U.S. DEPARTMENT OF COMMERCE • National Telecommunications and Information Administration

report series

NTIA Report 15-516

A Spectrum Sharing Case Study Leading 

to the Development of a Method for 

Identifying Interference Potential

Christopher Behm

Nicholas DeMinco

Timothy Riley

Linh Vu

U.S. DEPARTMENT OF COMMERCE

April 2015

NTIA Report 15-516

A Spectrum Sharing Case Study Leading 

to the Development of a Method for 

Identifying Interference Potential

Christopher Behm

Nicholas DeMinco

Timothy Riley

Linh Vu

iii

DISCLAIMER

Certain commercial equipment and materials are identified in this report to specify adequately 

the technical aspects of the reported results. In no case does such identification imply 

recommendation or endorsement by the National Telecommunications and Information 

Administration, nor does it imply that the material or equipment identified is the best available 

for this purpose.

v

CONTENTS

Figures........................................................................................................................................... vii

Tables........................................................................................................................................... xiv

Glossary of Terms..........................................................................................................................xv

Executive Summary.................................................................................................................... xvii

1. Introduction..................................................................................................................................1

2. Equipment Descriptions...............................................................................................................3

2.1 GOES-N/O/P Systems...........................................................................................................3

2.2 GOES-R Systems...................................................................................................................4

2.3 Radiosondes...........................................................................................................................5

2.4 Video Surveillance Subsystem (VSS) ...................................................................................5

2.5 General Comments on Equipment and the Analysis.............................................................6

3. Interference Analysis Approach ..................................................................................................8

3.1 Analysis Scenarios.................................................................................................................9

3.2 Computation of the Received Interference Signal Levels...................................................11

3.3 Noise level predictions for the analysis...............................................................................14

3.4 Protection ratio.....................................................................................................................15

3.5 Frequency-Dependent Rejection (FDR)..............................................................................15

3.6 The EMC metric of frequency separation (Δf) versus separation distance..........................21

3.7 Applying Propagation Models to Scenarios ........................................................................22

4. Interaction scenario results ........................................................................................................24

4.1 Scenario S02, Radiosonde Interference to VSS Victim Receiver .......................................24

4.1.1 Scenario S02 (QPSK).................................................................................................33

4.1.2 Scenario S02 (16QAM)..............................................................................................34

4.1.3 Scenario S02 (64QAM)..............................................................................................35

4.1.4 Summary for Analysis of Results for Scenarios S02 (QPSK), S02 (16QAM), 

& S02 (64QAM)..................................................................................................................36

4.2 Interactions for Scenarios S03 to S15, GOES-N and GOES-R Interference to VSS 

Victim Receiver.........................................................................................................................36

4.2.1 Computation of Interference Levels...........................................................................36

4.2.2 Summary for the Interactions for Scenarios S03 to S15, GOES-N and GOESR Interference to VSS Victim Receiver ..............................................................................37

4.3 Interactions for Scenarios S16 to S28, VSS Interference to GOES-N and GOES-R 

Victim Receiver.........................................................................................................................37

5. Measurements............................................................................................................................39

5.1 Interference of the Radiosonde to the VSS..........................................................................39

5.1.1 Actual Frequency Relationships Between the Radiosonde and the VSS...................39

5.1.2 VSS Configuration Space...........................................................................................40
vi

5.1.3 Test Qualifiers............................................................................................................41

5.1.4 Basic Test Setup .........................................................................................................42

5.1.5 VSS Video Failure Mode ...........................................................................................44

5.1.6 VSS Configuration Baseline Tests.............................................................................45

5.1.7 Interference Testing....................................................................................................46

5.1.8 Narrowband vs. Wideband Interference Comparison ................................................50

5.2 Interference of the VSS to the GOES ..................................................................................53

5.2.1 Considerations for GOES Receiver Testing...............................................................53

5.2.2 Test Plan.....................................................................................................................56

5.2.3 Test Setup...................................................................................................................56

5.2.4 Test Procedure............................................................................................................58

5.2.5 VSS to GOES Interference Test Conclusions............................................................63

6. Conclusions................................................................................................................................64

6.1 The Interference between the Incumbent and Entrant Systems...........................................64

6.2 The Importance of Using the Correct Propagation-Loss Prediction Model ........................65

6.3 The Method for Identifying Interference Potential..............................................................65

6.4 Miscellaneous Conclusions..................................................................................................66

7. References..................................................................................................................................67

Acknowledgements........................................................................................................................68

Appendix A. Frequency Dependent Rejection versus Offset Frequency Curves for all 

Scenarios........................................................................................................................................69

Appendix B. Scenarios..................................................................................................................74

Appendix C. GOES earth Station Locations and Alignments....................................................103

Appendix D. Frequency Separation vs. Separation Distance curves for VSS-into-GOES 

Scenarios......................................................................................................................................105
vii

FIGURES

Figure 1. Example plots of received power versus distance for the VSS to 

Radiosonde interference scenario S01 of Table 4..........................................................................13

Figure 2. Example plots of FDR versus separation distance for the VSS to 

Radiosonde interference scenario S01 of Table 3..........................................................................16

Figure 3. Example plot of FDR versus frequency offset for the VSS to 

Radiosonde Interference Scenario S01 of Table 4.........................................................................18

Figure 4. Frequency offset versus separation distance for tracking radiosonde 

near horizon with ht = 2 m and hr = 5 m – VSS transmitter interference into 

radiosonde receiver. .......................................................................................................................19

Figure 5. Frequency offset versus separation distance for tracking radiosonde 

near horizon with ht = 20 m and hr = 5 m – VSS transmitter interference into 

radiosonde receiver. .......................................................................................................................19

Figure 6. Frequency offset versus separation distance for 5° elevation angle with 

ht = 2 m and hr = 5 m – VSS transmitter interference into radiosonde receiver............................20

Figure 7. Frequency offset versus separation distance for 5° elevation angle with 

ht = 20 m and hr = 5 m – VSS transmitter interference into radiosonde receiver..........................20

Figure 8. Example plots of frequency offset versus separation distance for the 

VSS to Radiosonde Interference Scenario S01 of Table 4 (for S/N = 7.3 dB and 

S/I = 20 dB)....................................................................................................................................21

Figure 9. Near and far details of interference effects – low transmitter antenna 

height – low receiver antenna height. ............................................................................................25

Figure 10. Near and far details of interference effects – low transmitter antenna 

height – high receiver antenna height. ...........................................................................................25

Figure 11. Near and far details of interference effects – high transmitter antenna 

height – low receiver antenna height. ............................................................................................26

Figure 12. Near and far details of interference effects – high transmitter antenna 

height – high receiver antenna height. ...........................................................................................26

Figure 13. Near and far details of interference effects – very high transmitter 

antenna height – low receiver antenna height................................................................................27

Figure 14. Near and far details of interference effects – very high transmitter 

antenna height – high receiver antenna height...............................................................................27

Figure 15. Received power for VSS to VSS with ht = 2.0 m and hr = 2.0m. ...............................28
viii

Figure 16. Distance from interference source required to avoid interference as a 

function of VSS transmitter to VSS receiver separation distance. ................................................28

Figure 17. Victim VSS receiver with noise-like interferer (radiosonde and GOES 

satellites). .......................................................................................................................................30

Figure 18. FDR versus Df for the VSS transmitter to radiosonde receiver...................................32

Figure 19. FDR for scenario S02-15.3 for ht = 100 m and hr = 20 m – radiosonde 

to VSS (QPSK). .............................................................................................................................33

Figure 20. Df versus separation distance for scenario S02-15.3 for ht = 100 m and 

hr = 20 m –radiosonde to VSS (QPSK). ........................................................................................33

Figure 21. FDR for scenario S02-15.4 for ht = 100 m and hr = 20 m – radiosonde 

to VSS (16QAM). ..........................................................................................................................34

Figure 22. Df versus separation distance for scenario S02-15.4 for ht = 100 m and 

hr = 20 m –radiosonde to VSS (16QAM). .....................................................................................34

Figure 23. FDR for scenario S02-15.5 for ht = 100 m and hr = 20 m – radiosonde 

to VSS (64QAM). ..........................................................................................................................35

Figure 24. Df versus separation distance for scenario S02-15.5 for ht = 100 m and 

hr = 20 m –radiosonde to VSS (64QAM). .....................................................................................35

Figure 25. VSS-Radiosonde location extremes in the 1675–1695 MHz band. ............................39

Figure 26. VSS baseline test setup................................................................................................43

Figure 27. VSS interference injection test setup...........................................................................44

Figure 28. Sample frames from the video clip used for testing. ...................................................45

Figure 29. VSS failure-points with a simulated radiosonde interferer –

configuration 5...............................................................................................................................48

Figure 30. VSS failure-points with a simulated radiosonde interferer –

configuration 9...............................................................................................................................48

Figure 31(a). VSS failure-points with a simulated radiosonde interferer –

configuration 13.............................................................................................................................49

Figure 31(b). VSS failure-points with a simulated radiosonde interferer –

configuration 13 (large frequency separation)...............................................................................49

Figure 31(c). Calculated FDR for scenario S02 (radiosonde to VSS interference)......................50

Figure 32. Signal-to-interference ratio versus interference bandwidth – QPSK. .........................51
ix

