE 15-2. MCS CANNED MEASUREMENTS STARTUP SCREEN

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1505. RADAR AND ATCRBS ANTENNA PATTERN RECORDING. Radar antenna pattern recording is a
valuable product of RFI van measurements. It permits actual radiation pattern recording from any point in space
the measuring equipment can be located. It can be accomplished without the radar having to shut down or make
any changes in its normal operation, unless the measurements are made to allow various patterns to be measured
as the antenna or transmitter functions or hardware are changed. Done correctly, the measurement permits the
FMO to determine whether the radar and beacon radiated patterns are normal as well as the directional and
nondirectional pattern ratios of SLS operation. The FMO can make this determination on site, within the time it
takes to record one revolution of the radar antenna, usually between 5 and 15 seconds. The results then can be
transmitted to the site, to the SMO, or the OCC, so that a decision can be made immediately. An SA with printer
or a computer controlled spectrum analyzer (CCSA) with a printer provides superior results.
a. Primary Radar Antenna Pattern Plotting with field strength meter/X-Y plotter: This is a basic
measurement and requires only these devices: a receiver (including an SA), a high-speed recorder, a calibrated
step attenuator and a suitable calibrated antenna with a stable mount. NOTE: The procedure below is specifically
for a field strength meter as the receiver, but use of an SA will be similar except for some steps. Many SAs can
be manually tuned which simulates manual tuning of a field strength meter. See figure 15-3.
FIGURE 15-3. RECORDING SETUP AND SAMPLE TAPE

(1) Set the step attenuator to its highest attenuation (80 to 120 dB) to prevent damage to the field strength
meter from high-level signals.
(2) Connect the appropriate Horn antenna to the input of the attenuator, with the output of the
attenuator connected directly to the input of the field strength meter.
(3) Set the field strength meter internal attenuators to zero, to prevent AGC action from giving
nonlinear readouts.
(4) Set the antenna for proper polarization. If in doubt, try both horizontal and vertical polarization of the
horn and use the one giving highest signal level. Usually, there is about a 15 dB difference between correct and
reverse polarization indications. Adjust the azimuth to approximately the radar direction.

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(5) Tune in the radar on the field strength meter. This probably will require carefully reducing the step
attenuator in 10 dB steps while tuning the radar frequency. Adjust for on-scale meter and recorder by noting the
peak pass recorded on the recorder. The direct peak function of the field strength meter can be used for this
careful tuning process if the recorder is turned OFF. If a Spectrum Analyzer is used this step will be equivalent to
the Max Peak hold mode.
(6) Set the field strength meter bandwidth to 1 MHz or nearest value.
(7) Carefully rotate the antenna in azimuth for maximum signal to the field strength meter. This will
take a little time since the signal will be varying widely in intensity as the radar rotates. Increase the step
attenuation if it becomes necessary to keep an on scale reading.
(8) Set the field strength meter function to quasi-peak or slide-back peak. The goal is to obtain a time
constant of 10 msec without "dump." NOTE: In direct peak function, the EATON NM-65T field strength meter
will inject a reverse voltage at the end of the store time to restore the meter to a low value quickly to get ready for
the next peak pass. The high-speed recorder will slam against its lower reference level and could be damaged due
to the large reverse voltage applied. The field strength meter, with its slow ballistics due to damping, will not be
slammed.
(9) Connect the high-speed recorder to the Y or signal output of the field strength meter. NOTE: If the
recorder has been carefully calibrated before, only a quick check of levels would be required. If not, calibration
must be done at this time before any of the instrumentation controls are touched. Calibration of the high-speed
recorder is discussed in paragraph 1506.
(10) Adjust the attenuator so that a near maximum scale reading is received when the radar is "searchlighting" the RFI Van, the maximum signal to be received.
(11) Record at least one full pass of radar illumination, with two or three consecutive being preferable to
average out any anomalies or reflections in propagation, such as aircraft flying through, a passing vehicle's
ignition noise recorded, etc.
(12) Analyze the recording briefly and advise Technical Operations Services or service area air traffic
organization personnel waiting for the information. Retain the recording for follow-up detailed analysis and
documentation.
b. Primary Radar Antenna Pattern Recording with a CCSA: When the Computer Controlled Spectrum
Analyzer (CCSA) is coupled with a standard printer it will provide superior results. The basic setup is similar to
field strength meter/X-Y plotter, except the measurement components are replaced with a Spectrum Analyzer and
associated standard printer. The 12 steps listed in paragraph 1505a above are applicable. Careful attention should
be taken in the steps regarding preventing overload and nonlinear readout for the SA just like for the field strength
meter. The advantage is that the CCSA does its own internal calibration and prints these values as well as the grid
scale values on the print out. Expanded prints of the radar beam can easily be obtained by merely programming
the CCSA before a recorded or stored pass. Examples of CCSA printouts (reduced from a standard 8½" x 11")
are shown in Figure 15-4.

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FIGURE 15-4. EXAMPLES OF ANTENNA PATTERNS ON CCSA PRINTOUTS

c. Beacon Antenna Recordings: These are done the same way as mentioned in 1505a and 1505b, except for
two conditions. The field strength meter or CCSA bandwidth cannot be less than 1 MHz to prevent the possibility
of signal processing error due to the difference of pulses transmitted by the directional and omni-directional
antennas. Two plots must be made, one immediately after the other, with the SLS omni on, then off. This allows
the FMO to assure that there is no "punch through" of the directional signal on the normal SLS radiated pattern.
d. Pattern Recording Considerations: The previous list in paragraph 1505a of "how to perform
measurements" gives instruction on the actual recording process. However, every bit as important is the special
considerations that must be evaluated for each measurement.

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(1) Knowing the monitoring site location with respect to the radar being measured is very important.
Using maps for azimuth and distance and the on board altimeter, a close estimate of location can be obtained. If
the RFI Van has a beacon transponder and previous arrangements have been made with the service area air traffic
organization, a reading of the transponder's distance and azimuth from the associated radar coupled with the on
board altimeter, can give an exact location of the RFI van. Use of a GPS receiver is recommended.
(2) From the location determination, the vertical angle between the monitoring site and the radar antenna
site can be calculated. This is critically important. If the site is at 0° vertical angle or lower to the calculated
vertical angle of the radiated beam, the recording and resultant plot should be considered as reference only. It is
useful for checking radiating patterns at later dates, but should not be submitted as the actual pattern. This is
because the beam "nose" will be above the recording site, and thus all references to signal levels, which are used
to plot the ultimate pattern, will not have the correct "nose" reference and will be faulty. Below 0°, the antenna
pattern cuts off rapidly, while above 0° it falls off slowly so that only very little error ensues, even for a few
degrees. A site vertical angle of a degree or so above the beam line is best.
(3) An elevated monitoring position is essential. However, in mountainous terrain, reflections can lead to
false levels at some azimuths with respect to the radar. When in mountains, make a second recording a few feet
or a few hundred feet away, to assure the first site was a valid non-reflective site and vice versa. A quick
comparison of the two recordings can determine any appreciable differences.
(4) When a good monitoring site is not available, alternatives must be considered. Sometimes the top of
a building can provide a suitable site, if the measurement is made from the roof edge nearest the radar to reduce or
eliminate reflections. If the radar antenna is not mounted too high, a "cherry picker" can be used to get to the
proper height. In this case care must be taken to assure that the field strength meter is properly shielded to
provide a sufficient dynamic range of recording. Verify by placing a metallic cover cap or shorted coaxial
connector over the antenna input terminal. If a signal level is recorded it should be due to leakage. If that peak
level with the cap over the input terminal is 40 dB or more below the level indicated with the Horn antenna
connected normally, the recording can be considered accurate, at least down to that level. If none of these
alternatives are possible, then the situation of a "reference only" recording must be considered. Helicopters and
aircraft have been tried, but have not given good results due to the instability of the measurement platform for the
period of antenna revolution.
1506. HIGH-SPEED RECORDER CALIBRATION AND OPERATION. The following are the general
recommended procedures: (See figure 15-3)
a. Calibration. Setting the zero and span controls is necessary to establish levels that can be relied upon
from measurement to measurement. A calibration can be accomplished right on the tape itself. This is done by
using the incoming signal, which is recorded as the source for calibration of this recording only. After normal
pattern recording, slow the tape speed to the slowest practical. While the tape is recording, insert successive 10
dB steps of attenuation between each illumination so that each pass represents 10 dB less level. Adjust the span
control so that the 10 dB marks coincide with the tape horizontal lines.
b. Operation. Depending on the speed of antenna rotation, the tape pull rate should be 25 or 50 mm/sec.
This allows a good resolution of higher speed ASR plots, while still not making the ARSR plots too long
physically. If the recorder has easily changed speed ratios, it is most beneficial to be able to reduce the rate to
5 mm/sec or so when calibrating or tuning the system. This allows accuracy in reading the peak recorded, yet
does not waste yards of tape for those functions. If speed change is not easily done, the recorder can be turned off
between radar passes for calibrating, to save recording tape.
c. Documentation. While the FMO now has a completed tape, it should be incorporated into a technical
report of the operation. Reproduce the tape as recorded, but include calibration marks so that anyone can read it.
In addition, affix an identification label, which includes date, time, location, source and any other pertinent data.

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The calibration should be shown directly on the tape, with the "nose" of the pass indicating 0 dB and other
declining dB levels as minus, e.g., -10 dB, -20 dB.
1507. SPECTRUM ANALYSIS. Spectrum Analysis of any segment of the radio spectrum is valuable for
planning and problem solving and can be done in three ways. One uses a spectrum analyzer with photographs
taken of the scope presentation. The second uses a field strength meter and X-Y plotter. The third uses the CCSA
system to do it all.
a. Spectrum Analyzer Photographing: Taking a photograph of a rotating radar is relatively easy to obtain,
but generally does not yield as high a resolution as capturing the data with X-Y Plotter or Computer Controlled
SA printer. The following steps are recommended:
(1) If the antenna is stationary, plotting is easy. Merely scan the portion of the spectrum desired. Then
use a scope camera and take a picture of the spectrum appearing on the screen, but allow aperture opening long
enough to obtain a full scope sweep.
(2) If the antenna is rotating, it will be necessary to perform two steps. Allow several passes to
accumulate on the screen in the storage mode before taking the scope picture. Open the camera shutter while it is
on the scope and allow several passes (6 to 10 is recommended) to allow the camera to act as the storage medium.
An example of a spectrum picture from a spectrum analyzer is shown in figure 15-5.

FIGURE 15-5. PHOTO OF SPECTRUM FROM A SPECTRUM ANALYZER

b. Computer Controlled Spectrum Analyzer: There are great advantages in using this approach. The
results are readily seen in the reduced size spectrum plot shown in figure 15-6. Here, the amplitude (Y axis),
frequency range (X axis), bandwidth, storage time, and all essential parameters are transmitted to the computer
via a computer interface. Upon command, it simply stores, then prints or plots the results.

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FIGURE 15-6. CCSA PRODUCED RADAR SPECTRUM PLOT

c. X-Y Plotter Recordings: These are much more complicated to do, but provide much greater resolution,
particularly if a CCSA system is not available. However, the process of setup is complex and requires some
explanation.
(1) The X-Y Plotter essentially takes an X-axis variable voltage to provide the frequency base of an X-Y
plot. As the field strength meter is tuned from a reference frequency to a higher frequency, the X output voltage
increases in a linear manner with respect to frequency. Once the frequency range to be scanned is established, the
FMO must then set up the plotter so that its baseline represents a calibrated frequency line.
(2) Most field strength meters have variable output X voltage directly proportional to frequency. That is,
on a 1 to 10 GHz frequency range, the field strength meter linearly provides 1 to 10 V dc for the X-Y plotter Xaxis. The problem is that the X-Y plotter normally has only a 0 to 1 V recording range and a dc "bucking voltage"
capability is required to permit zeroing the left edge of the plot when the field strength meter X output voltage is
greater than 1 V.
(a) Assume an ASR spectrum is to be plotted and it is desired to plot from 2650 to 2950 MHz. That
means that when the field strength meter tunes from 2650 to 2950 MHz to cover the whole page, the X voltage
supplied the X-Y plotter will be 2.65 to 2.95 V dc, respectively. But since the X-Y plotter is designed to only
handle 0-1 V dc and it can only "buck" 1 V dc, the recording would be impossible. The recorder would be hard
against the right margin trying to reach a nonexistent 2+ V position.
(b) The solution is to provide an in-line variable "bucking" voltage. This can be accomplished by
placing a 10/1 voltage divider across the X output of the field strength meter. But this is not the most
recommended approach. Some X-Y plotters draw significant current through their X inputs, since it is only a
variable voltage divider in the first place. Any additional voltage divider then would be very nonlinear.
(c) A better solution is to build a stable and variable "bucking" voltage source to be placed in line with
the X output of the field strength meter. The basic dc sources can either be an ac driven transformer low ripple dc
supply, or a simple battery with a Zener diode. With the battery, of course, provision must be made for shutting
off the battery when not in use. A schematic diagram of a suitable "bucking" device is shown in figure 15-7.

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FIGURE 15-7. A DC BUCKING VOLTAGE SYSTEM FOR X-Y PLOTTERS

d. Calibration: Calibration of an X-Y plot is a process that takes some time, but takes less as the FMO
becomes familiar with it.
(1) Connect the "bucking" voltage in reverse series.
(2) Turn on the field strength meter and tune to the LOWEST frequency to be scanned V.
(3) Connect the X and Y outputs of the field strength meter to the X-Yplotter.
(4) Turn on the X-Y plotter with the pen lifted. Unless by chance the "bucking" voltage and field
strength meter X output voltage are nearly identical, the pen will go hard left or right. Immediately adjust the
bucking voltage control to bring the pen on scale.
(5) Use the X-Y plotter zero control as a vernier to put the pen on the zero left hand mark of the paper
being recorded upon.
(6) Tune the field strength meter to the HIGHEST frequency to be plotted.
(7) Now adjust the X-Y plotter span control so that the pen is on the right hand mark of the paper to be
recorded upon.
(8) Tune the field strength meter to the LOWEST frequency to be recorded again and note the position of
the pen. Most likely, it no longer will be on the zero mark previously set. This is because there is some
interdependence between the two controls.
(9) Tuning the field strength meter between the two limits of frequency to be recorded, carefully
"jockey" the zero and span controls until the pen exactly coincides with the frequency span of the field strength
meter between minimum and maximum frequencies to be recorded.
(10) To improve the frequency accuracy of the base line of the plot, it is wise to inject a small signal
from the signal generator into the field strength meter to positively locate an accurate frequency mark on the plot.
For instance, if 2700-2900 MHz were being recorded, it would be wise to inject alternately 2700 MHz then 2900
MHz with the "jockeying" so that the two ends are accurately marked. With the linearity of the X output, the
frequency marks from the grid paper on the plotter can be assumed to be reasonably accurate.
e. Y Axis Setup: The following steps are recommended:
(1) Set the field strength meter function to "Log".

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(2) With the field strength meter tuned off frequency or the input temporarily disconnected so that the
pen will drop down to its lowest voltage level to be recorded, adjust the Y axis zero control so that the pen is a
quarter of an inch or so above the bottom line on the grid paper.
(3) With the pen still up, carefully tune the field strength meter to the center of the radar frequency.
(4) Adjust the X-Y plotter Y output control so the peak of the pen sweep on illumination by the radar
goes up to 75 or 80 percent of full scale.
(5) Set the IF bandwidth to 0.5 or 1.0 MHz.
(6) Tune the field strength meter to the lowest frequency to be recorded (all the way to the left of the
paper grid) and recheck the X-axis zero level to assure no drift has occurred while setting up. Readjust zero and
span if necessary.
f. Plotting: The following steps are recommended for the plot:
(1) Tune the field strength meter to the start frequency and lower the pen to the paper. Allow sufficient
time for at least one pass of the radar beam.
(2) Carefully move the tuning a very small increment and wait for another pass. It is important not to
move the tuning while the beam is illuminating the van. Time the moves so that they are made near the back lobe
pass. It is essential that once a plot has begun, tuning be continued in the same direction. There are both
electrical and mechanical backlash, however small.
(3) Continue advancing the frequency in very small increments until a definite pass is indicated. Then
move in increments small enough to give the resolution desired. When tuning is nearing the peak, reduce the
advances to very small amounts, about the width of a pen stroke, to assure a very high-resolution plot.
(4) Continue to the end of the plot space. Lift the pen.
(5) When the plot is completed, tune the field strength meter back past the peak. Then carefully
approaching from the same increasing direction, precisely tune in the peak again. LEAVING ALL OTHER
CONTROLS UNTOUCHED, use only the X zero control to move the pen to almost the left edge of the paper
grid.
(6) Drop the pen onto the paper for just one pass, then lift it quickly again.
(7) With the X zero control, move the pen just slightly to the right.
(8) Using only the in-line attenuator, add 10 dB of attenuation.
(9) Lower the pen and record one pass. Lift pen. Repeat these sequences until the attenuated peak pass
signal is at a very low level, but not lower than -70 dB or so. It will be less if the plot is started well into the
emitted spectrum. The plot is now completed.
g. Documentation: As with the antenna plots described before, the completed spectrum plot needs to be
properly labeled and identified. Frequency marks should be placed at the bottom of the plot, at appropriate
locations. Using the amplitude calibration marks, horizontal lines should be drawn to indicate levels. A sample
plot is shown in figure 15-8.

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h. Discussion: Figure 15-8 provides a highly defined emitted spectrum plot, accurately keyed to a frequency
base. In essence, the field strength meter has acted as a very slow-moving focal plane shutter camera, imprinting
a "slice" view sequentially on the paper. The reason for the on-plot signal source calibration is twofold:
(1) It verifies the accuracy of the spectrum plot at time of review.
(2) It integrates all the limiting factors (any lost signal due to reduced bandwidth, ballistic drag of the
plotter pen drive system, etc.) so that the spectrum overall accuracy is assured.
(3) If only 50 to 60 dB dynamic range is required, the 10 dB steps will be quite linear. But if a larger
dynamic range is desired, it will be necessary to compress the upper 10 dB, in order to accommodate the wide
dynamic range. This is because most field strength meters have only a 60 dB dynamic meter range. There might
be small non-linearities noted between 10 dB levels. A check on any steady signal, using a similar on plot
calibration verified by comparison with the field strength meter panel meter, may show that the in-line attenuator
may not be perfectly linear, but should be < ±2 dB.
i. Signal Stability: If the signal being plotted has a stable level such as a radar "searchlighting" the RFI Van
(or a VOR or TACAN) the same procedure would be used, except the tuning could be done slowly but
continuously, completing the plot in a minute or so. If the field strength meter has automatic frequency scan, that
could be used, so long as the scan rate is slow enough to allow the damped pen to respond accurately to variations
as it is moved across the page.

FIGURE 15-8. SAMPLE SPECTRUM PLOT OF A ROTATING RADAR

1508. FREQUENCY MEASUREMENTS. Frequencies usually are measured in one of two basic ways. The
first is by direct means, the second by indirect means using a transfer standard. Both are easily accomplished with
the RFI Van.
a. Direct Measurements are done simply by using a frequency counter or frequency meter. The incoming
signal is fed to the frequency counter and read directly.

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b. Indirect Measurement method uses a signal generator or other frequency meter and a receiver or SA.
The desired signal is tuned in on the receiver or SA. An accurate calibrated signal source is also fed into the same
receiver or SA through a variable attenuator, so that an appropriate ratio between the signal and the generator can
be set. By vernier adjustment, the generator is adjusted to exactly the center of the spectrum distribution peak. In
cases of a very strong signal to be measured, the signal is centered in the pass band of the receiver or SA scope.
The signal is temporarily removed and the generator is fed to the receiver directly. The generator is then centered
on the receiver or SA scope and the frequency read from the generator or from another accurately calibrated
source measuring the generator. Most CCSA's have frequency measuring functions built in, either a marker with
frequency is shown or the center frequency on the screen is measured and printed out in the spectrum plot.
c. Extended Indirect Measurement is usually used only for frequencies above 1 GHz, unless a very
accurate signal generator is available for the microwave range. Most combination signal generators and
frequency meters cover from lower frequencies up to about 1 GHz. To measure frequencies accurately above
1 GHz, the lower frequency generator is used, driving a step-recovery diode. This set up permits abundant
harmonic output of the driving generator frequency and carries its level of accuracy. However, a step-recovery
diode needs in excess of 1 V of RF to push it into harmonic generation. Using whatever generator is available in
the van, add a small microwave amplifier, which in turn drives the diode with 1+ V, which will produce
harmonics up to the 10th.
d. Example: For instance, an accurate measurement of 2755 MHz can be done using the transfer standard
method by generating a 275.5 MHz signal, with the output signal at 2755 MHz at the 10th harmonic. Other
harmonics are generated as well, so care must be taken to ensure the right harmonic is being used. Accuracy of
the 2755 MHz signal will be equal to the signal generator, e.g., if the signal generator is accurate to .00001
percent, the 10th harmonic will also be accurate to .00001 percent.
e. Accuracy Resolution: This factor must be considered. Even though a meter or counter might have a 9 or
10 digit readout, the manufacturer's accuracy specification must be adhered to. A measurement of 10-8 resolution
is meaningless if the instrument is only accurate to 10-6. For example, an indicated measurement of 110.05061
MHz on an instrument of only 10-6 accuracy should be rounded off to 110.051 MHz to be commensurate with the
instrument's limit of accuracy.
1509. OFF THE AIR PRR MEASUREMENT. Pulse Repetition Rates (PRR) can be measured off-the-air in
several ways. The following are recommended:
a. Direct Pulse Rate Measurements: Direct pulse rate measurement instruments provide reasonably
accurate PRR measurements by sampling a radiated spectrum, removing the pulse elements, and automatically
predicting the total rate per second. Sampling rates can be as short as 50 μsecs. These instruments are very
expensive.
b. Detected Pulse Rate Measurements: The detected pulse rate measurement is commonly used. The
process consists of taking detected video from the output of a field strength meter or SA and feeding it directly to
a frequency counter. Most simple counters are designed for CW signals and may not respond well to a pulse
signal. One way to solve this is to take the detected video and feed it first into a resistor/capacitor (RC) time
delay circuit which will somewhat approximate a sine wave, then to the counter so it will read accurately.
(1) A Time Constant (TC) circuit, formed by a 10K ohm resistor and a 0.25 microfarad (µfd) capacitor
will frequently be sufficient without reducing the signal too much. The FMO should experiment with a steady
state pulse signal, while watching it on a scope, varying the TC to produce a reasonable replica of half a sine
wave. Signal shaping which will give stable PRR readout is the goal.

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(2) A varying pulse signal, such as from a rotating radar, requires that the gate time of the counter be
varied so that it does not include the actual searchlighting of the van. This large change in signal level can upset
the gate counting cycle and give an unrepeatable PRR.
c. Oscilloscope PRR Measurements: These kinds of measurements are also very useful for widely varying
amplitudes of signal.
(1) In one use, the video output of the field strength meter or receiver is fed to a calibrated scope. The
sweep is set to trigger on the leading edge of a pulse. By adjusting the trigger level, a quite stable pulse
presentation can be presented on the scope. The pulse period can be determined from the scope graticule and its
calibration. The PRR is simply the reciprocal of the period. The accuracy is limited by how accurately the pulse
period can be read. For example, a period of 2700 µsec measured would translate into 1 ÷ (2700 X 10-6) = 1 ÷
.0027 = 370.3, or approximately 370 pps.
(2) In another use, the video output of the field strength meter or SA is fed to channel 1 vertical input of a
two-channel scope. Using a function generator set for triangular wave output, connect it to channel 2 vertical
input of the scope and a frequency counter. Set the trigger to channel 1. Refer to figure 15-9 for a typical setup.
Either use the scope ADD function or position each of the channel presentations so that the detected pulse rides
the peak level of the triangular wave. Adjust the triangular wave frequency until two consecutive peaks exactly
match two consecutive pulses. Read the PRR from the frequency counter. Figure 15-10 shows correct and
incorrect presentations for accurate measurement conditions.

FIGURE 15-9. BLOCK DIAGRAM OF ONE METHOD OF MEASURING PRR

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FIGURE 15-10. SCOPE DISPLAYS FOR CORRECT AND INCORRECT MEASUREMENT

1510. thru 1599. RESERVED

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CHAPTER 16. IONIZED AND NON-IONIZED RADIATION MEASUREMENTS
1600. PURPOSE. This chapter specifies the procedures and considerations for ionized and non-ionized
radiation measurements to be made by the FMO.
1601. GENERAL. Order 3900.19B, the FAA Occupational Safety and Health Program, assigns specific
responsibility in the area of radiation safety and provides reference criteria for ionizing and non-ionizing radiation
exposure. The FMO is responsible for the actual definitive measurements of radiation levels as specified in Order
3900.19B. Detailed measurement procedures are contained in later sections of this chapter. [Previously, Order
3910.3A, which was cancelled by Order 3900.19B, set Permissible Exposure Limits (PEL) for all Radar, Tactical
Air Navigation (TACAN), Air-to-Ground communications (A/G), National Radio Communications System
(NCRS), etc., for frequencies from 0.3 MHz – 100 GHz]. Order 3900.19B adopted the most current version of
the Institute of Electrical and Electronics Engineers/the American National Standards Institute (IEEE/ANSI)
standards (the 1999 Edition of C95.1) for uncontrolled non-ionizing environments and the most current version
of the American Conference of Government Industrial Hygienists (ACGIH) Threshold Limit Values (TLVs) for
Non-Ionizing Radiation for controlled non-ionizing environments. In lieu of using the term PEL, the nonionizing exposure limits are called Maximum Permissible Exposures (MPE) in the 1999 Edition of IEEE/ ANSI
C95.1 and the TLVs in the ACGIH document. Both are specified in units of milliwatts per centimeter squared
(mW/cm²). Order 3900.19B also adopted the latest version of the ACGIH TLVs for ionizing radiation. The most
current version of these standards available at the time of a survey shall apply.
a. Technical Operations ATC Spectrum Engineering Services is an important element within the FAA
for performing radiation hazard measurements, both ionizing and non-ionizing. Technical Operations ATC
Facilities, Environmental, Energy Conservation, and Occupational Safety and Health (EEOSH) Services will
perform routine ionizing and non-ionizing radiation surveys for the purpose of accumulating data to use in the
exposure assessments. A Letter of Agreement (LOA) for the division of functional Radiation Safety Program
(RSP) Responsibilities was developed and agreed upon in September 2002 between the former FAA organizations
Spectrum Policy and Management Program (ASR) and the Resources Management Program (AFZ). An update of
this LOA is presented in figure 16-6 for reference. Figure 16-1 provides an outline of the process to be followed
in making a radiation hazard measurement, consistent with the LOA.

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FIGURE 16-1. PROCESS FOR OBTAINING A RADIATION HAZARD MEASUREMENT

Spectrum
Engr.Services

Note 1. Appropriate HQ Program Office will request Technical Operations ATC Spectrum Engineering
Services to conduct a baseline measurement.
Note 2. All requests for special RADHAZ measurements, other than those for commissioning, baseline, and
routine will be referred to the ROSHM who will then refer to their service area FMO.
Note 3. For commissioning and/or equipment modifications, the appropriate service area program office will
request that the service area FMO conduct a RADHAZ measurement.
Note 4. Technical Operations ATC Spectrum Engineering Services will either conduct the measurement or
determine what resource to use to conduct it: the Mike Monroney Aeronautical Center, the William J. Hughes
Technical Center, the service area FMO, or contractor. All measurements will be coordinated with
Environmental, Energy Conservation, and Occupational Safety and Health (EEOSH) Services. Refer to the
Letter of Agreement, 7-29-05 (figure 16-6), Technical Operations ATC Facilities item number 4, for
Environmental, Energy Conservation, and Occupational Safety and Health (EEOSH) Services measurements.
(Notes continued on next page)

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(FIGURE 16-1 notes, continued)
Note 5. Upon receipt of a special request for a RADHAZ measurement, the FMO will work with Technical
Operations ATC Spectrum Engineering Services. For commissioning or equipment modifications, the FMO
will notify Technical Operations ATC Spectrum Engineering Services and conduct the measurement.
Note 6. The following offices will receive a copy of the report: Technical Operations ATC Spectrum
Engineering Services, Environmental, Energy Conservation, and Occupational Safety and Health (EEOSH)
Services , the ROSHM, and the SMO. Technical Operations ATC Spectrum Engineering Services and/or the
FMO will immediately notify Environmental, Energy Conservation, and Occupational Safety and Health
(EEOSH) Services and the ROSHM when the measurements indicate radiation at or above the "Action"
levels. Environmental, Energy Conservation, and Occupational Safety and Health (EEOSH) Services will
initiate medical interpretation and related follow-on actions.
b. Technical Operations ATC Spectrum Engineering Services will be responsible for ensuring the ability
to perform radiation measurements in a timely manner, to include training of Technical Operations ATC
Spectrum Engineering Services engineers and service area FMOs.
c. Environmental, Energy Conservation, and Occupational Safety and Health (EEOSH) Services has
overall program management responsibility for environmental hazards, including
radiation hazards.
d. On an infrequent basis, it may be necessary for the FMO to perform a radar antenna pattern measurement
by solar means in order to advise on the radar antenna tilt angle to resolve RADHAZ issues. Refer to appendix 8
for detailed instruction on how to perform these measurements.
1602. IMPORTANCE OF MEASUREMENTS. The importance of this function cannot be overemphasized.
The results of the FMO's measurements can affect the safety, health, and in extreme cases, the life of a person
who shall work or be in the area being measured. The latest edition of ORDER 3900.19B SHALL BE
UNDERSTOOD BY THE FMO AND STAFF. The order is very detailed in its description of the two basic kinds
of radiation and the limits in which the human body can safely exist.
1603. FMO PARTICIPATION LIMITATION. Only measurements of level are made by the FMO.
1604. IMPORTANCE OF ACCURACY. The measurements made by the FMO are only as good as the
calibration of the instrumentation used and the accuracy, thoroughness, and professionalism of the FMO or staff
engineer making the measurements.
1605. INSTRUMENT CALIBRATION. The calibration of instrumentation is the responsibility of the FMO.
All instruments involved shall be calibrated at least annually, or more frequently if the manufacturer recommends.
In the case of ionized radiation instrumentation (Victoreen 440RF), the built-in calibrator will be used to verify
approximate calibration immediately before any measurements of record are made. If the built-in calibrator leads
to readings greater or less than 5 percent of the specified, the instrument will not be used for measurement until
the manufacturer or a certified field calibration station has recalibrated it.
1606. AVAILABILITY. The instruments shall be available at all times, and in condition for immediate use.
This means all required batteries are fresh, and internal calibration checks have been made at periodic intervals.
When Environmental, Energy Conservation, and Occupational Safety and Health (EEOSH) Services, Program
Office, or Flight Surgeon requests a measurement, the FMO response will be commensurate with the urgency of
that request. Particularly in the case of a suspected case of employee, general public or visitor radiation, the
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measurements shall be made as quickly as possible and the results given verbally to Technical Operations ATC
Spectrum Engineering Services and Environmental, Energy Conservation, and Occupational Safety and Health
(EEOSH) Services, even before the written report is completed. Technical Operations ATC Spectrum
Engineering Services also shall be advised of results by email or fax.
1607. RAMIFICATIONS. The FMO is charged by directive to be the responsible person in the service area to
make all nonroutine radiation hazard (RADHAZ) measurements. This is not a transferrable responsibility.
If the FMO cannot make the measurements for any reason, Technical Operations ATC Spectrum Engineering
Services shall be contacted immediately for assistance.
a. Any measurement made as a result of a complaint by any person, FAA or not, of radiation injury from
FAA equipment is likely to be used as a basis for liability assessment.
b. The person making the measurement may be required to appear as a Federal Government witness at an
administrative hearing or trial litigation and may be required to prove expertise based on knowledge and
experience in making measurements.
c. It is imperative that the FMO be thoroughly familiar with the equipment used. The FMO shall be
knowledgeable of the manufacturer's specifications on accuracy, calibration requirements, and procedures for use
and overall analysis procedures.
d. Except under extenuating circumstances, the FMO's RADHAZ equipment shall not be loaned outside
the FMO office.
e. The FMO shall assure that all personnel who would use the instruments are thoroughly trained in the use
of RADHAZ measurement equipment. The FAA will provide the necessary training. It is highly desirable that
regular measurements on NAS equipment, e.g., long-range radars, be done as a proficiency-training requirement.
1608. MEASUREMENT PHILOSOPHY.
a. The FMO is not authorized to make any judgment as to any health hazard or lack thereof. When
measurements have been completed, they shall be reported as required, followed by a written report signed by the
person actually making the measurements.
b. Order 3900.19B specifies that the measurements will be made with the full cooperation and assistance of
maintenance and management personnel responsible for the equipment concerned. It is likely that those persons
will be watching as the measurements are being made, to see whether the indications might show a hazardous
condition. The FMO should be fully open to those persons responsible who watch as to the numeric values
obtained. But the FMO or engineer making the measurements shall make no assumptions as to health hazards pro
or con. If pressed for comment, the FMO will refer the inquirer to Order 3900.19B, the service area Flight
Surgeon or the ROSHM.
1609. MEASUREMENT CONSIDERATIONS.
a. Where a radar is rotating, it will be nearly impossible to receive an average power density level above
the MPE. Considering the width of the radar beam and the antenna azimuth rate, a person at a fixed point (unless
it was in the immediate vicinity of the radar antenna sail) would receive only that percentage of power equal to
the beam width divided by 360, per unit time. For instance, a 2º beam width rotating radar would radiate any
given point only 2/360 or 0.55 percent of the power measured at the same point under radar fixed illumination.
There is substantial radiation from the side lobes, but normally -30 dB or so down from the main lobe peak.