Figure 33. Signal-to-interference ratio versus interference bandwidth - 16QAM........................52

Figure 34. Signal-to-interference ratio versus interference bandwidth - 64QAM........................52

Figure 35. GOES RF signals.........................................................................................................53

Figure 36. GOES IF signals received at the Boulder site. ............................................................54

Figure 37. GOES-N/O/P frequency plan (downlinks)..................................................................54

Figure 38. Test setup - VSS interference injection into GOES. ...................................................58

Figure 39. Results of calibration test – fixed attenuator at VSS output = 20 dB..........................59

Figure 40. Results of calibration test – fixed attenuator at VSS output = 30 dB..........................59

Figure 41. Results of Test 2, Step 4 – EMWIN, FEC = 1/2, Scrambling = ON...........................61

Figure 42. Results of Test 2, Step 4 – EMWIN, FEC = 1/2, Scrambling = OFF. ........................61

Figure 43. Results of Test 2, Step 4 – EMWIN, FEC = 7/8, Scrambling = ON...........................61

Figure 44. Results of Test 2, Step 4 – PDR, FEC = 1/2, Scrambling = OFF (left), 

ON (right).......................................................................................................................................62

Figure 45. Results of Test2, Step 4 – PDR, FEC = OFF, Scrambling = OFF (left), 

ON (right).......................................................................................................................................62

Figure A-1. Frequency dependent rejection versus offset frequency – scenario 

S01. ................................................................................................................................................69

Figure A-2. Frequency dependent rejection versus offset frequency – scenario 

S02. ................................................................................................................................................69

Figure A-3. Frequency dependent rejection versus offset frequency – scenario 

S03. ................................................................................................................................................69

Figure A-4. Frequency dependent rejection versus offset frequency – scenario 

S04. ................................................................................................................................................69

Figure A-5. Frequency dependent rejection versus offset frequency – scenario 

S05. ................................................................................................................................................69

Figure A-6. Frequency dependent rejection versus offset frequency – scenario 

S06. ................................................................................................................................................69

Figure A-7. Frequency dependent rejection versus offset frequency – scenario 

S07. ................................................................................................................................................70
x

Figure A-8. Frequency dependent rejection versus offset frequency – scenario 

S08. ................................................................................................................................................70

Figure A-9. Frequency dependent rejection versus offset frequency – scenario 

S09. ................................................................................................................................................70

Figure A-10. Frequency dependent rejection versus offset frequency – scenario 

S10. ................................................................................................................................................70

Figure A-11. Frequency dependent rejection versus offset frequency – scenario 

S11. ................................................................................................................................................70

Figure A-12. Frequency dependent rejection versus offset frequency – scenario 

S12. ................................................................................................................................................70

Figure A-13. Frequency dependent rejection versus offset frequency – scenario 

S13. ................................................................................................................................................71

Figure A-14. Frequency dependent rejection versus offset frequency – scenario 

S14. ................................................................................................................................................71

Figure A-15. Frequency dependent rejection versus offset frequency – scenario 

S15. ................................................................................................................................................71

Figure A-16. Frequency dependent rejection versus offset frequency – scenario 

S16. ................................................................................................................................................71

Figure A-17. Frequency dependent rejection versus offset frequency – scenario 

S17. ................................................................................................................................................71

Figure A-18. Frequency dependent rejection versus offset frequency – scenario 

S18. ................................................................................................................................................71

Figure A-19. Frequency dependent rejection versus offset frequency – scenario 

S19. ................................................................................................................................................72

Figure A-20. Frequency dependent rejection versus offset frequency – scenario 

S20. ................................................................................................................................................72

Figure A-21. Frequency dependent rejection versus offset frequency – scenario 

S21. ................................................................................................................................................72

Figure A-22. Frequency dependent rejection versus offset frequency – scenario 

S22. ................................................................................................................................................72

Figure A-23. Frequency dependent rejection versus offset frequency – scenario 

S23. ................................................................................................................................................72
xi

Figure A-24. Frequency dependent rejection versus offset frequency – scenario 

S24. ................................................................................................................................................72

Figure A-25. Frequency dependent rejection versus offset frequency – scenario 

S25. ................................................................................................................................................73

Figure A-26 Frequency dependent rejection versus offset frequency – scenario 

S26 .................................................................................................................................................73

Figure A-27. Frequency dependent rejection versus offset frequency – scenario 

S27. ................................................................................................................................................73

Figure A-28. Frequency dependent rejection versus offset frequency – scenario 

S28. ................................................................................................................................................73

Figure D-1. Frequency separation versus separation distance curves for scenario 

16 – VSS transmitter into GOES-N Sensor Data (SD) for VSS antenna height = 2 

m. .................................................................................................................................................106

Figure D-2. Frequency separation versus separation distance curves for scenario 

16 – VSS transmitter into GOES-N Sensor Data (SD) for VSS antenna height = 

20 m. ............................................................................................................................................107

Figure D-3. Frequency separation versus separation distance curves for scenario 

17 – VSS transmitter into GOES-N Processed Data Relay (PDR) for VSS antenna 

height = 2 m. ................................................................................................................................108

Figure D-4. Frequency separation versus separation distance curves for scenario 

17 – VSS transmitter into GOES-N Processed Data Relay (PDR) for VSS antenna 

height = 20 m. ..............................................................................................................................109

Figure D-5. Frequency separation versus separation distance curves for scenario 

18 – VSS transmitter into GOES-N Low Rate Info Transponder (LRIT WEFAX) 

for VSS antenna height = 2 m......................................................................................................110

Figure D-6. Frequency separation versus separation distance curves for scenario 

18 – VSS transmitter into GOES-N Low Rate Info Transponder (LRIT WEFAX) 

for VSS antenna height = 20 m....................................................................................................111

Figure D-7. Frequency separation versus separation distance curves for scenario 

19 – VSS transmitter into GOES-N Emergency Management Weather 

Information Network (EMWIN) for VSS antenna height = 2 m.................................................112

Figure D-8. Frequency separation versus separation distance curves for scenario 

19 – VSS transmitter into GOES-N Emergency Management Weather 

Information Network (EMWIN) for VSS antenna height = 20 m...............................................113
xii

Figure D-9. Frequency separation versus separation distance curves for scenario 

20 – VSS transmitter into GOES-N Multiuse Data Link (MDL) for VSS antenna 

height = 2 m. ................................................................................................................................114

Figure D-10. Frequency separation versus separation distance curves for scenario 

20 – VSS transmitter into GOES-N Multiuse Data Link (MDL) for VSS antenna 

height = 20 m. ..............................................................................................................................115

Figure D-11. Frequency separation versus separation distance curves for scenario 

21 – VSS transmitter into GOES-N Data Collection Platform Report (DCPR) for 

VSS antenna height = 2 m. ..........................................................................................................116

Figure D-12. Frequency separation versus separation distance curves for scenario 

21 – VSS transmitter into GOES-N Data Collection Platform Report (DCPR) for 

VSS antenna height = 20 m. ........................................................................................................117

Figure D-13. Frequency separation versus separation distance curves for scenario 

22 – VSS transmitter into GOES-N Command and Data Acquisition (CDA) 

Telemetry for VSS antenna height = 2 m. ...................................................................................118

Figure D-14. Frequency separation versus separation distance curves for scenario 

22 – VSS transmitter into GOES-N Command and Data Acquisition (CDA) 

Telemetry for VSS antenna height = 20 m. .................................................................................119

Figure D-15. Frequency separation versus separation distance curves for scenario 

23 – VSS transmitter into GOES-R Rebroadcast Data Transponder (GRB1 and 

GRB2) QPSK for VSS antenna height = 2 m..............................................................................120

Figure D-16. Frequency separation versus separation distance curves for scenario 

23 – VSS transmitter into GOES-R Rebroadcast Data Transponder (GRB1 and 

GRB2) QPSK for VSS antenna height = 20 m............................................................................121

Figure D-17. Frequency separation versus separation distance curves for scenario 

24 – VSS transmitter into GOES-R Rebroadcast Data Transponder (GRB1 and 

GRB2) 8PSK for VSS antenna height = 2 m...............................................................................122

Figure D-18. Frequency separation versus separation distance curves for scenario 

24 – VSS transmitter into GOES-R Rebroadcast Data Transponder (GRB1 and 

GRB2) 8PSK for VSS antenna height = 20 m.............................................................................123

Figure D-19. Frequency separation versus separation distance curves for scenario 

25 – VSS transmitter into GOES-R High Resolution Information Transponder 

(HRIT, EMWIN) for VSS antenna height = 2 m.........................................................................124

Figure D-20. Frequency separation versus separation distance curves for scenario 

25 – VSS transmitter into GOES-R High Resolution Information Transponder 

(HRIT, EMWIN) for VSS antenna height = 20 m.......................................................................125
xiii

Figure D-21. Frequency separation versus separation distance curves for scenario 

26 – VSS transmitter into GOES-R Data Collection Platform Report (DCPR #1) 

for VSS antenna height = 2 m......................................................................................................126

Figure D-22. Frequency separation versus separation distance curves for scenario 

26 – VSS transmitter into GOES-R Data Collection Platform Report (DCPR #1) 

for VSS antenna height = 20 m....................................................................................................127

Figure D-23. Frequency separation versus separation distance curves for scenario 

27 – VSS transmitter into GOES-R Data Collection Platform Report (DCPR #2) 

for VSS antenna height = 2 m......................................................................................................128