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b. In the near field, antenna lobes are not well defined and calculations based on them cannot be totally
relied upon. This point is very significant and should be brought out in any report as a result of measurements of
a rotating radar.
c. Use of a field strength meter for RADHAZ measurements shall be considered only when the level is less
than
1 mW/cm2. Greater levels may not be read accurately by the field strength meter due to the limit of the shielding
of the field strength meter, or front end overload. In those cases where a field strength meter is used, the "peak
hold" mode must be used so that the meter ballistics can be negated by the time hold. Conversion from dB/µv to
mW/cm2 must be accomplished after the field strength meter measurement is completed. For this procedure, refer
to the RFI manual described in paragraph 1400.
d. Persons uninformed about radiation may become overly concerned when they think they might be in a
hazardous field. In this regard, the FMO shall never rely upon inexpensive non-ionized "radiation detectors"
which can be bought for only a few dollars. Not only are they without any calibration, they usually are designed
to operate on peak power, rather than average. About the only thing that can be said for them, other than they
frighten people, is that they usually are very over-sensitive, so that persons using them probably are far safer than
they think.
e. Home made detectors can be a problem. In one instance, an FAA radar site employee claimed radiation
injury from the radar. The employee had constructed a standard Yagi antenna, resonant to the radar frequency,
and placed a small NE-2 neon bulb at the feed point. The bulb lit nearly anywhere on the transmitter floor level,
whenever the Yagi was pointed upward. Even considering the gain of the constructed Yagi, it took considerable
time and effort to show that the bulb was lighting from peak power. Actual calibrated measurements throughout
the area showed less than 5 percent of the MPE.
f. Diversity of opinion concerning radiation dangers must not in any way distract the FMO from absolutely
assuring every reported or suspected radiation hazard is thoroughly investigated and reported as required in Order
3900.19B.
1610. MEASUREMENT STANDARDS AND PROCEDURES. Whether ionized or non-ionized,
measurement of radiation is really just a form of field strength measurement, with which the FMO is very familiar
in spectrum surveillance work. The difference is that in an area where possible health hazard from ionized
radiation is being investigated, measurement shall be approached much more carefully than the usual field
strength measurement.
a. Action levels are those employee exposure levels that trigger the implementation of Chapter 14 of Order
3900.19B and related program guidelines, administered by Environmental, Energy Conservation, and
Occupational Safety and Health (EEOSH) Services. When these levels are exceeded, additional surveys may be
requested and protective steps will be initiated by FAA Safety personnel to ensure worker safety.
b. The latest approved version of the MPE Standards for uncontrolled environments (at the time of this
order, the 1999 Edition of IEEE/ANSI C95.1) shall be used as "action levels" for all environments where there is
potential for exposure to non-ionizing radiation. If these standards are exceeded, further measurements may be
requested by Environmental, Energy Conservation, and Occupational Safety and Health (EEOSH) Services to
determine whether non-ionizing radiation levels exceed the ACGIH TLVs for controlled environments. The
reference standard for ionizing radiation is provided by the most current version of the ACGIH TLVs.
c. All equipment used will have current calibration (e.g., less than one year since last calibration, or
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whatever the manufacturer recommends).
d. Equipment batteries will be checked and verified as good, or replaced before measurement.
e. Persons making the measurements shall have sufficient experience in making such measurements and/or
have completed the Academy RadHaz Course 44516, Radiation Hazard Theory and Measurement Procedures
and Course 40606, Radiation Measurement Procedures Lab. If questions arise concerning procedures, refer to
the above course materials.
f. The FMO surveyor shall not make any determination whether the noted value of radiation is "safe" or
"unsafe." That is for medical personnel and industrial hygienists to determine. However, if measured radiation
levels equal or exceed the non-ionizing or ionizing action levels, the appropriate management personnel of the
facility being surveyed, the Regional Occupational Safety and Health Manager (ROSHM) or Safety Officer, and
the Technical Operations ATC Spectrum Engineering Services shall be advised immediately of the level
indicated. If appropriate, inside or outside areas should be marked off as easily recognizable as a "do not enter"
area by the FMO.
g. When a measurement is completed, the FMO shall prepare a report and forward a copy to Technical
Operations ATC Spectrum Engineering Services, Environmental, Energy Conservation, and Occupational Safety
and Health (EEOSH) Services, the service area Operations Branch, and the System Management Office (SMO)
regardless of the level of the radiation measured.
h. Automated functions to facilitate the calculation and reporting of radiation measurements are available to
support the user, as highlighted in chapter 19, paragraph 1910.
1611. IONIZED RADIATION MEASUREMENT PROCEDURES.
a. Ionized radiation deals with those extremely short wavelengths in the x ray, alpha, beta and gamma ray
bands. The instrument supplied to all FMOs, and the only approved instrument is the Victoreen 440RF (Version
D). The "RF" portion of the model number indicates that it is shielded for operation in even very high RF fields.
Other instruments, especially the CDV-700, shall not be used without consulting Technical Operations ATC
Spectrum Engineering Services. While it is accurate for radiation purposes, the CDV-700 is not accurate in the
presence of high RF fields as may be encountered in FAA facilities.
b. Calibration and use.
(1) The very first action the measuring engineer shall take is to thoroughly read the instruction book that
comes with each instrument. Complete familiarity with its provisions is mandatory before every measurement.
(2) Next, battery level shall be checked by the integral meter. If not at an operating level, batteries shall
be replaced before the meter is used for measurement.
(3) Instrument self-calibration is accomplished by bringing the built-in calibration source into the
specified area of the sensing cylinder. Measurements may proceed only if the self-calibration test is satisfactory.
(4) Turn on the instrument to its most sensitive level. The circuit should be zeroed, if necessary.
Zeroing should be checked at all scale levels.
(5) The meter should read nearly zero except for an occasional flick at the lowest scale level, caused by
casual neutrons or gamma rays passing through the sensor. If the meter reads considerably upscale, the reason for
that level reading shall be determined before any further readings are made. It is important that the instrument is

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first turned on well outside any expected measurable radiation area.
(6) Once the meter is found to be operating normally, the area that is to be measured will be entered
slowly and carefully. Watching the meter, the FMO shall carefully "sweep" the area under measurement,
carefully noting and recording all readings above ambient zero level. The engineer accomplishes this by holding
the instrument with its ion chamber facing the source to be measured. The instrument is slowly moved over the
face of the cabinet or whatever container houses the suspected source. It shall be done slowly because the meter
is damped and there is a short delay time before the meter reaches its extremity value, up or down.
(7) Most likely areas of radiation will be around windows or door jambs of high power klystron or
magnetron tube cabinets, such as those found in TACANs and radars. Entire surfaces of cabinets, including the
power supplies, should be systematically swept for readings. X rays are generated by a stream of electrons
impinging upon a metal surface under the influence of high voltages, usually in excess of 20 kilovolts.
(8) During the sweep, the instrument shall be held well in front of the body, as it is moved toward or into
the suspected field. To the extent possible, if less than MPE, put the sensor face as close to the device being
measured as possible without touching it.
(9) Whenever a MPE is approached, the FMO will advance very slowly up to that limit. Should
readings above the MPE be required, the instrument will be placed into those higher fields by means of a pole or
other convenient device holding it, so the FMO is not subjected to levels above the MPE. At or above the MPE,
the levels vs. distance in inches or feet from the radiating source are very important and should be measured and
recorded for the report.
(10) Paragraph 1608 c. notwithstanding, if a level exceeding the MPE is found, the FMO shall advise
the facility management, the Safety and Environmental Compliance Manager (SECM), and the ROSHM, even if
after hours or a non-workday.
(11) Instrument calibration should be accomplished at least annually, or at any time its accuracy is
questioned.
1612. NON-IONIZED RADIATION MEASUREMENT AND PROCEDURES. Non-ionized radiation refers
to RF, even though it may be in the Extremely High Frequency (EHF) band, 30-300 GHz. Measurements of RF
fields employ resonant loops (LF, MF, and HF), resonant dipoles (VHF and UHF), or isotropic probes for varied
levels of high power in SHF and EHF. Measurements are made by field strength meters, calibrated in μv/m, dB
above 1 µv (dBμv), or power density meters calibrated in mW/cm2. Field strength meters are typically used for
lower level fields. Good treatises on this measurement theory are available in standard electronic engineering
handbooks.
a. The Narda power density meter is used for power levels of 1 mW/cm2 and greater. The instrument
consists of a hand-held calibrated detector circuit with an integral meter. Two associated probes for two different
ranges of power have been supplied. One or the other of the probes is used, connected by the supplied cable to
the detector. The Narda is usually used in connection with measurement of a high power radar or close proximity
measurements of TACAN. Other instruments that could be used are other field strength meters (e.g., Eaton NM65T, NM-67T, NM-37/57, Electrometrics Models EM-2135 (EMC-60), EM-2125 (EMC-30), EM-2110 (EMC11), spectrum analyzers (e.g., any of several HP or Tektronix, now used by FAA, or equivalent) with associated
antennas, or other FAA approved instrument. Unless otherwise noted, the following direction pertains to the use
of the Narda power density meter.
(1) First, the measuring engineer is to be thoroughly familiar with the instruction book for the
instrument. Familiarity with operation procedures covered in the instruction book may be a matter of inquiry in
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(2) The only calibration to be done is to check battery level and zero the instrument with appropriate
probe attached. Proceed only if readings are normal. Note: The calibration/zero procedure is described in the
instruction book. The probes need individual instrument insertion calibration for each use. The instruction book
contains the procedure. Note that they are very delicate and shall not only be handled with care, but not subjected
to levels in excess of their ratings.
(3) Once calibrated, the measurement procedure may begin. Using the highest power probe, approach
the source to be measured. If it is the radiation from the antenna of a rotating radar, prior arrangements will have
to have been made to get radar shutdown so that a steady-state radiation can be obtained for measurement.
(4) All radar types currently used by FAA have been measured previously and found well below MPE
below the antenna sail. Therefore, initial measurements can be started in the radome or at the pedestal level, so
long as the engineer's body does not extend into the plane of the sail area. However, if there is any doubt
whatsoever, measurements should be started well below the sail level and gradually moved up into the general
area.
(5) The probes are nondirectional, except that a signal coming from the direction of the handle would
not be measured accurately.
(6) To use the instrument, hold the detector in one hand, the probe in the other. Start well outside the
expected area of high radiation. Slowly move into the area and "sweep" the suspect area with the probe pointed
toward the source. "Toward" means that the probe handle is pointed away from the source. If the source is radar,
the radar antenna shall be stopped, and the measurement location searchlighted, if the main beam of the radar is
being investigated for radiation level. Hold the probe over the head at a reasonable distance. Using an elevating
device such as a "cherry picker," the FMO should slowly move up into the main beam with the probe, while
watching the Narda meter. Move the probe through the highest level of indicated radiation, until the level starts
dropping.
(7) Once the MPE is reached, further intrusion beyond will be by remote means only. The Narda is
supplied with a calibrated cable that is intended for this purpose. Use an appropriate non-metallic pole and
fashion a lashing or mount for the probe. Using it at the end of the pole, slowly position the probe into the "hot"
area being measured. All levels vs. distance shall be accurately measured so that values of distance in feet and
inches can be clearly shown on the report.
(8) If levels are found to be too low for the scale readings of the highest probe, the engineer should back
off from the high density area, change and recalibrate with the lower power probe, then return to the area for
measurement.
(9) For lower density devices, such as microwave ovens or microwave links, the process will be
essentially the same, except the expected power levels will be so low that poles and other "remote reading"
assisting devices will not be needed. If the level is below 1 mW/cm2, then a field strength meter may be required,
with appropriate antenna. Nonetheless, prudence shall be exercised in approaching the source to be measured.
(a) If a microwave dish is the source, the probe can be slowly swept all over the face of the dish, even
into the area of the feed horn. Since the average power is being measured from a pulsed source, the probe and
associated equipment need a little time to come up to the correct reading. CAUTION: The probe surface must
never touch any solid part of a device being measured. In some models, the contact can create an instantaneous
static discharge that can destroy the delicate probe.

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(b) If a microwave oven or similar device is the source, the probe should be swept over the entire
cabinet, with particular attention being given to the edges of the door, glass windows and vents. Again, it is
imperative that the probe not touch the source.
(10) Guidance for the distance vs. power density and MPE in the main beam for the various radars now
being used by FAA is found in Order 3900.19B. A chart of current conditions is provided in figure 16-2.
b. The field strength meter will be used for lower level measurement areas. The operation of the meters
will be in the normal field strength measurement mode and procedure. Since the upper measurement limit of
these instruments is well below the "safe" level, use normally will be at considerable distances from any high
power source. Since they are capable of being operated on their internal batteries, they are amenable to use in
portable conditions.
See also paragraph 1609, (1) (b).

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FIGURE 16-2. RADARS USED BY FAA WITH POWER DENSITIES >MPE

Radar
Type

Transmitter Power
Peak
Average
MW
W

Nominal
Frequency MPE
MHz
mW/cm2

AN/FPS-20

2.0

4319

1300

4.3

315

AN/FPS-60 (simplex)

2.0

4319

1300

4.3

315

AN/FPS-60 (duplex)

2.0

8638

1300

4.3

630

AN/FPS-6/90

2.8

2040

2800

9.3

264

ASDE

0.0045

3

15,950

10.0

*

ASR-4,-5,-6.

0.425

403

2800

9.3

29

ASR-7 (AN/GPN12)

0.5

475

2800

9.3

37

ASR-8 (AN/GPN-20/27)
(Simplex)

1.4

875

2800

9.3

92

ASR-8 (AN/GPN-20/27)
(Diplex)

1.4

1750

2800

9.3

172

ASR-9

1.237

1430

2800

9.3

205

ASR-11

.0229

324

2840

9.5

90

ARSR-1,-2

5.0

3595

1315

4.4

295

ARSR-3 (simplex)

4.6

3140

1315

4.4

230

ARSR-3 (duplex)

4.6

6280

1315

4.4

460

ARSR-4

0.93

558

1315

4.4

260

NEXRAD (WSR-88)

1.0

2000

2850

9.5

172

TDWR

0.31

550

5625

10.0

354

Distance#
Ft

* MPE not exceeded.
# Calculated distance from antenna to point on main beam axis where power density
equals the MPE.

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1613. MEASUREMENT CONSIDERATIONS AND REFERENCE DATA.
a. Radiation measurements below 100 MHz will normally be for a Non-Directional Beacon (NDB) and
Compass Locator (COMLO) in the 190-535 kiloHertz (kHz) band, NRCS (See Chapter 7) High Frequency (HF)
in the 2-28 MHz band or 75 MHz Marker transmitters. The NRCS HF is Single Sideband (SSB) Suppressed
Carrier emission, so measurements must be taken with the transmitter being modulated by a constant tone source
to stabilize the SSB radiation, set at what is considered 100 percent power output. In cases of frequencies
between 0.1 - 100 MHz, both the electric (E) field and the magnetic (H) field values shall be obtained by
measurement. This is to assure compliance in both fields.
The power density (PD) (also S) value in mW/cm2 is then calculated by using the formulas:
2

E Field: PDmW/cm = E2/3770

2

H Field: PDmW/cm = H2 x 37.7

b. Radiation measurements taken in the Very High Frequency (VHF) and Ultra High Frequency
(UHF) A/G bands shall be done with tone modulation at 100 percent to assure worst case condition.
c. Radiation measurements taken of Distance Measuring Equipment (DME) and TACAN as a pulsed
emission requires the measurement to be taken in peak values, then corrected for average values by introducing
the duty cycle (DC) factor. For the worst case, the DC is 0.04. Therefore, after the peak reading is obtained,
multiply it by 0.04 to get the average power. Only the E field is required.
d. Radiation measurements for rotating Airport Surveillance Radar (ASR), Air Route Surveillance Radar
(ARSR), Airport Surface Detection Equipment (ASDE), Terminal Doppler Weather Radar (TDWR) and Next
Generation Weather Radar (NEXRAD) radars have additional factors to be considered: (a.) the DC, obtained by
multiplying the pulse width (PW) (in seconds) times the pulse repetition rate (PRR) in pulses per second (pps);
(b.) the Fractional Exposure Time (FET) obtained by dividing the antenna beam width (BW) which is 4 degrees
by 360. Thus, FET= 4/360= 0.011.
(a) For rotating radar, only the peak E fields, usually in Volts per meter (V/m), need to be measured.
The Power Density (S) = (E2/3770) x DC x FET (using the peak E field value).
(b) For radar with antenna stationary and directly pointed at the point of measurement (searchlighting),
only the DC factor is used to determine average power from the measured peak power.
e. The electromagnetic MPEs for uncontrolled environments from the 1999 Edition of ANSI/IEEE
Standard C95.1 are presented in figure 16-3. It is important to use the most current version of the standard that is
available at the time of the survey. The Uncontrolled MPEs shall be used as action levels for all environments
where there is a potential for exposure to non-ionizing radiation.
f. The electromagnetic MPEs for controlled environments are presented in figure 16-4.
g. Figure 16-5 contains the 2001 ACGIH Ionizing Radiation TLVs. These guidelines are updated yearly. It
is important to use the most current version of the standards that is available at the time of the survey.

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FIGURE 16-3. NON-IONIZING MPE - UNCONTROLLED ENVIRONMENT

MAXIMUM PERMISSIBLE EXPOSURE FOR UNCONTROLLED ENVIRONMENTS
Electromagnetic fields*
Frequency Range
(MHz)

1
0.003 – 0.1
0.1 – 1.34
1.34 – 3.0
3.0 – 30
30 – 100
100 – 300
300 – 3000
3000 – 15000
15000 – 300000

Electric
field
Strength
(E) (V/m)
2

Magnetic field
Field Strength
(H) (A/m)

Power Density (S)
E-Field, H-Field
(mW/cm2)

Averaging Time
|E|2, S or |H|2
(Minutes)

3

4

5

614
614
823.8/f
823.8/f
27.5
27.5
-

163
16.3/f
16.3/f
16.3/f
158.3/f1.668
0.0729
-

(100,1000000)#
(1000, 10000/f2)#
(180/f2, 10000/f2)
(180f2 , 10000/f2)
(0.2940000/f3.336)
0.2
f/1500
f/1500
10

6
6
f2 / 0.3
30
30
30
30
90000/f
616000/f1.2

6
6
6
6
0.0636f1.337
30

Note-f is the frequency in MHz

* The exposure values in terms of electric and magnetic field strengths are the values obtained by
spatially averaging values over an area equivalent to the vertical cross section of the human body
(projected area).
# These plane-wave equivalent power density values, although not appropriate for near-field
conditions, are commonly used as a convenient comparison with MPEs at higher frequency and are
displayed on some instruments in use.

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FIGURE 16-4. NON-IONIZING MPE – CONTROLLED ENVIRONMENT

MAXIMUM PERMISSIBLE EXPOSURE FOR CONTROLLED ENVIRONMENTS
Electromagnetic fields*
Frequency
Range
(MHz)

Electric field
Strength (E)
(V/m)

Magnetic Field
Strength (H)
(A/m)

Power Density (S)
E-Field, H-Field
(mW/cm2)

Averaging Time
|E|2, |H|2, or S
(Minutes)

1

2

3

4

5

0.003 – 0.1
0.1 – 3.0
3.0 – 30
30 – 100
100 – 300
300 – 3000
3000 – 15000
15000 – 300000

614
614
1842/f
61.4
61.4
-

163
16.3/f
16.3/f
16.3/f
0.163
-

(100,1000000)#
(1000, 10000/f2)#
(900f2 , 10000/f2)
(1.0, 10000/f2)
1.0
f/300
10
10

6
6
6
6
6
6
6
616000/f1.2

Note-f is the frequency in MHz
* The exposure values in terms of electric and magnetic field strengths are the values obtained by
spatially averaging values over an area equivalent to the vertical cross section of the human body
(projected area).
# These plane-wave equivalent power density values, although not appropriate for near-field
conditions, are commonly used as a convenient comparison with MPEs at higher frequency and are
displayed on some instruments in use.

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FIGURE 16-5. IONIZING TLV
.
TYPE OF EXPOSURE

ANNUAL DOSE LIMIT

Effective Dose
a) in any single year
b) averaged over 5 years

50 mSv (millisievert) *
(See Note 1)
20 mSv per year

Annual Equivalent Dose to:
a) lens of the eye
b) skin
c) hands and feet

150 mSv
500 mSv
500 mSv

Embryo-Fetus exposures once the
pregnancy is known
•Monthly equivalent dose #
•Dose to the surface of women’s
abdomen (lower trunk)
•Intake of radionuclide

Radon Daughters

0.5 mSv (See Note 2)
2 mSv for the remainder of the
pregnancy
1/20 of Annual Limit
on Intake (ALI)
4 Working Level
Months (WLM)

# Sum of internal and external exposure but excluding doses

from natural sources as recommended in National Council on
Radiation Protection and Measurements (NCRP)
* Conversion factors:

Note 1: Action level any single year
50 mSv = 5000 mR
Action level = 5000 mR/yr or 2080 hrs/yr
Action level = 2.4 mR/hr (approximately)

10 mSv = 1 Rem = 1000 mR.
1 mSv = 100 mR
Note 2: Action level for pregnant women
0.5 mSv = 50 mR
Action level = 50 mR/mo or 60 hrs/mo
Action level = 0.3125 mR/hr

These action levels are cumulative maximums over a standard work-hour/year of 2080 hours and
a standard work-hour/month of 160 hours.

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FIGURE 16-6a. LETTER OF AGREEMENT SAFTEY PROGRAM RESPONSIBILITIES

Letter of Agreement for
Division of Functional Radiation Safety Program Responsibilities
Between Technical Operations ATC Spectrum Engineering Services
and Technical Operations ATC Facilities
In September 2002, the former Federal Aviation Administration
(FAA) organizations, the Resources Management Program, and the
Spectrum Policy and Management Program, signed a letter of
agreement (LOA) dividing the Radiation Safety Program (RSP)
responsibilities that were assigned to the former FAA
organization, the Airway Facilities Service, by Chapter 14 of
FAA Order 3900.19B: FAA Occupational Safety and Health
Program. This LOA replaces the 2002 LOA and highlights the
present FAA organizations responsible for the various duties
under the RSP. Specifically, it clarifies the duties assigned
to Technical Operations ATC Facilities and Technical
Operations ATC Spectrum Engineering Services.
Technical Operations ATC Facilities shall:
1.
Appoint a Radiation Protection Officer to serve as the
Agency focal point for all employee radiation health and
safety issues.
2. Serve as the budget advocate for funds to carry out
assigned Technical Operations ATC Facilities RSP duties.
3.

Perform FAA employee exposure assessments.

4.
Perform induced current measurements, dosimetry,
measurements of low frequency non-ionizing sources, and
other measurements as necessary, that are not performed by
Technical Operations ATC Spectrum Engineering Services as
established in FAA Order 6050.32, Spectrum Management
Regulations and Procedures Manual. These surveys are
required to assess employee exposure at FAA communication,
navigation and surveillance (CNS) facilities.
5. Perform routine ionizing and non-ionizing radiation
surveys to assess FAA employee exposure at CNS facilities.
6.
Provide technical assistance to regions in radiation
risk management, exposure assessment, and dosimetry as
required.

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6050.32B

FIGURE 16-6b. LETTER OF AGREEMENT SAFETY PROGRAM RESPONSIBILITIES

7.
Assist the Office of Environment and Energy (AEE) as
co-liaison in coordinating with organizations external to
the FAA such as the Occupational Safety and Health
Administration (OSHA), National Institute of Occupational
Safety and Health (NIOSH), American Conference of
Governmental Industrial Hygienists (ACGIH), and the
Environmental Protection Agency (EPA), on radiation health
and safety issues.
8.
Provide assistance to Technical Operations Services
organizations to ensure that FAA Maintenance Orders in the 6000
Directives Series and related publications incorporate radiation
risk management practices and current FAA radiation protection
policies.
9.
Ensure that annual field safety assessments of
employee work tasks and environments are conducted to
identify employees for inclusion in the RSP. Identify new
operations, maintenance activities, and modifications to
the work environment that may increase the potential for
radiation exposure.
10. Implement initial and periodic radiation hazard
evaluation training for safety and health professionals and
staff. Implement safety awareness training for employees
who work in environments where there is the potential for
exposure at or above adopted FAA standards. Document all
training and maintain all training records for the period
required by OSHA.
11. Coordinate with the Office of Aviation Medicine (AAM)
when seeking additional health or medical interpretation of
any radiation measurement data.
12. Assist AAM to ensure that all exposure records,
dosimetry measurement records, and related health and
medical records are maintained in accordance with OSHA
requirements.
13. Ensure that citizens and FAA employees have access to
radiation survey, investigation, and exposure assessment
data.
14. Coordinate with Technical Operations ATC Spectrum
Engineering Services to obtain radiation hazard
measurements on CNS systems in response to employee or
union requests.
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FIGURE 16-6c. LETTER OF AGREEMENT SAFETY PROGRAM RESPONSIBILITIES

15. Provide internal coordination within the FAA on
matters relating to radiation exposure assessment.
16. Serve as the point of contact for employee questions
related to radiation hazards from equipment that is not
part of the FAA's CNS facilities (e.g. microwave ovens,
video display terminals, etc.)
17. Develop and provide informational resources on
radiation safety to employees upon request.
Technical Operations ATC Spectrum Engineering Services
shall:
1. Serve as budget advocate for funds to carry out
assigned Technical Operations ATC Spectrum Engineering
Services duties.
2.
Serve as the focal point for performing ionizing and
non-ionizing radiation hazard measurements during the
baselining, or commissioning of FAA CNS facilities, or as
otherwise required by Order 6050.32, Spectrum Management
Regulations and Procedures Manual. Radiation hazard
measurements will also be performed in response to employee
requests. Written copies of all radiation measurements
reports will be provided to Technical Operations ATC
Facilities, Environmental, Energy Conservation, and
Occupational Safety and Health Services, and the Regional
Occupational Safety and Health Managers (ROSHM).
3. If a transmission tube (thyratron, klystron, magnetron,
or amplitron) is found to emit radiation above the action
level during a Radiation Survey (RS), the following
information shall be added to the RS report: tube
manufacturer, model, and serial number and current tube
operating voltage.
4.
Provide technical assistance to the service areas for
radiation hazard measurements, defining radiation hazard
environments, and radiation survey equipment calibration
and maintenance.

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FIGURE 16-6d. LETTER OF AGREEMENT SAFETY PROGRAM RESPONSIBILITIES

5.
Maintain an inventory of Frequency Management
Officers' (FMO) radiation hazard measurement equipment that
is updated annually. Ensure that radiation survey
equipment is calibrated in accordance with manufacturer
recommendations.
6.
Coordinate with Technical Operations ATC Facilities
and organizations external to the FAA such as
Interdepartmental Radio Advisory committee (IRAC),
Department of Defense (DOD), and the Federal Communications
Commission (FCC) on spectrum issues relating to radiation
hazards.
7.
Periodically update FAA Order 6050.32, spectrum
Management Regulations and Procedures Manual, and radiation
hazard measurement training to ensure compliance with
current radiation standards and policy.
8.
Provide the FAA's spectrum engineering staff initial
and periodic training in conducting ionizing and nonionizing radiation hazard measurements of CNS facilities.
9.
Make radiation measurement data available to citizens,
employees, and FAA service area and headquarters staff.
10. Perform radiation hazard measurements in response to
inquiries from other Federal agencies, Congressional Offices,
citizens, and other external parties.
Signed by
Jack Nager
Director, ATC Facilities
ATC Facilities
Date: 7/29/05

1614. thru 1699. RESERVED.

Page 232 (thru 234)

Signed by Jerrold B. Sandors
for Oscar Alvarez
Acting Director, ATC Spectrum
Engineering Services
Date: 7/27/05

11/17/05

6050.32B

CHAPTER 17. LAND MOBILE AND OTHER FM COMMUNICATIONS SYSTEMS
FREQUENCY ENGINEERING
1700. GENERAL. This chapter will present guidance and criteria for engineering frequencies for FAA land
mobile and other FM communications systems operating in the Federal Government fixed/mobile bands.
1701. FREQUENCY ENGINEERING. The FAA currently uses the bands 162-174 MHz and 406.1-420 MHz
for land communications. For a description of how to perform a detailed engineering analysis, refer to the NTIA
Manual, annex I.
a. While no formal criteria for cochannel and adjacent channel separation exist within FAA, separate
cochannel assignments by 100 nmi or RLOS, where possible. For data links, use the same rule unless unique
digital coding is available, such as in the Medium Intensity Approach Lighting System with Runway Alignment
Indicator Lights (MALSR). In this case, close separation (down to 5 nmi) has been found to work satisfactorily.
b. No first adjacent channel (12.5 kHz) protection standard is provided for fixed/land mobile
communications systems.
1702. SYSTEMS BASICS. FAA FM radio communications systems operating in the land mobile bands are of
two major types: repeater/base/portable/mobile voice systems, and voice/data links.
a. The repeater/base/portable/mobile systems are voice systems used in support of the National Radio
Communications Systems (NRCS), known internally as Command and Control Communications (C3).
b. The voice/data links are used for Low Level Wind Shear Alert System (LLWAS), MALSR, Remote
Maintenance Monitoring (RMM), Automated Weather Observing System (AWOS), Stand Alone Weather System
(SAWS) and other systems that require low capacity fixed RF links.
1703.

C3/NRCS. The C3/NRCS VHF FM COMM frequency plan is as shown in figure 17-1.

FIGURE 17-1. C3/NRCS COMMUNICATIONS FREQUENCY PLAN

Channel

Repeater
Uplink (MHz)

1
2
3
4
5
6

169.325
169.350
169.375
169.250
169.275
169.225

7
8
9
10

172.1250
172.7375
172.1750
166.1750

Repeater
Downlink (MHz)
172.925
172.950
172.975
172.850
172.875
172.825

simplex
simplex (except Alaska)
simplex
simplex

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a. The NRCS VHF FM system is a three-way voice system. It can be used either through a repeater
(duplex) or unit-to-unit (simplex.) See figure 17-2.

FIGURE 17-2. EXAMPLE OF A REPEATER/BASE/PORTABLE/MOBILE FM SYSTEM

b. Using the repeater, any base, mobile, portable or hand-held unit may communicate with any other unit
within RLOS range of the repeater by utilizing duplex operation. This consists of transmitting on one frequency
(uplink) which is automatically repeated on another frequency. This second frequency (downlink) is then
transmitted by the repeater and received by the intended unit and all others tuned to the same frequency.
c. Talkaround allows unit to unit direct communications without using the repeater. It is defined as simplex
operation, where both units within RLOS transmit and receive on a single frequency, in this case the repeater
output frequency (downlink). This permits short range communications without activating the repeater while
permitting reception of the repeater at any time the units are not engaged in simplex communications (standby).
d. Tone activated squelch (PL). The PL acronym comes from the trade name of the first tone-activated
squelch system (Motorola's Private Line). PLs are transmitted single tones between 67.0-254.1 Hz (42 total), but
they are normally not heard in a commercial FM land mobile system due to the 300-3000 Hz system voice band
pass filters built into the equipment. This is intentional, to permit use of control tones without interfering with the
voice communications on the same units. They are continuously transmitted when the transmitter is keyed. Upon
reception, the tones will open a matching PL squelched receiver, if PL is activated. If PL is activated on a
receiver, only stations transmitting the same PL can be heard. The normal PL for the current analog NRCS radios
is 136.5 Hz. In a few areas, a second PL may be used.

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1704.

Chapter 17 - continued

6050.32B

RF VOICE/DATA LINK SYSTEMS.

a. LLWAS radio links are used to relay wind speed/direction information from field sensors to a central
processor. LLWAS frequency requirements are satisfied within 406.1-420.0 MHz band. Frequencies for
LLWAS equipment shall be selected from the following (MHz):
409.1750

410.3000

412.5375

413.5875

414.7875

418.1750

b. MALSR radio links are used to control approach lighting from the ATCT when it is not practical to use
land lines. The frequency 165.7625 MHz shall be the primary channel for MALSR.
c. RMM radio links are used to relay maintenance and control data from a remote site back to a central
monitoring point. Frequencies shall be selected from the following (MHz):
408.8250
413.0625

410.0250
413.6000

412.9375
417.8250

412.9875
419.0250

413.0125

If these specific frequencies are not available, system frequencies should be engineered in accordance with the
NTIA Manual supplement for the 406.1-420.0 MHz band.
d. AWOS radio links are used to relay weather information from field sensors to a central processor. These
links will be operated within the 406.1-420 MHz band on a case-by-case basis.
e. SAWS radio links are simplex operating systems used to relay weather data from a remote site to a master
station. The frequencies 413.1125 MHz and 414.0125 MHz shall be the primary channels for this facility.
1705. MISCELLANEOUS RADIO LINKS. Low capacity RF links may be operated in the band
406.1-420.0 MHz on a case-by-case basis.

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1706. NARROW BAND REQUIREMENTS. Narrow band transmitter and receiver standards are presented in
the NTIA Manual, Chapter 5.3.5.2. The narrow band standards support a 12.5 kHz channel plan, versus the
previous 25 kHz channel plan. As of January 1, 2005, all systems implemented in the 162-174 MHz band must
meet these standards. All new systems, and after January 1, 2008, all systems implemented in the 406.100420.000 MHz band must also meet these standards. The following parameters will be affected:
Transmitter:
Necessary bandwidth
Unwanted emissions
Frequency deviation
Frequency tolerance*
Receiver
Necessary bandwidth
Spurious response attenuation
Adjacent channel selectivity
Intermodulation rejection
Conducted spurious emissions
Frequency tolerance*
*NTIA Manual Section 5.2

1707. thru 1799. RESERVED.

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6050.32B

CHAPTER 18. ELECTRONIC ATTACK (EA) EVALUATIONS
1800. PURPOSE.
a. Most RFI experienced by FAA facilities is of an uncontrollable and unexpected nature. Indeed, in many
instances, such RFI is unintended by the operator causing it. In many instances, FAA systems have methods of
filtering out this RFI. However, there is one type of RFI which is intended and which the FAA usually has the
ability to schedule, relocate or cancel. That type of RFI consists of EA military operations. Unfortunately, EA is
sometimes conducted without prior coordination by the military. In this case, the problem has to be handled just
as any unexpected RFI.
b. EA missions are military operations where electromagnetic signals are radiated intentionally or chaff is
dropped to cause RFI to other military units. These missions are conducted on various portions of the spectrum.
These radiations can cause severe RFI to FAA facilities, particularly GPS, TACAN and radar. While training in
electronic attack and dropping chaff is deemed necessary by the military to keep air crews combat-ready, it can
also present a serious hazard to air safety. FAA must carefully review requests for this type of activity. FAA
policy on EA activity is summarized below:
(1) The Technical Operations Services technical analysis performed by the applicable service area or
by Technical Operations ATC Spectrum Engineering Services evaluates the potential for NAS degradation. If the
proposed EA mission degrades the NAS, FAA will not concur with the operation. To accommodate DOD EA
training requirements, FAA will evaluate the possibility of NOTAMing affected facilities out to service (OTS)
during specific mutually agreed upon times, on a case-by-case basis.
(2) The affected ARTCC or other designated FAA facility has final authority, based on current air traffic
capacity, safety, weather or other valid reason, to allow an EA mission to proceed as scheduled or to refuse
concurrence. However, if such refusal occurs after previous national authorization of a military EA activity, then
the affected ARTCC or facility shall report such refusal through RFI or MCC reporting channels back to national
authorities.
(3) Technical Operations ATC Spectrum Engineering Services forwards the coordinated FAA
response after the technical Technical Operations Services analysis and coordination with the appropriate air
traffic organization. Technical Operations ATC Spectrum Engineering Services also passes on or assigns an
administrative EA control number to authorized operations. The military unit will refer to this control number
when contacting the ARTCC for final approval to dispense chaff or to conduct other EA activity.
(4) Technical Operations ATC Spectrum Engineering Services will evaluate all EA requests which
could impact GPS operations (e.g., 1164-1215 MHz and 1559-1610 MHz) and all Joint Tactical Information
Distribution System (JTIDS) operations outside the limits set by the DOT/DOD Memorandum of Agreement
(MOA) “Civil Use of GPS” (1993) Annex 3 (1999). JTIDS assignments covered by the MOA will be addressed
through the frequency assignment process.
1801. DEFINITIONS.
a. A Military Operating Area (MOA) is the established airspace outside positive control areas to
separate/segregate certain nonhazardous military activities from IFR traffic and to identify for VFR traffic where
these activities are conducted.

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b. A Restricted Area is airspace designated under FAR Part 73 within which the flight of the aircraft, while
not wholly prohibited, is subject to restriction. Restricted areas are designated when determined necessary to
confine or segregate activities considered to be a danger to nonparticipating aircraft.
c. A Warning Area is airspace of defined dimensions over international waters that contain activity that may
be hazardous to nonparticipating aircraft.
d. "Stop Buzzer/Chaff" or "Cease Buzzer/Chaff" are terms normally transmitted over "guard" channels
(121.5 MHz and 243.0 MHz) which directs any military unit to stop electronic attack or to stop dropping chaff, as
appropriate. It is important to realize that because of its slow fall rate and unpredictable winds, chaff may take
several hours to reach the ground, with uncontrollable RFI occurring until the chaff is at ground level.
1802. APPLICABLE REGULATIONS AND DOCUMENTS.
a. Order 7610.11A, Coordinating Electric Attack Mission Requests, establishes internal FAA
coordination procedures. It states that FMOs will coordinate with their respective service area air traffic
organizations when reviewing EA proposals and establishes Technical Operations ATC Spectrum Engineering
Services as the focal point for sending out the authorization to the military for EA operations after service area
analysis is completed.
b. Order 7610.4, Special Military Operations describes general guidelines for military units for requesting
and performing EA operations.
c. Order 7400.2, Procedures for Handling Airspace Matters, is primarily used by military units when
they need to establish new special use airspace. It states that desired EA operations shall be considered during the
planning stages of expanding or establishing new special use airspace.
d. DOD Chairman of the Joint Chiefs Staff Manual (CJCSM 3212.02A, Performing Electronic Attack
in the United States and Canada for Tests, Training and Exercises) details EA approval procedures for use by
the military services. The military instruction is coordinated with FAA to ensure that these procedures are
adequate to protect critical safety communications, navigation and surveillance systems from interference. Figure
18-3 indicates those frequency bands, designated as "National" coordination with a superscript "1," which shall be
coordinated and approved by the FAA prior to beginning EA operations. Paragraphs 1806-1808 of this order
were extracted from Appendix I of the CJCSM.
e. DOT/DOD Memorandum of Agreement “Civil Use of GPS” (1993) Annex 3 (1999). The 1993 MOA
is a broad overarching agreement delineating DOT and DOD responsibilities regarding civil use of GPS as DOD
developed and implemented GPS. The Annex 3 implements the actual coordination activities between DOT and
DOD to: facilitate coordination to ensure DOD can develop, test, exercise, and train necessary capabilities
“without unduly disrupting or degrading civilian uses” as governed by the 1996 Presidential Decision Directive;
facilitate timely reporting and resolution of GPs interference; specify jointly acceptable GPS interference analysis
tools; and designate Technical Operations ATC Spectrum Engineering Services as the DOT point of contact.
DOD is required to submit test requests 60 days prior to the test, and the FAA has 30 days to respond. Annex 3
establishes the organizational responsibilities for GPS interference.
1803. RESPONSIBILITIES.
a. Technical Operations ATC Spectrum Engineering Services shall:
(1) Establish guidance to ensure consistency for authorizing EA activity throughout the service areas.

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(2) Provide the written, consolidated FAA response and authorization to military EA requests based on
FMO analysis and coordination. This response may be transmitted via email, fax or message, depending upon the
request.
(3) Assign an administrative EA control number for reference, if required. Normally, the submitting
military agency assigns a control number to the proposed activity. If this does not occur, then the FAA assigns
this number. Such a control number will include a designator indicating the requesting agency, a representation
of the fiscal year in which the request is made, and a unique control number. An example of this would be
ACC 02-04, where ACC refers to the U.S. Air Force Air Combat Command, 02 refers to FY 2002, and 04 is a
number uniquely assigned to this request. To continue this example, NSAWC 02-04 would refer to the fourth test
sponsored by the Naval Strike Warfare Center in FY 2002.
b. Service area FMOs shall:
(1) Coordinate with their service area air traffic organizations and applicable FAA ARTCCs and
facilities as needed to determine whether FAA facilities could be impacted by the proposed EA mission.
(2) Perform a thorough analysis of the proposed EA impact on FAA systems within their service area.
(3) Provide a written NAS facilities EA impact analysis to Technical Operations ATC Spectrum
Engineering Services for the proposed EA along with any recommendations for restrictions; e.g., altitude, time of
day, prohibited frequencies, etc.
1804. ANALYSIS OF EA REQUEST.
a. The following general policy outlines the minimum analysis required when evaluating EA proposals.
(1) FAA does not allow its systems to experience RFI intentionally because of the possibility of
degradation of safety of flight.
(a) Military entities are requested to accept restrictions that will allow EA training without RFI to
FAA systems.
(b) In those cases where FAA allows RFI in order to accommodate military training, affected facilities
or Centers will NOTAM the systems OTS, where necessary.
(2) FAA does not allow EA training on 1030 MHz, 1090 MHz, 108-137 MHz,
960-1240 MHz, 1559-1610 MHz or 5030-5090 MHz except under highly restrictive and limited instances.
(3) There are certain frequency bands that require special consideration because they are used by civil
aviation for critical aeronautical radionavigation operations. However, the FAA does not centrally manage them.
For example, these bands include 4200-4400 MHz (radar altimeter) and 13.25-13.40 GHz (airborne weather
radar). Active EA operations are seldom performed in these bands, but chaff can impact these airborne systems.
Care will be taken that chaff operations are not allowed near air routes so that such airborne systems do not
receive interference.
b. The following general procedures will be used in evaluating EA electronic jamming proposals.
(1) Determine whether the electronic jamming is to be done in a frequency band in which FAA
supports air traffic services. FAA evaluates only those jamming operations that could cause RFI to FAA
operations.