Figure D-24. Frequency separation versus separation distance curves for scenario 

27 – VSS transmitter into GOES-R Data Collection Platform Report (DCPR #2) 

for VSS antenna height = 20 m....................................................................................................129

Figure D-25. Frequency separation versus separation distance curves for scenario 

28 – VSS transmitter into GOES-R Command and Data Acquisition (CDA) 

Telemetry for VSS antenna height = 2 m. ...................................................................................130

Figure D-26. Frequency separation versus separation distance curves for scenario 

28 – VSS transmitter into GOES-R Command and Data Acquisition (CDA) 

Telemetry for VSS antenna height = 20 m. .................................................................................131
xiv

TABLES

Table 1. GOES-N/O/P communication parameters........................................................................3

Table 2. GOES-R communication parameters................................................................................4

Table 3. Radiosonde communication parameters. ..........................................................................5

Table 4. Potential interference scenarios for analysis...................................................................10

Table 5. Propagation model loss analysis combinations for interference analysis 

applicable for all analysis scenarios...............................................................................................22

Table 6(a). Required Eb/N0 and S/N for a BER of 1.0 × 10-3 for noise-like and 

CW interference for S/I = 20 dB....................................................................................................31

Table 6(b). Required Eb/N0 and S/N for a BER of 1.0 × 10-3 for noise-like and 

CW interference for S/I = 18 dB....................................................................................................31

Table 6(c). Required Eb/N0 and S/N for a BER of 1.0 × 10-3 for noise-like and 

CW interference for S/I = 15 dB....................................................................................................31

Table 7. Computation of received interference power from the GOES satellites 

into the VSS receiver. ....................................................................................................................37

Table 8. VSS configurations.........................................................................................................40

Table 9. Non-critical VSS parameters. .........................................................................................41

Table 10. Results from VSS baseline tests. ..................................................................................45

Table 11. Characteristics of GOES-N/O/P channels in the 1675-1695 MHz band......................54

Table 12. Results from GOES baseline tests. ...............................................................................60

Table 13. Results from Test 2, Step 3...........................................................................................60
xv

GLOSSARY OF TERMS

16QAM 16 quadrature-amplitude modulation

64QAM 64 quadrature-amplitude modulation

α protection ratio

B IF bandwidth before the demodulation of symbols or the baseband bandwidth

Bi interferer’s 3dB bandwidth (Hz)

Br receiver’s 3dB bandwidth (Hz)

BER bit error rate

COFDM coded orthogonal frequency division multiplex

CW continuous wave

DHS Department of Homeland Security

DVB-T Digital Video Broadcasting-Terrestrial

Eb energy per bit

Eb/N0 energy-per-bit-per-Hz-to-noise power ratio

Es energy per symbol

EMC electromagnetic compatibility

Df frequency offset

fi interferer’s center frequency

fr receiver’s tuned frequency

FDR frequency dependent rejection loss (dB)

FEC forward error correction

FS free-space loss model

FS–6 free-space loss model minus 6 dB along the slant range

Gt gain of the transmitter antenna (dBi)

Gr gain of the receiver antenna (dBi)

GOES Geostationary Operational Environmental Satellites

H(f) normalized receiver transfer function

hr receiver’s antenna height (m)

ht transmitter’s antenna height (m)

I interfering signal strength (dB)

Io interference spectral density (W/Hz)

I/N interference-to-noise ratio

IF intermediate frequency

ITM ITS Irregular Terrain Model

ITS Institute for Telecommunication Sciences
xvi

LO local oscillator

LOS line-of-sight

Lp free-space propagation loss

Loss propagation loss between the transmitter and the receiver (dB)

LossT total loss between the transmitter and the transmitter antenna (dB)

LossR total loss between the receiver and the receiver antenna (dB)

LossP loss due to the mismatch between the polarizations of the transmitter and the receiver

(dB)

MIMO multiple-in, multiple-out

N noise (dB)

NF noise figure (dB)

No noise spectral density (W/Hz)

NOAA National Oceanographic and Atmospheric Administration

NTIA National Telecommunications and Information Administration

NWS National Weather Service

OFR off-frequency rejection

OTR on-tune rejection

Pd desired signal level (dB)

Pi interfering signal level (dB)

Pi(f) power spectral density of the interfering signal

Prec received signal power (dBm)

Pt transmitted signal power (dBm)

QPSK quadrature phase-shift keying

R information or signaling rate (bps)

RF radio frequency

S desired signal

S/I signal-to-interference ratio

S/N signal-to-noise ratio

SDR software-defined radio

SNR signal-to-noise ratio

UFM Undisturbed-Field Model

VSG vector signal generator

VQiPS Video Quality in Public Safety

VSS Video Surveillance System
xvii

EXECUTIVE SUMMARY

The Institute for Telecommunication Sciences (ITS), the laboratory of the National 

Telecommunications and Information Administration (NTIA), was tasked by the Department of 

Homeland Security (DHS) to examine the potential of spectrally relocating a Federal agency’s 

telecommunication services and to identify the possibility of sharing spectrum bands with 

services of other agencies. The specific systems involved were the National Oceanographic and 

Atmospheric Administration’s (NOAA) Geostationary Operational Environmental Satellites 

(GOES) and receivers, NOAA’s radiosondes, and the DHS’s Video Surveillance System (VSS). 

NOAA’s systems currently operate in the 1675–1695 MHz band. There is a proposal to move 

DHS’s VSS frequency allocation from the 1755–1850 MHz band to the 1675–1695 MHz band. 

When a VSS (the potential entrant to the band) is deployed near NOAA’s equipment (the 

incumbents), there will be a potential for interference.

To perform such an analysis, ITS developed a method to calculate the interference that could 

occur when Federal services must share a common frequency band. The primary objective is that 

the quality of the mission-critical communications for each service is maintained. A detailed 

electromagnetic compatibility (EMC) analysis is necessary to identify both the highest potential 

interference scenarios and those scenarios that have little to no effect.

Two primary interference mitigation techniques can be implemented to achieve electromagnetic 

compatibility: frequency offset (Df) and separation distance. The Df and separation distance 

necessary for a desired level of interference rejection can be calculated based on the frequency 

dependent rejection (FDR) between the interference source and the victim receiver. For all 

potential interference interactions, the Df and the separation distance can be adjusted to arrive at 

a solution for operation on a non-interference basis. Based on this method, interference levels 

were calculated and Df and separation distances were determined for acceptable operation of the 

VSS and the two NOAA systems.

Considering the interference from the VSS into the radiosonde, a separation distance of 4-36 km 

would be required to avoid interference for a Df ranging from a 6 MHz offset to an on-tune 

condition, based on a required FDR. In the other direction, a similar level of interference from 

the radiosondes into the VSS receiver require protection distances from 30-90 km for a Df of 6 

MHz. Other deployment scenarios can have the potential of reducing the predicted separation 

distances and frequency offsets. A further refinement of this investigation would involve a 

statistical analysis with service probability considerations.

Interference from the GOES satellites into the VSS receiver is not a problem. The satellite’s 

signal amplitude at ground level is very low while the VSS receiver has a very low gain antenna, 

which reduces the interference potential of the satellite’s signal.

In the other direction (VSS into GOES), the satellite earth station receiver’s antenna has an 

extremely high gain to receive the satellite’s signal, making it very susceptible to interference 

from a nearby ground-based VSS transmitter. Due to the range of signals that the GOES 

satellites transmit in the 1675–1695 MHz band, the Df and separation distance necessary for an 

acceptable level of interference rejection vary but are significant in all cases. Assuming that the 

VSS operates off the GOES antenna’s main axis, for a separation distance of 0 km (co-located), 
xviii

the VSS must maintain a Df of 10–22 MHz or greater, which places the VSS outside the 

frequency band in question. For the VSS to operate with a Df of 0 MHz, the separation distance 

must be 10–50 km or greater.

It is not the intent of this report to make pronouncements on how to achieve coexistence within a 

shared band. The intent is to examine and illuminate the engineering questions that need to be 

answered so that those who are responsible for Federal services in a band may negotiate and 

cooperate with their colleagues who are responsible for other Federal services in the same band.
1

A SPECTRUM SHARING CASE STUDY LEADING TO THE DEVELOPMENT OF A

METHOD FOR IDENTIFYING INTERFERENCE POTENTIAL

Christopher Behm, Nicholas DeMinco, Timothy Riley, Linh Vu1

This report details a method that was developed to identify all potential forms of 

interference that could occur with a proposed collocation of three Federal systems 

in the 1675–1695 MHz frequency band. The incumbents are the National 

Oceanographic and Atmospheric Administration’s (NOAA) Geostationary 

Operational Environmental Satellites (GOES) and receivers and radiosonde 

systems. The entrant is the Department of Homeland Security’s (DHS) Video 

Surveillance System (VSS). The primary objective is that the quality of the 

mission-critical communications for each service is maintained.

A detailed electromagnetic compatibility (EMC) analysis is used to identify both 

the highest potential interference scenarios and those scenarios that have little to 

no effect. Two primary interference mitigation techniques can be implemented to 

achieve electromagnetic compatibility: frequency offset (Df) and separation 

distance. Based on the frequency dependent rejection (FDR) between the 

interference source and the victim receiver, the Df and separation distance 

necessary for a desired level of interference rejection can be calculated. For all 

potential interference interactions, the Df and the separation distance can be 

adjusted to arrive at a solution for operation on a non-interference basis. It is not 

the intent of this report to make pronouncements on how to achieve coexistence 

within a shared band. The intent is to examine and illuminate the engineering 

questions that need to be answered so that those who are responsible for Federal 

services in a band may negotiate and cooperate with their colleagues who are 

responsible for other Federal services in the same band.

Keywords: spectrum sharing; FDR; frequency dependent rejection; frequency offset; separation 

distance; electromagnetic compatibility; interference mitigation

1. INTRODUCTION

As part of the President’s Spectrum Initiative to vacate 500 MHz of Federal spectrum to spur the 

innovation of new wireless services, Federal agencies have been instructed to examine the 

potential of spectrally relocating their telecommunication services and sharing spectrum bands

with services of other agencies. The Institute for Telecommunication Sciences (ITS), the 

laboratory of the National Telecommunications and Information Administration (NTIA), was 

 1 The authors are with the Institute for Telecommunication Sciences, National Telecommunications and Information 

Administration, U.S. Department of Commerce, Boulder, CO 80305.
2

tasked to conduct such an evaluation. This report details the method developed to evaluate the 

feasibility of coexistence of Federal communications services.

This work was performed under the direction of the Department of Homeland Security (DHS) 

lead task group charged with examining an exit strategy for equipment assigned to operate in the 

1755–1850 MHz band. It was proposed to relocate the frequency assignments of their services, 

which include a video surveillance system (VSS), to the 1675–1695 MHz band, which is

currently occupied by satellite and radiosonde communications services that are central to the 

mission of the National Oceanographic and Atmospheric Administration (NOAA).

The generalized method described in this report can be used to evaluate interference when other 

Federal services may be required to relocate to already occupied bands. All of the services being 

evaluated are unique, not only from a mission standpoint but also from a physical perspective. 

The mission of communications in a band can vary widely and will form a basic set of subjective 

constraints for an interference analysis. Physically, the propagation mechanisms that affect 

communication signals are not consistent across all radio frequencies. The physical 

characteristics of the band comprise a set of subjective inputs to an interference analysis. The 

principles of interference analysis, which describe how to maintain reliable communications for 

all systems collocated in a band, will be similar across the spectrum.

This report will detail the multitude of ways that the NOAA and DHS communications systems 

could interact and the potential forms of interference that could occur with the proposed merging 

of Federal services in the 1675–1695 MHz band. The analysis determines if interference will 

affect the performance of each system. The primary objective is that the quality of the missioncritical communications for each agency is maintained. Through this analysis, the worst-case 

scenarios will be identified so that subsequent tests and evaluations of equipment entering the 

incumbent band will be clearly understood by all involved. A detailed electromagnetic 

compatibility (EMC) analysis is necessary to identify both the highest potential interference 

scenarios and those scenarios that have little to no effect.

Performing an EMC analysis such as this will allow evaluation of spectrum sharing and 

frequency reassignments. Regulatory agencies need to perform EMC analyses to address 

potential interference problems between users of the crowded electromagnetic spectrum.
3

2. EQUIPMENT DESCRIPTIONS

2.1 GOES-N/O/P Systems

The Geostationary Operational Environmental Satellite (GOES) systems have several 

components that occupy the 1675–1695 MHz band [1]. Of the three currently deployed GOES 

satellites (N/O/P), two are operational and one is parked in a central location for use as a spare 

when needed. The two operational satellites are positioned over the Atlantic (at 75°W longitude, 

referred to as GOES-East) and the Pacific (135.4°W longitude, referred to as GOES-West). 

Table 1 lists the important physical parameters that describe the GOES-N/O/P transmitters, 

receivers, and antenna subsystems.

Table 1. GOES-N/O/P communication parameters.

Link Designation SD PDR LRIT2 EMWIN3 MDL DCPR4 CDA TLM

Function Name Sensor 

Data

Processed 

Data Relay

Low Rate 

Information 

Transmission

Emergency 

Manager’s 

Weather 

Informatio

n Network

Multiuse 

Data Link

Data Collection 

Platform Report

Command 

and Data 

Acquisition 

& 

Telemetry

Frequency 

(MHz) 1676.0 1685.7 1691.0 1692.7 1681.478 1694.5, 1694.8

(1694.4474–26)5 1694.0

Modulation UQPSK BPSK PCM/NRZL/BPSK OQPSK QPSK 8PSK PCM/BiØ-

-L/PM

Symbol Rate 

(ksps) TBD TBD 293.0 35.94 TBD

i) 300 bps - the output 

symbol rate shall be 150 

symbols per second 

±0.025%

ii) 1200 bps - the output 

symbol rate shall be 600 

symbols per second6

TBD

Data Rate (kbps) 2660 2110 128.0 19.2 400 0.1/0.3/1.2

4000 bps 

operational

1000 bps 

contingency

Data format 

notes GVAR CCSDS 

coding

i) 200 FDMA channels 

@ 1500 Hz- 100 and 

300 bps

ii) 33 FDMA channels @ 

3000 Hz - 1200 bps

Rx Max BER

(bps) 10-8 10-6 10-8 10-8 10-8 10-6

Tx filter

-3 dB 2.2 MHz 2.2 MHz 200 kHz 18 kHz 150 kHz 507 kHz 12 kHz

Tx Filter

-20 dB 8.0 MHz 6.2 MHz 600 kHz 26 kHz 400 kHz 650 kHz 40 kHz

Tx Filter

-60 dB 11.2 MHz 11.0 MHz 4.5 MHz 200 kHz 4.0 MHz 5.6 MHz 2.0 MHz

Tx Antenna

EOC Gain (dBi) 14.5 14.5 (± 9°) 14.5 (± 9°) 14.5 (± 9°) 14.5 14.5 (± 9°) -14.0

 2 http://www.noaasis.noaa.gov/LRIT/pdf-files/3_LRIT_Receiver-specs.pdf 3 http://www.nws.noaa.gov/emwin/transition/EMWIN-OQPSK%20Specifications%20Final.doc 4 http://www.noaasis.noaa.gov/DCS/docs/DCPR_CS2_final_June09.pdf 5 http://www.noaasis.noaa.gov/DCS/docs/MIT-Lincoln_Lab_RRC_Pres.ppt 6 http://www.noaasis.noaa.gov/DCS/htmfiles/GOES_13-14_freq_offset.html
4

In all of the United States and its territories, there are 26 GOES earth stations owned and 

operated by the Federal Government. Appendix C lists the stations by name, location, and the 

antenna bearings (azimuth and elevation) for the two operational GOES satellites. Since the 

1675-1695 MHz band only contains downlink channels, all of these sites are assumed to receive 

one or more channels from one or both of the operational satellites (GOES-West and GOESEast). Due to the extreme angles involved, some of the sites receive channels from only one 

satellite (at the sites in Hawaii and Alaska, GOES-East is below the horizon, and GOES-West is 

close to the horizon for the Puerto Rico site).

Due to differences in their individual requirements, not all sites monitor both satellites. Any site 

monitoring both satellites would need two antennas; physical constraints would require the 

antennas to be separated by some distance. However, this distance would be small enough 

compared to the overall distance to the satellites, that they could be considered co-located and 

still maintain reasonable accuracy regarding any geometric calculations.

Only interference involving these 26 sites will be considered in this report. Any privately owned 

and operated receiving sites are outside the scope of this report.

2.2 GOES-R Systems

The next generation GOES satellite (GOES-R) is scheduled to be launched in 2015. As a result, 

many of the design parameters (Table 2) have not been made available.

Table 2. GOES-R communication parameters.

Link Designation DCPR #1 DCPR #2 GRB #1 GRB #2 HRIT/EMWIN HK TLM

Function Name Data Collection 

Platform Report

GOES-R

Re-Broadcast

High Rate 

Information 

Transmission/ 

Emergency 

Managers Weather 

Information 

Network

Command and 

Data Acquisition & 

Telemetry

Frequency (MHz) 1679.7 to 1680.4 1686.6 1694.1 1693.0

Modulation FDM 8PSK QPSK 8PSK BPSK BPSK

Maximum Data Rate 

(kbps) 1.8/channel 17332 23480 927 64

Data format notes 933 channels @ 750 Hz 

steps* DVB-S2

Max BER (bps) 10-6 10-10 10-8 10-7

RF Selectivity -3 dB 27.0 MHz 27.0 MHz 27.0 MHz 27.0 MHz

RF Selectivity -20 dB 35.0 MHz 35.0 MHz 35.0 MHz 35.0 MHz

RF Selectivity -60 dB 50.0 MHz 50.0 MHz 50.0 MHz 50.0 MHz

IF Selectivity -3 dB 0.6/0.15 kHz 8.7 MHz 7.9 MHz 950 kHz 45.0 kHz

IF Selectivity -20 dB 1.2/0.3 kHz 10.9 MHz 9.8 MHz 1430 kHz 80.0 kHz
5

Link Designation DCPR #1 DCPR #2 GRB #1 GRB #2 HRIT/EMWIN HK TLM

IF Selectivity -60 dB 6.0/1.6 kHz 13.0 MHz 12.0 MHz 4000 kHz 350.0 kHz

Polarization Linear RHCP & LHCP Linear RHCP

Data for all of the transmitters was extracted from the Fast Track report [1] where available.