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(2) Determine whether the jamming is to be done in an area within RLOS of facilities supporting the
National Airspace System and in a frequency band of concern to the FAA. Note: consider terrain shielding, if
applicable.
(3) Determine whether the power level will be sufficient to cause RFI to FAA facilities if the jamming
is to be within RLOS.
(4) Determine possible restrictions (e.g., altitude limitations, possible use of spot frequencies rather than
bands, etc.) which could be imposed to allow the jamming.
c. The following general guidelines shall be followed when evaluating EA chaff proposals:
(1) Only consider the primary and "second time around" targets when evaluating chaff. Experience
has shown that "third (or higher) time around" targets are not detected by FAA radars.
(2) Chaff normally interferes with radar. However, there is a small possibility that it could cause RFI
to microwave systems such as RCL if dropped within 500 feet of the microwave beam.
(3) Determine whether the chaff is designed to affect a frequency band in which FAA has radar or
microwave facilities.
(4) If the chaff is designed to affect a frequency of interest to FAA, determine whether it is to be within
RLOS. Note: terrain shielding may be considered in this evaluation. See (1) above regarding "second time
around."
1805. CONCLUSIONS. Analysis of EA operations, both electronic jamming and chaff, is complicated and
requires good engineering practices. FAA is committed under Title 49. U.S.C., to provide a safe and efficient
NAS. This Act also requires the FAA to make every effort to accommodate necessary military EA training. By
careful analysis and proper procedures, FAA can permit most military EA training without impacting aeronautical
safety.
1806. OPERATIONAL BAND AND CHANNEL CODES. The following bands and channels are set up to
give one standard system of frequency band designations for EA operations and to facilitate the operational
control of EA. The bands are identified in alphabetical sequence. Each band is divided into 10 numerical
channels. The phonetic alphabet and numerical channel numbers are used to identify the EW frequency. During
operations, when it becomes necessary to identify an exact frequency, the frequency is specified as a numerical
designation (lowest frequency in any channel) plus frequency in MHz above the base frequency. Example for
1315 MHz: DELTA 4 covers the frequency range 1,300-1,400 MHz; 1,315 MHz would therefore be designated
DELTA 4 plus 15. See Figure 18-1.

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FIGURE 18-1. FREQUENCY BAND DESIGNATIONS

Band
A(lpha)
B(ravo)
C(harlie)
D(elta)
E(cho)
F(oxtrot)
G(olf)
H(otel)
I(ndia)
J(uliet)
K(ilo)
L(ima)
M(ike)
N(ovember)
O(scar)

Frequency (MHz)
0 – 250
250 – 500
500 - 1,000
1,000 - 2,000
2,000 - 3,000
3,000 - 4,000
4,000 - 6,000
6,000 - 8,000
8,000 - 10,000
10,000 - 20,000
20,000 - 40,000
40,000 - 60,000
60,000 - 100,000
100,000 - 200,000
200,000 - 300,000

Channel Width (MHz)
25
25
50
100
100
100
200
200
200
1,000
2,000
2,000
4,000
10,000
10,000

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1807. FREQUENCY BAND CORRELATION. Figure 18-2 depicts the correlation between previous
frequency band designations (sometimes used by ARTCCs) and band designators defined in this chapter.

FIGURE 18-2. FREQUENCY BAND CORRELATION
Frequency Range

0-250 MHz
250-500 MHz
500-1,000 MHz
1-2 GHz
2-3 GHz
3-4 GHz
4-6 GHz
6-8 GHz
8-10 GHz
10-20 GHz
20-40 GHz
40-60 GHz
60-100 GHz
100-200 GHz
200-300 GHz

EW Frequency Band

* Radar Design
Frequency Band

A
B
C
D
E
F
G
H
I
J
K
L
M
N
O

HF/VHF
UHF
UHF
L
S
S
C
C
X (8-12.5 GHz)
Ku (12.5-18 GHz)
K (18-26.5 GHz)
Ka (26.5-40 GHz)
40-100 Millimeter
Sub-millimeter
Sub-millimeter

* Band designations sometimes used by ARTCC

1808. EA COORDINATION REQUIREMENTS BY FREQUENCY BAND.
a. Canada: All EA performed in Canada requires national coordination.
b. United States: Figure 18-3 has been coordinated at the national level. The status of the frequency bands
for EW in the United States is annotated below as “Local,” “Local (FCC),” or “National.” Each status is defined
in the Glossary of this manual and in the procedures in Enclosure C.
c. National Coordination: In Figure 18-3, “National” coordination requires that the request be forwarded to
the cognizant Military Department (MILDEP) FMO for coordination. The frequency bands are listed
consecutively to include all frequencies for ease of understanding. Obviously, one frequency cannot be both
national and local. Therefore, the following rules apply. All frequency bands designated national are inclusive.
All “Local” or “Local (FCC)” frequencies adjacent to a national frequency band begin or end at the first
increment adjacent to the national frequencies. Local (FCC) frequencies are inclusive when adjacent to a local
frequency. For example, in the band 25-50 MHz, all frequencies from 25 MHz through 50 MHz require national
coordination; frequencies 50.001 MHz through 53.999 MHz require local coordination; and frequencies 54MHz
through 72.999 MHz require local (FCC) coordination. NOTE: The reallocation of federal RF spectrum is an
ongoing process. Reallocation may affect testing in some of the spectrum bands listed in Figure 18-3. The

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6050.32B

MILDEP FMOs have the latest information on spectrum reallocation actions and will factor this knowledge into
the national coordination process.

FIGURE 18-3a. COORDINATION LEVEL REQUIRED BY CHANNEL AND FREQUENCY

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FIGURE 18-3b. COORDINATION LEVEL REQUIRED BY CHANNEL AND FREQUENCY

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6050.32B

FIGURE 18-3c. COORDINATION LEVEL REQUIRED BY CHANNEL AND FREQUENCY

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FIGURE 18-3d. COORDINATION LEVEL REQUIRED BY CHANNEL AND FREQUENCY

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FIGURE 18-3e. COORDINATION LEVEL REQUIRED BY CHANNEL AND FREQUENCY

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FIGURE 18-3f. COORDINATION LEVEL REQUIRED BY CHANNEL AND FREQUENCY

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FIGURE 18-3g. COORDINATION LEVEL REQUIRED BY CHANNEL AND FREQUENCY

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FIGURE 18-3h. COORDINATION LEVEL REQUIRED BY CHANNEL AND FREQUENCY

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FIGURE 18-3i. COORDINATION LEVEL REQUIRED BY CHANNEL AND FREQUENCY

1809. thru 1899. RESERVED.

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CHAPTER 19. AUTOMATED ENGINEERING
1900. PURPOSE. The purpose of this chapter is to present policy and an overview on the use of various
computer system elements developed to support FAA spectrum engineering. These system elements facilitate the
automation of various engineering functions used by Headquarters to evaluate and make frequency assignments.
1901. AUTOMATED FREQUENCY MANAGER (AFM). The AFM system should be used by any FAA
spectrum engineer to engineer frequencies, submit or track frequency assignment applications, investigate RFI or
analyze the contents of the AFM data base, which includes data obtained from the GMF, FAA pending frequency
assignments, and various international, FCC, and ARINC sources. Headquarters is responsible for engineering
and recommending approval/disapproval to NTIA for all frequency assignments, both Government and nonGovernment, delegated to the AAG (see NTIA Manual, Chapter 1), as well as all FAA frequency assignments in
all frequency bands. FAA registers all of its own frequency assignments, as well as non-Government frequency
assignments in the AAG bands, with the NTIA. The frequency assignments are then incorporated into the GMF.
See paragraph 1907. The AFM is also used as a tool for frequency assignment coordination between Government
entities requesting frequency assignments in the AAG bands.
1902. AFM AGENDA SYSTEM. The AFM Agenda System program is designed to allow Headquarters users
to evaluate and vote on frequency assignments in a Windows environment. The program allows users to review
and vote on all assignments processed by NTIA. Agenda sections are downloaded from, and voted records
returned to, NTIA daily. See paragraph 1908.
1903. AIRSPACE ANALYSIS MODEL (AAM). The AAM was designed to assist the FMO in determining
the effects of various radio transmitters (in particular FM stations) on aircraft navigation and communications
receiver facilities. The model determines the effects of FM broadcast stations on ILS localizer and VOR signals.
It allows the selection of a proponent FM station at any location within the U.S. and provides a complete
compatibility analysis between the proponent and any selected localizer within 30 nmi of the proponent. See
paragraph 1909.
1904. RFI and RADHAZ DATA BASE. The Spectrum Management Data Base (SMDb) is used to record RFI
events affecting the NAS, and to facilitate the calculation and reporting of radiation measurements. The SMDb
significantly enhances the means to address these issues and to share information across the Technical Operations
Services organizations. See paragraph 1910.
1905. EXPANDED SERVICE VOLUME (ESV) MANAGEMENT SYSTEM (ESVMS). The ESVMS is an
advanced web-accessible application that provides a set of functions in an easy-to-use interface. This program
was developed to improve the processing time for new ESVs and to provide an effective tool in recording and
tracking all ESV requests, from origination to final approval and registration into the national ESV data base.
It provides for the generation and printing of reports for all Pending, Approved, Disapproved, Cancelled, and
Restricted ESVs. See paragraph 1911.
1906. RADIO COVERAGE ANALYSIS SYSTEM (RCAS). RCAS is a web-accessible modeling and
analysis tool used to perform radio coverage and analysis studies. RCAS allows a visualization of the predicted
radio coverage patterns, taking into account terrain data. This tool also facilitates the siting of communications,
navigation, and radar equipment. This can be done by overlaying the analysis with state boundaries, sector
boundaries, ground features, etc.

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1907. OVERVIEW OF THE AFM
a. The AFM. The AFM software application is an Internet based application consisting of primarily Client,
Business/Application, and Data base service/server tiers. Service area users can access the AFM Internet based
application via the FAA Network, the Internet via a Secure Socket Layer (SSL) or a secure Virtual Private
Network (VPN) connection, as well as a Dial-up Remote Access Server (RAS) connection. Service area users
can also run and access program files and the data base locally if necessary.
b. Uses.
(1) Create and modify FAA and NG applications, edit them to ensure they conform to FAA and NTIA
standards and send them to NTIA for incorporation into the GMF.
(2) Track the progress of applications through the approval process.
(3) Produce management reports on the status of the assignment process.
(4) Produce new FTA forms as applications are approved.
(5) Register frequencies internationally (planned future application).
(6) Review assignments regularly (at least every 5 years) to ensure that the frequencies are still in use
and the assignments correctly reflect the usage.
(7) Create and modify DOD and other Government applications in the AAG bands to test for
frequency suitability, i.e., to provide coordination with other agencies.
c. Frequency engineering. Each proposed frequency shall be tested to ensure that it meets FAA standards
for sufficient signal strength within its FPSV and receives the required protection from interference. The AFM
system provides several models for engineering interference-free frequencies. These models protect both the
proposed target and all existing sites, i.e., testing is done on the target as both desired and undesired. These
models assist the user in engineering and selecting the best frequency to assign for the most efficient use of the
spectrum. The model's results detail reasons for failure/interference, thus assisting the user in exploring ways to
engineer a successful frequency, e.g., by using filters, changing the power, etc.
(1) The Air/Ground model is a tool for engineering frequencies in the 118-137 MHz and 225-400 MHz
bands. This model performs the following tests, which are further described in Chapter 9 and Appendix 2.
(a) A cochannel test protects against using the same frequency in two coverage areas within
interference range of each other.
(b) An adjacent channel test protects against using frequencies separated by ± 25 kHz or ± 50 kHz
from being used in nearby service areas, which otherwise could result in interference.
(c) A cosite test protects against the potential for interference from nearby transmitters, which
otherwise would be allowed to operate at a frequency separation less than an established minimum, usually
± 500 kHz for VHF or ± 1 MHz for UHF.
(2) The NAVAIDS Model performs intersite analysis tests in the bands 108.20-117.95 MHz (LOC,
VOR/VOT), 328.6-335.4 MHz (GS), 960-1215 MHz (DME/TACAN), and 5031-5091 MHz (MLS). For GS and
MLS testing, cochannel and adjacent channel testing involves identifying those sites having interferers within

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designated distances. For DME/TACAN, VOR/VOT, and LOC testing, an Equivalent Signal Ratio (ESR) is
calculated and the interpolation of appropriate curves is carried out to determine the required separation distance,
as described in Chapter 10 and Appendix 3 of this manual. If ESVs are associated with the target or potential
interferer, they are also tested. The target's ESV signal strength is also tested. In order to protect paired NAVAID
frequencies, dummy assignments have been created for unassigned associated frequencies.
(3) The NDB model tests nondirectional beacons in the frequency band 190-535 kHz. All potential
interferers within a frequency ± 6 kHz from the proposed target are tested. The required separation distance is
calculated, based upon the prediction curves and calculation methods described in Chapter 11 of this manual.
(4) Frequency assignments for fixed, mobile communications, HF communications, radio
communications links, and radar are tested by using a generic model, which produces a circle report of potential
interferers.
d. OTHER AFM ENGINEERING FEATURES. Additional features of the AFM assist spectrum
engineers in performing engineering analyses. FCC, ARINC, and international data bases are maintained and are
used by the models and browse/query routines.
(1) Browse and query routines are provided to assist engineers in analyzing the distribution of
frequencies throughout the spectrum.
(2) A graphics routine lets users display model and browse/query results on appropriate maps. Users can
also choose to map ILS keyholes, glide slope and ESV wedges, DME/VOR circles, and TSV ATC sectors.
(3) An intermod program helps engineers investigate possible sources of RFI. The frequencies tested as
well as the potential interferer frequencies can be user-entered, selected from a browsed list, and/or selected from
a circle report.
(4) A TSV data base is periodically updated. The Centrad model lets users modify a pending TSV data
base. The A/G model as well as the graphics routines uses these data bases.
(5) ESV data can be added to NAVAIDS assignments. The NAVAIDS model is used to test ESVs for
signal strength and interference.
(6) Engineering tools are also provided. These include bearing/distance calculations and power/density
calculations.
(7) The system documentation includes formulas used in creating the models and tools. This
documentation is included in the on-line help.
1908. AFM AGENDA SYSTEM. This system allows FAA Technical Operations ATC Spectrum Engineering
Services users to vote on "frequency applications" submitted by other government agencies via records received
from the NTIA.
a. The system is comprised of three programs: Import, Export, and Vote Agenda.
(1) Import is run daily to import all new "sections" of data from NTIA.
(2) Export is run daily to export all "voted" applications to NTIA.

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(3) Technical Operations ATC Spectrum Engineering Services users can run the Vote Agenda
program, throughout the day, to review and vote "applications."
b. Vote Agenda. Users log into the system using a User ID that identifies which AFM frequency "bands"
the user can access and review. A band access table identifies the frequency bands each user can access and it is
user modifiable.
1909. AIRSPACE ANALYSIS MODEL (AAM)
a. Overview of the AAM
(1) The primary purpose of the AAM is to serve as a tool to help evaluate the effects of FM broadcast
signals on ILS localizer, VOR and COMM signals received by airborne receivers, as well as by ground receivers
in the case of COMM. This includes intermodulation, receiver front-end overload and adjacent channel
interference.
(2) This model differs significantly from earlier methods of analyzing compatibility in that a complete
three dimensional analysis is performed. This analysis takes into consideration the vertical radiation patterns of
the FM broadcast antennas as well as the vertical structure of the Navaid service volume. The output of this
model consists of computer-generated plots, which indicate regions within the Navaid service volume where
interference is predicted.
(3) The AAM consists of standard RF propagation equations and a quantity of empirical data acquired
from various sources involved in the investigation of the compatibility between FM broadcast and aeronautical
radio services. The data were obtained from measurements performed on a range of equipment under a variety of
conditions. A mathematical representation of the data is used to categorize the immunity performance of a
representative receiver under a wide range of signal conditions.
(4) The potential for RFI is determined by calculating the signal conditions present at a specific site by
identifying the relevant RF emitters in the area, applying standard propagation equations and adjusting for system
losses to find the signal levels at the receiver input, and then examining the empirical data to see if the
representative receiver would experience interference under those conditions.
b. Signal Level Prediction
(1) The AAM calculates the signal-in-space conditions by starting with the parameters of the transmitting
system and accounting for propagation loss. Transmitting parameters for an FM broadcast station include the
transmitter power as well as the vertical and horizontal gain patterns of the transmitting antenna. For aeronautical
facilities, the AAM accesses a subset of the GMF to determine the array type of the facility being analyzed and
then performs the needed calculations to determine the signal-in-space conditions. For example, signal levels for
the localizer are calculated by modeling the free-space, vertical pattern of the localizer as a Sin2 θ pattern. Ground
reflections are modeled by assuming the ground to be an infinite, flat plane with a dielectric constant of 12 and a
conductivity of .003 Mhos per meter.
(2) The signal-in-space value is then corrected by the losses in the receiving system (including losses due
to the frequency-gain response of the receiving antenna) to determine the levels of the signals (both desired and
undesired) present at the input to the receiver.

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c. Interference Calculations
(1) Several receiver models have been examined through a series of bench measurements taken by the
FAA and the FCC. The receivers were chosen to represent a broad cross-section of the existing population.
Statistics on the population of receivers and aircraft were obtained from the FAA, the NTSB, the General
Aviation Manufacturers Association (GAMA), and the AOPA. The receiver models included in the
measurements constitute combined sales of more than 200,000 units spread among the 215,000 active civil
aircraft in United States (including air carrier, commuter, and general aviation categories).
(2) Various combinations of these receivers were tested for sensitivity to interference by
overload/desensitization (type B2), adjacent channel (type A2), and two-signal/three-signal third-order
intermodulation (type B1). The results were tabulated and used to develop empirical interference threshold
criteria. A step-by-step description of the AAM calculations in shown below.
(a) The AAM identifies the boundaries of the FPSV for the aeronautical facility of interest and
generates a grid of test locations throughout the area of interest within the FPSV. This grid is on a maximum
spacing of 1000' x 1000' centers for the ILS localizer, a maximum spacing of 6076' x 6076' centers for the VOR,
and a maximum spacing of 2 percent of the service-volume radius or 9999', whichever is less, for VHF
communications facilities (except for ground-based VHF communications facilities which are only examined at
the location of the facility).
(b) The AAM identifies the undesired RF emitter sources and calculates the field-in-space for
every emitter, at every grid location, based on the transmitted power, the radiation patterns of the transmitting
antennas, and the propagation losses.
(c) The AAM adjusts the field-in-space values for receiving system losses (including the frequency
vs. gain response of the receiving antenna and polarization loss) to determine the signal levels at the receiver input
for both the undesired signals and the aeronautical signal.
(d) The AM applies the A2 (adjacent-channel) and B2 (overload/desensitization) interference
criteria at every grid location for every undesired emitter to determine if the representative receiver will
experience A2/B2 interference based on the signal levels at that grid location.
(e) The AAM identifies every relevant RF emitter (including broadcast and aeronautical facilities)
located within 30 nmi of the FPSV boundaries and computes every potential two-signal and three-signal, thirdorder intermodulation (IM) product. It then identifies every IM product falling within 200 KHz of the
aeronautical facility being studied.
(f) The AAM calculates the signal levels [using the parameters discussed in step (a) and step (b)
above] of every component of every IM product identified in step (e), and applies the B1 (IM) interference criteria
to determine if the representative receiver will experience B1 interference based on the signal levels at that grid
location.
(g) A map of the FPSV is generated containing a plot of every grid location at which interference is
predicted to occur.
1910. RFI AND RADHAZ SUPPORT
a. The SMDb provides automated tools to help satisfy analysis and reporting functions for both RFI and
RADHAZ cases, as highlighted in paragraph 1904. The capabilities and operational environment of the SMDb
are briefly highlighted below.

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b. The RFI portion of the SMDb application enables users to record RFI events affecting the airspace for
which they manage the radio spectrum. Recording these events is accomplished through an easily accessible
application with improved navigation and functionality. This application also allows for the sharing of resolution
information across the Technical Operations Services organizations. The RFI portion of the SMDb supports the
following:
(1) Provides a library of audio files capturing the sound of recorded interferences to be accessed through
the FAA intranet 24 hours a day, seven days a week.
(2) Serves as a reporting system. Many ad hoc queries can be performed on the data collected in this
system.
(4) RFI reports are entered and viewed through a number of means. The SMDb is envisioned to be the
one place to report, record RFI and collect information concerning ongoing investigations, as well as view
historical data on events from previous years. Service areas, as well as Headquarters, can use this repository to
view all interference problems and their resolution.
(5) Uploading any type of file to be linked with the Interference Record.
(6) Records the funds expended to investigate the RFI.
(7) Add utility screens for choices which did not previously exist to drop-down boxes in a simple
manner, without the use of a programmer. These screens can be accessed from the menu panel.
(8) Maintain data integrity through many validations. For example, if the frequency, facility type, and facility
identifier do not match the frequency assignment listed in the AFM, the system will not allow an RFI event to be recorded
against that facility.
c. The RADHAZ portion of the SMDb facilitates the calculation and reporting of Radiation Measurements, from the
time of a RADHAZ request through the reporting and approval of the measurements. It is also acts as a repository of all
FAA RADHAZ survey reports. The RADHAZ portion of the SMDb supports the following:

(1) Upload an electronic version of a RADHAZ report document (scanned or original) to be linked to
a facility record and include it in a RADHAZ online repository.
(2) Download available RADHAZ reports in online repository for viewing purposes.
(3) Write and print RADHAZ reports using a predetermined format, including writing and submitting
special request or baseline RADHAZ survey reports.
(4) Approve and publish reports by an approving authority, from reports submitted by a user.
(5) Search and view RADHAZ survey reports related to a specified facility.
d. SMDb Operating Environment. The SMDb resides as a web-based application on the FAA’s Intranet.
Users access the system using Microsoft Internet Explorer web browser. The SMDb does not have a "client"
software application. Most application functions will occur centrally on the server either using the web
application server or the data base server. FAA personnel will have access to data in a "real-time" environment.
Updates to data made by a user will be instantaneously available to all other users having access to the
application.

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1911. ESV
a. Background. ESVs are not registered in the NTIA or GMF. Thus, Technical Operations ATC Spectrum
Engineering Services maintains a separate data base within the AFM system for all ESVs used in the NAS. The
ESV process previously required the procedures specialist to apply for an ESV by FAA Form 6050-4 that requires
FMO and FIFO approval. The development of the ESVMS provides an automated and much more flexible means
of processing ESVs.
b. Capabilities. The ESVMS enables users to process ESV requests to establish, revise or cancel ESVs. It
provides an enhanced workflow with on-line tracking of ESV requests 24 hours a day, seven days a week. During
the process, users have the ability to view the status of all ongoing ESV requests through an easily accessible
system using intuitive format and navigation. ESVMS gives the user the option of saving an application while it
is being worked on and selecting it again, at another time, to complete and send forward in the process. The
system offers administrative users the functionality to manage and update user information and privileges. The
ESVMS also presents the capability of reporting detailed and summary data.
c. Operating Environment. The ESVMS resides on a web application server and operates on the FAA's
Intranet. Users may access the system using Microsoft Internet Explorer web browser. The ESV application does
not have a "client" software application. Most application functions will occur centrally on the server either using
the web application server or the data base server. All concerned FAA entities will have access to data in a "realtime" environment. Updates to data made by any user will be instantaneously available to all other users having
access to the ESVMS.
1912. – 1999. RESERVED

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APPENDIX 1. AIRSPACE EVALUATION
SECTION 1. BACKGROUND AND PROCEDURES
1. INTRODUCTION. The authority, regulations, and basic procedure for handling airspace evaluations are
discussed in chapter 5. This appendix will establish detailed methods for such evaluations.
2. BACKGROUND. Due to the rapid growth of both aeronautical and commercial broadcast services, the
number of interference cases involving aircraft and commercial broadcast emissions has increased dramatically.
Interference is usually most severe at airports with high power FM and TV broadcast facilities nearby.
a. COMM receivers experience interference in the form of nuisance background noise, actual broadcast
audio, and distorted or garbled reception of desired ground transmissions. NAVAID receivers (VOR and LOC)
experience nuisance audio, actual errors in course deviation indicators, and erroneous flag indications. This
interference to NAVAID receivers is the most serious. Course deviation errors during an approach and landing,
the most critical phase of flight operation, are usually not as evident to the pilot as disrupted communications.
b. There are many factors that contribute to this problem. One is the broad power differential between
commercial broadcast and aeronautical service transmitters. FM stations may operate at as much as 100 kW and
many TV stations operate above the 100 kW level. In contrast, a LOC transmitter is typically operated at only 20
W, plus 12 to 20 dB gain “on course.” Outside the LOC antenna's main beam, the EIRP is considerably reduced.
c. There is no guard band between the high end of the FM broadcast band (107.9 MHz) and the low end of
the aeronautical NAVAID band (108.0 MHz). Spurious emission levels from commercial transmitters are
significant as far as 600 kHz off channel. Also, due to operating necessity, the minimum performance standards
for aircraft receivers require them to be a broadband device.
3. FM BROADCAST TOLERANCES. FCC Rules and Regulations Part 73 authorize the operation of FM
broadcast transmitters within certain standards and tolerances.
a. FMOs should review Part 73 which establishes policy that proponents who either (1) commence program
tests, or (2) replace their antennas, or (3) request facility modifications and are issued a new construction permit,
must satisfy all complaints of interference to aeronautical facilities during a one year period. Resolution of
complaints will be at no cost to the FAA.
b. FM broadcast stations operate on 100 channels in the 88-108 MHz band (see figure 1). Channel carriers
are 200 kHz apart on odd decimal frequencies. The first assignable channel is 88.1 MHz (Ch 201) and the last is
107.9 MHz (Ch 300). The FCC allocates FM channels to towns and cities across the nation according to a
coordinated geographic assignment plan.

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FIGURE 1. FM CHANNELS AND CENTER FREQUENCIES

Page 2

CHNL
NO.

FREQ
MHZ

201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250

88.1
88.3
88.5
88.7
88.9
89.1
89.3
89.5
89.7
89.9
90.1
90.3
90.5
90.7
90.9
91.1
91.3
91.5
91.7
91.9
92.1
92.3
92.5
92.7
92.9
93.1
93.3
93.5
93.7
93.9
94.1
94.3
94.5
94.7
94.9
95.1
95.3
95.5
95.7
95.9
96.1
96.3
96.5
96.7
96.9
97.1
97.3
97.5
97.7
97.9

CHNL
NO.
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300

FREQ
MHZ
98.1
98.3
98.5
98.7
98.9
99.1
99.3
99.5
99.7
99.9
100.1
100.3
100.5
100.7
100.9
101.1
101.3
101.5
101.7
101.9
102.1
102.3
102.5
102.7
102.9
103.1
103.3
103.5
103.7
103.9
104.1
104.3
104.5
104.7
104.9
105.1
105.3
105.5
105.7
105.9
106.1
106.3
106.5
106.7
106.9
107.1
107.3
107.5
107.7
107.9

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6050.32B

c. Maximum spurious emission levels for FM broadcast stations are:
Any spurious emission
removed from the main
carrier frequency by:

Must be attenuated
below the unmodulated
carrier by at least:

120-240 kHz

25 dB

240-600 kHz

35 dB

Beyond 600 kHz

43 dB + 10 Log P or 80 dB,
whichever is the lesser
(P = power output in watts)

d. An FM transmitter operates with a maximum allowable deviation of ±75 kHz around the carrier. Actual
deviation is governed by the amplitude of the modulating signal and the rate of deviation is determined by the
modulating frequency. An infinite number of sidebands theoretically results. Only sidebands down to 1 percent
of the carrier amplitude are considered significant. Therefore, the total occupied bandwidth of an FM broadcast
emission extends beyond ±75 kHz, but is subject to the spurious emission standards stated in subparagraph b. and
shown in figure 2.

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FIGURE 2. SPURIOUS EMISSION LEVEL OF AN FM BROADCAST
TRANSMITTER ON 107.9 MHZ

e. The radiated power of an FM station is set by FCC standards, according to the class of station and the
transmitter antenna height. Power can be up to 600 kW in some cases.
f. The horizontal radiation pattern of a typical FM broadcast antenna is considered omnidirectional. The
vertical pattern is a function of the gain and number of elements (bays) used by the antenna. Antenna radiation
polarization may be horizontal, vertical or both.
4. TV BROADCAST TOLERANCES. FCC Rules and Regulations Part 73 authorizes the operation of TV
broadcast transmitters within certain standards and tolerances.
a. TV broadcast stations operate on 12 VHF channels between 54-216 MHz and 56 UHF channels between
470-806 MHz (see figure 3). Channel carriers are 6 MHz apart. FCC allocates TV channels to towns and cities
across the nation according to a coordinated geographic assignment plan.
b. The visual carrier is 1.25 MHz (±1 kHz) above the channel lower limit and may be offset by ±10 kHz.
The aural carrier is 0.25 MHz (±1 kHz) below the upper channel limit (see figure 4).
c. The minimum radiated power for all classes of TV stations is 100 W.

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6050.32B

d. Maximum power for TV stations is set by FCC standards according to the operating frequency
(channel), geographical location and transmitter antenna height. Radiated power can reach as high as 5 MW for
UHF channels under some conditions.
e. The TV broadcast transmission consists of the amplitude modulated visual carrier with a composite
picture and synchronizing signals, together with the aural carrier frequency modulated by the audio signal. A
vestigial sideband filter reduces the lower sideband width.
f. Spurious emissions, including RF harmonics, are required to be maintained at as low a level as the state of
the art permits. All emissions removed in frequency in excess of ±3 MHz of the respective channel edge shall be
attenuated no less than 60 dB below the visual transmitted power. These levels are measured at the output
terminals of the transmitter.
g. Directional antennas may be employed to improve coverage. Polarization may be horizontal or circular.
The maximum to minimum ratio of radiation in the horizontal plane shall not exceed 10 dB for channels 2-13 and
15 dB for channels 14-69.
5. AM AND OTHER NONBROADCAST STATION STANDARDS. Other stations such as AM, cellular,
microwave, etc. have different standards. For these facilities, the airspace evaluation is handled differently. Refer
to Chapter 8 of this Order, paragraph 808.
6. STANDARD FPSVS FOR FAA FACILITIES. The FPSVs for various facilities are discussed in detail in
the portions of this order pertaining to specific types of equipment. Of concern in this appendix are the ILS LOC
and VOR FPSVs. The standard and optional service volume dimensions for ILSs and VORs are shown in
Appendix 3.

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Appendix 1, Section 1 – continued

FIGURE 3. TV CHANNELS AND ASSOCIATED FREQUENCIES

CHNL
NO.
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35

Page 6

FREQ
MHZ

CHNL
NO.

FREQ
MHZ

54-60
60-66
66-72
76-82
82-88
174-180
180-186
186-192
192-198
198-204
204-210
210-216
470-476
476-482
482-488
488-494
494-500
500-506
506-512
512-518
518-524
524-530
530-536
536-542
542-548
548-554
554-560
560-566
566-572
572-578
578-584
584-590
590-596
596-602

36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69

602-608
608-614
614-620
620-626
626-632
632-638
638-644
644-650
650-656
656-662
662-668
668-674
674-680
680-686
686-692
692-698
698-704
704-710
710-716
716-722
722-728
728-734
734-740
740-746
746-752
752-758
758-764
764-770
770-776
776-782
782-788
788-794
794-800
800-806

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Appendix 1, Section 1 - continued

6050.32B

FIGURE 4. IDEALIZED STANDARD TV CHANNEL SPECTRUM

7. EVALUATION PROCEDURE OUTLINE. It is essential that airspace case study methods be thorough and
consistent from service area to service area. An improper evaluation may cause difficult and lengthy legal
proceedings for the agency. The outline presented in figure 5 is a guide for each evaluation.
8. DATA ASSEMBLY.
a. It is difficult to establish specific sources for retrieving the data necessary for an evaluation. Commercial
broadcast data exist as hard copy listings and additional information can be obtained through FCC or from the
broadcasters themselves. The AM, FM and TV data bases are available through the automated frequency
management system (AFM).
b. When identifying commercial broadcast stations for an aeronautical study, specific radii have been
established for each of the broadcast services based on probability and empirical tests. The greatest potential for
interference comes from high power FM, particularly those stations operating at the high end of the FM band.
c. FAA and non-Fed facilities may be identified using the CIRCLE program or other search programs
available through the AFM. If the proposed construction is an FM transmitter, the search should be for a 30 nmi
radius around the new coordinates; if for a TV transmitter, 10 nmi; if for AM, 3 nmi.

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Appendix 1, Section 1 – continued
FIGURE 5. EVALUATION PROCEDURE OUTLINE CHART

A. ASSEMBLE DATA
1) Commercial stations
a.
b.
c.
d.
e.
f.

Frequency
Coordinates
Power (EIRP)
Site elevations
Antenna height (AGL, AMSL, RCAMSL)
Antenna types and radiation patterns

2) FAA facilities
a.
b.
c.
d.
e.
f.

Frequency
Coordinates
FPSVs
Site elevations
Antenna height (AMSL)
Associated facilities

3) Charts
a.
b.
c.
d.

Low Altitude Sectional Charts
VFR Terminal Area Chart
Instrument Approach Plates
Topographical Maps (if necessary)

B. INTERMOD STUDY
1) Obtain third order intermod products
2) Use bandwidth of FAA facilities (usually ±100 kHz NAV
and ±50 kHz COMM)
3) Include facilities within appropriate radii
C. GROUND FACILITIES
1) Calculate out-of-band signal level
2) Calculate in-band signal level
3) Include vertical patterns if necessary
D. AIRBORNE RECEIVERS
1) NAV interference — Use the Airspace Analysis Model to determine
interference from FM broadcast stations to ILS localizer signals and VOR.
2) COMM interference (include vertical patterns if necessary)
a. Calculate brute force radius
b. Plot Venn diagrams along with FPSVs
c. Calculate intermod radii

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Appendix 1, Section 1 - continued

6050.32B

d. Once these transmitters have been identified, specific data should be compiled for each. These shall
include the station frequency, geographic coordinates, power (EIRP), terrain elevation, antenna elevation above
mean sea level (AMSL) or above ground level (AGL), radiation center above mean sea level (RCAMSL), radiated
power and possibly the radiation pattern of the antenna. When dealing with a TV transmitter, use the visual
carrier frequency for all calculations, 1.25 MHz above the bottom frequency of the channel assignment; e.g., CH2
video carrier is 55.25 MHz within channel limits of 54-60 MHz.
e. The search should provide frequency, geographic coordinates, power (EIRP), terrain elevations, antenna
elevations AGL and AMSL, FPSVs and associated facilities. The CIRCLE program automatically provides all
these, plus the distance of each facility from the search coordinates.
f. NAVAID frequencies between 108.1-108.9 MHz and FM frequencies between 107.1-107.9 MHz
particularly should be scrutinized. If a high power high band FM and a low band NAVAID are located within 30
nmi of each other, the likelihood of interference is high and requires very careful analysis. VHF TV channels 4
and 5 bracket the frequency used for ILS marker transmitters, 75 MHz, so careful analysis is required when these
channels are proposed near ILS marker facilities.
g. AM, TV and non-broadcast sources should be plotted and studied in accordance with procedures
outlined in sections 2 and 3 of this appendix.
h. FM sources are covered under the Airspace Analysis Model (AAM) program described in section 2 of
this appendix.
9. INTERMOD STUDY.
a. A receiver will experience intermod interference whenever two or more signals or their integer multiples
combine in such a manner that the product is the frequency to which the receiver is tuned (fO). These signals
combine in the nonlinear receiver input and other nonlinear external devices to produce sum and difference
frequencies through heterodyne action. If a strong signal causes the receiver input to be overdriven, the effect is
more pronounced.
b. These intermod products are of the following form:

Af1 ± Bf2 = f0

Af1 + Bf2 – Cf3 = f0

2Af1 ± Bf2 = f0

c. The order of the intermod product is the sum of the coefficients in the formulas (A, B, and C). Products
through the third order are of primary concern to airspace studies. Intermod calculations are very tedious. There
are several desk calculator and computer programs available that will run all desired orders of intermod by just
entering the subject frequencies. Consideration also must be given to the bandwidth of the victim receiver which
is fO ± bandwidth.
10. GROUND FACILITIES.
a. Both VHF and UHF ground receivers require protection from nearby commercial FM and TV broadcast
stations. They may be affected by spurious (in-band) emissions and single frequency overload (out-of-band)
interference. The latter is often referred to as "brute force" interference.