2.3 Radiosondes

A radiosonde is a measurement system that consists of a battery-powered instrument package 

attached to a balloon and a receiver that may use a motorized tracking antenna. The transmitter 

measures dry-bulb and wet-bulb temperatures and barometric pressure directly; wind speed and 

direction are calculated from either the tracking antenna’s orientation or an on-board GPS 

receiver. Data is generally correlated to the height above the ground and can be used to detect 

atmospheric boundary layers. Radiosondes are allowed to operate in the band 1675-1683 MHz.

Table 3. Radiosonde communication parameters.

Transmitter Function Transmitter Parameter Receiver Function Receiver Parameter

Modulation FSK Modulation FSK

Duty Cycle in Percent 100 Duty Cycle in Percent 100

Maximum Data Rate (bps) 9600 Maximum Data Rate (bps) 9600

Emission Spectrum 3 dB 

Bandwidth (kHz)

135 Receiver IF Bandwidth 

(kHz)

150

Relative Attenuation (dB) 

vs. Frequency Offset

Frequency Offset (kHz) Receiver Selectivity (dB) Receiver Frequency Offset 

(kHz)

3

36

48

52

56

58

67.5

200

400

600

800

1000

3

20

60

75

270

600

Peak Power (dBm) 23.8 Sensitivity (dBm)

Noise Figure (dB)

-115.7

6.5

Antenna Gain (dBi) 4.3 Maximum Antenna Gain 

(dBi)

28.0

Antenna Polarization LHCP Antenna Polarization LHCP

Interference Level (dBm) 

based on I/N = -6.0 dB

-121.7

Information on the radiosondes was supplied by DHS (the sponsor).

2.4 Video Surveillance Subsystem (VSS)

The VSS consists of a coded orthogonal frequency division multiplex (COFDM) transmitter, 

capable of transmitting a single video channel following the Digital Video Broadcasting-
6

Terrestrial (DVB-T) standard, and two audio channels, with 250 mW output power and a 

maximum bandwidth of 8 MHz. The matching receiver has two antenna input channels, allowing 

for a single transmit, dual receive, multiple-in, multiple-out (MIMO) antenna configuration. The 

receiver has a front panel received signal level bar graph display for each input channel and is 

able to display bit-error rate (BER) and signal-to-noise ratio (SNR) for each channel via an 

overlay at the video output. The system was supplied by the sponsor as a prototype unit that was 

specially re-programmed to operate in the target 1675-1695 MHz band.

Both devices support eight frequency channels within their operating band that can be selected 

by manual switches. Each device can be connected to a computer through a serial port for 

programming the various parameters (frequency, bandwidth, guard interval, mode, forward error 

correction (FEC) rate, polarity, etc.).

The purpose of the guard interval is to provide a space between successive symbols so that 

extraneous signals (due to propagation delays and multipath effects) do not corrupt the data 

stream. In DVB-T, four guard interval values are available, specified as fractions of a symbol 

period (1/32, 1/16, 1/8, and 1/4).

The VSS parameters relevant to the tests (Tables 8 and 9 in Section 5.2) came from information 

supplied by the sponsor. Additional information came from the operation manuals that 

accompanied the VSS hardware.

2.5 General Comments on Equipment and the Analysis

Appendix B contains a more detailed description of the published equipment specifications for 

each system; those specifications will be used in this analysis. The analysis starts with the 

collection of transmitter and receiver specifications for the systems that are proposed to occupy 

the 1675–1695 MHz band. The systems affected by this proposed relocation include NOAA’s 

GOES-N/O/P and GOES-R satellites and receivers (incumbents), NOAA radiosondes 

(incumbents), and the VSS (the entrant). In the case of GOES-R, referenced parameters only 

refer to current design specifications and not actual equipment. The specification data, once 

compiled, helps identify what additional data will be necessary to continue the analysis. As with 

many calculations involving complex communications systems, some parameters will need to be 

estimated and/or measured. In cases where measurements and/or estimation are required,

pertinent details will be given in this document.

NOAA uses a geographically distributed receiver system. When VSS systems operate in 

proximity to the NOAA GOES and radiosonde receiver system, there will be a potential for 

interference. The analysis will not be concerned with actual user patterns but will concentrate on 

examining potential interactions. This approach will insure to both the entrant and incumbent 

system users that all interference possibilities will be examined. It is assumed that some 

interference scenarios will be of low enough probability that more resources can focus on higher 

probability scenarios. Therefore, an electromagnetic compatibility (EMC) analysis will be used 

to evaluate the compatibility of all systems that are planned to occupy the band.

An apparent inconsistency should be noted. One main parameter used in the analysis was the 

maximum bandwidth of the VSS, which was stated to be 7.5 MHz in the sponsor-supplied 
7

specifications. When ITS received the actual hardware, it was found that the VSS could be set to 

utilize bandwidths of 6, 7, and 8 MHz, but not 7.5 MHz. As a result, the analysis uses 7.5 MHz, 

while the VSS was set to 8 MHz for testing. The difference between the analysis values for the 

two bandwidths will be no more than 10 × log(8.0/7.5), or 0.28 dB (assuming a uniform power 

spectral density, which is a close description of the VSS transmitter’s output). This is much less 

than the 1 dB resolution of the attenuators used, the measurement equipment’s noise figures, or 

the tested equipment’s repeatability.
8

3. INTERFERENCE ANALYSIS APPROACH

Propagation loss is in part a result of the separation distance between an interference source 

(transmitter) and a victim (receiver) and is one mechanism for obtaining EMC between them. To 

evaluate this mechanism, the analyst needs to calculate the radio-wave propagation loss between 

the systems using an appropriate propagation model or models. Another EMC mechanism would 

be the frequency dependent rejection (FDR) between the interference source and the victim 

receiver. The FDR of a communication receiver is a figure of merit indicating how well a 

receiver is isolated from potential interference sources as a function of frequency. The victim

receiver’s ability to reject interference is a function of the following parameters of the 

interferer’s transmitter:

• Operating frequency

• Emission bandwidth

• Transmitter power

• Modulation

• Antenna parameters

Characterizing the interference potential is also a function of the following parameters of the

victim’s receiver:

• Operating frequency

• Bandwidth

• Sensitivity

• Modulation

• Off-tune rejection

• On-tune rejection

• Frequency dependent rejection

• Antenna parameters

The antenna orientations of the interference source and victim receiver are important for 

calculating separation distances, as well as the relative positions of the source and receiver. 

Additional parameters for the receiver would include a signal-to-noise ratio for the required BER

or similar performance metric.

The parameters necessary for an interference analysis are first gathered from the published 

specifications of each receiver and transmitter. Typical transmitter information includes:

• Transmitter power

• Operating frequency

• Modulation(s)

• Emission bandwidth with roll-off of the emission spectra at the band edges

• Antenna gain

• Antenna patterns

• Feed losses
9

Receiver information includes:

• Operating frequency

• Sensitivity

• Bandwidth with sufficient information to characterize rejection outside the receiver 

bandwidth

• Interference-to-desired signal ratio for desired performance

• Antenna parameters, including gain patterns

A required interference-to-noise ratio (I/N) or desired signal-to-interference signal ratio (S/I) are 

also needed to perform the interference analysis. This is where the type of modulation must be 

accounted for. In the absence of adequate interference interaction information between different 

modulations, the I/N will be set to -6.0 dB for general analysis of systems interference, and

−10.0 dB where requirements are critical or there is a safety of life requirement. This is a simple 

but adequate approach, but more sophisticated procedures have been developed using an energyper-bit-per-Hz-to-noise power ratio (Eb/N0) for a required BER which could help to determine a 

more specific I/N criterion.

The analysis approach used here determines the S/I, the I/N, and the signal-to-noise ratio (S/N)

based on the modulation type, the bandwidth, and the data rate. A digital system usually has a 

BER requirement for proper operation and this BER corresponds to a certain S/N. There are 

tables and graphs with this information [2], [3]. The required BER is sometimes associated with 

Eb/N0, where N0 is the noise per unit bandwidth, N0·= N/B, and B is the IF bandwidth directly 

before demodulation. The relationship between required S/N and Eb/N0 is:

0

Eb B S

N RN

= ×

where R is the information or signaling rate in bits per second, and S is the signal power. The 

BER versus Eb/N0 curves allow us to determine the Eb/N0 values for a desired BER and calculate 

the S/N necessary to meet the required system performance.

3.1 Analysis Scenarios

After obtaining all the parameters of the systems involved, the analysis scenarios are created by 

deciding what interference interactions are going to take place. Table 4 describes all of the 28 

potential interference interactions and Appendix B lists descriptions of the scenarios in detail. By 

knowing the deployment procedures for each of these systems, the analyst can set up a range of 

possible interference distances and antenna heights at which the different geometric scenarios of 

the systems can occur. Radio waves propagate differently over these different scenarios, because 

of the different distances and antenna height combinations involved. The basic phenomena that 

can occur over these scenarios that will affect these radio waves include refraction, diffraction, 

line-of-sight propagation, and troposcatter. The propagation models selected for each scenario 

result in the best prediction of radio-wave propagation loss between the candidate interference 

sources and the victim receivers with respect to distances and antenna heights.
10

Table 4. Potential interference scenarios for analysis.

Interference

Scenario

Interference Receiver

Source | Service Antenna Height Receiver | Service Antenna Height

S01 VSS 2 m and greater Radiosonde 5 m

S02 Radiosonde 1m to 33 km VSS 2 m and greater

S03 GOES-N | SD 35,787 km VSS 2 m and greater

S04 GOES-N | PDR 35,787 km VSS 2 m and greater

S05 GOES-N | LRIT 35,787 km VSS 2 m and greater

S06 GOES-N | EMWIN 35,787 km VSS 2 m and greater

S07 GOES-N | MDL 35,787 km VSS 2 m and greater

S08 GOES-N | DCPR 35,787 km VSS 2 m and greater

S09 GOES-N | CDALM 35,787 km VSS 2 m and greater

S10 GOES-R | GRB #1 35,787 km VSS 2 m and greater

S11 GOES-R | GRB #2 35,787 km VSS 2 m and greater

S12 GOES-R | HRIT 35,787 km VSS 2 m and greater

S13 GOES-R | DCPR #1 35,787 km VSS 2 m and greater

S14 GOES-R | DCPR #2 35,787 km VSS 2 m and greater

S15 GOES-R | CDA TLM 35,787 km VSS 2 m and greater

S16 VSS 2 m and greater GOES-N | SD 20, 25, 33 m

S17 VSS 2 m and greater GOES-N | PDR 20, 25, 33 m

S18 VSS 2 m and greater GOES-N | LRIT 20, 25, 33 m

S19 VSS 2 m and greater GOES-N | EMWIN 20, 25, 33 m

S20 VSS 2 m and greater GOES-N | MDL 20, 25, 33 m

S21 VSS 2 m and greater GOES-N | DCPR 20, 25, 33 m

S22 VSS 2 m and greater GOES-N | CDA TLM 20, 25, 33 m

S23 VSS 2 m and greater GOES-R | GRB #1 20, 25, 33 m

S24 VSS 2 m and greater GOES-R | GRB #2 20, 25, 33 m

S25 VSS 2 m and greater GOES-R | HRIT 20, 25, 33 m

S26 VSS 2 m and greater GOES-R | DCPR #1 20, 25, 33 m

S27 VSS 2 m and greater GOES-R | DCPR #2 20, 25, 33 m

S28 VSS 2 m and greater GOES-R | CDA TLM 20, 25, 33 m

The scenarios can be ranked by evaluating their applicable technical parameters, as well as 

taking into consideration non-technical aspects of the systems, such as the type of information 

being transmitted (video, voice, still images, raw digital data), how the information will be used 

(subjective, task-based quality requirements), and information on the users themselves 

(deployment parameters such as position and density).

For a full analysis, considerations such as usage patterns, geographical deployment, and missioncritical and service priorities need to be taken into account; this information must be supplied by 

the potential victim. In considering the VSS, the quality requirements of the video (task-based 
11

video quality) were not addressed. BER can be used as an objective measure until more 

sophisticated metrics are developed. For the purposes of these tests, a subjective method based 

on perceived video failure was used.

This analysis has identified 28 scenarios. The number of necessary tests could be many multiples 

of 28, given the possibility of using up to four different propagation models (based on separation 

distance and antenna height) and taking into account multiple antenna configurations and 

modulation schemes. It is necessary to prioritize the scenarios and variants to reduce the number 

of tests to a manageable number.

Determining interference versus Df and separation distance for the various scenarios (and 

variants) is the ultimate goal. Interference versus separation distance, given a fixed channel plan, 

will form the basis to develop exclusion zones. Interference versus Df will aid in the development 

of channel plans.

3.2 Computation of the Received Interference Signal Levels

It is important to use the correct propagation model for different geometric scenarios to 

determine the signal strength of the interfering signal. Use of the wrong propagation model could 

result in either predicting interference when no interference is present or not predicting 

interference when interference is actually present. Basing subsequent interference mitigation 

techniques on inaccurate use of propagation models could result in either over- or undercompensation for calculated interference. This could result in an expensive mitigation solution or 

unexpected interference. An example of this is the use of free-space loss, which does not include 

all of the physical phenomena (such as the surface wave and the effects of the ground on the 

antenna performance) in the prediction of transmission loss. The propagation effects of 

diffraction and troposcatter are also not included in free-space loss. ITS has developed many 

specific radio-wave propagation models to meet the requirements for EMC analyses and other 

applications. These radio-wave propagation models have to be used in accordance with the range 

restrictions on input parameters.

Four propagation models were used to determine the basic transmission loss and received signal 

levels: the Undisturbed-Field Model (UFM) [6], the ITS Irregular Terrain Model (ITM) [7], [8], 

a free-space loss model (FS), and a free-space loss model minus 6 dB along the slant range

(FS-6) [9]. These models assume that the propagation takes place over a smooth spherical earth. 

The UTM, FS, and FS-6 models do not include the effects arising from terrain. The ITM model 

can take terrain effects into account in its point-to-point mode but, in this case, it was used in its 

area prediction mode, which uses a smooth spherical earth. The use of the idealized smooth 

spherical earth is a worst case for an interference analysis, since the loss is at a minimum 

compared to the case where terrain effects are present. The minimum propagation loss is what 

should be used to assure that the interference analysis provides the maximum possible 

interference signal-level prediction.

There are situations where a minimum propagation loss could occur with a terrain-covered earth 

when the interfering transmitter and victim receiver are at very different heights due to the actual 

terrain elevations and there is a clear path between the interfering transmitter and victim receiver. 
12

This could be examined further either statistically or when the specific geographic locations are 

known and the actual terrain can be determined and used as input.

The ITM is a good method for medium to long distances with antenna heights of up to 3,000 

meters, and it includes line-of-sight, diffraction, and troposcatter phenomena over a spherical 

earth. The ITM model has been verified with measured data and other accurate models. It takes 

the presence of ground into account in addition to diffraction around a spherical earth. The ITM 

model also takes into account troposcatter propagation. The ITM model can also be used with 

input files of terrain for specific locations when the terrain files are available.

The UFM includes line-of-sight phenomena at medium and close-in distances less than 6.8 km, 

and for low antenna heights less than 10 meters [6]. It includes the direct and reflected waves as 

well as the surface wave. The surface wave is an important component of the total 

electromagnetic wave at close-in distances even at the higher frequencies. The distance of 6.8 km 

is used because at a frequency of 1800 MHz the Earth can be assumed flat out to a distance of 

6.8 km [6]. The UFM will include all of the destructive and constructive interference behavior 

over a real smooth-earth environment, which will appear on a plot of received signal versus 

distance plot with many oscillations (Figures 1(a1) and 1(b1) for close-in distances). The UFM 

has been verified with measured data and other accurate propagation prediction techniques.
13

(a1) Low VSS antenna height, close distance,

ht = 2.0 m, hr = 5.0 m.

(a2) Low VSS antenna height, far distance,

ht =2.0m, hr = 5.0m.

(b1) High VSS antenna height, close distance,

ht = 20.0 m, hr = 5.0 m.

(b2) High VSS antenna height, far distance,

ht = 20.0 m, hr = 5.0 m.

Figure 1. Example plots of received power versus distance for the

VSS to Radiosonde interference scenario S01 of Table 4.

The analysis technique can be best explained by going through an actual interference analysis 

example. The first interference interaction (denoted by S01 from Table 4) involves the 

interference from the VSS transmitter to the victim Radiosonde receiver. For long distances and 

both low and high antenna heights, Figures 1(a2) and 1(b2) don’t show the constructive and 

destructive interference, since it doesn’t occur at the longer distances. For the shorter distances of 

less than 6.8 km, the vertical and horizontal scale factors of Figures 1(a1) and 1(b1) make the 

constructive and destructive interference more discernible. Rather than trying to determine the 

exact received signal level at a specific distance, which may be difficult due to the occurrence of 

lobes in the received power versus distance curve, it is advisable to take the envelope of the 

maximum received signal level predicted by this model for a worst-case analysis. The height of 

the maximums (distance between the average value of received signal level and the maximum 

value of received signal level) can be as much as 6.0 dB over perfectly conducting ground. The 

maximum value of this excursion over average ground is about 4.0 to 5.0 dB.

The remaining two received signal prediction models are the FS and the FS-6. The FS-6 model

results in an absolute maximum signal level that follows the minimum propagation loss predicted

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

10

20

0 1 2 3 4 5 6 7 8

ITM

FS-6

FS

UFM

Received Power (dBm)

Distance (km)

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

10

20

Received Power (dBm)

Distance (km)

0 10 20 30 40 50 60 70 80 90 100

ITM

FS-6

FS

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

10

20

0 1 2 3 4 5 6 7 8

Received Power (dBm)

Distance (km)

ITM

FS-6

FS

UFM

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

10

20

0 10 20 30 40 50 60 70 80 90 100

Received Power (dBm)

Distance (km)

ITM

FS-6

FS
14

by the UFM. The FS-6 model is more suitable than FS model because it takes into account the 

maximum possible interference signal level due to interference phenomena predicted by the 

UFM. This is demonstrated by the plots in Figures 1(a1) and 1(b1) for the UFM. This 

phenomenon occurs in line-of-sight (LOS) scenarios. The FS model does not take into account 

any propagation phenomena other than the free-space loss. Decisions on whether to use the UFM

or the FS-6 models are made based on which method would provide the best estimate of received 

signal level. An example of this is explained in the next paragraph and Figure 1(b1).