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b. The major factors involved in calculating interference from spurious emissions (in-band) are the receiver
sensitivity, the FCC-specified spurious emission limits, and the offending EIRP. Antenna, filter and receiver
selectivity have no effect, since the spurious signal is an on-frequency interference. Spurious interference will
result if the signal level from the broadcast station at the on-frequency input to the victim receiver exceeds
-104 db above one milliwatt (dBm). This is calculated as:
LEVEL = EIRP - Lv - Ld - Lp- Lr - Sr
IN-BAND level at victim frequency cannot exceed –104 dBm

Where:
EIRP = Power of the potential interfering station in dBm.
[EIRP (in dBm) = 10 log (power in kW) + 62.2]
Lv = Free space transmission loss in dB at the victim receiver frequency.
Ld = Antenna vertical directivity loss in dB. This term requires antenna pattern data from the
proponent. If the value is unknown, use 0 dB.
Lp = Polarization loss between the victim and broadcast antennas in dB. If the broadcast antenna
is horizontally polarized, Lp = 16 dB; if circularly polarized,
use 0 dB.
Lr = Receiver system on-frequency losses in dB. If value is unknown, use 3 dB.
Sr = FCC spurious emission tolerance in dB. Use 80 dB for FM transmitters and
60 dB for TV transmitters, except where the calculated value is less.
Example of Sr calculation:
The FCC spurious emission limit for FM is:
43 + 10 log ERP(Watts) or 80 dB, whichever is lesser
For an FM station with an ERP of 10 kW = 10,000 W:
10 log 10,000 = 10 x 4 = 40
Spurious limit = 43 + 40 = 83
(Note that any power >5,000 W would be limited to -80 dB suppression.)
For an FM station with an ERP of 1,000 W:
10 log 1,000 = 10 x 3 = 30
Spurious limit = 43 + 30 = 73
Since 73 < 80, the spurious limit for this station is -73 dB from the main carrier.
For a TV station, the formula is:
43 + 10 log ERP(Watts) or 60 dB, whichever is lesser.

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Appendix 1, Section 1 - continued

6050.32B

c. Ground RCF antenna gains vary considerably over the VHF and UHF range of possible interference.
Plots of those gains through 800 MHz are shown in figure 6.
FIGURE 6. TYPICAL FAA VHF AND UHF RCF
GROUND ANTENNA GAIN VS. FREQUENCY PLOTS

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Appendix 1, Section 1 – continued

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d. The Intermediate Frequency (IF) selectivity of a ground receiver will not provide any protection from
single frequency front end overload because this effect occurs in the receiver RF section which will respond to
most frequencies within the commercial broadcasting bands. Tests have shown that a high power signal at the
input to the victim receiver will overload the RF section when it exceeds -4 dBm. This level is calculated from
the following relationship:

LEVEL = EIRP – Li - Ld – Lp – Lr - La
OUT-OF-BAND level cannot exceed -4 dBm
where:
EIRP = Power of the potential interfering station in dBm.
[EIRP (in dBm) = 10 log (power in kW) + 62.2]
Li = Free space transmission loss in dB at the frequency of
the potential interfering station.
Li = 20 log (freq in MHz x Da in ft) - 37.9]
Ld = Antenna vertical directivity loss in dB. This term requires antenna pattern
data from the proponent. If the value is unknown, use 0 dB.
Lp = Polarization loss between the victim and broadcast antennas in dB. If the
broadcast antenna is horizontally polarized, Lp = 16 dB; if circularly
polarized, use 0 dB.
Lr = Receiver system on-frequency losses in dB. If value is unknown, use 3 dB.
La = Typical A/G antenna loss in dB. If unknown, use 3 dB.

e. The slant range distance Da in feet between antennas is calculated using the Pythagorean theorem. One
side of the right triangle is the difference in the antenna heights (AMSL) X in feet and the other side d is the
distance in feet between the antenna coordinates. The slant distance (Da) will then be the hypotenuse of the
triangle. See figure 7. The GROUND.WK1 computer program works this out automatically, or to calculate the
distance (in feet) between the antenna coordinates, use the following method:

Da =

(d

2

+ X 2)

Distances in feet between two locations expressed in coordinates can be determined by any of the great circle
distance computer programs readily available, or if close, can be measured by tape.

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Appendix 1, Section 1 - continued

6050.32B

FIGURE 7. EXAMPLE OF A PLOT FOR CALCULATING SLANT RANGE

11. AIRBORNE RECEIVERS. Data obtained through a series of bench and flight tests conducted by the FAA
at the FAA William J. Hughes Technical Center has established the signal strength levels required for intermod
and brute force interference to occur. These data have been incorporated into the AAM which is used for all
evaluations of the effects of FM broadcast station on ILS localizers and VORs. Testing to add COMM receivers
and other FAA facilities as well as other potential interferers is currently underway. Until that testing is finished,
the Venn diagram method described below will be used for all situations not covered by the AAM.
a. For brute force predictions, signal levels of -10 dBm or greater are necessary. To produce intermod
interference, at least one of the combining frequencies must be at a prime level, while the others are at a
secondary level. The prime level will overdrive the receiver causing the nonlinearity required for heterodyning.
For COMM receivers the prime level is -10 dBm and for NAV receivers, -20 dBm. In both receivers the
secondary level is -30 dBm.
b. Since most commercial stations radiate omnidirectionally, these power contours can be constructed in
the form of Venn diagrams. Wherever the Venn diagrams of prime and secondary signal levels overlap, intermod
interference can be expected. Whenever the -10 dBm contour intersects a NAV or COMM FPSV, receiver
overload will occur, regardless of the receiver frequency. If the station uses a directional antenna, the Venn
diagram would have to be modified to match the contour level of radiation of the particular antenna.

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Appendix 1, Section 1 – continued

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c. These contour distances can be calculated using a form of the space loss formula:

d=

[

]

anti log ( EIRP − Pr − 37.8 − Lr ) / 20
f

Where:
EIRP
Pr
Lr
37.8
d
f

= Power of the station in dBm (ERP + 2.2)
= Value of the desired signal strength (-10, -20, -30 dBm)
= Antenna loss of aircraft [See data in subparagraphs (1) and (2)]
= Free space loss conversion for distance in nmi
= distance of Venn radius in nmi
= station frequency in MHz

(1) Lr for COMM antennas:
Above 175 MHz
100-108
88-108
Below 88

15 dB
10 dB
10 dB + 2 dB/MHz below 100 MHz
34 dB + 0.5 dB/MHz below 88 MHz

(2) Lr for NAV antennas:
Above 175 MHz
88-108
Below 88

15 dB
03 dB + 1 dB/MHz below 108 MHz
23 dB + 0.5 dB/MHz below 88 MHz

d. A plot of these functions is shown in figure 8.
e. Except for ILS localizer and VOR frequencies, if IM products exist at any FAA frequency, the Venn
diagram procedure must be applied. Plot the locations of the offending stations on a chart along with the location
of the FAA facility and/or its FPSV. Calculate the Venn diagram contour distances for prime and secondary
levels according to the type of receiver effected. Plot these contours on the chart and note the intersecting areas.
If the intersecting areas fall within the FPSV of the victim COMM facility, interference is probable.
f. The same procedure is followed for brute force interference. Plot the location of the offending station and
construct only the -10 dBm contour. If this contour intersects the FPSV of any COMM or NAV facility,
interference is probable while the aircraft is flying through the area. The frequency to which the aircraft receiver
is tuned is irrelevant for brute force interference.
g. The AAM is to be used for all evaluation of the effects of FM broadcast proponents to ILS localizers and
VORs. Detailed instructions on using the AAM as well as technical background on the AAM is contained in the
User's Manual and Technical Reference for the Airspace Analysis Model. This document is available from
Technical Operations ATC Spectrum Engineering Services.
12. SAMPLES. Samples of obstruction evaluation (OE) case studies will be found in the following sections 2
and 3 of this appendix. Figure 9 is the form filed by the proponent with typical data inserted.

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Appendix 1, Section 1 - continued

6050.32B

FIGURE 8. RELATIVE GAIN OF AIRBORNE COMM AND NAV ANTENNAS

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Appendix 1, Section 1 – continued

FIGURE 9a. FAA FORM 7460-1, NOTICE OF PROPOSED
CONSTRUCTION OR ALTERATION

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Appendix 1, Section 1 - continued

6050.32B

FIGURE 9b. ADDENDA TO FAA FORM 7460-1, NOTICE OF PROPOSED
CONSTRUCTION OR ALTERATION

Addenda to FAA Form 7460-1 Re: WASR-FM

8-14-95
MARKEY BROADCAST ENGINEERING CONSULTANTS
1060 Coronado St.
Marlboro, MD 20772

Re: WASR-FM application for new FM station Antenna Tower.
The proposed antenna is a guyed 335' tower, with 5-bay loop and 5-bay vertical dipole array, sidemounted antennas, with antenna array tops not exceeding the supporting tower height. The
proposed Frequency is 103.7 MHz, @ 43 kW ERP.
It is proposed that painting and lighting not be required, as there is a 550' tower 123' due North of
the proposed tower, which is painted and lighted per FAA/FCC requirements.

FIGURES 10. thru 14. RESERVED.
13. thru 16. RESERVED.

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6050.32B

SECTION 2. ENGINEERING PROCEDURES FOR
OE CASES FOR FM BROADCAST AND ILS/VOR
17. PURPOSE. The purpose of these procedures is to determine whether a new FM broadcast station
(88-108 MHz) can be safely operated without causing destructive RFI to an in-place or proposed FAA ILS or
VOR. (See appendix 3 for using the AAM to check ILS frequency proposals.)
a. Both airborne receivers aboard aircraft and FAA ground receivers are to be considered. The FMO
conducts a study, then makes a recommendation to the appropriate service area air traffic organization as to
whether to concur or non-concur. Simultaneously, while the FMO is studying the RFI potential, other services in
the service area office are studying whether the new tower or structure would have an adverse effect on the safe
and efficient use of airspace. A non-concur recommendation can stop the proponent (PROP) from getting FCC
approval for the station. The engineering study that results in the decision must be carefully and thoroughly done,
since there are considerable political and financial pressures involved.
b. Referring to the PROP's location, a check is made to find the nearest FAA or military A/G VHF or UHF
communications facility within RLOS. Once located, the FM station's anticipated signal level at that site is
determined. The frequencies involved are 118-137 MHz and 225-400 MHz. If the PROP's out-of-band signal
level is calculated to exceed -4 dBm, the decision is non-concur, because at that level ground receivers will
overload and function improperly. If the in-band spurious emission level would exceed -104 dBm, then a concur
with comment determination is made. This states that the frequency management office will concur provided
sufficient additional attenuation is provided by the PROP for the above bands to assure that the -104 dBm or
better level is met within those bands. See paragraphs 10 and 11, Section 1 of this appendix.
c. These same levels are used for other sources of potential RFI, such as Police and Fire transmitters, Radio
Paging transmitters and any of the many sources in the FCC's Radio Services. That procedure is covered in
Section 3 of this appendix.
d. The AAM is used for evaluating the potential interference to ILS/VOR from FM broadcast stations. The
AAM negates tedious calculation after all parameters have been inputted.
18. OE CASE EVALUATION PROCEDURE. A work sheet is a very handy guide. It assures that all needed
functions are accomplished and describes what conditions led to the concur/non-concur decision. See figure 15
for a practical worksheet. To start with, gather the heading information from the Form 7460-1. It is needed in
working the AAM. Use the antenna AMSL height from 5C of that form, unless the PROP supplies an antenna
drawing with dimensions so that the RCAMSL of the transmitting antenna is specified. Use RCAMSL if it is
available.

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Appendix 1, Section 2 – continued
FIGURE 15. SAMPLE OE CASE WORKSHEET FOR FM

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Appendix 1, Section 2 - continued

6050.32B

a. Task 1. Use the CIRCLE program to obtain a circle search of all FAA and military COMM facilities
within 30 nmi of the PROP's location. When the CIRCLE report prints out, look first for the lowest/closest FAA
or military VHF frequency. If none is found, then look for the first UHF. In the rare event that no FAA/military
ground VHF/UHF COMM is found, then skip Task 2, below, and go on directly to Task 3. Normally there will
be a site. Complete the key in front of the appropriate entry for this function in the worksheet. A sample printout
is shown in figure 16.
b. Task 2. Determine the actual levels, using the GROUND.WRK1 File. Enter the data from the
worksheet and antenna data from the graphs within the program. When completed, type "P" and the form will
print out on your printer. A sample printout is shown in figure 17. Notice the last two lines on the page. If the
calculated values are less than the two maximum permissible values shown, this part of the study is completed.
Note that they are negative values, so a lesser value of signal is a greater negative number. Mark the first two
keys of the result on the worksheet. If either exceeds, complete that portion of the sub-status statements on the
work sheet and be guided accordingly for the final recommendation as to concur/non-concur or concur with
comment.
c. Task 3. Run the AAM program. Instructions are contained in the User's Manual and Technical
Reference to the Airspace Analysis Model.

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Appendix 1, Section 2 – continued

FIGURE 16. SAMPLE PC CIRCLE REPORT

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Appendix 1, Section 2 - continued

6050.32B

FIGURE 17. SAMPLE GROUND.WK1 REPORT

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Appendix 1, Section 2 – continued

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19. EXAMPLE OF AAM PROGRAM FOR FM/ILS
a. The following illustrates a typical OE case study. For the example, FM station KHTN is requesting to
move its facilities to another location. Both the present and new location of KHTN must be earmarked as
"PROP'S" by placing a "1" in the appropriate column for KHTN.
b. Using the parameters in figures 9 and 15, the AAM program will produce a plot of the ILSs that need to
be studied (see figure 18). Although all 5 ILSs within 30 nmi shown on the plot must be checked, only MCE is
used for this example. Even though the AAM may prompt for the back courses, the Terminal Procedures manual
should be consulted to verify whether the back course must be evaluated.
c. After the FM and VOR database has been edited and the AAM has run this phase, it produces the
RFI.PRT which indicates RFI for both the PROP and the present station. See figure 19. Note in the summary at
the end of the report that a greater number of IM points exists for KTHN than for the PROP.
d. Figures 20 and 21 are the horizontal printouts of the predicted RFI. The numbers 1 through 9 and letters
a through d indicate the intensity of the predicted RFI. The higher the number (or letter), the higher the intensity.
Their locations within the FPSV indicate the predicted RFI location and altitude. Because of the small font size
of the numerals or letters, a dot-matrix printer or low dots-per-inch (dpi) printer may not resolve them, but show
only dots. No letters or numerals in the printout would indicate no RFI is predicted. The bold lines in these
horizontal studies printout pages indicate the altitude "slice" studied, in this case, the default, the bottom of the
FPSV.
e. Figures 22 and 23 are the vertical printouts of the predicted RFI. The numbers and letters represent the
same information as in figures 20 and 21. The bold lines in these vertical studies printout pages indicate the
azimuth of the vertical "slice."
f. Based on the MCE analysis data, a PROP's move to the requested location would reduce the potential
RFI to MCE (front course), thus would be advantageous to FAA. The action would be concur with conditional
statement. That statement would indicate that the move would be satisfactory by reducing the RFI potential.
However, if there is increased RFI, the PROP must take steps to remedy the problem at the onset.
g. The GROUND.WK1 printout showed that the in-band level of -104 dBm would be exceeded, so an
additional concur with comment is appropriate which advises the PROP that the spurious emissions must be
additionally attenuated to assure the -104 dBm level is not exceeded at the Merced RCF.

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Appendix 1, Section 2 - continued

6050.32B

FIGURE 18. AAM PROGRAM SAMPLE SEARCH PLOT

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6050.32B

Appendix 1, Section 2 – continued
FIGURE 19a. AAM PROGRAM SAMPLE RFI.PRT PRINTOUT

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Appendix 1, Section 2 - continued

6050.32B

FIGURE 19b. AAM SAMPLE RFI.PRT PRINTOUT (Continued)

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Appendix 1, Section 2 – continued

11/17/05

FIGURE 20. AAM SAMPLE PLOT OF PREDICTED RFI - HORIZONTAL - KHTN

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Appendix 1, Section 2 - continued

6050.32B

FIGURE 21. AAM SAMPLE PLOT OF PREDICTED RFI - HORIZONTAL - PROP

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Appendix 1, Section 2 – continued
FIGURE 22. AAM SAMPLE PLOT OF PREDICTED RFI - VERTICAL - KHTN

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Appendix 1, Section 2 - continued

6050.32B

FIGURE 23. AAM SAMPLE PLOT OF PREDICTED RFI - VERTICAL - PROP

FIGURES 24. thru 30. RESERVED
20.-24. RESERVED

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Appendix 1 - continued

6050.32B

SECTION 3. ENGINEERING PROCEDURES FOR OBSTRUCTION
EVALUATION (OE) CASES FOR NON-FM BROADCAST
25. STATUS. It is recognized that at the time of this revision of Order 6050.32, a rulemaking was underway
which was expected to substantially change this section, with respect to the facilities to be addressed and the
procedures to be used. However, since the final results of the rulemaking were not known at the time of this
revision, the following procedures are still in effect. Technical Operations ATC Spectrum Engineering Services
will advise the FMOs when the final changes have been made and of the changes related to this section.
26. NON-FM BC STUDY PROCEDURES.
a. The initial step is the CIRCLE REPORT. The search radius varies with the service being investigated.
The radii are:
(1) Cellular telephone - 2 nmi
(2) Land mobile/microwave - 12 nmi
(3) AM Broadcast - 3 nmi
(4) TV Broadcast - 10 nmi
(5) Other - as appropriate for the service
b. After the report has been printed, review it for FAA facilities within the radii shown in subparagraph a.
above. The following are the parameters for concur/non-concur statements.
c. Cellular
(1) If source is greater than 1 nmi, concur.
(2) If source is equal to or less than 1 nmi, check in/out-of-band levels.
(3) If in-band/out-of-band levels are exceeded, proceed per subparagraph i.
d. AM Broadcast
(1) If source is greater than 1 nmi, concur.
(2) If source is equal to or less than 1 nmi, check in/out-of-band levels.
(3) If in-band/out-of-band levels are exceeded, proceed per subparagraph i.
e. TV Broadcast
(1) If source is greater than 10 nmi, concur.
(2) If source is equal to or less than 10 nmi, check in/out-of-band levels.
(3) If in-band/out-of-band levels are exceeded, then:
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Appendix 1, Section 3 – continued

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(a) If VHF-TV, issue a determination of no hazard with conditional statement.
(b) If UHF-TV and the problem cannot be corrected by reducing power, lowering the antenna or
moving the site, then issue a determination of no hazard with conditional statement.
f. Microwave
(1) Not in government band, concur.
(2) In government band, check in/out-of-band levels.
(3) If in-band/out-of-band levels are exceeded, proceed per subparagraph i.
g. Land mobile
(1) If source is greater than 12 nmi, concur
(2) If source is equal to or less than 12 nmi, check in/out-of-band levels
(a) If the out-of-band level is between -4 to -30 dBm, run the INTERMOD program for 118-137 MHz
(COMM receivers) to determine whether there will be IM's which will overlap at the receiver site.
(b) If there is no overlap, concur.
(c) If there is overlap, non-concur.
(d) If the level is ≥ -4 dBm, non-concur.
h. Band levels
(1) In-band spurious level < -104 dBm - concur
(2) In-band spurious level ≥ -104 dBm - concur with comment
(3) Out-of-band radiation level < -4 dBm - concur
(4) Out-of-band radiation level ≥ -4 dBm - non-concur
i. Procedure for AM, cellular and microwave. Refer to Chapter 8, paragraph 807 of this order for detailed
procedures involving AM broadcast and non-broadcast facilities.
27. A NON-FM BC EXAMPLE.
a. The example is a 60 W Land Mobile transmitter on 155.25 MHz to be located about 200' from an FAA
ATCT COMM facility. See sample work sheet figure 31.
(1) The GROUND.WK1 program was run, which produced in-band radiation level of -65.7 dBm and
out-of-band level of -8.6 dBm. This would require a "concur with comment" letter that essentially states FAA
concurrence with the installation provided sufficient spurious suppression is installed to assure a level
< -104 dBm at the FAA band 118-137 MHz. See figure 32.

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Appendix 1, Section 3 - continued

6050.32B

FIGURE 31. SAMPLE NON-FM WORK SHEET

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Appendix 1, Section 3 – continued
32. PARAGRAPH 26 a. (1) EXAMPLE GROUND.WK1 PRINTOUT

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Appendix 1, Section 3 - continued

6050.32B

(2) The -8.6 dBm level was below the -4 dBm maximum level. However, the possibility of -10 dBm and
-30 dBm IM levels overlapping at the site needs to be checked.
(3) The IM program was run. The PROP frequency of 155.25 MHz was added in the edit mode before
it was run. See figure 33 for the configuration.
FIGURE 33. PARAGRAPH 26 a. (3) EXAMPLE OF IM PROGRAM CONFIGURATION

Source
GMF
PND
AM
FM
TV
CAN
GMF
PND
AM
FM
TV
CAN

Type
TX
TX
TX
TX
TX
TX

Invol Cons Radius
nmi
yes yes
12
yes yes
12
yes yes
2
yes yes
30
yes yes
10
no
no
2

Path/Filename
\GMF\
\PND\
\FCC\AM\
\FCC\FM\
\FCC\TV\
\CAN\

(4) In this case, the IM complete report was blank, indicating there were no IMs within the selected
range. See figure 34.
FIGURE 34. PARAGRAPH 26 a. (4) EXAMPLE OF IM PROGRAM PRINTOUT

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Appendix 1, Section 3 – continued

11/17/05

(5) Had there been IMs, the CIRCLE report would have to have been run. An area of one-half mile
radius would need to be checked. If any IM overlaps occurred in this area, a Venn diagram would be required to
determine whether the -10 dBm and -30 dBm contours of the subject sources would overlap the site. In this
unlikely event, a "non-concur" would have to be given.
b. If the exact distance is known, the actual loss can be calculated from the modified free space formula
found in paragraph 10 b., section 1, of this appendix. Using this formula, the actual loss in dB can be determined.
With the PROP EIRP in dBm, the loss can be subtracted and the result in dBm can be compared to the -10 dBm
and the -30 dBm limits for ground receivers. This will quickly determine whether the PROP's two critical
contours would overlap with any other nearby FAA or broadcast critical contours which would predict RFI at the
FAA ground site.

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6050.32B

APPENDIX 2. TECHNICAL DATA FOR VHF/UHF COMMUNICATIONS
FREQUENCY ENGINEERING
FIGURE 1. VHF ALLOCATIONS - 118-137 MHz
118.000—121.400

ATC

122.975—123.000

UNICOM – Uncontrolled Airports

121.425—121.450

Gov AWOS/ASOS

123.025

Helicopter air-to-air

121.475

Band Protection for 121.500

123.050—123.075

UNICOM – Uncontrolled Airports

121.500

Emergency Search and Rescue
(ELT operational Check, 5 Sec.)

123.100

SAR; Temp. ATCTs and fly-ins with
with SAR coordination

121.525

Band Protection for 121.500

123.125—123.275

Flight Test

121.550—121.575

Gov AWOS/ASOS

123.300

Aviation Support

121.600—121.925

ATC (Old Gnd Cntl Freq Band)

123.325—123.475

Flight Test

121.775

SAR ELT Location training

123.500

Aviation Support

121.950

Aviation Support

123.525—123.575

Flight Test

121.975

FSS Private Aircraft Advisory

123.600—123.650

ATC (Formerly Air Carrier Advisory.
FSS Uses to be phased out)

123.675—126.175

ATC

126.200

Military Common (Advisory)

126.225—128.800

ATC

128.825—132.000

Operational Control

132.025—134.075

ATC

134.100

Military Common (Advisory)

134.125—135.825

ATC

135.850

FAA Flight Inspection

135.875—135.925

ATC

135.950

FAA Flight Inspection

135.975—136.400

ATC

136.425—136.475

FIS until 2011

136.500—136.875

Domestic VHF

136.900—136.975

International and Domestic VHF

122.000—122.050

EFAS

122.075—122.675

FSS Private Aircraft Advisory

122.700—122.725

UNICOM - Uncontrolled Airports

122.750

Fixed wing aircraft - Air-to-Air

122.775

Aviation Support

122.800

UNICOM - Uncontrolled Airports

122.825

Domestic VHF

122.850

MULTICOM

122.875

UNICOM - Domestic VHF

122.900

MULTICOM, SAR training

122.925

MULTICOM - Special Use/ National Resp. Mgt.

122.950

UNICOM - full time ATCT, FSS

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6050.32B

Appendix 2 – continued

11/17/05

1. VHF/UHF FREQUENCY ENGINEERING. Frequencies available to the FMO for engineering VHF
assignment are given in figure 1 and UHF ATC frequencies are found in the latest version of the 225-400 MHz
channel plan. VHF is used normally for communication with civil aircraft and a limited number of military
aircraft. UHF is used only for communication with military aircraft. Military non-ATC communications shall not
use VHF ATC frequencies. Military tactical and training (TAC and training) operations and Research, Test,
Development, and Evaluation (RTDE) shall not use UHF ATC frequencies.
a. In en route functions, a VHF and a UHF frequency are normally paired. In addition, a tactical UHF
frequency may be assigned to an en route sector to support military operations.
b. In terminal functions, a VHF and a UHF are paired for only some functions.
2. FPSV.
a. COMM frequencies are engineered for distinct volumes of airspace and are guaranteed to be free from a
preset level of interference from an undesired source. Each specific function has its own FPSV. Some are
cylinders, while others are odd geometric solids. These odd shapes are normally required for en route ATC
functions. All FPSVs are valid only within Radio Line Of Sight (RLOS). Refer to paragraph 4 for details.
b. Cylindrical service volumes (CSV) are defined as radii in nmi usually centered on the facility, with the
maximum altitude of the cylinder defined in feet. These parameters are defined for the various ATC functions in
paragraph 2d, below. A sketch of a cylindrical service volume is shown in figure 2.
c. Tailored or "multipoint" service volumes (TSV) are unique shapes designed to afford necessary
coverage within a designed interference-free protection level. The geometric center of the tailored service is the
center point for the radius that is the distance to the farthest point of the TSV. A sketch of a typical TSV is also
shown in figure 2. The geometric center and radius can be found by using the center point and radius of the
smallest circle that will cover all of the TSV.
FIGURE 2. FPSVs

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Appendix 2 - continued

6050.32B

d. FPSV graphic representations in this manual are drawn for illustrative purposes. They are not drawn to
scale, but rather to a standard of clarity. An example of High Altitude En Route and Local Control to scale and
as normally drawn is shown in figure 3. In addition, all FPSVs are drawn planar and do not include the curvature
of the earth, as also shown in figure 3.
FIGURE 3. HIGH ALTITUDE ENROUTE AND LOCAL CONTROL FPSVs
TO APPROXIMATE SCALE AND AS NORMALLY SHOWN PICTORIALLY

(1) ARTCC. Frequency assignments for ARTCC facilities are located at Remote Control Air/Ground
(RCAG) sites. These RCAGs are connected to the ARTCC by telephone lines, microwave or other radio links.
They are divided into categories of Low Altitude En Route, High Altitude En Route and Super High Altitude En
Route. They normally have tailored or multipoint service volumes, the maximum altitude and radius usually not
exceeding the values shown in figure 4. Under no circumstances will an FPSV be approved with a radius greater
than the RLOS distance.
FIGURE 4. EXAMPLE OF EN ROUTE DIMENSIONS
Service

Altitude (feet)

Radius nmi

>45,000' AMSL

150

High Enroute

45,000' AMSL

150

Low En Route

24,000' AMSL

75

Super High En Route

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6050.32B

Appendix 2 – continued

11/17/05

(2) ATCT. These frequencies are usually found in the tower itself or at an RCF on or near the airport it
serves. The service volumes normally have cylindrical shapes; the radius and flight levels are shown in figure 5.
If there is uncertainty as to an appropriate FPSV for terminal operations, the letter of agreement between the
terminal facility and the center will specify the delegated airspace. FPSVs should not exceed the delegated air
space. Under no circumstances will an FPSV be approved with a radius greater than the RLOS distance.

FIGURE 5. TYPICAL TERMINAL FPSV DIMENSIONS
SERVICE

Ground Control
Clearance Delivery
Local Control

SMALL

TYPICAL

LARGE

--2,500' & 10 nmi

100' & 3 nmi
100' & 3 nmi
5,000' & 15 nmi

--10,000' & 30 nmi

7,500' & 30 nmi
3,000' & 15 nmi
3,000' & 20 nmi
2,500' & 10 nmi

10,000' & 45 nmi
4,000' & 20 nmi
-5,000' & 15 nmi

24,000' & 55 nmi
5,000' & 25 nmi
5,000' & 30 nmi
5,000' & 30 nmi

2,500' & 10 nmi
3,000' & 15 nmi
5,000' & 15 nmi
-Match or slightly exceed Arrival
-100' & 3 nmi

5,000' & 20 nmi
10,000' & 25 nmi
25,000' & 60 nmi
--

Approach/Departure
Arrival
Final
Satellite Airport
Helicopter
GCA/PAR/SFA
(Including pattern)
AWOS/ASOS
ATIS
Departure ATIS

(3) Flight Service Station (FSS). FSS frequencies, including low altitude En Route Flight Advisory
Service (EFAS), are located either at the FSS or at a nearby RCF. High altitude EFAS channels are assigned on
ATC channels. Multiple high altitude EFAS facilities serving the same ARTCC must share a single frequency.
FSS frequencies are protected as much as is possible considering that many sites geographically within RLOS use
the same frequency. This is normally accomplished by separating FSS cochannel assignments by at least 100
nmi, where possible.
e. Noncovered Services. The following VHF aeronautical frequency services are not covered by this
appendix, since all are controlled and authorized by FCC. Refer to FCC Part 87 Rules and Regulations for details
and frequencies.
(1) Aviation Support. Flying schools, soaring, ballooning, etc.
(2) Aeronautical Advisory (UNICOM). Fixed base operators.
(3) MULTICOM. A special use UNICOM.
(4) Flight Test. Manufacturer's use for flight tests of aircraft or equipment.

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Appendix 2 - continued

6050.32B

(5) Operational Control. Airlines' own use.
(6) Search And Rescue. As name implies.
(7) Airport Utility. Non-FAA vehicles on airports.
3. ATC ASSIGNMENT CRITERIA. There are basic criteria for engineering a COMM frequency assignment.
a. Sufficient signal must be provided at the aircraft's receiver to ensure satisfactory performance at a point in
the FPSV furthest from the ground transmitter. ICAO Standards and Recommended Practices (SARPs)
recommends a signal-in-space field strength of 75 µv/m (-109 dBW /m2), which translates to –82.5 dBm,
assuming a 0 dB aircraft antenna gain (ICAO Annex 10, Volume 3, Part 2, Chapter 2). RTCA Minimum
Operational Performance Standards (MOPS) specifies that the input to the aircraft receiver should be 10 µv
(across a 50 ohm impedance), or –87 dBm (RTCA DO-186a). Therefore, approximately 4.5 dB of margin is
provided for the losses between the input to the antenna and the input to the receiver. Such losses include antenna
gains of less than 0 dB and cabling losses between the antenna and the input to the receiver. A series of curves
for VHF and UHF limits of coverage, for a receiver input power of –87 dBm, are found in figures 13 through 24
of this appendix.
b. Protection criteria. ICAO recommends 20 dB desired to undesired (D/U) frequency assignment
protection criteria, but has recognized that in areas with severe frequency assignment congestion, such as the
Continental U.S., a lesser but safe value of 14 dB D/U can be applied. The 14 dB D/U is applicable for all ATC
functions with station class of FA, FAB, FAC and FLU. In addition, a maximum of -4 dBm out-of-band and a
maximum of -104 dBm in-band limit protections are provided from external signals.
c. Transmitter power. Existing policy on transmitter output power is to use 2.5W for AWOS, ASOS and
Automated Remote Radio Access System (ARRAS) operations, and to not exceed 10 W for all other operations.
The need for higher power must be justified in the FMO’s application for frequency approval.
d. ATIS, AWOS and ASOS frequency assignment priorities are described in paragraphs 904 and 905 of
this order.
4. RLOS. In space, radio signals tend to propagate in a straight line. Near large bodies they tend to "bend"
toward the body. In the case of the earth, a sufficiently close approximation of the "effective radio horizon" can
be obtained by using the formula in subparagraph a. below which assumes the earth to be 4/3 its actual radius,
hence the "4/3 radius" phenomenon. The formula approximation assumes a "smooth" earth, since intervening
terrain will stop or attenuate VHF and higher signals.

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6050.32B

Appendix 2 – continued

11/17/05

a. At any given altitude, a transmitted signal will travel only a specific earth distance before it becomes
tangent to the earth's radio horizon. Distances beyond the tangency do not ordinarily receive any VHF or higher
signals, except under anomalous propagation. Treatises on RLOS can be found in engineering manuals, such as
the ITT REFERENCE DATA FOR RADIO ENGINEERS, under radio wave propagation. The formula for RLOS
is:

RLOS ( statute miles ) = 2h
Where: h = height in feet, AMSL.
+++++++++++++++++++++++++++++++++++++

RLOS (nmi) = 0.87 2h = 1.23 h
Where: h = height in feet, AMSL.
b. Where two elevated sites are involved, the formula is:

RLOS (nmi) = 1.23 h1 + 1.23 h2
Where h1 and h2 are respective point altitudes, in feet, AMSL.
c. A sketch of 4/3 earth radius radio coverage is found in figure 6.

FIGURE 6. COMPARISON OF DISTANCE TO HORIZON FROM THE SAME ALTITUDE BETWEEN
ACTUAL AND HYPOTHETICAL 4/3 EARTH RADIUS

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Appendix 2 - continued

6050.32B

5. INTERSITE FREQUENCY ENGINEERING PROCEDURES. These procedures require the
determination that at the worst-case, an aircraft will receive a signal from the desired facility 14 dB stronger than
from a cochannel undesired facility, that is, D/U = 14 dB. (Adjacent channel will be covered later in this
discussion). The determination is based on the free-space loss formula (Lfs):
Lfs (dB) = 37.8 + 20 log f + 20 log d
NOTE: Lfs formula is valid only for distances less than RLOS where:
f = frequency in MHz
d = distance in nmi
a. Note that a signal level only decreases by 6 dB when the distance is doubled, since the signal voltage
(thus current) ratio is only halved at twice the distance (i.e., 20 log (2) = 6dB).
b. Note that the loss constant and the 20 log f variable are fixed when dealing with a cochannel study.
Only the 20 log d varies.
c. Since the 14 dB D/U is determined by the ratio of the distances of undesired to desired sources, dU/dD,
from the critical point, only the 20 log d need be used to determine required separation (see figure 7). The signal
strength D/U is inversely proportional to the distance ratio (DR) from dU to dD. The equation becomes
D/U = 20 log (dU/dD) ≥ 14 dB.
d. The critical point is that point on the edge of the FPSV where an aircraft is simultaneously furthest from
the desired facility and closest to edge of a cochannel or adjacent channel FPSV, where another aircraft would be
the "undesired signal" DU.

FIGURE 7. COCHANNEL CONFIGURATION FOR
UNDESIRED/DESIRED DISTANCE RATIO

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Appendix 2 – continued

11/17/05

e. In figure 7, to achieve a difference of 14 dB at the critical point, the DR, dU/dD, should be 5 or greater or
the antilog of 14 divided by 20.
20 log dU/dD = 14
log dU/dD = 14/20 = 0.7
antilog 0.7 = 5.01
NOTE: When dU is beyond RLOS, protection will be greater than 14 dB.
f. To complete the analysis, the configuration must now be analyzed with the desired and undesired stations
reversed. For the systems to operate properly without interference, both configurations must meet the cochannel
criteria.
6. INTERSITE COCHANNEL ANALYSIS BY THE TABLE METHOD. If only cylindrical standard
FPSVs are considered, the figure 8 may be used to assure the 14 dB D/U ratio.

FIGURE 8. MILEAGE SEPARATION TABLES FOR USUAL FPSVs
FACILITY
TYPE
High Altitude

SERVICE
RADIUS

ACFT TO ACFT
SEPARATION

(Desired)

(Critical Points)

TOTAL
REQUIRED

150

+

525*

675 + R

Approach/Departure 60

+

300

360 + R

Local

30

+

150

180 + R

GCA/PAR/SFA

15

+

75

90 + R

Note: "R" is the service radius in nmi of the competing facility.
* Separation modified by RLOS.

7. ADJACENT CHANNEL CONSIDERATIONS. Adjacent-channel signals 25 kHz away are suppressed
approximately 60 dB by the bandpass characteristics of the 720 channel receiver. A +14 dB D/U ratio is required
on-channel, leaving a net ratio of -46 dB, the value that an adjacent channel signal must not exceed on-channel to
maintain the +14 dB D/U ratio. Empirical tests have shown that between 0.5 and 0.6 nmi separation between the
undesired signal source and the desired critical point will provide this protection. Since aircraft operating in a
difference sector/service may also be separated by 0.5-0.6 nmi in altitude, vertical adjacent channel separation
may also be considered. A conservative vertical separation of 7000' has been included in the automated spectrum
assignment program. The use of vertical adjacent channel separation requires the proper coding of the lower
flight level in high and super high sector assignments. The use of the conservative vertical separation value of
7000' in the model is provided to ensure that adequate adjacent channel separation will be provided while
experience is gained with using vertical adjacent channel separation. Figure 9 graphically illustrates vertical
adjacent channel separation.

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Appendix 2 - continued

6050.32B

a. For en route functions, AT procedures require aircraft to be separated 3 nmi, so that an adjacent-channel
aircraft will never be closer than the minimum distance required.
b. For terminal functions, aircraft can be much closer, so that a small worst-case protection is required.
Any separation greater than 0.6 nmi between edges of adjacent channel FPSVs will provide adequate protection;
see the example in figure 10.
c. 2nd adjacent channel assignments need no consideration in intersite analysis.