One must be careful in choosing the correct propagation model for EMC analysis. There are 

situations where the UFM should be used in preference to the two free-space models. 

Figure 1(b1) demonstrates that the predicted received interference signal level for the UFM is 

less than the received level predicted by the FS-6 model for distances greater than 3 km, and 

would be more accurate for distances above 3 km. However, for distances less than 3 km the 

UFM has lobes in the received power predictions, which are real, but are difficult to use as a 

general limit for maximum signal if the exact distance is not known. These lobes are bounded by 

the FS-6 model. In this case, the FS-6 model would be better to use for distances that are less 

than 3 km. The UFM is a more accurate model than the FS-6 model, so it would result in lesser 

separation distances for avoiding interference than the other free-space models for distances 

greater than 3 km and less than 6.8 km.

For distances less than 3 km the UFM (Figure 1(b1)) predicts the exact received signal level, but 

the FS 6 model follows the envelope of the varying signal level. In this case, it would be better to 

use the FS 6 model rather than be concerned about the actual locations of the peaks and nulls in 

the received signal level. The amount of frequency dependent rejection required would also be 

less for a fixed distance.

Figures 1(a2) and 1(b2) for the far distance scenarios demonstrate that the received signal level 

for the ITM model is much less than that for the two free-space models. This would allow much 

reduced separation distances and frequency dependent rejection for avoiding interference.

3.3 Noise Level Predictions for the Analysis

The noise level of the victim receiver in the analysis can be determined from the equation [10]:

Noise dBm dBm Hz NF dB B Hz ( ) =− + + 174 / ( ) ( ) 10log( n ( ))

where:

NF is the receiver’s noise figure (dB)

Bn is the receiver’s noise equivalent bandwidth in (Hz).

The received signal power from a desired transmitter is given by:

( ) ( ) () ()

() () () ()

P dBm P dBm G dBi G dBi rec t t r

Loss dB LossT dB LossR dB FDR dB

= ++

−− − −

where:
15

Prec is the received signal power from the desired transmitter or the interference source 

(dBm)

Pt is the transmitted signal power from the desired transmitter or the interference 

source (dBm)

Gt is the gain of the antenna at the desired transmitter or the interference source (dBi)

Gr is the gain of the antenna at the receiver (dBi)

Loss is the propagation loss between the desired transmitter (interference source) and 

the receiver (dB)

LossT is the loss between the transmitter (interference source) and its antenna, including

cable and feed losses (dB)

LossR is the loss between the receiver and its antenna, including cable loss (dB)

FDR is the frequency dependent rejection loss that is a result of the transmitter and 

receiver frequency differences, emission bandwidth of the transmitter, and filter 

characteristics of the receiver (dB).

3.4 Protection Ratio

The interference protection ratio, α, is a value indicating the tolerance between the desired signal 

level, Pd, and the interfering signal level, Pi:

( ) P P dB d i − ≥α

The protection ratio forms the basis of the interference criteria. In this analysis, the interference 

is based on the published maximum BER performance for GOES-N, an assumed maximum BER

performance for GOES-R, and the minimum performance criteria for video quality as 

determined by the testing described in Section 5. Once these performance criteria are established, 

the protection ratio can be determined. The protection ratio determines the minimum separation 

distance between the interferer and the target.

3.5 Frequency-Dependent Rejection (FDR)

If analysis determines that a reasonable separation distance between the on-tune interference 

source and the victim receiver is not adequate to reduce the interfering signal to an acceptable 

level, then it is necessary to apply FDR. FDR (in dB) is the signal loss that is calculated from the 

transmitter and receiver center frequency offset (Δf), emission bandwidth of the transmitter, and 

filter characteristics of the receiver. FDR is the ability of a receiver to reject a specific interfering 

signal at a frequency offset from the receiver’s center frequency. FDR defines the necessary 

frequency separation between the receiver and interferer to avoid interference [5]. It also can be 

used to determine the physical separation distance required, at a given Δf, to avoid interference. 

The plots of Figure 2 are examples taken from a single scenario for an entrant transmitter and 

incumbent receiver. The plots were calculated using the received interference signal power, and 

the S/I, S/N, and I/N ratios for the example scenario.
16

(a1) Low VSS antenna height,

close distance, ht = 2.0 m, hr = 5.0 m.

(a2) Low VSS antenna height,

far distance, ht =2.0 m, hr = 5.0m.

(b1) High VSS antenna height,

close distance, ht = 20.0 m, hr = 5.0 m.

(b2) High VSS antenna height,

far distance, ht = 20.0 m, hr = 5.0 m.

Figure 2. Example plots of FDR versus separation distance for the

VSS to Radiosonde interference scenario S01 of Table 3.

FDR is a convenient way to define the discrimination of the communications circuit in terms of 

attenuation or rejection due to receiver selectivity [4]. Typically, the FDR is calculated from the 

transmitter spectral density Pi(f) and the normalized receiver transfer function or receiver 

selectivity curve. FDR is given as the ratio of the total effective power at the receiver over the 

transmitted power.

( ) ( )

0

2

0

( )

( )

i

i

P f df

FDR f

P f H f f df

∞

∞ D =

+ D

∫

∫

where:

Pi(f) is the power spectral density of the interfering signal

H(f) is the normalized receiver transfer function

Δf = fi-fr where fi is the interferer’s center frequency and fr is the receiver’s tuned 

frequency.

30

40

50

60

70

80

90

100

110

120

0 1 2 3 4 5 6 7 8

Distance (km)

Frequency Dependent Rejection (dB)

FDR for Free Space Loss

FDR for Exact Model

-30

-20

-10

0

10

20

30

40

50

60

70

80

0 10 20 30 40 50 60 70 80 90 100

Frequency Dependent Rejection (dB)

Distance (km)

0 1 2 3 4 5 6 7 8

Distance (km)

Frequency Dependent Rejection (dB)

50

60

70

80

90

100

110

120

FDR for Free Space Loss

FDR for Exact Model

-30

-20

-10

0

10

20

30

40

50

60

70

80

0 10 20 30 40 50 60 70 80 90 100

Frequency Dependent Rejection (dB)

Distance (km)
17

The above assumes that the channel transfer function is slowly varying relative to the product of 

the interferer spectral density and the receiver transfer function [5]. This is often not the case 

near the radio horizon.

When Δf = 0 then the FDR equals the on-tune rejection (OTR). When Δf ≠ 0 then the offfrequency rejection (OFR), which is the additional rejection that occurs when the receiver is 

detuned relative to the interferer, can be found from the following:

OFR FDR OTR = −

The calculation of the FDR shows the importance of determining the IF filter bandwidth at the 

last stage before demodulation to characterize the interference potential accurately. In the case 

where the receiver bandwidth is less than the interferer bandwidth, OTR can be approximated 

from the following:

10log r

r i

i

B OTR B B

B

  ≈ ≤    

where:

Br is the receiver’s 3dB bandwidth (Hz)

Bi is the interferer’s 3dB bandwidth (Hz).

For this analysis, estimations of the integrals in the FDR equation will be used when possible.

The required FDR was calculated for the VSS to Radiosonde interferer/receiver pair as a 

function of separation distance (Figure 2). The FDR achieved as a function of the transmitter and 

receiver parameters mentioned previously and the frequency offset also was calculated 

(Figure 3). This results in the estimation of the potential interference rejection for this entrant 

transmitter into the incumbent receiver. The FDR was computed for all interactions of Table 4. 

Appendix A contains the plots of FDR versus Δf for all of the interactions of Table 4. The plots

in Appendix A contain the total of on- and off-tune rejection that is equal to the FDR. These 

plots will determine the amount of frequency offset needed to attain compatibility and this can be 

used to trade off or reduce the required separation distance between the interferer and the victim 

receiver.
18

Figure 3. Example plot of FDR versus frequency offset for the

VSS to Radiosonde Interference Scenario S01 of Table 4.

The FDR required to bring the interference signal level down to meet the I/N and S/N

requirement is given by:

FDR dB P dBm N dBm I N dB ( ) = −− rec ( ) ( ) / ( )

0

S R Eb

NNB

= ×

( ) ( ) ( ) I SS dB dB dB

NNI = −

The S/N = 7.3 dB was computed from an Eb/No = 7.0 dB, a data rate R = 8.0 Mbps and a

bandwidth B = 7.5 MHz [2]. The BER curves will allow for the calculation of the SNR at a given 

signal-to-interference (S/I) ratio. The Eb/No = 7.0 was obtained from the curves in [2] for a precorrection BER of 10-3 and QPSK modulation with an S/I = 20 dB. The resultant I/N is -12.7 dB. 

The FDR computed from the equation is a function of distance since the received power 

Pr (dBm) is also a function of distance, so the plots in Figure 2 are a function of distance.

This analysis assumes that the radiosonde’s receiver antenna is pointed directly at the VSS 

transmitter, which is worst case. In a more realistic situation, where the radiosonde’s receiver 

antenna is not directly pointed at the VSS transmitter, then a reduction in interference level from 

the VSS into the radiosonde occurs and, as a result, the FDR versus distance decreases. In this 

case, the geometric orientation (elevation angle and distance) and the antenna patterns are taken 

into account. This is shown in the following four cases.