FIGURE 9. ADJACENT CHANNEL VERTICAL SEPARATION

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Appendix 2 – continued

11/17/05

FIGURE 10. 1ST ADJACENT CHANNEL SEPARATION REQUIRED

8. INTERSITE COCHANNEL ANALYSIS.
a. To determine the DR of any critical point, first determine if dU is beyond RLOS using the formula in
paragraph 4b. The dU for this RLOS criterion is the shortest distance between the two cochannel FPSVs. If dU is
beyond RLOS, the DR will be greater than 14 dB for both FPSVs. When both cochannel FPSVs are cylindrical
and the transmitters are in the center of the FPSVs, the worst- case DR is where the dU is the shortest distance
between FPSVs and dD is the cylinder radius. The configuration is shown in figure 8 and the calculation of DR is
shown in paragraph 5d, above.
b. When the transmitter is not at the center of the FPSV or the FPSV is tailored and not cylindrical, the
worst-case DR can occur when dU is not a minimum and dD can be the maximum distance between the transmitter
and the perimeter of the FPSV. An example of a calculation for a noncylindrical FPSV is demonstrated in figures
11 and 12. The dU for the worst-case DR for the cylindrical FPSV1 is the minimum distance between FPSVs
which is shown as 226 nmi. The worst-case DR would then be 226 nmi divided by the 30 nmi radius or 7.53.
FPSV1 thus passes the DR criteria as the DR is greater than 5. The dU for the worst case DR for the
noncylindrical FPSV2 occurs where the dU is about 330 nmi. With dD being 65 nmi, the worst case DR for
FPSV2 would be 330 ÷ 65 or 5.08. FPSV2 passes the DR criteria. It is important to consider that all points on a
TSV must be checked when using the DR criteria.
c. In this example, a common channel frequency can be used. If either FPSV1 or FPSV2 fails the DR = 5 or
14 dB criterion, then the same frequency cannot be use for both FPSVs. Since the new facility FPSV2 is not a
cylindrical FPSV, the worst-case situation is not an "in-line" function. The worst-case DR must be determined by
direct map measurement as shown in figure 12. FAA’s automatic A/G computer model does the calculation for
cylinders or equivalent cylinders with off-center transmitter locations. (NOTE: The AFM uses actual TSV points

Page 10

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Appendix 2 - continued

6050.32B

to calculate DR if the TSV option is selected.) An equivalent cylinder to a TSV can be overprotected by the
computer model and should be further checked by direct map measurement if it fails the computer model's DR.

FIGURE 11. COCHANNEL ANALYSIS BY CALCULATION

FIGURE 12. COMPARISON OF D/U AND DISTANCE BETWEEN FACILITIES
WITH ONE TAILORED SERVICE VOLUME

9. COSITE INTERFERENCE CONSIDERATIONS. Cosite interference results from the interaction of
transmitters and receivers in close proximity. Usually this means in the same building, or in adjacent buildings up
to one mile away for 50 watt transmitters and 2,000' away for 10 watt transmitters, but in the case of high power
FM and TV broadcast stations, it can mean several miles away. The appendix contains a discussion of
interference involving commercial broadcast stations.
a. Adjacent sources. In FAA cosite installations, the standard is a minimum separation of 500 kHz for VHF
and 1 MHz for UHF when there is an 8' minimum separation between transmit antennas and an 80 minimum
separation between transmit and receive antennas.
b. Harmonics. These come from two general sources.

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Appendix 2 – continued

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(1) FAA equipment. This is usually the second or third harmonic of VHF transmitters afflicting UHF
receivers. It is generally quite difficult to operate a receiver on a direct harmonic of a transmitter cosite, even with
transmitter band-pass filtering. Direct harmonic operation shall be avoided cosite.
(2) External sources. These can come from a variety of sources, FM and TV aural and video spurious
emissions and harmonics in VHF and UHF, Land Mobile 35-50 MHz spurious emissions and harmonics in VHF,
CB and Amateur in both VHF and UHF. The only ones that can be planned against are the FM and TV
harmonics.
c. Spurious emission. Any frequency put out by a transmitter which is not the fundamental frequency is
spurious. These are normally harmonics, which are easy to plan against, but also there are multiples and odd
multiples of crystal oscillators or synthesizer mixers. Receivers also are subject to local oscillator radiation which
can affect other receivers in the same rack or room. Principally, "image" interference to receivers, reception of a
signal which mixes with the local oscillator to produce the receiver's IF, should be avoided. The FMO should be
familiar with IFs used in receivers in a given site so that direct image reception can be avoided.
d. Intermod. This is the most common source of cosite interference. It results from the mixing of two or
more cosite transmitters which, when added or subtracted from one another in some sequence, produces a
resultant frequency equal to one being received elsewhere at the site. Discussion of intermod calculations will be
found in paragraph 1405a(3)(d) of this order. FAA policy is to not assign frequencies having third order IM
prediction from nearby possible sources..
e. Image interference. Interference can be generated by nearby strong signals which produce the IF by
mixing with the LO in the receiver. This problem normally occurs only with nearby and/or very strong signal
sources. See paragraph 1405a(3)(e) for details.
10. LIMITS OF COVERAGE CHARTS.
a. A sufficient signal level is required at the aircraft anywhere within the FPSV as described in paragraph 3
of this appendix. A major factor in the coverage is the height of the antenna above effective ground and the
roughness of the terrain surrounding the antenna location. Charts showing coverage at the two standard powers of
10 W and 50 W at different antenna heights are shown in figures 13-24.
b. The Brewster Angle is the term applied to the effect of lobing of the theoretical "doughnut" radiation
pattern around a vertical antenna in space. In practice, most FAA RCF antennas are ground planes, and have a
modified radiation pattern just from the plane effect. In addition, there are direct rays from the antenna to the
aircraft and rays which are received as a result of reflection from the ground.
c. Lobing is caused by the difference in phase of the transmitted signal arriving at the receiving point as a
combination of direct rays and reflected rays. Depending on frequency and antenna height above effective
ground, these rays can combine to produce an out-of-phase condition resulting in a very low level of signal, or an
in-phase condition where the signal level is enhanced. These conditions vary with altitude, distance, power,
frequency and ground antenna height above effective ground.
d. The charts shown in figures 13-24 are intended to indicate the volumes of airspace within which a
proposed FPSV or ESV will be provided with the required minimum signal of -87 dBm at the aircraft receiver
(RTCA MOPS, DO-186a; see paragraph 3a above). All areas to the left of the respective curves are expected to
have the minimum required signal level at any azimuth. However, there are definitely inaccuracies in some areas,
particularly at the higher AGL antennas due to a discontinuity of signal levels at some altitudes at some distances.

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Appendix 2 - continued

6050.32B

FIGURE 13. LIMITS OF COVERAGE - VHF - ANTENNA HEIGHT = 10'

Page 13

6050.32B

Appendix 2 – continued

FIGURE 14. LIMITS OF COVERAGE - VHF - ANTENNA HEIGHT = 25'

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Appendix 2 - continued

6050.32B

FIGURE 15. LIMITS OF COVERAGE - VHF - ANTENNA HEIGHT = 50'

Page 15

6050.32B

Appendix 2 – continued

FIGURE 16. LIMITS OF COVERAGE - VHF - ANTENNA HEIGHT = 75'

Page 16

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Appendix 2 - continued

6050.32B

FIGURE 17. LIMITS OF COVERAGE - VHF - ANTENNA HEIGHT = 100'

Page 17

6050.32B

Appendix 2 – continued
FIGURE 18. LIMITS OF COVERAGE - VHF - ANTENNA HEIGHT = 150'

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Appendix 2 - continued

6050.32B

FIGURE 19. LIMITS OF COVERAGE - UHF - ANTENNA HEIGHT = 10'

Page 19

6050.32B

Appendix 2 – continued

FIGURE 20. LIMITS OF COVERAGE - UHF - ANTENNA HEIGHT = 20'

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Appendix 2 - continued

6050.32B

FIGURE 21. LIMITS OF COVERAGE - UHF - ANTENNA HEIGHT = 30'

Page 21

6050.32B

Appendix 2 – continued
FIGURE 22. LIMITS OF COVERAGE - UHF - ANTENNA HEIGHT = 40'

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Appendix 2 - continued

6050.32B

FIGURE 23. LIMITS OF COVERAGE - UHF - ANTENNA HEIGHT 50'

Page 23

6050.32B

Appendix 2 – continued

FIGURE 24. LIMITS OF COVERAGE - UHF - ANTENNA HEIGHT = 75'

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6050.32B

APPENDIX 3. NAVAID FREQUENCY ENGINEERING
DATA AND PROCEDURES
SECTION 1 - FREQUENCY/CHANNELIZATION CHART

FIGURE 1a. CHANNEL AND FREQUENCY PAIRING WITH DME PULSE TIME/CODES

DME AIRBORNE
INTERROGATE
DME
CHN
NO.
1X
1Y
2X
2Y
3X
3Y
4X
4Y
5X
5Y
6X
6Y
7X
7Y
8X
8Y
9X
9Y
10X
10Y
11X
11Y
12X
12Y
13X
13Y
14X
14Y
15X
15Y
16X
16Y
17X
17Y
18X
18Y
19X
19Y
20X
20Y

MLS
-------------FREQUENCY---MHz---------- CHN
LOC
GS
VOR
MLS
NO.
108.10
108.15
108.30
108.35

334.70
334.55
334.10
333.95

108.00
108.05
108.20
108.25
-

5043.0
5031.0
5043.6
5044.2
5031.6
5044.8

540
500
542
544
502
546

DME GROUND
REPLY

NORMAL
DME
FREQ
µs

IA
µs

DME/P
FA
µs

1025
1025
1026
1026
1027
1027
1028
1028
1029
1029
1030
1030
1031
1031
1032
1032
1033
1033
1034
1034
1035
1035
1036
1036
1037
1037
1038
1038
1039
1039
1040
1040
1041
1041
1042
1042
1043
1043
1044
1044

---------------------------------36
12
36
-36
12
36

---------------------------------42
18
42
-42
18
42

12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36

DME
FREQ

PC
µs

962
1088
963
1089
964
1090
965
1091
966
1092
967
1093
968
1094
969
1095
970
1096
971
1097
972
1098
973
1099
974
1100
975
1101
976
1102
977
1103
978
1104
979
1105
980
1106
981
1107

12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30

Page 1

6050.32B

Appendix 3, Section 1 – continued

11/17/05

FIGURE 1b. CHANNEL AND FREQUENCY PAIRING WITH DME PULSE TIME/CODES
(CONTINUED)

DME AIRBORNE
INTERROGATE
DME
CHN
NO.
21X
21Y
22X
22Y
23X
23Y
24X
24Y
25X
25Y
26X
26Y
27X
27Y
28X
28Y
29X
29Y
30X
30Y
31X
31Y
32X
32Y
33X
33Y
34X
34Y
35X
35Y
36X
36Y
37X
37Y
38X
38Y
39X
39Y
40X
40Y

Page 2

MLS
-------------FREQUENCY---MHz---------- CHN
LOC
GS
VOR
MLS
NO.
108.50
108.55
108.70
108.75
108.90
108.95
109.10
109.15
109.30
109.35
109.50
109.55
109.70
109.75
109.90
109.95
110.10
110.15
110.30
110.35

329.90
329.75
330.50
330.35
329.30
329.15
331.40
331.25
332.00
331.85
332.60
332.45
333.20
333.05
333.80
333.65
334.40
334.25
335.00
334.85

108.40
108.45
108.60
108.65
108.80
108.85
109.00
109.05
109.20
109.25
109.40
109.45
109.60
109.65
109.80
109.85
110.00
110.05
110.20
110.25
-

5045.4
5032.2
5046.0
5046.6
5032.8
5047.2
5047.8
5033.4
5048.4
5049.0
5034.0
5049.6
5050.2
5034.6
5050.8
5051.4
5035.2
5052.0
5052.6
5035.8
5053.2
5053.8
5036.4
5054.4
5055.0
5037.0
5055.6
5056.2
5037.6
5056.8

548
504
550
552
506
554
556
508
558
560
510
562
564
512
566
568
514
570
572
516
574
576
518
578
580
520
582
584
522
586

DME GROUND
REPLY

NORMAL
DME
FREQ
µs

IA
µs

DME/P
FA
µs

1045
1045
1046
1046
1047
1047
1048
1048
1049
1049
1050
1050
1051
1051
1052
1052
1053
1053
1054
1054
1055
1055
1056
1056
1057
1057
1058
1058
1059
1059
1060
1060
1061
1061
1062
1062
1063
1063
1064
1064

-36
12
36
-36
12
36
-36
12
36
-36
12
36
-36
12
36
-36
12
36
-36
12
36
-36
12
36
-36
12
36
-36
12
36

-42
18
42
-42
18
42
-42
18
42
-42
18
42
-42
18
42
-42
18
42
-42
18
42
-42
18
42
-42
18
42
-42
18
42

12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36

DME
FREQ

PC
µs

982
1108
983
1109
984
1110
985
1111
986
1112
987
1113
988
1114
989
1115
990
1116
991
1117
992
1118
993
1119
994
1120
995
1121
996
1122
997
1123
998
1124
999
1125
1000
1126
1001
1127

12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30

11/17/05

Appendix 3, Section 1 - continued

6050.32B

FIGURE 1c. CHANNEL AND FREQUENCY PAIRING WITH DME PULSE TIME/CODES
(CONTINUED)

DME AIRBORNE
INTERROGATE
DME
CHN
NO.
41X
41Y
42X
42Y
43X
43Y
44X
44Y
45X
45Y
46X
46Y
47X
47Y
48X
48Y
49X
49Y
50X
50Y
51X
51Y
52X
52Y
53X
53Y
54X
54Y
55X
55Y
56X
56Y
57X
57Y
58X
58Y
59X
59Y
60X
60Y

MLS
-------------FREQUENCY---MHz---------- CHN
LOC
GS
VOR
MLS
NO.
110.50
110.55
110.70
110.75
110.90
110.95
111.10
111.15
111.30
111.35
111.50
111.55
111.70
111.75
111.90
111.95
-

329.60
329.45
330.20
330.05
330.80
330.65
331.70
331.55
332.30
332.15
332.90
332.75
333.50
333.35
331.10
330.95
-

110.40
110.45
110.60
110.65
110.80
110.85
111.00
111.05
111.20
111.25
111.40
111.45
111.60
111.65
111.80
111.85
112.00
112.05
112.10
112.15
112.20
112.25
-

5057.4
5038.2
5058.0
5058.6
5038.8
5059.2
5059.8
5039.4
5060.4
5061.0
5040.0
5061.6
5062.2
5040.6
5062.8
5063.4
5041.2
5064.0
5064.6
5041.8
5065.2
5065.8
5042.4
5066.4
-

588
524
590
592
526
594
596
528
598
600
530
602
604
532
606
608
534
610
612
536
614
616
538
618
-

DME GROUND
REPLY

NORMAL
DME
FREQ
µs

IA
µs

DME/P
FA
µs

1065
1065
1066
1066
1067
1067
1068
1068
1069
1069
1070
1070
1071
1071
1072
1072
1073
1073
1074
1074
1075
1075
1076
1076
1077
1077
1078
1078
1079
1079
1080
1080
1081
1081
1082
1082
1083
1083
1084
1084

-36
12
36
-36
12
36
-36
12
36
-36
12
36
-36
12
36
-36
12
36
-36
12
36
-36
12
36
---------

-42
18
42
-42
18
42
-42
18
42
-42
18
42
-42
18
42
-42
18
42
-42
18
42
-42
18
42
---------

12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36

DME
FREQ

PC
µs

1002
1128
1003
1129
1004
1130
1005
1131
1006
1132
1007
1133
1008
1134
1009
1135
1010
1136
1011
1137
1012
1138
1013
1139
1014
1140
1015
1141
1016
1142
1017
1143
1018
1144
1019
1145
1020
1146
1021
1147

12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30

Page 3

6050.32B

Appendix 3, Section 1 – continued

11/17/05

FIGURE 1d. CHANNEL AND FREQUENCY PAIRING WITH DME PULSE TIME/CODES
(CONTINUED)

DME AIRBORNE
INTERROGATE
DME
CHN
NO.
61X
61Y
62X
62Y
63X
63Y
64X
64Y
65X
65Y
66X
66Y
67X
67Y
68X
68Y
69X
69Y
70X
70Y
71X
71Y
72X
72Y
73X
73Y
74X
74Y
75X
75Y
76X
76Y
77X
77Y
78X
78Y
79X
79Y
80X
80Y

Page 4

MLS
-------------FREQUENCY---MHz---------- CHN
LOC
GS
VOR
MLS
NO.
-

-

112.30
112.35
112.40
112.45
112.50
112.55
112.60
112.65
112.70
112.75
112.80
112.85
112.90
112.95
113.00
113.05
113.10
113.15
113.20
113.25
113.30
113.35

5067.0

620

DME GROUND
REPLY

NORMAL
DME
FREQ
µs

IA
µs

DME/P
FA
µs

1085
1085
1086
1086
1087
1087
1088
1088
1089
1089
1090
1090
1091
1091
1092
1092
1093
1093
1094
1094
1095
1095
1096
1096
1097
1097
1098
1098
1099
1099
1100
1100
1101
1101
1102
1102
1103
1103
1104
1104

---------------------------------------36

---------------------------------------42

12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36

DME
FREQ

PC
µs

1022
1148
1023
1149
1024
1150
1151
1025
1152
1026
1153
1027
1154
1028
1155
1029
1156
1030
1157
1031
1158
1032
1159
1033
1160
1034
1161
1035
1162
1036
1163
1037
1164
1038
1165
1039
1166
1040
1167
1041

12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30

11/17/05

Appendix 3, Section 1 - continued

6050.32B

FIGURE 1e. CHANNEL AND FREQUENCY PAIRING WITH DME PULSE TIME/CODES
(CONTINUED)

DME AIRBORNE
INTERROGATE
DME
CHN
NO.
81X
81Y
82X
82Y
83X
83Y
84X
84Y
85X
85Y
86X
86Y
87X
87Y
88X
88Y
89X
89Y
90X
90Y
91X
91Y
92X
92Y
93X
93Y
94X
94Y
95X
95Y
96X
96Y
97X
97Y
98X
98Y
99X
99Y
100X
100Y

MLS
-------------FREQUENCY---MHz---------- CHN
LOC
GS
VOR
MLS
NO.
-

-

-

-

113.40
113.45
113.50
113.55
113.60
113.65
113.70
113.75
113.80
113.85
113.90
113.95
114.00
114.05
114.10
114.15
114.20
114.25
114.30
114.35
114.40
114.45
114.50
114.55
114.60
114.65
114.70
114.75
114.80
114.85
114.90
114.95
115.00
115.05
115.10
115.15
115.20
115.25
115.30
115.35

5067.6 622
5068.2 624
5068.8 626
5069.4 628
5070.0 630
5070.6 632
5071.2 634
5071.8 636
5072.4 638
5073.0 640
5073.6 642
5074.2 644
5074.8 646
5075.4 648
5076.0 650
5076.6 652
5077.2 654
5077.8 656
5078 4 658
1124
5079.0 660

NORMAL
DME
FREQ
µs
1105
1105
1106
1106
1107
1107
1108
1108
1109
1109
1110
1110
1111
1111
1112
1112
1113
1113
1114
1114
1115
1115
1116
1116
1117
1117
1118
1118
1119
1119
1120
1120
1121
1121
1122
1122
1123
1123
12
-1124

IA
µs

12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36

-36
-36
-36
-36
-36
-36
-36
-36
-36
-36
-36
-36
-36
-36
-36
-36
-36
-36
-36
--

36

36

DME GROUND
REPLY

DME/P
FA
µs
-42
-42
-42
-42
-42
-42
-42
-42
-42
-42
-42
-42
-42
-42
-42
-42
-42
-42
-42
1187
42

DME
FREQ
1168
1042
1169
1043
1170
1044
1171
1045
1172
1046
1173
1047
1174
1048
1175
1049
1176
1050
1177
1051
1178
1052
1179
1053
1180
1054
1181
1055
1182
1056
1183
1057
1184
1058
1185
1059
1186
1060
12
1061

PC
µs
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
30

Page 5

6050.32B

Appendix 3, Section 1 – continued

11/17/05

FIGURE 1f. CHANNEL AND FREQUENCY PAIRING WITH DME PULSE TIME/CODES
(CONTINUED)
DME AIRBORNE
INTERROGATE
DME
CHN
NO.
101X
101Y
102X
102Y
103X
103Y
104X
104Y
105X
105Y
106X
106Y
107X
107Y
108X
108Y
109X
109Y
110X
110Y
111X
111Y
112X
112Y
113X
113Y
114X
114Y
115X
115Y
116X
116Y
117X
117Y
118X
118Y
119X
119Y
120X
120Y
121X
121Y
122X
122Y
123X
123Y
124X
124Y
125X
125Y
126X
126Y

Page 6

MLS
-------------FREQUENCY---MHz---------- CHN
LOC
GS
VOR
MLS
NO.
-

-

115.40
115.45
115.50
115.55
115.60
115.65
115.70
115.75
115.80
115.85
115.90
115.95
116.00
116.05
116.10
116.15
116.20
116.25
116.30
116.35
116.40
116.45
116.50
116.55
116.60
116.65
116.70
116.75
116.80
116.85
116.90
116.95
117.00
117.05
117.10
117.15
117.20
117.25
117.30
117.35
117.40
117.45
117.50
117.55
117.60
117.65
117.70
117.75
117.80
117.85
117.90
117.95

5079.6
5080.2
5080.8
5081.4
5082.0
5082.6
5083.2
5083.8
5084.4
5085.0
5085.6
5086.2
5086.8
5087.4
5088.0
5088.6
5089.2
5089.8
5090.4
-

662
664
666
668
670
672
674
676
678
680
682
684
686
688
690
692
694
696
698
-

DME GROUND
REPLY

NORMAL
DME
FREQ
µs

IA
µs

DME/P
FA
µs

1125
1125
1126
1126
1127
1127
1128
1128
1129
1129
1130
1130
1131
1131
1132
1132
1133
1133
1134
1134
1135
1135
1136
1136
1137
1137
1138
1138
1139
1139
1140
1140
1141
1141
1142
1142
1143
1143
1144
1144
1145
1145
1146
1146
1147
1147
1148
1148
1149
1149
1150
1150

-36
-36
-36
-36
-36
-36
-36
-36
-35
-36
-36
-36
-36
-36
-36
-36
-36
-36
-36
---------------

-42
-42
-42
-42
-42
-42
-42
-42
-42
-42
-42
-42
-42
-42
-42
-42
-42
-42
-42
---------------

12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
35
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36
12
36

DME
FREQ

PC
µs

1188
1062
1189
1063
1190
1064
1191
1065
1192
1066
1193
1067
1194
1068
1195
1069
1196
1070
1197
1071
1198
1072
1199
1073
1200
1074
1201
1075
1202
1076
1203
1077
1204
1078
1205
1079
1206
1080
1207
1081
1208
1082
1209
1083
1210
1084
1211
1085
1212
1086
1213
1087

12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30
12
30

11/17/05

Appendix 3 - continued

6050.32B

SECTION 2. VOR AND DME/TACAN FREQUENCY ENGINEERING
1. FREQUENCY ENGINEERING.
a. Frequency channelization. VOR, Distance Measuring Equipment (DME) and Tactical Air Navigation
equipment (TACAN) frequencies are listed in figure 1. The frequencies 108.00/978 MHz and 108.05/1104 MHz
are specifically designated for radio navigation test generators (ramp testers) and shall not be used for operational
VOR and DME/TACAN facilities.
b. Use of paired channels. The use of paired frequencies as listed in figure 1 requires that stations be
collocated in accordance with one of the following:
(1) Coaxial collocation. VOR and TACAN or DME antennas are located on the same vertical axis.
(2) Offset collocation for:
(a) Standard VOR used in terminal areas for approach procedures, the separation of the VOR antenna
and the associated DME or TACAN antenna shall not exceed 100'.
(b) Doppler VOR used in terminal areas for approach procedures, the separation of the VOR antenna
and the associated DME or TACAN antenna shall not
exceed 260'.
(c) Any non-terminal procedures, where the highest position-fixing accuracy of the system is
required, the antenna separation limits of subparagraphs (a) and (b) apply.
(d) For all other procedures, the separation of a VOR antenna and associated DME or TACAN
antenna shall not exceed 2,000'.
c. FPSV's. The standard circular FPSVs for Terminal (T), Low Altitude (L), and
High Altitude (H) VOR-DME/TACAN are shown in figure 2. [Note: These are referenced to site elevation (i.e.,
FPSV altitudes are in AGL). Adjustments must be made if MSL elevations are needed.]
d. VOR D/U criteria. Harmful interference to VOR facilities is avoided by geographically separating
cochannel and adjacent-channel assignments. Within each FPSV, the D/U ratio shall be at least the following, on
a basis of 95 percent time signal availability.

Cochannel
Channel
_________
+23 dB

1st Adjacent
2nd Adjacent
Channel
(±50 kHz)
(±100 kHz)
_____________ _____________
-4 dB Interim
-31 dB Final

-43 dB

Page 7

6050.32B

Appendix 3, Section 2 – continued

11/17/05

FIGURE 2. FPSVS FOR VOR, DME/TACAN

(1) A D/U ratio of -4 dB is necessary to assure protection of 100 kHz (100 channel) navigation receivers.
This -4 dB D/U ratio is referred to as the interim criterion and shall be used to protect 100 kHz assignments.
(2) A D/U ratio of -31 dB is for 50 kHz (200 channel) navigation receivers. This is referred to as the final
criterion and shall be used for 50 kHz assignments.
(3) All the D/U ratio values include a value of +3 dB to take into account transmitter power degradation
before system shutdown.
e. DME/TACAN D/U criteria. Harmful interference to DME/TACAN facilities is prevented in the same
manner as for VOR's in subparagraph d. The +3 dB factor is included and the values are:

Cochannel

_________

1st Adjacent
Channel
(±1 MHz)
____________

+11 dB

-39 dB

2nd Adjacent
Channel
(±2 MHz)
____________
-47 dB

2. FREQUENCY ENGINEERING PROCEDURES. To ensure that the proposed VOR-DME/TACAN
frequencies would provide interference-free operations within their FPSV's, the following analyses must be
performed on the proposed frequencies:

Page 8

11/17/05

Appendix 3, Section 2 - continued

6050.32B

a. Intersite analysis is used to determine whether the proposed frequencies meet the assignment criteria as
specified in subparagraphs 1d and 1e. There are two analysis methods, table and calculation.
b. In addition, differences in site elevation calculations are necessary.
3. INTERSITE ANALYSIS BY THE TABLE METHOD FOR VOR. Analysis for VOR facilities may be
performed on a proposed VOR frequency through the use of the following tables which show
conservative/worst-case separation distances required, with respect to VOR/VOR and VOR/adjacent channel
LOC:
a. Figure 3 for VOR/VOR cochannel.
b. Figure 4 for VOR/VOR 1st adjacent channel (interim).
c. Figure 5 for VOR/VOR 1st adjacent channel (final).
d. Figure 6 for VOR/VOR 2nd adjacent channel.
e. Figure 7 for VOR/LOC Undesired 1st adjacent (interim).
f. Figure 8 for VOR/LOC Undesired 1st adjacent (final).
g. Geographical separations are not required between VOR stations and between VOR and LOC stations
which differ in frequency by more than 100 kHz. Therefore, there are no tables for 3rd adjacent channel VOR
separations. However, facilities that differ in frequency by 150 kHz or less should not have overlapping FPSVs.
4. INTERSITE ANALYSIS BY THE TABLE METHOD FOR DME/TACAN. DME/TACAN facility
analysis may be performed on a proposed DME/TACAN frequency through the use of the following tables which
show conservative/worst-case separation distances:
a. Figure 9 for DME/TACAN cochannel, TACAN undesired.
b. Figure 10 for DME/TACAN 1st adjacent channel, TACAN undesired.
c. Geographical separations are not required between DME/TACAN facilities separated more than 1
channel (1 MHz). There are no tables for 2nd adjacent DME/TACAN channels.
5. DME/TACAN REQUIRED SEPARATION. In most cases, DME/TACAN facilities, separation is greater
than for the frequency-paired VOR facility, even though the FPSVs for like categories (H, L and T) are equal.
a. For example, look at the VOR and DME/TACAN tables of mileage separations in figures 3 and 9. From
figure 3, it can be seen that two cochannel L-VORs of equal power require 180 nmi separation. From figure 9,
two L-DMEs or L-TACANs of equal power require 204 nmi separation. The same holds true for T-VOR and
T-DME/TACAN.
b. For most power difference levels, the same is true for H-DME/TACAN, but not all.
c. DME/TACAN spaced 63 MHz. Interference may occur between DME/TACAN spaced
63 MHz apart. Reply transmissions from Channel 17Y, for instance, could interfere with interrogation signals
on Channels 80X and 80Y. This can result in receiver desensitization. To preclude this problem, DME/TACAN
ground stations shall not be assigned on frequencies which differ by 63 MHz unless they are separated by at least
15 nmi (28 km).

Page 9

6050.32B

Appendix 3, Section 2 – continued
Channel

Interr. Frequency

17Y
80X
80Y

11/17/05

Reply Frequency

1041 MHz
1104 MHz
1104 MHz

1104 MHz
1167 MHz
1041 MHz

6. USE OF THE LARGER SEPARATION REQUIREMENT. In all cases, the larger requirement shall be
used, whether it be cochannel or adjacent channel. This requires that in each VOR or DME/TACAN frequency
engineering project, a determination must be made as to which has the larger mileage separation requirement, and
that value used for the assignment search. This procedure is mandatory whether both of the facilities or only one
of them is actually installed.
7. PERMISSIBLE USE OF TABLES. If a proposed facility meets all the requirements of all appropriate
tables, the frequency request may be submitted. VOR and DME/TACAN separation are shown in figures 3
through 10.
FIGURE 3. VOR/VOR COCHANNEL SEPARATIONS

FACIL
CLASS
(dB)

Page 10

VOR DESIRED, VOR UNDESIRED
+23 dB PROTECTION
---------------EIRP RATIO---------------+9
+6 +3
±0
-3
-6
-9

H-VOR

370

383

(nmi)
390 395

L-VOR

138

152

167

180

195

206

212

T-VOR

090

100

110

122

134

146

161

398

402

406

11/17/05

Appendix 3, Section 2 - continued

6050.32B

FIGURE 4. VOR/VOR INTERIM 1ST ADJACENT CHANNEL -50 kHz- SEPARATIONS

FACIL
CLASS
(dB)

VOR DESIRED, VOR UNDESIRED
-4 dB PROTECTION
----------------EIRP RATIO---------------+9
+6
+3 ±0
-3
-6

-9

H-VOR

233

248

(nmi)
259 270

284

298

305

L-VOR

70

73

76

80

85

89

93

T-VOR

40

42

44

48

51

55

57

FIGURE 5. VOR/VOR FINAL 1ST ADJACENT CHANNEL -50 kHz- SEPARATIONS

VOR DESIRED, VOR UNDESIRED
FACIL
-31 dB PROTECTION
CLASS
---------------EIRP RATIO---------------(dB)
+9
+6
+3
±0
-3
-6
-9

H-VOR

143

147

(nmi)
152 158

175

184

195

L-VOR

44

47

50

52

54

57

61

T-VOR

32

33

34

35

36

38

39

Page 11

6050.32B

Appendix 3, Section 2 – continued

11/17/05

FIGURE 6. VOR/VOR 2ND ADJACENT CHANNEL -100 KHZ- SEPARATIONS

FACIL
CLASS

VOR DESIRED, LOC UNDESIRED
-31 dB PROTECTION

--------------EIRP RATIO---------------+9
+6
+3
±0
-3
-6
-9
(nmi)
138 140

H-VOR

132

135

L-VOR

43

44

45

T-VOR

25

25

26

143

146

149

46

47

48

50

26

27

28

29

FIGURE 7. VOR/LOC INTERIM 1ST ADJACENT CHANNEL -50 kHz- SEPARATIONS

FACIL
CLASS

VOR DESIRED, LOC UNDESIRED
-4 dB PROTECTION
---------------EIRP RATIO-----------------

Page 12

(dB)

+9

+6

(nmi)
+3
±0

-3

-6

-9

H-VOR

210

225

238

250

263

275

285

L-VOR

64

67

71

73

77

80

86

T-VOR

37

40

42

44

50

51

46

11/17/05

Appendix 3, Section 2 - continued

6050.32B

FIGURE 8. VOR/LOC FINAL 1ST ADJACENT CHANNEL -50 kHz - SEPARATIONS

FACIL
CLASS

VOR DESIRED, LOC UNDESIRED
-31 dB PROTECTION

--------------EIRP RATIO---------------+9
+6
+3
±0
-3
-6
-9

H-VOR

145

148

(nmi)
154 161

168

173

181

L-VOR

46

47

49

50

52

54

57

T-VOR

28

28

29

29

31

31

32

FIGURE 9. DME/TACAN COCHANNEL SEPARATIONS

DME/TACAN DESIRED, DME/TACAN UNDESIRED
+11 dB PROTECTION
EIRP RATIO
D/U DME/TACAN
dB
+21
+18
+15
+12
+9
+6
+3
±0
-3
-6
-9
-12
-15
-18
-21

DISTANCE IN NM
CLASS OF DESIRED FACILITY
H
L
T
220
260
310
339
379
385
388
390
392
394
396
398
401
406
411

60
66
82
102
139
163
192
204
207
210
212
214
216
218
220

40
45
55
65
85
98
120
140
161
164
166
168
172
172
175

Page 13

6050.32B

Appendix 3, Section 2 – continued

11/17/05

FIGURE 10. DME/TACAN 1ST ADJACENT CHANNEL SEPARATIONS

DME/TACAN DESIRED, TACAN UNDESIRED
-39 dB PROTECTION
EIRP RATIO
D/U DME/TACAN
dB
+21 to ±0
-3
-6
-9
-12
-15
-18
-21

DISTANCE IN NMI
CLASS OF DESIRED FACILITY
H
L
T
145
145
148
159
163
175
194
208

45
46
48
48
50
57
63
67

30
30
30
30
30
31
31
32

8. INTERSITE ANALYSIS BY THE CALCULATION METHOD. Intersite analysis may also be
performed by calculating ESR and determining the required geographical separation for that ESR through the use
of appropriate facility separation curves in figures 14-47.
a. ESR is an adjusted D/U ratio due to the differences in carrier power and antenna gain between two
stations. It is defined as follows:
ESR = D/U – PD + PU – AD - + AU
Where: D/U = required D/U ratio - e.g., +23 dB for cochannel VOR;
-4 dB for 1st adjacent channel VOR; +11 dB for
cochannel DME/TACAN, etc.
PD
PU
AD
AU

= carrier power of the desired facility in dBW.
= carrier power of the undesired facility in dBW.
= antenna gain of the desired facility in dB.
= antenna gain of the undesired facility in dB.

b. If both the desired and undesired facilities have the same carrier power and antenna gain, the ESR value
would be +23 dB for cochannel VOR, +11 dB for cochannel DME/TACAN.
c. VOR and DME/TACAN antennas, in most cases, are nondirectional, so the gain is the same in all
horizontal directions. However, different models of antennas have somewhat different gains which have to be
taken into account as shown in subparagraph a. They are:

Page 14

11/17/05

Appendix 3, Section 2 - continued

6050.32B

FIGURE 11. VOR, DME, AND TACAN ANTENNA GAIN FIGURES
Type
VOR

FA-none (Four loop)
FA-none (Doppler)
FA-none (Slot)
FA-none (Dipole Array)

DME

FA 10153
CA3167
FA8974
FA9639
FA9783
FA-none (MK3)
FA-none (1020 Butler)
FA-none (5351A Aerocom)
5960 (Wilcox)
DB-510A (ASII)
DBSystems Inc. (5100A)

TACAN

FA6239/1 or /2 (RTA-2)
FA6339/1 or /2 (Mod RTA-2)
FA6339 (GRN-9 dipole)
FA-none (YN103/4)

Gain dBd
2
2
2
4
8
11
11
11
11
9
9
9
8
8
8
7
9
6
9

d. Using the calculated ESR value and appropriate facility separation curves, the required geographical
separation (S) can be determined. Figures 14 through 20 will be used for VOR cochannel geographical
separations; figures 21 through 29 for adjacent channel VOR separations; figures 30 through 38 for adjacent
channel LOC separations; figures 39 through 45 for DME/TACAN cochannel separations; and figures 46 and 47
for DME/TACAN adjacent channel separations. Figures 48-60 are reserved.
e. (S) is determined as follows:

(S) = dD + dU

Where:

dD = the distance from the desired facility to the critical point where the
intersite analysis is being made, i.e., ESV.
dU = the distance from the critical point to a potential interfering facility.

9. SAMPLE OF COCHANNEL INTERSITE ANALYSIS BY THE CALCULATION METHOD.
Page 15

6050.32B

Appendix 3, Section 2 – continued

11/17/05

FIGURE 12. VORTAC COCHANNEL INTERSITE ANALYSIS PLOT

a. Calculate VOR ESR as follows (see Paragraph 8 a):
ESR = +23 dB - 21.8 + 21.8 - 2 + 2 = +23 dB

b. Use figure 17 (VOR facility separation curves having ESR of +23 dB) to determine (S). The distance dD
is 40 nmi and the altitude (AGL) is 18,000', since the FPSV of the proposed L-VOR is 40 nmi up to 18,000'. Find
the point where the dD and the altitude lines intersect. (S) for that point is 180 nmi. The required separation
between the proposed VOR and the existing VOR is 180 nmi.
c. Calculate DME/TACAN ESR as follows:
ESR = +11 dB - 30 + 30 - 6 + 6 = +11 dB
d. Use figure 42 (DME/TACAN facility separation curves having ESR of +11 dB) to determine the required
(S).
e. Determine the same 40 nmi and 18,000' intersect point. The DME/TACAN separation requirement is
204 nmi, which is the greater of the two, so this is the separation requirement.

Page 16

11/17/05

Appendix 3, Section 2 - continued

6050.32B

10. INTERSITE ANALYSIS OF ADJACENT CHANNELS. This is done in a similar manner,
except a different set of curves is used (see figure 13).
FIGURE 13. VORTAC 2ND ADJACENT CHANNEL INTERSITE ANALYSIS

a. Calculate VOR ESR as follows:
ESR = -43 dB - 21.8 + 21.8 - 2 + 2 = -43 dB.
b. Use figure 21 (VOR/VOR facility separation curve at 1,000') to determine the required geographical
separation. The distance dD is 40 nmi and the ESR is -43 dB. Find the point where the dD and the ESR lines
intersect. (S) for that point is 45 nmi by interpolation. The required geographical separation between the
proposed VOR and the existing VOR on the 2nd adjacent channel is thus 45 nmi. It should be pointed out that the
critical point for the 2nd adjacent channel analysis is 40 nmi at 1,000' (the lower edge of the L-VOR FPSV). For
cochannel analysis, the higher edge of the FPSV, i. e., 18,000' is the critical point.
c. Use figure 46 (DME/TACAN vs. DME/TACAN facility separation curve at 1,000') to determine required
geographical separation. The distance at 40 nmi and 1,000' will be found to be 42 nmi by interpolation. The
lower edge of the FPSV is used as in subparagraph b. The VOR separation requirement is the greater, so it will
be used.

Page 17

6050.32B

Appendix 3, Section 2 – continued

11/17/05

11. DIFFERENCES IN SITE ELEVATION. When VOR facilities differ in site elevations 1000' or more, the
station separation required to protect the station with the higher site elevation must be increased as follows:

H-VOR : 3 nmi for each 1,000' elevation difference
L-VOR : 4 nmi "

"

"

"

"

T-VOR : 7 nmi "

"

"

"

"

12. thru 13. RESERVED.

Page 18

11/17/05

Appendix 3, Section 2 - continued

6050.32B

FIGURE 14. VOR FACILITY SEPARATION CURVES FOR ESR = +14 dB

FIGURE 15. VOR FACILITY SEPARATION CURVES FOR ESR = +17 dB
Page 19

6050.32B

Page 20

Appendix 3, Section 2 – continued

11/17/05

11/17/05

Appendix 3, Section 2 - continued

6050.32B

FIGURE 16. VOR FACILITY SEPARATION CURVES FOR ESR = +20 dB

Page 21

6050.32B

Appendix 3, Section 2 – continued

11/17/05

FIGURE 17. VOR FACILITY SEPARATION CURVES FOR ESR = +23 dB

FIGURE

Page 22

18.

11/17/05

Appendix 3, Section 2 - continued

6050.32B

VOR FACILITY SEPARATION CURVES FOR ESR = +26 dB

FIGURE
VOR

19.

Page 23

6050.32B

Appendix 3, Section 2 – continued
FACILITY SEPARATION CURVES FOR ESR = +29 dB

Page 24

11/17/05

11/17/05

Appendix 3, Section 2 - continued

6050.32B

FIGURE 20. VOR FACILITY SEPARATION CURVES FOR ESR = +32 DB

FIGURE 21. ESR RATIO - VOR/VOR @ 1,000'
Page 25

6050.32B

Appendix 3, Section 2 – continued

FIGUR
E 22. ESR RATIO - VOR/VOR @ 5,000'

Page 26

11/17/05

11/17/05

Appendix 3, Section 2 - continued

6050.32B

FIGURE 23. ESR RATIO - VOR/VOR @ 10,000'

Page 27

6050.32B

Page 28

Appendix 3, Section 2 – continued

11/17/05

11/17/05

Appendix 3, Section 2 - continued

6050.32B

FIGURE 24. ESR RATIO - VOR/VOR @ 15,000'

Page 29

6050.32B

Appendix 3, Section 2 – continued
FIGURE 25. ESR RATIO - VOR/VOR @ 18,000'

FIGURE 26. ESR RATIO - VOR/VOR @ 20,000'

Page 30

11/17/05

11/17/05

Appendix 3, Section 2 - continued

6050.32B

FIGUR
E 27. ESR RATIO - VOR/VOR @ 30,000'

Page 31

6050.32B

Page 32

Appendix 3, Section 2 – continued

11/17/05

11/17/05

Appendix 3, Section 2 - continued

6050.32B

FIGURE 28. ESR RATIO - VOR/VOR @ 40,000'

FIGUR
E 29. ESR RATIO - VOR/VOR @ 50,000'
Page 33

6050.32B

Appendix 3, Section 2 – continued

11/17/05

FIG
URE 30. ESR RATIO - VOR/LOC. VOR IS DESIRED @ 1,000'

Page 34

11/17/05

Appendix 3, Section 2 - continued

6050.32B

FIGURE 31. ESR RATIO - VOR/LOC. VOR IS DESIRED @ 5,000'

Page 35

6050.32B

Page 36

Appendix 3, Section 2 – continued

11/17/05

11/17/05

Appendix 3, Section 2 - continued

6050.32B

FIGURE 32. ESR RATIO - VOR/LOC. VOR IS DESIRED @ 10,000'

FIG
URE 33. ESR RATIO - VOR/LOC. VOR IS DESIRED @ 15,000'
Page 37

6050.32B

Page 38

Appendix 3, Section 2 – continued

11/17/05

11/17/05

Appendix 3, Section 2 - continued

6050.32B

FIGURE 34. ESR RATIO - VOR/LOC. VOR IS DESIRED @ 18,000'

Page 39

6050.32B

Appendix 3, Section 2 – continued

FIGURE 35. ESR RATIO - VOR/LOC. VOR IS DESIRED @ 20,000'

FIGU
RE

Page 40

11/17/05

11/17/05

Appendix 3, Section 2 - continued

6050.32B

36. ESR RATIO - VOR/LOC. VOR IS DESIRED @ 30,000'

Page 41

6050.32B

Appendix 3, Section 2 – continued
FIGURE 37. ESR RATIO - VOR/LOC. VOR IS DESIRED @ 40,000'

Page 42

11/17/05

11/17/05

Appendix 3, Section 2 - continued

6050.32B

FIGURE 38. ESR RATIO - VOR/LOC. VOR IS DESIRED @ 50,000'

Page 43

6050.32B

Appendix 3, Section 2 – continued

11/17/05

FIGURE 39. DME/TACAN FACILITY SEPARATION CURVES FOR ESR = +2 dB

FIGURE

40.
DME/TACAN FACILITY SEPARATION CURVES FOR ESR = +5 dB

Page 44

11/17/05

Appendix 3, Section 2 - continued

6050.32B

FIGURE 41. DME/TACAN FACILITY SEPARATION CURVES FOR ESR = +8 dB

Page 45

6050.32B

Appendix 3, Section 2 – continued

FIGURE

42.
DME/TACAN FACILITY SEPARATION CURVES FOR ESR= +11 dB

Page 46

11/17/05

11/17/05

Appendix 3, Section 2 - continued

6050.32B

FIGURE 43. DME/TACAN FACILITY SEPARATION CURVES FOR ESR = +14 dB

Page 47

6050.32B

Page 48

Appendix 3, Section 2 – continued

11/17/05

11/17/05

Appendix 3, Section 2 - continued

6050.32B

FIGURE 44. DME/TACAN FACILITY SEPARATION CURVES FOR ESR = +17 dB

FIGURE 45. DME/TACAN FACILITY SEPARATION CURVES FOR ESR = +20 dB
Page 49

6050.32B

Page 50

Appendix 3, Section 2 – continued

11/17/05

11/17/05

Appendix 3, Section 2 - continued

6050.32B

FIGURE 46. ESR RATIO - DME/TACAN TO DME/TACAN @ 1,000'

Page 51

6050.32B

Appendix 3, Section 2 – continued

FIGURE 47. ESR RATIO - DME/TACAN TO DME/TACAN @ 18,000'

FIGURES 48. thru 60. RESERVED.

Page 52 (thru 60)

11/17/05

11/17/05

Appendix 3 - continued

6050.32B

SECTION 3. ILS AND DME FREQUENCY ENGINEERING
14.

FREQUENCY ENGINEERING FOR ILS AND DME.

a. ILS and DME frequencies. These frequencies and channels are listed in figure 1, section 1.
The frequencies 108.10/979 MHz and 108.15/1105 MHz are specifically designated for radio navigation
test generators (ramp testers) and shall not be used for operational ILS and DME facilities.
FIGURE 61. LOC FRONT COURSE FPSVS

Page 61

6050.32B

Appendix 3, Section 3 – continued

11/17/05

b. Paired frequencies. Paired frequencies as listed in figure 1 require that DMEs be located on
the airport near the runway for zero range indication or the transponder will be adjusted to
indicate zero range.
c. FPSVs. FPSVs for the various classes of ILS/DME are shown in figures 61 through 64.

FIGURE 62. LOC BACK COURSE FPSVS

Page 62

11/17/05

Appendix 3, Section 3 - continued

6050.32B

FIGURE 63. FPSV FOR ILS GS

FIGURE 64. FPSVS FOR DMES ASSOCIATED WITH ILS

Page 63

6050.32B

Appendix 3, Section 3 – continued

11/17/05

d. ILS D/U criteria. Harmful interference to ILS and associated DME facilities is avoided by geographically
separating cochannel and adjacent channel assignments. Within each FPSV, the D/U ratio shall be at least the
following, on a basis of 95 percent time signal availability. All D/U ratios include the +3 dB factor per Section 2
paragraph 1b(3).
LOC
Cochannel

+23 dB

1st Adjacent
Channel
(±50 kHz)

2nd Adjacent
Channel
(±100 kHz)

-4 dB Interim
-31 dB Final

3rd Adjacent
Channel
(±150 kHz)

-43 dB

-47 dB

(1) A D/U ratio of -4 dB is necessary to assure protection of 100 kHz (100 channel) navigation receivers.
This -4 dB D/U ratio is referred to as the interim criterion and shall be used whenever possible to protect 100 kHz
assignments.
(2) A D/U ratio of -31 dB is for 50 kHz (200 channel) navigation receivers. This is referred to as the final
criterion and shall be used for 50 kHz assignments.
GS
Cochannel

1st Adjacent
Channel
(±150 kHz)

+23 dB

-17 dB

2nd Adjacent
Channel
(±300 kHz)

3rd Adjacent
Channel
(±450 kHz)

-37 dB

-37 dB

e. DME D/U criteria. Harmful interference to DME is prevented in the same manner as for ILS.
DME

Cochannel

+11 dB

1st Adjacent
Channel
(±1 MHz)
-39 dB

2nd Adjacent
Channel
(±2 MHz)
-47 dB

15. FREQUENCY ENGINEERING PROCEDURES. To ensure that the proposed ILS and DME frequencies
will provide interference-free operations within their FPSVs, the following analyses must be performed on the
proposed frequencies:
a. Intersite analysis is used to determine whether the proposed frequencies meet the assignment criteria
specified in paragraphs 14 d. and e. There are two analysis methods — table and calculation.

Page 64

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Appendix 3, Section 3 - continued

6050.32B

b. Cosite analysis is used to avoid interference caused by interaction between the proposed ILS and DME
frequencies and other frequencies, including FM/TV in the vicinity of the proposed site. The cosite analysis
procedures are discussed in the appendix.
c. Other analysis shall be performed as needed, such as correction for site elevation differences.
d. Frequency compatibility with the in-place FM Broadcast environment must be assured. See Section 4 of
this appendix for use of the AAM for this function.
16. INTERSITE ANALYSIS BY THE TABLE METHOD FOR ILS LOCS. Intersite analysis may be
performed on a proposed ILS frequency pair through the use of the tables in figures 66 through 71 which show
conservative-worst-case separation distances required with respect to ILS/ILS and ILS/adjacent channel VOR. In
addition, the nature of the ILS LOC antenna pattern makes the cochannel and adjacent channel circumferences
different. Those diagrams are shown in figure 65.
a. Figure 66 is for LOC/LOC cochannel.
b. Figure 67 is for LOC/LOC 1st adjacent channel (interim).
c. Figure 68 is for LOC/LOC 1st adjacent channel (final).
d. Figure 69 is for LOC/VOR undesired 1st adjacent. channel (interim).
e. Figure 70 is for LOC/VOR undesired 1st adjacent channel (final).
f. Figure 71 is for LOC/VOR undesired 2nd adjacent channel.
g. Site elevation differences require some compensation, for cochannel ILS LOCs. For Standard and Option
B FPSVs, an additional 6.5 nmi must be added to rt for each 1000 of altitude difference. For Options A and C
FPSVs, an additional 7 nmi must be added for r1 and 5.5 nmi for r2, for each 1,000' See figures 65 through 71 for
rt, r1 and r2 values.
h. There are no GS tables, since GS FPSVs are protected by the geographic area covered by the FPSV of
the associated LOC. However, there can be one problem which must be checked. In a few cases, LOC 1st
adjacent channels are not always paired with matched GS frequencies. See channels 18X, 18Y and 38X in figure
1, section 1. The FMO must assure that a proposed "clear" LOC does not have an associated GS frequency only
150 kHz removed from an ILS at the same airport.
i. Note that RLOS is a factor. RLOS for Standard and Option B LOC FPSV is 101 nmi. RLOS for Options
A and C LOC FPSV is 123 nmi.
17. INTERSITE ANALYSIS BY THE TABLE METHOD FOR ILS-DME. ILS-DME intersite analysis may
be performed on a proposed DME frequency through the use of the table in figure 72 for ILS-DME cochannel
which show conservative-worst-case separation distances required and figure 73 for ILS-DME with 1st adj.
channel TACAN/DME undesired. Geographical separations are not required between DME and TACAN
facilities separated more than 1 channel (1 MHz). There are no tables for 2nd adjacent DME/TACAN channels.
18. ILS-DME REQUIRED SEPARATION. ILS-DME facilities required separation is greater than for the
frequency paired LOC facility. This is clearly evident from comparison of the LOC and DME/TACAN tables for
paired frequencies. In addition, any DME associated with an ILS will have a much reduced FPSV, as indicated in
figure 64, as compared to those otherwise operating.
Page 65

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Appendix 3, Section 3 – continued

11/17/05

19. USE OF THE LARGER SEPARATION REQUIREMENT. In all cases, the larger separation requirement
shall be used, whether it be cochannel or adjacent channel. This requires that for each ILS frequency engineering
project, a determination must be made as to whether the LOC or associated DME has the larger separation
requirement.
20. ILS-ASSOCIATED DME ADJACENT CHANNEL UNDESIRED. In this case, the facilities will
ordinarily be regular L-DME or T-DME of the VOR FPSV size. In these cases, the tables listed in paragraph 17
shall be used. As in all other cases, the larger requirement shall always be used whether cochannel or adjacent
channel.

FIGURE 65. LOC SEPARATION DISTANCES DEFINED
(For use with figures 66-71)

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Appendix 3, Section 3 - continued

6050.32B

FIGURE 66. LOC/LOC COCHANNEL RADII SEPARATIONS
LOC DESIRED, LOC UNDESIRED
+23 dB PROTECTION

EIRP RATIO
D/U LOC OPTIONS A & C
dB

r1

+18
+15
+12
+9
+6
+3
±0
-3
-6
-9
12

74
83
93
100
106
110
114
118
122
#
#

STD AND OPTION B

(nmi) r2

r1 (nmi) r2

65
73
82
92
101
105
110
115
121
#
#

47
53
61
69
78
85
90
95
100 100
100 100
*

48
54
61
69
79
86
91
96
*

* = RLOS is 101 nmi for STD and Option B
# = RLOS is 123 nmi for Options A & C

FIGURE 67. LOC/LOC 1ST ADJACENT CHANNEL - 50 kHz - SEPARATIONS -- INTERIM
LOC DESIRED, LOC UNDESIRED
-4 dB PROTECTION
EIRP RATIO
D/U LOC/VOR
dB
+18
+15
+12
+9
+3
±0
-9
-12
-15
-18

OPTIONS
A&C
rt
31
34
37
41
52
57
80
88
97
106

STANDARD &
OPTION B
(nmi)
rt
24
26
28
30
36
40
55
62
68
75

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Appendix 3, Section 3 – continued

11/17/05

FIGURE 68. LOC/LOC 1ST ADJACENT CHANNEL - 50 kHz - SEPARATIONS -- FINAL

LOC DESIRED, LOC UNDESIRED
-31 dB PROTECTION
EIRP RATIO
OPTIONS
STANDARD &
D/U LOC/VOR
A&C
OPTION B
(nmi)
rt
dB
rt
+18
+15
+12
+9
+6
+3
±0
-3
-6
-9
-12
-15
-18

17
18
19
20
22
23
25
27
29
31
33
36
39

16
17
18
18
19
20
21
22
23
25
27
29
31

FIGURE 69. LOC/VOR 1ST ADJACENT CHANNEL - 50 kHz - SEPARATIONS -- INTERIM
LOC DESIRED, VOR UNDESIRED
-4dB PROTECTION
EIRP RATIO
D/U LOC/VOR
dB
+18
+15
+12
+9
+6
+3
±0
-3
-6
-9
-12
-15
# = Beyond RLOS

Page 68

OPTIONS
A&C
rt
35
39
44
49
55
62
70
80
91
103
117
#

STANDARD &
OPTION B
(nmi)
rt
26
28
31
34
38
42
47
53
59
67
79
94

11/17/05

Appendix 3, Section 3 - continued

6050.32B

FIGURE 70. LOC/VOR 1ST ADJACENT CHANNEL - 50 kHz - SEPARATIONS -- FINAL
LOC DESIRED, VOR UNDESIRED
-31 dB PROTECTION
EIRP RATIO
OPTIONS
STANDARD &
D/U LOC/VOR
A&C
OPTION B
dB
rt
(nmi)
rt
+18
+15
+12
+9
+6
+3
±0
-3
-6
-9
-12
-15
-18

23
24
25
26
27
28
29
30
32
35
38
44
49

14
15
16
17
18
19
20
22
24
26
28
31
34

FIGURE 71. LOC/VOR 2nd ADJACENT CHANNEL - 100 kHz - SEPARATIONS
LOC DESIRED, VOR UNDESIRED
-43 dB PROTECTION
EIRP RATIO
D/U LOC/VOR
dB
+18
+15
+12
+9
+6
+3
±0
-3
-6
-9
-12
-15
-18

OPTIONS
A&C
rt
17
18
19
20
21
22
23
24
25
26
28
30
32

STANDARD &
OPTION B
(nmi)
rt
11
12
13
14
15
16
17
18
19
20
21
22
23

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Appendix 3, Section 3 – continued

11/17/05

FIGURE 72. ILS-DME COCHANNEL SEPARATIONS
ILS-DME DESIRED, ILS-DME UNDESIRED
+11 dB PROTECTION
FACILITY
CLASS

SEPARATION
DISTANCE
(nmi)

STD & OPTION B

101

OPTION A & C

123

FIGURE 73. ILS-DME 1ST ADJACENT CHANNEL SEPARATIONS
ILS-DME DESIRED, DME/TACAN UNDESIRED
-39 dB PROTECTION
FACILITY
CLASS

STANDARD AND
ALL OPTIONS

SEPARATION
DISTANCE
(nmi)
H
145

L

T

45

30

Note: DMEs associated with ILS are all terminal
functions of equal power.

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Appendix 3, Section 3 - continued

6050.32B

21. INTERSITE ANALYSIS OF ILS BY CALCULATION METHOD. LOC antennas are highly directional,
and introduce an additional factor into the ESR calculation process. That factor is the gain of the antenna system
with respect to the desired facility.
a. ESR is an adjusted D/U ratio due to the differences in the carrier power and antenna gain between two
stations. It is defined as follows:

ESR= D/U - PD + P U - AD+ AU + GU – GD

Where: D/U = required D/U ratio +23 dB for cochannel LOC;
-4 dB for 1st adjacent channel LOC;
+11 dB for cochannel DME/TACAN
PD = carrier power of the desired facility, dBW
PU = carrier power of the undesired facility, dBW
AD = antenna gain of the desired facility, dBi
AU = antenna gain of the undesired facility, dBi
GD = relative antenna gain (dB) of desired facility,
at point of interest, with respect to the
main beam antenna gain
GU = same for undesired facility
b. Antenna gains (main beam and relative antenna) for individual types of LOC antennas are shown in
figures 74 and 111-130.

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Appendix 3, Section 3 – continued

11/17/05

FIGURE 74. LOC ANTENNA GAINS AND GRAPH REFERENCE

NOMENCLATURE

STYLE

MK20, FA9913

LPD (14-10)
LPD (20-10)

FIGURE
111

FA5692, FA5693, FA5707,
FA5708, FA8001, FA8002,
FA8035, FA8036, FA8038,
FA8621, FA8622, FA8719,
FA8720, FA8843, FA8844.

V RING

12

112

FA9320

TRVLG WAVE (8 EL)

14

113

FA9325

TRVLG WAVE (14 EL)

17

114

FA9358, FA9708, FA9912
MK2, MK12.

LPD 8 EL ARRAY

17

115

FA9358, FA9708, FA9912
MK2, MK12.

LPD 14 EL ARRAY

20

116

FA9759, AN/GRN29, AN/GRN30

LPD

23

117

AN/GRN_27

TRVLG WAVE (14/6)

17

118

AN/GRN_27 (NARROW)

PARABOLIC

17

119

AN/GRN_27 (WIDE)

PARABOLIC

17

120

AN/MRN7

DIPOLE

12

121

REDLICH

LPD (14-10)

26

122

MODIFIED V RING

MOD V RING

12

123

1201

DIPOLE

16

124

1203

LPD

17

125

1204

DIPOLE

14

126

1261

DIPOLE

15

127

STAN37

DIPOLE

12

128

55

TWIN TEE

13

129

STANDARD 14 EL

V-RING

14.6

130

NOTE: LPD = Log Periodic Dipole

Page 72

MAINBEAM
GAIN dB
28
28

11/17/05

Appendix 3, Section 3 - continued

6050.32B

c. Using the calculated ESR value and appropriate facility separation curves, the required (S) can be determined.
Figures 79 through 107 will be used for LOC cochannel separations; figures 108 through 110 for adjacent channel
VORs, ILS desired; figures 111 through 130 for ILS antenna radiation pattern charts; and figures 46 and 47 for
DME/TACAN adjacent channel ESR curves.
d. (S) is defined as (see figure 75):

(S) = dD + dU
Where:

dD = the distance from the desired facility to a critical point where the intersite analysis is
being made.
dU = the distance from that point to a potential interfering facility.
FIGURE 75. CRITICAL POINT SEPARATION DISTANCE

22. SPECIAL CONSIDERATION FOR ILSs ON OPPOSITE ENDS OF A RUNWAY. In some congested
areas, frequencies may not be available for a new ILS requirement. In that case, consideration must be given to
putting the required ILS on the same frequency as the installed one on the opposite end of the runway. If this is
necessary, the following restrictions apply:
a. ILS identification. Each ILS, which includes any COMLOs and DMEs, if installed, must have separate
and distinct identifiers.
b. Interlock requirements. Fail-safe interlock systems must be installed to prevent both ILS and any
ancillary COMLO and DME from being operated simultaneously.
c. NOTAM requirement during ILS maintenance. If radiating a signal during maintenance activities is
necessary, the opposite end ILS shall be NOTAMMED out of service as unusable from the Middle Marker
inward. Of course, the ILS being maintained must also be NOTAMMED out of service during the maintenance
period.

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Appendix 3, Section 3 – continued

11/17/05

FIGURE 76. LOC INTERSITE ANALYSIS BY CALCULATION

23. LOC CALCULATION EXAMPLE. Refer to figure 76. The LOC facility separation, ESR, and LOC
antenna patterns curves are used in these calculations. They are found in figure 36 and figures 79 through 129.
a. The facilities are: A = Option A LOC, 25 nmi @ 6250' on 109.50 MHz, with a standard V-Ring antenna;
B = T-VOR on 109.60 MHz; and New (N) is a proposed new standard LOC, 18 nmi @ 4500' on 109.50 MHz,
also with a V-Ring antenna.
b. The proposed LOC has its main beam pointed directly at the T-VOR site. The FPSV of the T-VOR is 25
nmi at 12,000', and as the larger FPSV, it will be checked first. New is 2nd adjacent channel to B, so
D/U = -43 dB. (Para 14 d.)
ESR = D/U - PD + PU - AD + AU + GU - GD (Para 21)
(1) For B as desired and N as undesired,
ESR = -43 - 22 + 13 -2 + 12 + 0 - 0
= -42 dB
NOTE: With the nondirectional VOR antenna and the LOC pointed at 0°
with respect to the VOR location, both GU and GD are zero. Refer to
figure 30, ESR curves for ILS-VOR @ 1,000 feet; VOR is desired.
By interpolation, a 25 nmi FPSV @ -42 dB requires a separation of
(S) = 27 nmi. The example shows a distance of 65 nmi, so B is protected.

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Appendix 3, Section 3 - continued

6050.32B

(2) For N as desired and B as undesired, with "desired" roles being reversed,
ESR = -43 - 13 + 22 - 12 + 2 + 0 -0
= -44 dB
NOTE: Refer to figure 108. At 18 nmi and -44 dB, (S) = approximately 17 nmi.
Since the actual separation is shown as 65 nmi, that value is >> 17, so N is protected.
(3) For N as desired and A as undesired,
ESR = +23 - 13 + 13 - 12 + 12 + (-7) - (-10)
= +26 dB
NOTE: N’s critical point is 16º off A’s main beam and 35° off its own main beam (see figure 112 for
GU and GD).
(4) Refer to figure 105, ILS/ILS facility separation curves for ESR = +26 dB. By interpolation, 10 nmi
@ 4,500' yields (S) = 55 nmi. At the critical point on N, an aircraft will be 10 nmi from N and
80 NM from A; (S) = 80 + 10 = 90 nmi. The value 90 > 55, so N will be protected.
(5) For A as Desired, and N as Undesired,
ESR = +23 - 13 + 13 - 12 + 12 + (-20) – (-5)
= +23 - 0 - 15 = +8 dB
NOTE: A’s critical point is 133º off N’s main beam and 10º off its own main beam
(fig 112).
(6) Refer to figure 99. For 25 nmi @ 6,250', interpolation will show (S) = 67 nmi.
A’s 25 nmi FPSV plus the 45 nmi separation = 70 nmi. The value 70 > 67; A is protected.
(7) All four conditions of cochannel and adjacent channel are satisfied. Unless there is an adjacent
channel GS frequency problem (see paragraph 16h), the proposed assignment could be considered safe.
(8) However, the assignment may not be made until the paired DM channel is checked.

Page 75

6050.32B

Appendix 3, Section 3 – continued
FIGURE 77. DME AND TACAN ANTENNA GAIN FIGURES
TYPE

D
M
E

T
A
C
A
N

GAIN (dB)

CA3167 (Discone)
11
FA8974
″
11
FA9639
″
11
FA9783
″
11
M3
″
9
596B
″
9
1020
″
9
5351A (Dipole)
10
5960
8
FA 10153
8
DB-510A
8
1118 (ASII)
8
5100 A-D UNIDIRECTIONAL 12 (Fig 131)
510 A BD BIDIRECTIONAL
13 (Fig 132)
FA6239 (TRA-2)
FA6339 (MOD.. TRA-2)
YNI103A or YNI104A
AN/GRN9
GRA047 (Dipole)

7
9
6
9
6

FIGURE 78. DME INTERSITE ANALYSIS BY CALCULATION

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Appendix 3, Section 3 - continued

6050.32B

24. DME Calculation Example. Refer to Figure 78. The DME facility separation, ESR, antenna pattern curves
are used in these calculations. They are found in figures 39 through 47.
a. The facilities are: A= ILS-DME, 18 NM at 4500' on 993.0 MHz with a standard DME antenna;
B= T-VOR/DME on 994.0 MHz with a standard DME antenna; N= a proposed new ILS-DME, 18 NM at 4500'
with a bi-directional DME antenna.
b. The proposed directional DME antenna has its main beam pointed directly at the T-VOR/DME site. The
FPSV of the T-VOR/DME is 25 NM at 12,000 feet, and has the larger FPSV. This will be checked first. N is the
1st adjacent channel to B, so D/U= −39 dB. (Paragraph 14e.)
ESR = D/U − PD + P U − AD + AU + GU − GD (Paragraph 21a)
(1) B is desired and N undesired,
ESR = −39 − 20 + 20 − 8 + 13 − 0 + 0
= −34 dB
NOTE: With the non-directional VOR/DME antenna and the bi-directional DME pointed at 0° with
respect to the VOR/DME location, both GU and GD are zero. Refer to figure 46 ESR curves for
DME/TACAN at 1,000'. The VOR/DME is desired. By interpolation, a 25 NM FPSV at −34 dB
requires a separation of (S) = 27 NM. The example shows a distance of 65 NM, B is protected.
(2) N is desired and A is undesired.
ESR = +11 − 20 +20 − 13 + 8 + 0 − (−6.25)
= +12.25 dB
NOTE: N’s critical point is 35° off its own main beam. Refer to figure 132.
GD is − 6.5 dB off the main beam, GU is 0 dB. Refer to figures 42 and 43 curves
for DME/TACAN at ESR = 12.25 dB. By interpolation, a 10 NM FPSV
at +12.25 dB requires a separation of (S) = 85 NM.
(S) = dD + dU (paragraph 21d)
= 10 + 95
= 105 NM ≥ 85 NM, N is protected
(3) A is desired and N is undesired
ESR = +11 − 20 + 20 − 8 + 13 + (−9.5) − 0
= +6.5 dB
Note: A is 48° off the backside of N’s bi-directional antenna. Refer to figure 132. GU is −9.5 dB off the
rear beam, GD is 0. Refer to figures 40 and 41 curves for DME/TACAN at ESR=+6.5 dB. By
interpolation, an 18 NM FPSV requires a separation of (S) = 92 NM. The example shows a distance of
95 NM, A is protected.

Page 77

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Appendix 3, Section 3 – continued

11/17/05

25. ILS MARKERS. Markers are continuously operating low power transmitters, with antennas radiating
signals in an upward direction in a fan shape. They are to indicate to the pilot flying a course that the aircraft has
passed over a particular point on the ground below.
a. Markers are located at specified distances from the touchdown point on a runway, and are called "Inner",
"Middle", "Outer" and "Back Course" markers (IM, MM, OM and BCM).
b. Each Marker has its own distinctive type identification. The exact identification is:
(1) OM: — — — — — (continuous dashes @ 400 Hz)
(alternating dots and dashes @ 1300 Hz)

(2) MM:

(3) IM: . . . . . . . . . . . . . (continuous dots @ 3000 Hz)
(4) BCM: .. .. .. .. .. .. .. .. (alternating pairs of dots @ 3000 Hz)
c. Marker frequency is 75.000 MHz. It is used for all markers, world-wide. Protection between adjacent
area Markers is provided by the narrow upward antenna radiation pattern. Power and pattern are determined by
Flight Inspection at the time of commissioning of the facility. Normally, the FMO is not required to do any
frequency engineering. Occasionally, parallel runways close together may have the markers tuned offset in
frequency to prevent RFI between the sites.
26. THRU 30. RESERVED.

FIGURE 79. LOC FACILITY SEPARATION CURVES FOR ESR = -52 dB

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Appendix 3, Section 3 - continued

6050.32B

Page 79

6050.32B

Appendix 3, Section 3 – continued
FIGURE 80. LOC FACILITY SEPARATION CURVES FOR ESR = -49 dB

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Appendix 3, Section 3 - continued

6050.32B

FIGURE 81. LOC FACILITY SEPARATION CURVES FOR ESR = -46 dB

Page 81

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Appendix 3, Section 3 – continued
FIGURE 82. LOC FACILITY SEPARATION CURVES FOR ESR = -43 dB

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Appendix 3, Section 3 - continued

6050.32B

FIGURE 83. LOC FACILITY SEPARATION CURVES FOR ESR = -40 dB

Page 83

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Appendix 3, Section 3 – continued
FIGURE 84. LOC FACILITY SEPARATION CURVES FOR ESR = -37 dB

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Appendix 3, Section 3 - continued

6050.32B

FIGURE 85. LOC FACILITY SEPARATION CURVES FOR ESR = -34 dB

Page 85

6050.32B

Appendix 3, Section 3 – continued
FIGURE 86. LOC FACILITY SEPARATION CURVES FOR ESR = -31 dB

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Appendix 3, Section 3 - continued

6050.32B

FIGURE 87. LOC FACILITY SEPARATION CURVES FOR ESR = -28 dB

Page 87

6050.32B

Appendix 3, Section 3 – continued
FIGURE 88. LOC FACILITY SEPARATION CURVES FOR ESR = -25 dB

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Appendix 3, Section 3 - continued

6050.32B

FIGURE 89. LOC FACILITY SEPARATION CURVES FOR ESR = -22 dB

Page 89

6050.32B

Appendix 3, Section 3 – continued

FIGURE 90. LOC FACILITY SEPARATION CURVES FOR ESR = -19 dB

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Appendix 3, Section 3 - continued

6050.32B

FIGURE 91. LOC FACILITY SEPARATION CURVES FOR ESR = -16 dB

Page 91

6050.32B

Appendix 3, Section 3 – continued
FIGURE 92. LOC FACILITY SEPARATION CURVES FOR ESR = -13 dB

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Appendix 3, Section 3 - continued

6050.32B

FIGURE 93. LOC FACILITY SEPARATION CURVES FOR ESR = -10 dB

Page 93

6050.32B

Appendix 3, Section 3 – continued
FIGURE 94. LOC FACILITY SEPARATION CURVES FOR ESR = -7 dB

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Appendix 3, Section 3 - continued

6050.32B

FIGURE 95. LOC FACILITY SEPARATION CURVES FOR ESR = -4 dB

Page 95

6050.32B

Appendix 3, Section 3 – continued
FIGURE 96. LOC FACILITY SEPARATION CURVES FOR ESR = -1 dB

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Appendix 3, Section 3 - continued

6050.32B

FIGURE 97. LOC FACILITY SEPARATION CURVES FOR ESR = +2 dB

Page 97

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Appendix 3, Section 3 – continued
FIGURE 98. LOC FACILITY SEPARATION CURVES FOR ESR = +5 dB

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Appendix 3, Section 3 - continued

6050.32B

FIGURE 99. LOC FACILITY SEPARATION CURVES FOR ESR = +8 dB

Page 99

6050.32B

Appendix 3, Section 3 – continued
FIGURE 100. LOC FACILITY SEPARATION CURVES FOR ESR = +11 dB

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Appendix 3, Section 3 - continued

6050.32B

FIGURE 101. LOC FACILITY SEPARATION CURVES FOR ESR = +14 dB

Page 101

6050.32B

Appendix 3, Section 3 – continued
FIGURE 102. LOC FACILITY SEPARATION CURVES FOR ESR = +17 dB

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Appendix 3, Section 3 - continued

6050.32B

FIGURE 103. LOC FACILITY SEPARATION CURVES FOR ESR = +20 dB

Page 103

6050.32B

Appendix 3, Section 3 – continued
FIGURE 104. LOC FACILITY SEPARATION CURVES FOR ESR = +23 dB

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Appendix 3, Section 3 - continued

6050.32B

FIGURE 105. LOC FACILITY SEPARATION CURVES FOR ESR = +26 dB

Page 105

6050.32B

Appendix 3, Section 3 – continued
FIGURE 106. LOC FACILITY SEPARATION CURVES FOR ESR = +29 dB

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Appendix 3, Section 3 - continued

6050.32B

FIGURE 107. LOC FACILITY SEPARATION CURVES FOR ESR = +32 dB

Page 107

6050.32B

Appendix 3, Section 3 – continued
FIGURE 108. ESR RATIO – LOC/VOR. LOC IS DESIRED FACILITY @ 1,000'

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Appendix 3, Section 3 - continued

6050.32B

FIGURE 109. ESR RATIO – LOC/VOR. LOC IS DESIRED FACILITY @ 4,500'

Page 109

6050.32B

Appendix 3, Section 3 – continued
FIGURE 110. ESR RATIO – LOC/VOR. LOC IS DESIRED FACILITY @ 6,250'

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Appendix 3, Section 3 - continued

6050.32B

FIGURE 111. LOC LPD (14-10) and (20-10) ANTENNA RADIATION PATTERNS

Page 111

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Appendix 3, Section 3 – continued

FIGURE 112. LOC V RING ANTENNA RADIATION PATTERN

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Appendix 3, Section 3 - continued

6050.32B

FIGURE 113. LOC TRVLG WAVE 8 ELEMENT ANTENNA RADIATION PATTERN

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Appendix 3, Section 3 – continued

11/17/05

FIGURE 114. LOC TRVLG WAVE 14 ELEMENT ANTENNA RADIATION PATTERN

Page 114

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Appendix 3, Section 3 - continued

6050.32B

FIGURE 115. LOC LPD 8 ELEMENT ANTENNA RADIATION PATTERN

Page 115

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Appendix 3, Section 3 – continued

FIGURE 116. LOC LPD 14 ELEMENT ANTENNA RADIATION PATTERN

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Appendix 3, Section 3 - continued

6050.32B

FIGURE 117. LOC LPD GRN-29 ANTENNA RADIATION PATTERN

Page 117

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Appendix 3, Section 3 – continued

FIGURE 118. LOC TRVLG WAVE 14/6 ANTENNA RADIATION PATTERN

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Appendix 3, Section 3 - continued

6050.32B

FIGURE 119. LOC PARABOLIC NARROW ANTENNA RADIATION PATTERN

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Appendix 3, Section 3 – continued
FIGURE 120. LOC PARABOLIC WIDE ANTENNA RADIATION PATTERN

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Appendix 3, Section 3 - continued

6050.32B

FIGURE 121. LOC MRN-7 DIPOLE ANTENNA RADIATION PATTERN

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Appendix 3, Section 3 – continued

FIGURE 122. LOC REDLICH LPD (14-10) ANTENNA RADIATION PATTERN

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Appendix 3, Section 3 - continued

6050.32B

FIGURE 123. LOC MODIFIED V RING ANTENNA RADIATION PATTERN

Page 123

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Appendix 3, Section 3 – continued

FIGURE 124. LOC 1201 DIPOLE ANTENNA RADIATION PATTERN

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Appendix 3, Section 3 - continued

6050.32B

FIGURE 125. LOC 1203 DIPOLE ANTENNA RADIATION PATTERN

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Appendix 3, Section 3 – continued
FIGURE 126. LOC 1204 DIPOLE ANTENNA RADIATION PATTERN

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Appendix 3, Section 3 - continued

6050.32B

FIGURE 127. LOC 1261 DIPOLE ANTENNA RADIATION PATTERN

Page 127

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Appendix 3, Section 3 – continued

FIGURE 128. LOC STAN 37 DIPOLE ANTENNA RADIATION PATTERN

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Appendix 3, Section 3 - continued

6050.32B

FIGURE 129. LOC TWIN TEE ANTENNA RADIATION PATTERN

FIGURE 130. STANDARD 14 EL V-RING

Page 129

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Page 130

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Appendix 3, Section 3 - continued

6050.32B

FIGURE 131. DME UNIDIRECTIONAL ANTENNA RADIATION PATTERN

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Appendix 3, Section 3 - continued

FIGURE 132. DME BIDIRECTIONAL ANTENNA RADIATION PATTERN

FIGURES 133. thru 140. RESERVED

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Appendix 3 - continued

6050.32B

SECTION 4. CHECKING AN FAA PROPOSED ILS FREQUENCY
WITH THE AAM
31. ILS FREQUENCY STUDY PROCEDURE.
a. The AAM must be used to determine whether a proposed FAA ILS localizer frequency will be
compatible with the existing FM broadcast environment. This is a case where the FAA must accept the status quo
for any and all FM stations either operating or which have been approved within the OE case process.
b. To start, select an ILS channel for the proposed installation in accordance with Section 3 of this appendix,
then proceed with the steps outline in paragraph 32, below.
32. STEP-BY-STEP STUDY PROCEDURE.
a. Select "NAVAID."
b. Select "Manual Entry."
c. On the next screen;
(1) Select "ILS" under "Navaid Type."
(2) Enter the coordinates of the Localizer.
(3) Enter the Localizer Identifier.
(4) Enter the Localizer Frequency.
(5) Enter the Localizer fron course (under "Rwy Hdg").
(6) Enter the Localizaer Field Elevation.
(7) Select "OK."
d. On the next screen, select "Service Volume Type," and "OK."
e. On the next screen, select "Save" the indicated file name (in which the run data will be stored for future
access).
f. On the next screen, select "Navaid Data."
(1) Enter the runway length.
(2) Select the antenna type from the options presented under "Array Type."
g. Select "RF Sources" at the top of the screen, followed by :
(1) Select proponent status ("PropStatus").

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Appendix 3, Section 4 – continued

11/17/05

(2) Enter all the proponents by selecting "All Non-Proponent > Proponent."
(3) For all hred highlighted FM stations (indicating incomplete record data), enter a "click" in the far
left hand column (resulting in an "x" being entered).
(4) "Click" on "Insert/Delete," and select "Delete Tagged Rows," followed by "OK."
(5) Select "File," followed by "Save, Run Simulation."
(6) Select "Display Results," followed by "Simulation Report" and "OK."
(7) The Run file will be displayed.
(8) To Print out the file, select "File" and then "Print."
h. If the run is clear, the frequency is OK.
i. If there is a problem, plots will be available for printout and analysis. Vertical plots are not needed, since
any problem at any altitude within the FPSV will rule out selecting that frequency for an ILS.
j. To obtain plots, select "Files of Type," and "All plot files."
k. Under "File Name," select (highlight) each file (only one file can be selected at a time) with an FM
station call sign associated with it, click "OK," and the file will be displayed. To print out the report, select "File"
and the "Print." Click "Exit" to return to the "File Name" screen and list to select any remaining files to print out.
33. STUDY RESULTS.
a. If there are no IM points, then the selected frequency is satisfactory, as far as the in-place FM broadcast
environment is concerned. It has been run against all FM stations within the search range, each being used
independently as a proponent.
b. If there is any IM point, then the FM stations making up the IM combination must be studied further to
include the proper antenna type, duplicate applications, etc. If there are still IM points, the frequency is not usable
since the FM stations are in place and FAA cannot ask an FM station to move to accommodate a new ILS
frequency.
c. Sample runs have been made for the lowest and highest assignable ILS localizer frequencies of 108.3 and
110.3 MHz, as shown in figures 142a – 142f. On 108.3 MHz, there are no IM points, but for 110.3 MHz, there is
a small number of IM points, as present in the plots. Note them at the very top corner of the "arrow."
34. thru 40. RESERVED.

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Appendix 3, Section 4 - continued

6050.32B

FIGURE 141a. AAM PRINTOUT PAGE 1

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Appendix 3, Section 4 – continued

FIGURE 141b. AAM PRINTOUT PAGE 2

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Appendix 3, Section 4 - continued

6050.32B

FIGURE 142a. AAM PRINTOUT PAGE 1

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Appendix 3, Section 4 – continued

FIGURE 142b. AAM PRINTOUT PAGE 2

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Appendix 3, Section 4 - continued

6050.32B

FIGURE 142c. AAM PRINTOUT PAGE 3

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Appendix 3, Section 4 – continued

FIGURE 142d. AAM PRINTOUT PAGE 4

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Appendix 3, Section 4 - continued

6050.32B

FIGURE 142e. AAM PRINTOUT PAGE 5

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Appendix 3, Section 4 – continued
FIGURE 142f. AAM PRINTOUT PAGE 6

FIGURES 143. thru 154. RESERVED

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Appendix 3 - continued

6050.32B

SECTION 5. NAVAID RECEIVER TEST FACILITIES FREQUENCY ENGINEERING
41. FREQUENCY ENGINEERING FOR VOT TEST FACILITIES. A VOT is provided to give the pilot an
opportunity to check the aircraft's VOR avionics on the ground before a flight. Frequency protection for VOTs is
not provided in the air.
a. The frequencies used are those found in figure 1, section 1.
b. VOT FPSVs are not specifically described, except for the Area VOT (AVOT), which is described in
subparagraph d.
c. The FPSV is set by flight check inspection at the time of commissioning. The VOT check point is
physically located on the field.
(1) VOT power output may not exceed 2 watts, and may be somewhat less, depending on flight inspection
determination of necessary local airport coverage.
(2) VOT cochannel separation from another VOT is that distance required to assure they are beyond
RLOS to each other.
d. An AVOT is a VOT whose power may exceed 2 watts, and is intended to be received in the air, or if
installed at an elevated site, to cover several airports. Although it emits a special VOT signal which only tests VOR
receivers, it can cause interference to other cochannel and adjacent channel operational facilities. Frequency
engineering is done in the same manner as with any two VOR's and depends on the power and service volumes of
the facilities involved.
42. FREQUENCY ENGINEERING FOR SECONDARY RECEIVER TEST FACILITIES. Other
ground-based receiver test facilities also may radiate low power signals to test NAVAID (VOR, ILS, DME,
DME/P, MLS) systems aboard an aircraft, including the antenna. They are commonly called "test generators" or
"ramp testers" and are located in and operated by Fixed Base Operators or airlines facilities on an airport, and FAA
Flight Inspection facilities. They are restricted as follows:
a. If operated by a non-Federal entity, they must be licensed by FCC.
b. If operated by a Federal agency (including military and FAA), they must be authorized by NTIA.
c. They may operate only on the following frequencies:
(1) 108.00/978, 108.05/1104 MHz for VOR/DME test, 1 W maximum.
(2) 108.10/334.70/979 MHz, for ILS/DME test, 1 W maximum.
(3) 108.15/334.55/1105 MHz, for 50 kHz ILS channel, 100 mW maximum.
(4) 5031.0/979.0 MHz, for MLS/DME/P, 1 W maximum.
d. If interference is received by aircraft in the normal testing area from nearby or strong FM Broadcast
stations, a frequency other than those listed in subparagraph c above may be assigned, upon coordination with
Technical Operations ATC Spectrum Engineering Services.

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Appendix 3, Section 5 – continued

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43. VOT FREQUENCY ENGINEERING BY THE TABLE METHOD. The tables and diagram in figures
155-157 may be used for VOT frequency engineering. If the indicated cochannel mileages are not exceeded, and
the adjacent channels are compliant with paragraph 7 of this appendix, the frequency request may be filed without
further study. Note that the highest power in figures 155 and 157 is 20 dBW (100 W) EIRP. Since there usually is
1.5-2.0 dB loss in cable and connectors, this encompasses VOR's of 150/200 W normal operating power closely.
Differences can be interpolated.

FIGURE 155. COCHANNEL SEPARATION OF VOT AND OPERATING VORs

VOR
--------VOR EIRP-----------CLASS 20 dBW
17 dBW
14 dBW
SEPARATION FROM VOR'S

(nmi)

H

355

375

386

L

150

162

172

T

105

111

120

FIGURE 156. LOC RADII DEFINED, COCHANNEL

(See Figure 157)

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Appendix 3, Section 5 - continued

6050.32B

FIGURE 157. COCHANNEL SEPARATION OF ILS AND ILS-TEST

VOR
CLASS

--------ILS EIRP-----------20 dBW
17 dBW
14 dBW
(nmi)

r1

r2

r1

r2

r1

r2

STD &
OPT B

11 32

13

35

16

38

OPTS
A&C

19 43

22

49

24

54

(See Figure 156)

44. VOT FREQUENCY ENGINEERING BY THE CALCULATION METHOD. The required distance
separation may also be determined by calculation. This is needed when there is a nonstandard FPSV or ESV on the
cochannel operating facility. A graphical sample is shown in figure 158. A nonstandard VOR FPSV of 60 nmi
radius @ 20,000' is assumed. Appropriate facility separation curves will be found in figures 159 through 161.

FIGURE 158. VOR VERSUS COCHANNEL VOT BY CALCULATION

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Appendix 3, Section 5 – continued

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a. Calculate the EIRP of the operating VOR as follows:
VOR output = 100 W
VOR antenna gain
VOR cable and connector losses
VOR ERP

= +20.0 dBW
= +2
dBi
= - 2.5 dB
______________
= +19.5 dBW

b. Use figure 161, the closest separation curve on the high protection side for VOR/VOT.
c. Determine the required separation by interpolation. Since this is a cochannel problem, the highest
altitude of the FPSV will be used. Locating the intersection of the 20,000' altitude line and the 60 NM line,
interpolation will show the required separation to be 190 NM.

45. thru 50. RESERVED

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Appendix 3, Section 5 - continued

6050.32B

FIGURE 159. VOR/VOT COCHANNEL FACILITY SEPARATION CURVES +14 dBW

Page 155

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Appendix 3, Section 5 – continued

11/17/05

FIGURE 160. VOR/VOT COCHANNEL FACILITY SEPARATION CURVES +17 dBW

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Appendix 3, Section 5 – continued

6050.32B

FIGURE 161. VOR/VOT COCHANNEL FACILITY SEPARATION CURVES +20 dBW

FIGURES 162. thru 164. RESERVED.

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Appendix 3 - continued

6050.32B

SECTION 6. ESV FREQUENCY ENGINEERING
51. FREQUENCY ENGINEERING FOR ESV. An ESV is a volume of airspace in addition to the normal
FPSV of a NAVAID, protected from interference from other NAVAID facilities.
a. An ESV merely adds to a standard FPSV. The ESV extends the standard FPSV in a particular direction,
distance, altitude, and shape. Since power availability curves are in altitude AGL, the FMO will need to make an
appropriate adjustment when analyzing ESV suitability because ESVs are designated in altitude MSL.
b. An ESV can be placed on any VOR, ILS-DME or TACAN. When a DME or TACAN and VOR are
paired, BOTH shall have identical ESVs for safety reasons (except in those cases where the DME ESV supports
DME/DME RNAV operations). ESVs may be added to any class of NAVAID facilities, including NDBs.
c. An ESV is frequency engineered just like the parent facility using the same facility separation and ESR
curves.
d. The extension of the coverage distance involves a new dimension, not covered in previous sections of this
appendix. That is the power availability of the facility at the extremity of the ESV. In all standard FPSVs, the
power availability of a standard NAVAID has been assured. However, extending the FPSV substantially can put
the outer most critical point outside the acceptable signal level range. For example, an H-VOR has an FPSV of
130 nmi. If it were requested to protect an ESV at some azimuth out to 165 nmi, the FMO should first check
signal availability before doing the whole study. Obviously, if the standard signal strength is not available at the
critical point, the ESV cannot be used, regardless of the freedom from calculated interference for both cochannel
and adjacent channel. The FMO should ask the proponent to adjust their requirements to meet the available signal
level. If the signal level requirement is marginal, flight inspection can determine the minimum altitude.
52. MINIMUM POWER AVAILABLE REQUIREMENTS. To satisfy defined FAA national standards, the
minimum powers listed in the table in figure 165 must be available at the aircraft antennas for the identified
NAVAIDs. (Note: these minimum power values correspond to the powers which would be obtained from
signals-in-space using isotropic (0 dB gain) receiving antennas.)
FIGURE 165. POWER AVAILABLE REQUIREMENTS FOR NAVAID RECEIVERS
FACILITY

MINIMUM POWER

VOR

-123.0 dBW @ 117.95 MHz

ILS LOCALIZER

-123.0 dBW @ 111.95 MHz

DME & TACAN

(> 18,000’) -114.5 dBW @ 1213.0 MHz
(< 18,000’) -109.0 dBW @ 1213.0 MHz

53. AN EXAMPLE OF POWER AVAILABILITY. The typical geographic (distance vs. altitude) usable
signal coverage for a VOR is shown in figure 166.

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Appendix 3, Section 6 - continued

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FIGURE 166. POWER AVAILABLE - VOR

a. Figure 166 is a composite of VOR power available curves and is for illustrative purposes only.
b. Suppose a proposed ESV asks for 160 nmi @ 18,000' to 25,000'. (Note that this request will be for MSL
altitude.) From figure 165, it will be seen that a -123 dBW level is required. Assume the site at 2,000' elevation.
c. Refer to figure 171, the power available curves for VOR. Trace the 160 nmi line from the bottom of the
graph up to the -123 dBW curve. At that intersection, follow the horizontal line to the left to find that the
minimum altitude to reach the needed power level is 26,000' AGL, or 28,000' MSL. On that basis, the ESV could
not be used below 28,000' MSL, at 160 nmi. The requestor would have to be informed to revise the ESV request
downward in mileage or upward in ESV floor before any further study could be done.
d. Had the ESV been for 160 nmi from 28,000' - 45,000' MSL, it would have met the needs of figure 171.
54. THE INTERRELATIONSHIP OF THE VOR AND DME/TACAN ESV. If a VOR exists and there is an
associated DME/TACAN, they must have identical ESVs for safety reasons (except in those cases where the
DME ESV supports DME/DME RNAV operations). Refer to figure 173. It will be noted that a TACAN cannot
meet a 160 nmi requirement except above 32,000' AGL. Thus any ESV which will be certified as protected must
have the power availability for both collocated facilities as well as frequency protection for both before it can be
approved. In the example of paragraph 53, the lowest permissible VORTAC ESV for 160 nmi would be 32,000',
or some lower minimum altitude at a lesser radial distance.
55. VOR/DME/TACAN ESV DETERMINATION PROCEDURE. Once the power available has been
determined to be satisfactory, the actual calculation to determine protection can begin. The same curves used for
standard FPSV protection are used for ESV determination, so they will not be repeated in this section. Whenever
an ESV is to be calculated, use the ESR curves associated with the facility in Section 3.
a. When an ESV is designed, it is necessary to make the determination at the critical point. That point is
defined as that which is furthest from the desired facility and simultaneously closest to the undesired facility, as
shown in figure 167.

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Appendix 3, Section 6 - continued

6050.32B

FIGURE 167. CRITICAL POINT MEASUREMENT OF AN ESV

b. Refer to figure 168 and figure 17 in Section 2, VOR separation curves for ESR = +23 dB. Following the
60 nmi base line of figure 17 upward to its intersection with the 20,000' line will produce the value of (S) =
235 nmi. With the 60 nmi ESV, that means any cochannel L-VOR or T-VOR must be at least 175 nmi from the
desired critical point. Were the cochannel VOR an H-VOR, the ESV would be automatically protected in that
direction, due to the H-VOR separation requirement of 395 nmi previously required for the two to be cochannel at
standard FPSVs.
FIGURE 168. EXAMPLE OF VOR ESV BY CALCULATION

c. If a DME or TACAN were collocated, the DME/TACAN separation requirement would have to be
determined in the same manner. Refer to figure 42, Section 2, DME/TACAN separation curves for ESR = +11
dB. Follow the same procedure as subparagraph a. By interpolation, (S) = 235 nmi.

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Appendix 3, Section 6 - continued

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d. To meet the ESV protection required in figure168, it would be necessary that the nearest cochannel
VOR/DME be at least 175 nmi away from the critical point. As in subparagraph a, if the nearest cochannel is an
H-VOR/DME, the requirement of 395 nmi (S) would more than protect the example ESV.
e. Adjacent channel determination is made exactly the same way that a VOR/DME/TACAN FPSV is
frequency engineered. Using the values of Section 2, paragraph 1e, the appropriate ESR curves are used to
determine the required distance from the critical point on the ESV to the nearest adjacent channel, for both VOR
and DME/TACAN.
56. ILS-DME ESV DETERMINATION PROCEDURE. An ESV on an ILS is handled the same way as the
VOR in paragraph 55 using the appropriate ESR curves and the LOC antenna radiation patterns.
As indicated in section 3, the DME function nearly always requires a greater geographical separation than its
associated ILS. Therefore, the FMO should check the DME requirements first. If the DME ESV fits, the ILS
ESV will nearly always fit easily.
57. ESV SPECIAL CONSIDERATIONS.
a. ESV operational radials and areas have a definite tolerance to maintain.
(1) Radials
(a) VOR/DME/TACAN ±4.5°.
(b) ILS ±10°.
(c) NDB ±10°.
(2) Wedge areas
(a) VOR/DME/TACAN — add 4.5° in both directions.
(b) NDB — add 10° in both directions.
(3) Holding patterns (HP) are described by an arc enclosing two radials, e.g., 306°-322°, 83 nmi, and
shall enclose the HP.
b. When the FMO receives a request via the ESV Management System (ESVMS) to establish, revise or
cancel and ESV, the FMO shall engineer each ESV and approve the proposed request, if appropriate, via the
ESVMS. As a result of an approval, the Flight Inspection Office will conduct a flight check of the ESV. The
results of this action will be communicated to Technical Operations ATC Spectrum Engineering Services (via the
ESVMS) for final review and approval. Technical Operations ATC Spectrum Engineering Services will enter the
approval into the ESVMS, which subsequently generates an input into the AFM national data base and a
notification of the action taken back to the FMO.
c. FMO’s shall review each ESV in their service areas on a yearly basis to confirm the accuracy of the
national ESV data base.

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Appendix 3, Section 6 - continued

6050.32B

FIGURE 169. SAMPLE ESV RECORD FORMAT

58. thru 62. RESERVED

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Appendix 3, Section 6 - continued

FIGURE 170. POWER AVAILABLE CURVES - 100 W - VOR 0-50 NMI

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Appendix 3, Section 6 - continued

6050.32B

FIGURE 171. POWER AVAILABLE CURVES - 100 W - VOR 0-220 NMI

Page 171

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Appendix 3, Section 6 - continued

11/17/05

FIGURE 172. POWER AVAILABLE CURVES - 5 KW - TACAN 0-50 NMI

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Appendix 3, Section 6 - continued

6050.32B

FIGURE 173. POWER AVAILABLE CURVES - 5 KW - TACAN 0-220 NMI

Page 173

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Appendix 3, Section 6 - continued

11/17/05

FIGURE 174. POWER AVAILABLE CURVES - 100 W -CARDION DME 0-50 NMI

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Appendix 3, Section 6 - continued

6050.32B

FIGURE 175. POWER AVAILABLE CURVES - 100 W - CARDION DME 0-220 NMI

Page 175

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Appendix 3, Section 6 - continued

11/17/05

FIGURE 176. POWER AVAILABLE CURVES - 100 W - MONTEK DME 0-50 NMI

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Appendix 3, Section 6 - continued

6050.32B

FIGURE 177. POWER AVAILABLE CURVES - 100W - MONTEK DME 0-220 NMI

Page 177

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Appendix 3, Section 6 - continued

11/17/05

FIGURE 178. POWER AVAILABLE CURVES - 1 KW - CARDION DME 0-50 NMI

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Appendix 3, Section 6 - continued

6050.32B

FIGURE 179. POWER AVAILABLE CURVES - 1 KW - CARDION DME 0-220 NMI

Page 179

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Appendix 3, Section 6 - continued

11/17/05

FIGURE 180. POWER AVAILABLE CURVES - 1 KW - MONTEK DME 0-50 NMI

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Appendix 3, Section 6 - continued

6050.32B

FIGURE 181. POWER AVAILABLE CURVES - 1 KW - MONTEK DME 0-220 NMI

Page 181

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Appendix 3, Section 6 - continued

11/17/05

FIGURE 182. POWER AVAILABLE CURVES - 100W - FA10153 DME 0-50 NMI

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Appendix 3, Section 6 - continued

6050.32B

FIGURE 183. POWER AVAILABLE CURVES - 100W - FA10153 DME 0-220 NMI

Page 183

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Appendix 3, Section 6 - continued

11/17/05

FIGURE 184. POWER AVAILABLE CURVES - 100W - dBS5100A DME 0-50 NMI

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Appendix 3, Section 6 - continued

6050.32B

FIGURE 185. POWER AVAILABLE CURVES - 100W - dBS5100A DME 0-220 NMI

FIGURE 186 RESERVED

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Appendix 3 - continued

6050.32B

SECTION 7. MLS AND DME/P FREQUENCY ENGINEERING
63. FREQUENCY ENGINEERING FOR MLS AND DME/P.
a. MLS and associated DME/P frequencies are listed in Section 1, figure 1.
b. Use of a paired channel as listed in figure 1 requires that DME/Ps be collocated with the MLS antennas,
which means within 100' of the antenna.
c. FPSVs for MLS and DME/P are as shown in figures 187-190.
FIGURE 187. FPSV FOR MLS APPROACH AZIMUTH/DATA COVERAGE

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Appendix 3, Section 7 – continued
FIGURE 188. FPSV FOR MLS APPROACH ELEVATION COVERAGE

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Appendix 3, Section 7 - continued

6050.32B

FIGURE 189. FPSV FOR MLS BACK AZIMUTH/DATA COVERAGE

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Appendix 3, Section 7 – continued

FIGURE 190. FPSV FOR MLS DME/P

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Appendix 3, Section 7 - continued

6050.32B

d. The MLS approach azimuth and elevation horizontal service volumes are conical segments, 80' wide
with a complex vertical service volume. Figure 191 shows the D/U values.
FIGURE 191. INTERIM MLS COCHANNEL AND ADJ. CHANNEL
SEPARATION D/U VALUES

COCHANNEL

+26.5 dB D/U

1ST ADJ. CHANNEL

-19 dB D/U

2ND ADJ. CHANNEL

-23.5 dB D/U

e. Harmful interference to DME/Ps associated with MLS is prevented by geographically separating
cochannel and adjacent-channel assignments. Within each FPSV, the DME/P D/U ratio shall be at least the
values shown in figure 192, on a basis of 95 percent availability.

FIGURE 192. DME/P COCHANNEL AND ADJACENT CHANNEL
SEPARATION D/U VALUES

Cochannel @ 22 nmi
Same Pulse Code
Different Pulse Code

+9.5 dB
-40.5 dB

1st Adjacent Channel @ 22 nmi
Same Pulse Code
Different Pulse Code

-40.5 dB
-73.5 dB

2nd Adjacent Channel @ 7 nmi
Same Pulse Code
Different Pulse Code

-73.5 dB
-73.5 dB

NOTES:
All D/U ratios include the +1.5 dB factor for transmitter power
variation.
Cochannel and 1st adj. channel D/U values are for the protection
of a 22 nmi radius.
2nd adjacent channel D/U values are for the protection
of a 7 nmi radius.

Page 201

6050.32B

Appendix 3, Section 7 – continued

11/17/05

64. FREQUENCY ENGINEERING PROCEDURES. To ensure that the proposed MLS-DME/P frequencies
would provide interference-free operations within their FPSVs, the following analysis must be performed on the
proposed frequencies. Intersite analysis is used to determine whether the proposed frequencies meet the
assignment criteria as specified in paragraph 63 d. There are two analysis methods, table and calculation.

65. MLS INTERSITE ANALYSIS BY TABLE METHOD. Intersite analysis may be performed on a proposed
MLS frequency through the use of the tables shown in figure 192, which shows conservative-worst-case
separation distances. Figure 193 is for MLS/MLS cochannel and adjacent channel. Adjacent channel criteria
require a minimum of 1.2 MHz separation for MLS sites at the same airport.

FIGURE 193. INTERIM MLS COCHANNEL SEPARATION DISTANCE

MLS DESIRED, MLS UNDESIRED.
FACILITY CLASS

Page 202

+26.5 dB PROTECTION
SEPARATION (NMI)

MLS

205

1st Adjacent Channel

32

2nd Adjacent Channel

32

11/17/05

Appendix 3, Section 7 - continued

6050.32B

66. DME/P INTERSITE ANALYSIS BY TABLE METHOD. Intersite analysis may be performed on a
proposed DME/P frequency through the use of the table shown in figure 194 which shows the
conservative-worst-case separation distance.

FIGURE 194. MLS DME/P ASSIGNMENT CRITERIA

DME/P

VS.

DME/P
(nmi)

T-DME
nmi)

L-DME
(nmi)

H-DME
(nmi)

COCHANNEL

SAME CODE
DIFFERENT CODE

205*
50

205
50

205
170

400
170

1ST ADJ. CHNL

SAME CODE
DIFFERENT CODE

25
25

30
30

45
45

145
145

2ND ADJ. CHNL SAME CODE
DIFFERENT CODE

8
8

9
9

12
12

14
14

*RLOS to protect MLS angle receiver at 20,000Ν.
Pulse loading criteria:

Maximum 3 DME, DME/P or TACAN sites
within 50 nmi radius and within ±3 MHz.

Ground receiver protection: ±63 MHz minimum 15 nmi separation.

67. thru 70. RESERVED

FIGURES 195 thru 200 RESERVED.

Page 203 (thru 210)

11/17/05

Appendix 3 - continued

6050.32B

SECTION 8. LOCAL AREA AUGMENTATION SYSTEM FREQUENCY ENGINEERING
71. FREQUENCY ENGINEERING.
a. Frequencies. The Local Area Augmentation System (LAAS) is planned to operate on center frequencies
from 112.050 to 117.950 MHz. However, the last upper assignable LAAS channel will be center on 117.150 MHz
to protect adjacent air/ground voice communications operations. The international ICAO standard Ground Based
Augmentation System (GBAS) is planned to operate on center frequencies from 108.000 to 117.950 MHz.
b. Channeling Plan. While the LAAS equipment is capable of operating with 25 kHz frequency assignments,
the LAAS channel plan will only use 50 kHz frequency assignments until otherwise changed. Thus, with the
present channel plan, the first adjacent channel is at 50 kHz.
(1) Time Slots. The modulation format used by the LAAS is D8PSK. This has eight separate time slots.
One transmitter will use two time slots allowing the additional time slots to be assigned on the same channel.
(2) Coverage. More than one LAAS transmitter may be required at a specific location to provide the
required coverage.
(3) A/G Communications. The highest LAAS transmitter frequency to be assigned is 117.15 MHz. This
limits the LAAS ground transmitter to 400 feet or greater to an A/G communications facility.
(4) FM Broadcast Immunity. The LAAS receivers conform to the ICAO
Annex 10 1998 Immunity criteria.
c. FPSVs. The standard FPSV is a 23 NM cylinder up to 10,000 feet with the option for 20,000 feet coverage.
[Note: These are referenced to site elevation (i.e., FPSV altitudes are in AGL). Adjustments must be made if MSL
elevations are needed.]
d. LAAS D/U criteria. Harmful interference to LAAS facilities is avoided by geographically separating cochannel and adjacent channel VOR/LAAS/ILS assignments. Within each FPSV, the D/U ratio shall be at least the
following, on a basis of 95 percent time signal availability.
FIGURE 201. LAAS/LAAS/VOR SEPARATION CRITERIA
Co-Channel D/U
LAAS/LAAS
LAAS/VOR

+26 dB
+26 dB

1st Adjacent (50 kHz)
LAAS/LAAS
LAAS/VOR

−46 dB
−4 dB (Interim)
−34 dB (Final)

Page 211

6050.32B

Appendix 3, Section 8 – continued

11/17/05

(1) D/U ratio of −4 dB. The −4 dB D/U ratio is referred to as the interim criterion and shall be used
whenever possible to protect 100 kHz assignments (100 channel receivers).
(2) D/U ratio of −34 dB. The −34 dB is referred to as the final criterion and shall be used for 50 kHz
assignments (200 channel receivers).
(3) All the D/U ratio values. The D/U value includes a +3 dB to take into account transmitter power
degradation before system shutdown.
72. FREQUENCY ENGINEERING PROCEDURES. To ensure that the proposed LAAS frequencies would
provide interference-free operations within their FPSVs, the following analyses must be performed on the proposed
frequencies:
a. Intersite analysis is used to determine whether the proposed frequencies meet the assignment criteria as
specified in subparagraph 71d. There are two analysis methods, table and calculation. The calculation method will
be used in a manner similar to that used for VOR analysis.
b. The LAAS antenna polarization is elliptical. The total ERP is 70 W, with 50 W Horizontal and 20 W
Vertical.
73. INTERSITE ANALYSIS BY THE TABLE METHOD FOR LAAS. Analysis for LAAS facilities may be
performed on a proposed LAAS frequency through the use of the following tables that show separation distances
required, with respect to LAAS/LAAS and LAAS/VOR:
a. Figure 202 for LAAS/LAAS co-channel.
b. Figure 203 for VOR/LAAS 2nd adjacent channel (interim).
c. Figure 204 for VOR/LAAS 2nd adjacent channel (final).
d. Geographical separations are not required between LAAS facilities which differ in frequency by more
than 25 kHz. LAAS/VOR separations that differ in frequency by 150 kHz or less should not have overlapping
FPSVs.

FIGURE 202. LAAS/LAAS CO-CHANEL SEPARATIONS

Page 212

10,000 FT

159 NM

20,000 FT

206 NM

11/17/05

Appendix 3, Section 8 - continued

6050.32B

FIGURE 203. LAAS/VOR INTERIM 1st ADJACENT CHANNEL 50 kHz SEPARATIONS

VOR DESIRED, LAAS UNDESIRED
-4 dB PROTECTION
H-VOR

250 NM

L-VOR

75 NM

T-VOR

40 NM

FIGURE 204. LAAS/VOR FINAL 1st ADJACENT CHANNEL 50 kHz SEPARATIONS

VOR DESIRED, LAAS UNDESIRED
−34 dB PROTECTION

H-VOR

187 NM

L-VOR

56 NM

T-VOR

35 NM

Page 213 (thru 214)

11/17/05

6050.32B

APPENDIX 4. TECHNICAL DATA FOR VHF/UHF LINKS

FIGURE 1. TECHNICAL PARAMETERS, ATT FR8 RCL

Frequency range
RF output power

7125-8400 MHz
Low
High

0 dBw, 1 W, 30 dBm
5 dBw, 3 W, 35 dBm

Emission
Power Amplifier Output

M20F9
1.6 W, 32 dBm
5.0 W, 37 dBm

Transmitter freq. stability

±0.0005 percent

Receiver RF bandpass

-3 dB @ 52 MHz
-30 dB @ 86 MHz
-60 dB @ 134 MHz

Receiver IF bandpass

-3 dB @ 44 MHz
-20 dB @ 56 MHz

Receiver IF frequency

70 MHz

Receiver noise figure

< 6 dB

Receiver threshold

-77 dBm, -118 dBW

Image rejection

> 90 dB

Page 1

6050.32B

Appendix 4 – continued

FIGURE 2. FR8 INTERFERENCE SUSCEPTIBILITY CURVES

Page 2

11/17/05

11/17/05

Appendix 4 - continued

6050.32B

FIGURE 3. TECHNICAL PARAMETERS, TML

Frequency range

14.40 - 15.25 GHz

RF output power

150 mW (-8.2 dBW)

Emission

27M0F9W

Spectral purity

3 dB @ 18 MHz
20 dB @ 40 MHz
0 dB @ 135 MHz

Transmitter freq. stab.

±0.005%

Receiver RF bandwidth

-3 dB @ 45 MHz
-20 dB @ 80 MHz
-60 dB @ 270 MHz

Receiver IF bandwidth

-3 dB @ 44 MHz
-20 dB @ 60 MHz
-60 dB @ 120 MHz
Receiver IF frequency

70 MHz
Receiver noise figure

10.5 dB

Receiver tangential sensitivity -117 dB
Image rejection

60 dB

NOTE: RF and IF bandwidth may vary
20-55 MHz, depending on equipment used.
Associated antennas
Parabolic Reflector
(Diameter in feet)

4'

-3 dB beamwidth

1.4Ε H x 1.4Ε V

Gain

42.5 dBi

Max. sidelobe gain
Polarization

-15.0 dB
H or V

Page 3

6050.32B

Appendix 4 – continued

FIGURE 4. TML INTERFERENCE SUSCEPTIBILITY CURVES

Page 4

11/17/05

11/17/05

Appendix 4 - continued

6050.32B

FIGURE 5. FAA LOW DENSITY RCL PATH DESIGN CRITERIA

RADIO TYPE

XMT POWER
(dBm)

RCV THRESHOLD
(dBm)

NOTES

9xx MHz UHF 12 CH
UHF Hi-Pwr Option

+37
+45

-87

2

DIG 1.8 GHz 1-DS1
DIG 1.8 GHz 8-DS1
DIG 1.8 GHz Hi-Pwr

+30
+30
+35

-78.5
-75.5

1,2
1,2

DIG 23 GHz 8-DS-1
DIG 23 GHz Hi-Pwr

+16.8
+21.2

-74.5

1,2

Notes:
1 - Receiver threshold at 10-6 BER.
2 - Receiver threshold includes 3:3 hot standby loss.
DS1 - 1.544 Mbit/sec North American rate
BER = Bit Error Rate

Page 5

6050.32B

Appendix 4 – continued

11/17/05

FIGURE 6. MDR 6XO8 SPECIFICATIONS

TRANSMIT POWER AT ANTENNA PORT
MDR 6X08
MDR 6X08

Standard Power
Low Power

28 dBm
15 dBm

7125-8500 MHz
Frequency Range
------------------------------------------------------------------------------------------INTERFERENCE SPECIFICATION IN dB

Threshold/Interference, Cochannel
Threshold/Interference, Adjacent Channel
Carrier/Interference(C/I in dB), BER = 10-3
Carrier/Interference(C/I in dB), BER = 10-6

MDR-6508
28
-8
17
20

MDR-6708
34
-8
23
26

-----------------------------------------------------------------------------------------------------------------------------------MINIMUM CHANNEL SEPARATION (MHz)
Transmit-to-transmit
Transmit-to-transmit
Transmit-to-receive
Transmit-to-receive
Transmit-to-receive

Transmitters on same antenna, same polarization
Transmitter on different antennas
Transmitter and Receiver on same antenna, same polarization
Transmitter and Receiver on same antenna, different polarization
Transmitter and Receiver on different antennas

46 MHz
30 MHz
115 MHz
95 MHz
30 MHz

-----------------------------------------------------------------------------------------------------------------------------------RADIO TYPE

CAPACITY
DS1

Page 6

B/W
(MHz)

RX THRESHOLD
(dBm)
-3

BER=10

-6

DISPERSIVE FADE
MARGIN (dB)
-3

BER=10

BER=10

-6

BER=10

MDR-6508-2
MDR-6508-4
MDR-6508-8
MDR-6508-12
MDR-6508-16

2
8
8
12
16

1.25
2.50
3.75
5.50
7.50

-89
-86
-83
-81
-80

-87
-84
-81
-79
-78

80
76
67
64
62

78
74
65
62
60

MDR-6708-2
MDR-6708-4
MDR-6708-8
MDR-6708-12
MDR-6708-16

2
4
8
12
16

0.80
1.25
2.50
3.75
5.00

-85
-82
-79
-77
-76

-83
-80
-77
-75
-74

83
79
70
67
65

81
77
68
65
63

11/17/05

Appendix 4 - continued

6050.32B

FIGURE 7. NOMOGRAPH FOR FREE SPACE PROPAGATION LOSS

Page 7

6050.32B

Appendix 4 – continued

FIGURE 8. NOMOGRAPH FOR PARABOLIC ANTENNA GAIN

Page 8

11/17/05

11/17/05

Appendix 4 - continued

6050.32B

FIGURE 9. AVAILABLE COMPUTER ANALYSIS MODELS

MSAM
The Microcomputer Spectrum Analysis Models are a collection of engineering
programs useful for spectrum management. These models were adapted to run on
Windows computers by the NTIA. These programs have not been rigorous tested, but
have been verified to be correct for many scenarios run over a number of years.
Specific programs are listed below.
a. SHADO – Calculates and plots the areas around a fixed point that are within RLOS.
b. HORIZON – Calculates the RLOS for 360º around a specified site, using an on-line
digitized terrain data base.
c. PROFILE – Calculates elevation versus distance data path Profile between two specified
sites using an on-line digitized data base.
d. SATAZ – The Satellite Azimuth program computes the distance and various angles from an
earth station a satellite (both geostationary and nongeostationary) and from a satellite to
an earth station.
e. APD – The Antenna Power Density program provides simplified procedures for estimating
the near field power density of a number of common types of antennas and graphically
checking the compliance of systems with different emission exposure standards or userdefined limits.
f. FDR -- Computes Frequency Dependent Rejection and optionally, frequency-distance
relationships between a transmitter and a receiver.
g. ITM – Estimates radio propagation losses over irregular terrain for VHF, UHF and SHF
frequencies as a function of distance and the variability of signal in time and space.
h. INTMOD – Performs harmonic and intermodulation analysis of 2 and/or 3 signal of 3rd, 5th
or 7th order mixing.
i. SEAM – The Single Emitter Analysis Model estimate the signal level received at a specified
propagation distance in terms of the field strength or emitter power of a single emitter.
j. ANNEX1 – The program is based on the procedures outline in Annex 1 of the NTIA Manual.
It is for use as a frequency selection aid to evaluate proposals for a new station to be
introduced into an existing environment of fixed and/or mobile station in the
30 – 960 MHz band.
k. LMS – Terrestrial Land Mobile Services model is a package of empirical models. It uses
Okumura-Hata ITU-R-529, Cost 231 and Okumura-Hata-Davidson models.
l. BDIST -- Computes the true Bearings and great circle Distance given the coordinates of the
two endpoints using the WGSD-84 ellipsoid.

Page 9 (and 10)

11/17/05

6050.32B

APPENDIX 5. GLOSSARY OF ACRONYMS
A
AAG
AAM
AC
AC
ACDO
ADS-B
AFC
AFM
A/G
AGC
AGL
ALPA
AM
AMCP
AMSL
ANC
AOPA
ARINC
ARP
ARRAS
ARSR
ARTCC
ASD
ASDE
ASR
ASOS
AS T
ATA
ATC
ATCRBS
ATCT
ATIS
AVOT
AWOS

Aeronautical Assignment Group
Airspace Analysis Model
Alternating Current
Approach Control
Air Carrier District Office
Automatic Dependant Surveillance – Broadcast
Area Frequency Coordinator (military)
Automated Frequency Management system
Air-to-Ground (communications)
Automatic Gain Control
Above Ground Level
Air Line Pilots Association
Amplitude Modulation (Broadcast Station)
Aeronautical Mobile Communications Panel
Above Mean Sea Level (altitude)
Air Navigation Comission
Aircraft Owners and Pilots Association
Aeronautical Radio, Incorporated
Azimuth reference pulse
Automated Remote Radio Access System
Air Route Surveillance Radar
Air Route Traffic Control Center
Aircraft Situation Display
Airport Surface Detection Equipment
Airport Surveillance Radar
Automated Surface Observation System
Air Show, Temporary
Air Transport Association of America
Air Traffic Control
Air Traffic Control Radar Beacon System
Air Traffic Control Tower
Automatic Terminal Information Service
Area VOT
Automated Weather Observing System

B
BC
BCM
BEACON
BFTE
BLM
BUEC

Broadcast
Back Course Marker
Old name for ATCRBS
Beacon False Target Eliminator
Bureau of Land Management
Backup Emergency Communication (system)

Page 1

6050.32B

Appendix 5 – continued
C

C3
CAP
CB
CCCC
CCSA
CD
CFR
CIP
CNS
COMM
COMLO
CONUS
COTS
CP
cps
CSV
CW

Command and Control Communications
Civil Air Patrol
Citizens Band
Communications Crises Control Center
Computer Controlled Spectrum Analyzer
Clearance Delivery
Code of Federal Regulations
Capital Investment Plan
Communications, Navigation and Surveillance
Communications
Compass Locator
Conterminous (or Contiguous) United States (48)
Commercial off-the-shelf
Construction Permit (Issued by FCC)
Cycles per second
Cylindrical Service Volume
Continuous Wave
D

D
dB
dBd
dBi
dBm
dBµv
dBuv/m
DBRITE
dc
DC
dD
DECCO
DF
DGPS
DME
DME/N
DME/P
DOC
DOD
DOD AFC
dpi
DR
DTMF
dU
D/U

Page 2

Desired (facility)
Decibel
Decibel gain over a dipole antenna
Decibel gain over an isotropic antenna
Decibels above 1 milliwatt
Decibels above 1 microvolt
Decibels above 1 microvolt per meter
Digital Bright Radar Indicator Tower Equipment
Direct Current
Departure Control
Distance from the desired facility to the edge of the desired service volume
Defense Commercial Communications Office
Direction-Finding, Direction-Finder
Differential Global Positioning System
Distance Measuring Equipment
Distance Measuring Equipment - Normal
Distance Measuring Equipment - Precision
Department of Commerce
Department of Defense
Department of Defense Area Frequency Coordinator
Dots Per Inch
Distance ratio
Dual Tone Multiple Frequency
Distance from the undesired facility service volume edge
to the edge of the desired service volume
Ratio between the dD and dU facilities, in dB

11/17/05

11/17/05

Appendix 5 - continued

6050.32B

E
EA
ECM
ECP
ECS
EFAS
EHF
EIRP
ELT
EMC
EMI
EMS
EPS
ER
ERP
ESR
ESV
ESVMS

Electric Attack
Electronic Countermeasures (now known as EA)
Engineering Change Proposal
Emergency Communications System (also C3)
En Route Flight Advisory Service
Extremely High Frequency
Effective Radiated Power above an Isotropic antenna
Emergency Locator Transmitter
Electromagnetic Compatibility
Electromagnetic Interference (same as RFI)
Emission
Emergency Planning Subcommittee
Emergency Readiness
Effective Radiated Power
Equivalent Signal Ratio
Expanded Service Volume
ESV Management System
F

FA
FAA
FAR
FAS
FCC
FET
FFT
FICO
FIS
FM
FMF
FMO
FOT
FPSV
FRUIT
FS
FSDO
FSFO
FSL
FSS
FTA

Final Approach (MLS)
Federal Aviation Administration
Federal Air Regulations
Frequency Assignment Subcommittee
Federal Communications Commission
Fractional Exposure Time
Fire Fighting Temporary (prefix)
Flight Inspection Central Operations
Flight Information Service
Frequency Modulation
Facility Master File
Frequency Management Office(r)
Frequency for Optimum Transmission
Frequency Protected Service Volume
False Returns Unsynchronized In Time
Flight Standards (Division or Service)
Flight Standards District Office
Flight Standards Field Office
Free Space Loss
Flight Service Station
Facility Transmitter Authorization
G

GADO
GAMA
GBAS
GC

General Aviation District Office
General Aviation Manufacturers Association
Ground Based Augmentation System
Ground Control

Page 3

6050.32B
GENOT
GHz
GMF
GNSS
GNSSP
GPS
GPS L1
GPS L5
GS

Appendix 5 – continued
General Notice
GigaHertz
Government Master File
Global Navigation Satellite System
Global Navigation Satellite System Panel
Global Positioning System
GPS Civil Signal L1
GPS Civil Signal L5
Glideslope
H

H
H
HE
HC
HF
HH
HIWAS
Homer
HP
Hz

High Altitude (VOR/DME/TACAN)
High Power Non-directional Beacon
High Altitude En Route (A/G)
Helicopter Control
High Frequency
High power Non-directional Beacon
Hazardous Inflight Weather Advisory System
Nondirectional Radio Beacon
Holding Pattern
Hertz
I

IA
ICAO
ID
IF
IFF
IFR
ILS
IM
Intermod
iOE/AAA
IRAC
ISLS
ITS
ITU

Initial Approach (MLS)
International Civil Aviation Organization
Identification
Intermediate Frequency
Identification, Friend or Foe
Instrument Flight Rules
Instrument Landing System
Intermodulation Product (same as Intermod)
Intermodulation Product (same as IM)
Internet Obstruction Evaluation/Airport Airpace Analysis
Interdepartment Radio Advisory Committee
Improved Side Lobe Suppression
Institute For Telecommunications Science
International Telecommunication Union
J

JTIDS

Joint Tactical Information Distribution System
K

kHz
kW

Page 4

KiloHertz
KiloWatt

11/17/05

11/17/05

Appendix 5 - continued

6050.32B

L
L
LAAS
LAD
LAX
LE
LC
LDRCL
LF
LIR
LLF
LLWAS
L/MF
LO
LOA
LOB
LOC
LMM
LOM
LPTV
LSB
LUF

Low Altitude (VOR/DME/TACAN)
Local Area Augmentation System
Administrative Report
Los Angeles, CA ILS System Identifier
Low Altitude En Route (A/G)
Local Control
Low Density Radio Communications Link
Low Frequency
Interrupt Report
Line/Frequency
Low Level Wind Shear Alert System
Low and Medium Frequency bands combined
Local Oscillator
Letter of Agreement
Line of Bearing
ILS Localizer
Compass Locator at a Middle Marker
Compass Locator at an Outer Marker
Low Power TV
Lower Sideband
Lowest Usable Frequency (MF/HF)
M

MAG
MALSR
MCS
MF
MH
MHz
MILDEP
MLS
MM
mm/m
mm/min
MMS
MOA
Mode S
MOPS
MPE
m/s
msec
MUF
MULTICOM
mV
MWARA
mW/cm2

Military Assignment Group
Medium Intensity Approach Lighting System with Runway
Alignment Indicator Lights
Management Control System (RFIM Van)
Medium Frequency
Medium Power Nondirectional Beacon
MegaHertz
Militaary Department
Microwave Landing System
Middle Marker
Millimhos Per Meter
Millimeters Per Minute
Maintenance Management System
Military Operating Area
Specialized ATCRBS with discrete address capability
Minimum Operational Performance Standards
Maximum Personal Exposure
Meters Per Second
Millisecond
Maximum Usable Frequency (MF/HF)
Special Conditional Use Frequency (FCC)
Millivolt
Major World Air Route Areas
Milliwatts Per Square Centimeter

Page 5

6050.32B

Appendix 5 – continued

N
NAFEC
NADIF
NAPRS
NAS
NASE/RFI
NAVAID
NBAA
NCP
NDB
NDI
NEXRAD
NIFC
NIST
nm
nmi
NOCC
*NRM
NRCS
NRQZ
NSEP
NSF
NTIA
NTIA Manual
NWS

National Airway Facilities Experimental Center (now, the FAA
William J. Hughes Technical Center)
NAFEC Dipole Feed
National Automated Performance Reporting System
National Airspace System
Navigational Aids Signal Evaluator/Radio Frequency Interference
Navigational Aid
National Business Aircraft Association
NAS Change Proposal
Nondirectional Beacon
Non Development Item
Next Generation Weather Radar
National Interagency Fire Center
National Institute of Science and Technology
Nautical Miles (used in computer printout copies)
Nautical Miles (used in text)
National Operations Control Center
Number of stations (NTIA Form 19-A)
National Radio Communications System
National Radio Quiet Zone
National Security Emergency Preparedness
National Science Foundation
National Telecommunications and Information Administration
Manual of Regulation and Procedures For Federal
Radio Frequency Management, published by NTIA
National Weather Service
O

OCC
OE
OM
OSHA
OTS

Operational Control Center
Obstruction Evaluation
Outer Marker
Occupational and Safety Hazards Administration
Out to Service
P

PAR
PEL
PL
pps
PROP
PRR
PRT
PTP
PTT
PTTA
PWR

Page 6

Precision Approach Radar
Permissible Exposure Limit
Private Line (squelch tones)
Pulses Per Second
Proponent
Pulse Repetition Rate (formerly PRF)
Pulse Repetition Time
Point-To-Point
Push-To-Talk
Postal Telegraph and Telephone Authority
Power

11/17/05

11/17/05

Appendix 5 - continued

6050.32B

Q
None
R
(R)
RAD
*RAD
RADHAZ
RAL
RAPM
RBPM
RC
RCAG
RCAMSL
RCAS
RCF
RCL
RCOM
RCS
RDARA
RF
RFI
RFI Van
RFIM
RLA
RLG
RLOS
r/min
RML
RMM
ROSHM
r/s
RSC
RTCA
RTDE
RTR
RX or Rx

Route (used with "aeronautical Mobile")
Receive Antenna Dimensions (NTIA Form 19-A)
Authorized Area of Operation (NTIA Form 19-A)
Radiation Hazard
Receive Antenna Location (NTIA Form 19-A)
Regional Associate Program Manager
Radar Beacon Performance Monitor
Resistor/Capacitor Combination
Remote Control A/G facility
Radiation Center Above Mean Sea Level
Radio Coverage Analysis System
Remote Communications Facility
Radio Communications Link
Recovery Communications (Previously NARACS)
Radio Conference Subcommittee
Regional and Domestic Air Route Area
Radio Frequency
Radio Frequency Interference (same as EMI)
Radio Frequency Interference Van
Radio Frequency Interference Monitoring (Van or System)
Receive Antenna Latitude (NTIA Form 19-A)
Receive Antenna Longitude (NTIA Form 19-A)
Radio Line Of Sight
Revolutions Per Minute
Radar Microwave Link
Remote Maintenance Monitoring
Regional Occupational Safety and Health Manager
Revolutions Per Second
Receive State (NTIA Form19-A)
RTCA, Incorporated (formerly the Radio Technical Commission for Aeronautics)
Research, Test, Development and Evaluation
Remote Transmitter/Receiver
Receive, Receiver
S

(S)
SA
SAR
SARP
SAWS
SCAT-I
SE
SECRA

Required facility geographical separation
Spectrum Analyzer
Search And Rescue
Standards and Recommended Practices
Stand Alone Weather System
Special Category I (DGPS)
Super High Altitude Enroute
Secondary Radar (old name for ATCRBS

Page 7

6050.32B
SHF
SIF
SLC
SLS
SMDb
smi
SMO
SOC
SPS
SSL
SSS
STA
STALO
STC

Appendix 5 – continued
Super High Frequency
Selective Identification Feature (modified IFF)
Space Loss Calculator
Side Lobe Suppression
Spectrum Management Data Base
Statute Miles
System Maintenance Office
System Operations Center
Spectrum Planning Subcommittee
Secure Socket Layer
Space Systems Subcommittee
Special Temporary Authorization (FCC)
Stabilized Local Oscillator
Station Class (NTIA Form 19-A)
T

T
TACAN
TC
TDWR
TFR
TIMDS
TIOA
TIS
Title 49 U.S.C.
TLS
TML
T/R
TRACON
TSC
TSV
TV
TWEB
TX
TX LO

Terminal (VOR/DME/TACAN)
Tactical Air Navigation
Time Constant
Terminal Doppler Weather Radar
Temporary Flight Restrictions
Transportable Interference Monitoring Detection System
Transmitter Identification and Operation Authorization
Travelers Information Service
Codified FAA Act of 1958, as amended
Transponder Landing System
Television Microwave Link
Transmit and Receive
Terminal Radar Approach Control
Technical Subcommittee
Tailored Service Volume
Television
Transcribed Weather Broadcast
Transmit, Transmitter
Transmitter Local Oscillator

U
U
UAT
ufd
UHF
UNICOM
USAF
USB
usec
USER ID
USFS

Page 8

Undesired (facility)
Universal Access Transceiver
Microfarad
Ultra High Frequency
Aeronautical Advisory Station (FCC)
United States Air Force
Upper Sideband
Microsecond
User Identification
United States Forest Service

11/17/05

11/17/05
USN
uV/m

Appendix 5 - continued

6050.32B

United States Navy
Microvolts Per Meter
V

V
VFR
VHF
VIP
VLF
VOLMET
VOR
VORTAC
VOT
VPN

Volt
Visual Flight Rules
Very High Frequency
Variable Interpulse Period
Very Low Frequency
Meteorological Area Weather Broadcasts
VHF Omnidirectional Radio Range
VOR with TACAN
VHF Omnidirectional Radio Range Test
Virtual Private Network
W

W
WAAS
WRC
WSR-88D

Watt
Wide Area Augmentation System
World Radiocommunication Conference
Next Generation Weather Radar (NEXRAD)
X

XAD
XAL
XAZ
XLA
XLG
XSC/RSC

Transmit Antenna Dimensions (NTIA Form19-A)
Transmit Antenna Location (NTIA Form19-A)
Transmit Azimuth (NTIA Form 19-A)
Transmit Antenna Latitude (NTIA Form19-A)
Transmit Antenna Longitude (NTIA Form 19-A)
Transmit State (NTIA Form 19-A)

Y
None
Z
None

Page 9

11/17/05

6050.32B

APPENDIX 6. EMISSION DESIGNATORS
FACILITY TYPE/FREQUENCY BAND

DESIGNATOR

STATION CLASS

NDB (single carrier) (190-535 kHz)
2K04A2A
NDB (two carrier) (190-535 kHz)
1K12XXA
#
#
Marker Beacon [75 MHz (OM)]
800HA2A
Marker Beacon [75 MHz (MM)]
2K60A2A
Marker Beacon [75 MHz (IM/BCM)]
6K00A2A
#
#
Localizer capture effect (108.30-111.95 MHz)
8K00A9W
Localizer (108.30-111.95 MHz)
2K04A2A
LAAS (108.025-117.950 MHz)
14K0G7DET
Glide Slope (328.600-335.400 MHz)
300HA1N
Glide Slope capture effect (328.600-335.400 MHz)
8K30A1N
DME (960-1215 MHz)
650KM1A
DME/P (960-1215 MHz)
750KM1A
TACAN (960-1215 MHz)
650KV1A
VOR with voice (108.2000-117.9875 MHz)
20K9A9W
VOR without voice (108.2000-117.9875 MHz)
20K9A2A
MLS (5000-5250 MHz)
150KM1D
#
#
Radar (ASDE-X) (9000-9200 MHz)
35M00P0N
Radar (TDWR) (5600-5650 MHz)
4M00P0NAN
Radar (ASR-11) (2700-2900 MHz)
2M80Q3N/5M10P0N
Radar (ASR-9) (2700-2900 MHz)
5M00P0N
Radar (ASR-8) (2700-2900 MHz)
6M00P0N
Radar (ASR-7) (2700-2900 MHz)
8M00P0N
Radar (ARSR-4) (1215-1400 MHz)
5M00P0N
Radar (ARSR-3) (1215-1400 MHz)
6M00P0N
Radar (ARSR1/2) (1215-1400 MHz)
10M0P0N
Radar (ASDE-3) (15.7-16.2 GHz)
28M0P0N
ATCRBS (transmit 1030 MHz - receive 1090 MHz)
6M00M1D
ATCBI-6 (transmit 1030 MHz – receive 1090 MHz)
21M50V1D
Mode S (transmit 1030 MHz – receive 1090 MHz)
21M50V1D
MSSR (transmit 1030 MHz – receive 1090 MHz)
9M001D
Multi-Lat (transmit 1030 MHz – 1090 MHz)
9M20M1D
RPBM/CPME (transmit 1030 MHz–receive 1090 MHz) 14M00V1D
#
#
Voice communications using double sideband
6K00A3E
(118.000-136.475 and 225.000-400.000 MHz)

#
VDL-3 (TDMA) communications
(118.000-136.475 MHz)

#
14K07WET

ALB
ALB
#
ALA
ALA
ALA
#
ALL
ALL
DGP
ALG
ALG
AL
AL
AL
ALO
ALO
ALL,ALG
#
LR
SMD
ALS
ALS
ALS
ALS
ALS
ALS
ALS
LR
RN
RN
RN
RN
RN
ALTO
#
FA (enroute)
FAC (lcl ctl, apch ctl, etc.)
FAB (ATIS, AWOS, etc.)
FLU (gnd ctl, clnc dlvy, etc.)
#
FA (enroute)
FAC (lcl ctl, apch ctl, etc.)
FAB (ATIS, AWOS, etc.)
FLU (gnd ctl, clnc dlvy, etc.)

Page 1

6050.32B

Appendix 6 – continued

FACILITY TYPE/FREQUENCY BAND
VDL-2 (FIS-only) data link communications
(136.425-136.475 MHz)
#
HF (3-30 MHz)

#
RCL (ATT FR8) (7125-8500 MHz)
RCL (Alcatel MDR6508-4) (7125-8500 MHz)
RCL (Alcatel MDR6508-8) (7125-8500 MHz)
RCL (Alcatel MDR6508-16) (7125-8500 MHz)
TML (14.40-15.35 GHz)
#
Land Mobile (C3) (162-174 MHz)
Fixed (406.100-420.000 MHz)

Page 2

DESIGNATOR
14K0G1DE
#
1K28F1B
3K00J3E
2K80J3E
6K00B9W
#
20M0F9W
2M50D7W
3M75D7W
7M50D7W
27M0F9W
#
8K10F1E
11K00F1D

11/17/05

STATION CLASS
FA (enroute)
FAC (lcl ctl, apch ctl, etc.)
#
FX, FA, MA, FB, ML
FX, FA, MA, FB, ML
FX, FA, MA, FB, ML
FX, FA, MA, FB, ML
#
FX
FX
FX
FX
FX
#
FXR, FB, ML
FX

11/17/05

6050.32B

APPENDIX 7. FORMULAS USED IN THIS ORDER
(S)

Required nmi separation distance between NAVAID's or COMM's

CH 11 Pg 106
APX 3 Pg 015
APX 3 Pg 073

GdB

Gain of parabolic antenna

CH 12 Pg 113

Lfs

Free space loss in nmi

CH 12 Pg 115
APX 2 Pg 007

Li

Free space loss in feet of interferer (sub item in LEVEL out-of-band)

APX 1 Pg 012

fi

PRR "running rabbits" interferer's frequency

CH 14 Pg 182

fo

Intermod products, any set of frequencies

APX 1 Pg 009

LEVEL

Maximum in-band level of power in dBm before RFI occurs

APX 1 Pg 010

LEVEL

Maximum out-of-band level of power in dBm before RFI occurs

APX 1 Pg 012

Da

Slant range distance in any standard between two elevated antennas

APX 1 Pg 012

d

Venn diagram RFI radii, 10, 20 or 30 dBm distances in nmi

APX 1 Pg 014

RLOS

Radio line of sight between two points in nmi and smi

APX 2 Pg 006

ESR

Equivalent signal ratio, used in connection with VOR ESV's

APX 3 Pg 014

ESR

Equivalent signal ratio, used in connection with ILS's and ESV's

APX 3 Pg 071

Page 1 (and 2)

11/17/05

6050.32B

APPENDIX 8. SOME PROCEDURES FOR RADAR ANTENNA VERTICAL PATTERN
MEASUREMENT BY SOLAR MEANS
1. GENERAL. FMOs ordinarily do not perform "solar" antenna measurements (see paragraph 1601 d. of this
order). When such measurements are done, the procedures described below are suggested. There are several
procedures, but all have the same purpose.
a. The methods described in this chapter use the sun's electromagnetic radiant "noise" as a signal source.
Measurement is accomplished with a field strength meter or SA in either a manual or computer-controlled
recording system and recorders of either pen type or floppy disc. This system also requires shutdown of the radar,
since the radar antenna is connected to the measurement system. The antenna is left at its normal mechanical tilt
and rotated at its normal speed, with the transmitter and receiver turned off. These "solar" procedures described
below are examples of some of the available and effective procedures.
b. As the earth rotates, the sun "rises" above (or "sets" into) the horizon, and it effectively passes through
the radar antenna's main beam. That relatively stable noise source is recorded at each revolution. Since the
radar's rotation is very rapid with respect to the angular velocity of the sun, many antenna revolution sun passes
are possible at approximately the same elevation, thus enabling the recording system to average out small
differences and give a very high degree of resolution.
c. The RFIM van is equipped to make horizontal radar antenna pattern measurements. The van equipment
may be used by the FMO for the vertical pattern measurements described in this appendix. Some additional
equipment may be needed depending on which method of measurement is used.
d. There is considerable equipment setup and calibration required which, instead of being in the van, must
be transported to the radar site, set up, taken down, then the results either manually plotted or fed into an
automatic plotter back at the FMO's office.
2. TWO METHODS OF SOLAR MEASUREMENTS. Two methods of solar-based radar antenna pattern
measurement are manual and automated. Each will produce quality results, but the automated method does away
with any manual extrapolation, interpolation, and plotting. It produces a superior product at the expense of using
a computer and considerable other equipment.
3. MANUAL MEASUREMENT. A vertical antenna pattern can be produced manually from just the NM-65T
field strength meter, an attenuator, an amplifier, and a strip chart recorder. The recorded signal will be the signal
received from the sun's noise radiation as the antenna sweeps past the sun's azimuth. A block diagram of the
necessary equipment setup is found in figure 1, with a procedural description following.

Page 1

6050.32B

Appendix 8 – continued

11/17/05

FIGURE 1. BLOCK DIAGRAM OF MANUAL MEASUREMENT

a. Equipment required for a radar antenna measurement using the sun as a source is essentially the same as
the setup in the RFIM van. However, the relatively weaker source (sun noise) requires extra amplification and a
source of accurate time is needed.
(1) Any good high-gain amplifier with a low noise figure may be used. The AVENTEK AMG 2021 or
2022 for 1-2 GHz or the AMG 4031 for 2-4 GHz are examples.
(2) An accurate field strength meter. The Eaton NM-65T field strength meter supplied the FMOs is
excellent. The later model NM-67T is also excellent for those who have it. The signal output of a quality
spectrum analyzer could also be used in lieu of the field strength meter.
(3) An in-line step attenuator, with at least 30 dB total attenuation, in steps of 1 or 2 dB is required.
(4) A strip chart recorder is needed. This is a key element in the measuring package. It must have low
ballistics so that it follows the detected noise signal accurately; e.g., 10 msec or less from zero to full scale. It
also must be capable of quite slow paper travel to permit recording the passes in a reasonable length of paper. An
HP 17401A recorder has been used satisfactorily, but this is a two channel device and requires considerable
adjustment to get the crossover of the two channels to match. There are several strip chart recorders available
which will do the job satisfactorily. The principal concern is that it have sufficient span to accurately record a
25-30 dB range of values and that it is capable of being set to a slow speed of around 5 millimeters per minute
(mm/min).
(5) A time source accurate to a few seconds a day is required. Before using the time source, it should be
coordinated with an accurate time source such as radio station WWV. If a time-tick device is available, that
device can be used to put a marked tick on the recording automatically. If not, a manual mark each minute will be
sufficient.
(6) An accurate determination of the sun's position is essential. The sun's position with respect to
time, date, and geographical position of the radar must be accurately known, otherwise the whole measurement
will be faulty. The radar's coordinates can be obtained from the IRAC authorization document, GMF files or
GPS receiver. The sun's actual position minute-to-minute is determined from the Air Almanac or Nautical
Almanac, published by the Naval Observatory, Washington, DC.

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11/17/05

Appendix 8 - continued

6050.32B

b. Measurement procedure.
(1) Connect the system components as shown in figure 1, with the calibrating signal generator
connected to the input of the in-line step attenuator.
(2) Set the in-line attenuator to 0 dB.
(3) Set and calibrate the NM-65T to the frequency of the radar.
(4) Set the NM-65T attenuator to the 0 dB position.
(5) Set the NM-65T function.
(a) The function setting is critical to the calibration procedure, thus to the overall accuracy of the
measurements. Some experimentation will be necessary and will depend on many factors. Whether field
intensity, direct peak, or quasi-peak function is used will depend upon the systems setup, the ballistics of the strip
recorder, the radar antenna azimuth rate and the antenna beam width (±3 dB). For instance, an ARSR with a rate
of 4 revolutions per minute (r/min) and a beam width of 2° would mean an illumination of the antenna within its
beam width for 2/360 x 15 secs = 83.33 msec. That means the strip recorder has only 83 msec to reach its full
swing position and come to rest before it starts down again. A 2° beam width of an ASR of 15 r/min would give
illumination for only 2/360 x 4 secs = 22.22 msec to accomplish the same swing. Depending on the ballistics of
the recorder and the time constant of the field strength meter, this could be sufficient to give an accurate reading,
or could lag behind the actual value due to the "drag" resulting in an inaccurate reading.
(b) Testing of the setup must be done before the first measurement is made. Once done, the
parameters will be known and set for all subsequent measurements, using the same equipment and antenna rates.
The manufacturer's instruction book should specify the slew rate of the pen. If it will make a full excursion in 20
msec or less, then both the examples in subparagraph b(5)(a) above would be operable in quasi-peak function.
However, if as is often the case with recorders which have slow paper rates, the manufacturer specifies the slew
rate as 500 msec or so, another function will be required, most likely peak with 0.5 sec hold time.
(c) Peak function in the NM-65T holds the meter reading (and thus the recorder output) for 0.5
or 5 sec, switchable. This is to permit easy reading of a very short pulse, even a µsec or less. Setting the time
constant to 0.5 sec would match a 500 msec slew rate of a strip recorder. The NM-65T inserts a brief "dump"
voltage (a reverse voltage) at the end of the selected hold time in direct peak function to restore the charging
circuit to zero quickly to be ready for the next pulse to be measured. This is satisfactory if the strip recorder is
partially damped or has a slow slew rate. Damping allows the pen to return to zero safely, without "ramming" it
down and possibly damaging the recorder. The 5 sec peak time constant would be acceptable for an ARSR rate of
4r/min, but not an ASR of 15 r/min because the next illumination would come before the 5 sec "hold" time had
expired.
(d) Quasi-peak in the NM-65T has a time constant of around 10 msec which is ideal for the
Techni-rite 711 high-speed recorder used for antenna patterns described in chapter 13 of this order. The TR-711
would be excellent for this solar measurement, except the slowest normal speed would run out quite a bit of paper
for the hour or more required for a complete sun "pass." If the TR-711 is reduced in tape speed to be usable for
this function, then quasi-peak must be used, or the "dump" feature of direct peak will render the recording useless
and could damage the recorder. The TR-711 has a slew rate of approximately 5 msec to full scale and no
damping.

Page 3

6050.32B

Appendix 8 – continued

11/17/05

(6) Calibrate the strip recorder by injecting a known signal at a level about 150 to 250 milliVolts (mV)
and adjusting the recorder scan to a desired scale reading, usually about 75 percent. Experience will soon teach
what level is expected to be the peak noise recorded off each type of radar antenna and frequency. The NM-65T
will handle a 60 dB dynamic range of level without distortion. Should the recorded level be above scale with the
in-line attenuator set at 0, insert sufficient attenuation with this device to bring the pen to an on-scale reading for
the whole recording session. DO NOT reduce signal level with the NM-65T internal attenuator. Doing so would
activate AGC action within the NM-65T which occurs at other than 0 dB setting and would upset recording
linearity. Set the recording paper speed at an appropriate rate, nominally around 5mm/min.
(7) Insert steps of attenuation with the signal generator untouched, (maximum of 2 dB/step) so that the
individual levels of attenuation are shown on the recorder paper. After step intervals of 25 to 30 dB attenuation
levels have been recorded and marked on the recording strip, return the attenuator to 0 dB.
(8) Disconnect the generator and connect the radar antenna to the input of the attenuator. With the
radar turned off, start the antenna rotating.
(9) Sunrise (or sunset) time will have to have been previously determined for the particular day of the
measurement. The actual recording should be started 2-3 min before sunrise. If the measurement is to be made at
the sunset period, start the recording in sufficient time to assure a full range of vertical azimuth desired. Also start
the time ticks and assure they are marked either manually or automatically on the recording for later data
resolution.
(10) Run the recording for as long as needed to show the range of vertical pattern desired. For a
NADIF, for instance, this is just over an hour. Once the peak has been reached and further sun azimuthal
excursion drops the sun noise passes more than 20 to 25 dB from the peak, recording may be stopped.
(11) Rerun the calibration on the recording at this time, to assure that parameters have not drifted
significantly. Should they somehow have done so, it will be necessary to check all equipment and the overall
system to find the cause of the apparent drift before another recording is made.
(12) Dismantle the setup and disconnect the equipment. The recording is now ready to be analyzed to
permit drawing the actual radiation pattern. Refer to figure 2.
c. Data analysis. With the recorded signal in hand, it is now possible to calculate the actual vertical beam
pattern. The recorder sheet already has the calibration on it, so the only analysis required is to correlate the sun's
azimuth with the time ticks on the recording.
(1) Using the sun's position determined from the Naval Observatory Almanac, mark each fractional
degree of sun azimuth on the recording aside the time tick marks. These should be small increments of 0.1° or so.
(2) Using the previous calibration marks, evaluate and mark each azimuth increment with a dB value.
Generally, there will be a small variation of ±1 dB or less between successive passes. If so, take a simple average
of those passes nearest the marked increment.
(3) Analyzing the calibrated recording, work up a chart of vertical azimuth in degrees versus amplitude
in dB. Refer to figure 3.

Page 4

11/17/05

Appendix 8 - continued

6050.32B

(4) Using the data now available, plot the chart values onto a graph of expanded angular scale to produce a
graphic view of the actual vertical beam antenna pattern of the radar measured. Be sure to subtract any
mechanical tilt from the plot, or to specifically indicate that the plot is true vertical azimuth as installed, rather
than the actual vertical radiation pattern of the antenna itself.

FIGURE 2. SAMPLE RECORDING WITH CALIBRATION, TIME
AND AMPLITUDE MARKINGS

Page 5

6050.32B

Appendix 8 – continued

11/17/05

FIGURE 3. SAMPLE PLOT OF ANALYZED RECORDING

4. AUTOMATED MEASUREMENT. Automated systems of measurement have been developed by a few
service areas to permit not only automated recording of the sun's azimuth passing through the antenna's beam, but
then to produce automatically the graph of the beam resulting from the data collection. They use the equipment
indicated previously in the manual method with the addition of a high-speed digital voltmeter, a real time clock,
and a desktop computer. One service area used the HP 3437A voltmeter, the HP 98035A clock and the HP
9825A desktop computer. A block diagram of the setup is found in figure 4.
a. Automated mode operation is different from that of the manual mode described in paragraph 1702. The
field strength meter output is fed to a digital voltmeter, then to a microcomputer which is time calibrated by a real
time clock input. When the data collection is completed, the recorded information is taken back to the FMO's
office and plotted by using the microcomputer and a suitable plotter. The final product is a vertical pattern plotted
by the automated system.
(1) Azimuth reference is required for the system to identify the "window" to record. The purpose here
is twofold. First, it greatly reduces extraneous signals from other radars from getting into the data base.
Secondly, it reduces the need for memory and permits putting the whole recording on one tape. As the block
diagram shows, the radar's Azimuth Reference Pulse (ARP) is used in conjunction with the clock to open the data
window only for a few degrees before and then closing it a few degrees after the antenna scans the sun area.

Page 6

11/17/05

Appendix 8 - continued

6050.32B

(2) The digital voltmeter is used to assure the overall signal applied to the computer does not exceed 1.5
V, the system maximum permissible value. It also serves to integrate the ARP into the system.
(3) The microcomputer is used primarily to program the measurement system, and once done, needs
only "fill-ins" to run other radar measurements. It also serves to provide magnetic tape recording of the data as it
is produced. After the recording is completed, it is used to playback the data and provide program information to
the plotter for the final plotting.
(4) The plotter is used purely for graphics in plotting the final graph itself. Any good plotter compatible
with the program language may be used.
(5) Strip recording can be done simultaneously to allow eye viewing of real time progress of the
recording session. It is valuable as a monitoring tool to assure that all peripherals are operating in their proper
mode. It allows the FMO to see the increasing, peaking and decreasing levels as the sun traverses the vertical
beam path. For this reason, it is shown as optional in the block diagram of figure 4.

FIGURE 4. AUTOMATED RADAR ANTENNA SOLAR MEASUREMENT
BLOCK DIAGRAM

b. The service area automated program upon which this description has been based is available as a
16-page, three-file program from Technical Operations ATC Spectrum Engineering Services. Other programs
have been developed subsequently by other service areas and also are available through Technical Operations
ATC Spectrum Engineering Services. At present, the decision as to whether the FMO should use an automated
system or manual is dependent upon the FMO's choice and availability of equipment. The computer programs are
not included in this manual. With the rapid growth in microcomputers, laptop computers, and engineers'
knowledge of programming, any FMO who wishes to write a program is encouraged to do so. If a successful
program for automated solar measurements is written, it is requested that the FMO forward it to Technical
Operations ATC Spectrum Engineering Services for study and circulation to other service areas.

Page 7

6050.32B

Appendix 8 – continued

11/17/05

c. A Headquarters automated system has been devised by the Technical Operations Support National
Airway Systems Engineering Office. It is designed to use with ASR, ARSR and ATCRBS antennas. It utilizes
low-noise amplifiers, HP 8500 series spectrum analyzers and a microcomputer with HP-Basic language. The
information entitled Radar Antenna Solar Data Recording And Analysis can be procured from Technical
Operations ATC Spectrum Engineering Services.
5. DOCUMENTATION. As with other engineering data described in other chapters of this manual, any and all
measurements and plots will be placed in the facility file as part of the permanent engineering record of the
facility. Since spectrum management records are exempt from the destruction schedule, these records will serve
as a permanent record of antenna capability and performance. They also can provide important clues to any
suspected improper operation of the facility.

Page 8