10

15

20

25

30

35

40

45

50

55

60

0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0

FDR (dB)

Frequency Separation (MHz)
19

• Case 1 (Figure 4): the receiver was tracking a radiosonde near the horizon with the VSS 

transmitter antenna height at 2 meters and the radiosonde receiver antenna at its normal 

height of 5 meters.

Figure 4. Frequency offset versus separation distance for tracking radiosonde near horizon

with ht = 2 m and hr = 5 m – VSS transmitter interference into radiosonde receiver.

• Case 2 (Figure 5): the receiver was tracking a radiosonde near the horizon with the VSS 

transmitter antenna height at 20 meters and the radiosonde receiver antenna at its normal 

height of 5 meters.

Figure 5. Frequency offset versus separation distance for tracking radiosonde near horizon

with ht = 20 m and hr = 5 m – VSS transmitter interference into radiosonde receiver.

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Df (MHz)

Distance (km)

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Df (MHz)

Distance (km)
20

• Case 3 (Figure 6): the receiver was tracking a radiosonde at an elevation angle of 5 

degrees above the horizon with the VSS transmitter antenna height at 2 meters and the 

radiosonde receiver antenna at its normal height of 5 meters.

Figure 6. Frequency offset versus separation distance for 5° elevation angle

with ht = 2 m and hr = 5 m – VSS transmitter interference into radiosonde receiver.

• Case 4 (Figure 7) the receiver was tracking a radiosonde at an elevation angle of 5 

degrees above the horizon with the VSS transmitter antenna height at 20 meters and the 

radiosonde receiver antenna at its normal height of 5 meters.

Figure 7. Frequency offset versus separation distance for 5° elevation angle

with ht = 20 m and hr = 5 m – VSS transmitter interference into radiosonde receiver.

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Df (MHz)

Distance (km)

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Df (MHz)

Distance (km)
21

Figures 8(a) and 8(b) are examples of the frequency offset versus separation distance for the 

worst-case situation (on-boresight, with the radiosonde receiver pointed directly at the VSS 

transmitter). They were computed for the example entrant transmitter/incumbent receiver pair 

based on their parameters. For the entrant transmitter this would include the emission bandwidth 

with roll-off of the emission spectra at the band edges and beyond. For the incumbent receiver 

the information includes the receiver bandwidth with sufficient information for the receiver 

rejection characteristics outside of the receiver bandwidth.

(a) Low VSS antenna height, ht = 2.0 m, hr = 5.0 m. (b) High VSS antenna height, ht = 20.0 m, hr = 5.0 m.

Figure 8. Example plots of frequency offset versus separation distance for the

VSS to Radiosonde Interference Scenario S01 of Table 4 (for S/N = 7.3 dB and S/I = 20 dB).

Compared to Figures 8(a) and 8(b), cases 1 through 4 (Figures 4 through 7) show that there is 

some reduction in interferer to victim-receiver separation distance. A statistical analysis could be 

performed that would determine the probability of interference and take into account the offboresight cases in a stochastic representation.

3.6 The EMC Metric of Frequency Separation (Δf) Versus Separation Distance

From S/N and S/I, the I/N can be calculated which will allow a determination of Δf versus 

separation distance from the FDR curves (Figure 8). For a given separation distance between the 

entrant (interferer) and the incumbent (receiver), a certain Δf must be maintained between them. 

In this example, if the incumbent receiver is operating at a frequency that is 5 MHz away from 

the entrant interference source, the entrant transmitter (at a rooftop height of 20 meters) would 

have to be at least 13 km away from the incumbent receiver to avoid a harmful interference level. 

At greater distances, the frequency offset between the two systems can be less; at greater than 

36 km, the two devices can operate on the same frequency, since Figure 8 shows that Δf is equal 

to zero at a 36 km separation. If the entrant interfering transmitter antenna were at a 2 meter 

height, it could operate at a frequency that is only 4.5 MHz from the incumbent receiver with a 

6 km separation distance.

0

1

2

3

4

5

6

7

8

9

10

11

12

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Δf (MHz)

Distance (km)

0

1

2

3

4

5

6

7

8

9

10

11

12

6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40

Δf (MHz)

Distance (km)
22

3.7 Applying Propagation Models to Scenarios

Table 5 groups the 28 interference scenarios into 20 propagation classes, based on antenna 

heights. For each class, the most appropriate radio-wave propagation loss model (ITM, UFM, 

FS, or FS-6) is shown first for separation distances of 6.8 km or less and then for greater 

separation distances. The fourth column lists the scenario applicable to that class.

Table 5. Propagation model loss analysis combinations for

interference analysis applicable for all analysis scenarios.

Antenna Heights ht/hr

(meters)

Separation Distances

≤ 6.8 km

Separation Distances

> 6.8 km Applicable Scenario

2/5 UFM ITM VSS to Radiosonde

20/5 FS-6 ITM VSS to Radiosonde

2/33 UFM or FS-6 ITM VSS to GOES-N or R RCVR

20/33 FS-6 ITM VSS to GOES-N or R RCVR

1/2 UFM ITM Radiosonde to VSS

1/20 UFM ITM Radiosonde to VSS

100/2 FS-6 ITM Radiosonde to VSS

100/20 FS-6 ITM Radiosonde to VSS

1000/2 FS-6 FS-6 Radiosonde to VSS

1000/20 FS-6 FS-6 Radiosonde to VSS

3000/2 FS-6 FS-6 Radiosonde to VSS

3000/20 FS-6 FS-6 Radiosonde to VSS

10/2 UFM ITM Radiosonde to VSS

10/20 FS-6 ITM Radiosonde to VSS

20,000/2 FS-6 FS Radiosonde to VSS

20,000/20 FS-6 FS Radiosonde to VSS

33,000/2 FS-6 FS Radiosonde to VSS

33,000/20 FS-6 FS Radiosonde to VSS

35,786,000/2 FS FS GOES-N to VSS

GOES-R to VSS

35,786,000/20 FS FS GOES-N to VSS

GOES-R to VSS

The antenna heights (in meters) are based on the following definitions:

1: minimum radiosonde transmitter height

2: average standing VSS height

5: radiosonde receive antenna height

10: intermediate value

20: highest VSS rooftop height

33: maximum satellite dish height

100, 1000, 3000: valid ranges of the propagation models

20,000: antenna height limit for groundwave model

33,000: maximum radiosonde altitude

35,786,000: satellite synchronous orbit
23

For the FS-6 model, the slant distance is the actual distance between the transmitter and the 

receiver as opposed to the distance along the smooth spherical earth. The minimum propagation 

loss should be used to assure that the interference analysis is on the safe side of the interference 

signal level prediction.
24

4. INTERACTION SCENARIO RESULTS

The previous section outlined the analysis approach with an example (scenario S01) that will be 

used to describe the analysis for other interactions contained in Table 4.

4.1 Scenario S02, Radiosonde Interference to VSS Victim Receiver

The effects of interference will be evaluated for the VSS’s wideband mode, which can use one of 

three modulations (QPSK, 16QAM, and 64QAM), since the VSS is used primarily in this mode 

and the wide bandwidth represents a worst case situation. The first step is to calculate the 

interference power levels from the radiosonde into the VSS receiver. This computation was 

performed over all ranges of antenna heights and distances that both the radiosonde and the VSS 

would encounter during normal operation. The ranges were listed in Table 5 of the previous 

section. Plots of received interference power versus distance are illustrated in Figures 9-14.
25

(a) Received power for scenario S02-15.1 for

ht = 1.0 m and hr = 2.0 m – Radiosonde to VSS.

(b) Received power for scenario S02-15.1 for

ht = 1.0 m and hr = 2.0 m – Radiosonde to VSS.

Figure 9. Near and far details of interference effects –

low transmitter antenna height – low receiver antenna height.

(a) Received power for scenario S02-15.1 for

ht = 1.0 m and hr = 20.0 m – Radiosonde to VSS.

(b) Received power for scenario S02-15.1 for

ht = 1.0 m and hr = 20.0 m – Radiosonde to VSS.

Figure 10. Near and far details of interference effects –

low transmitter antenna height – high receiver antenna height.

Distance (km)

Received Power (dBm) -150

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

0 1 2 3 4 5 6 7 8

ITM

FS-6

FS

0 10 20 30 40 50 60 70 80 90 100

Distance (km)

-180

-170

-160

-150

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

Received Power (dBm)

ITM

FS-6

Distance (km)

Received Power (dBm)

0 1 2 3 4 5 6 7 8 -110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

ITM

FS-6

FS

0 10 20 30 40 50 60 70 80 90 100

Distance (km)

-180

-170

-160

-150

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

Received Power (dBm)

ITM

FS-6
26

(a) Received power for scenario S02-15.1 for

ht = 100.0 m and hr = 2.0 m – Radiosonde to VSS.

(b) Received power for scenario S02-15.1 for

ht = 100.0 m and hr = 2.0 m – Radiosonde to VSS.

Figure 11. Near and far details of interference effects –

high transmitter antenna height – low receiver antenna height.

(a) Received power for scenario S02-15.1 for

ht = 100.0 m and hr = 20.0 m – Radiosonde to VSS.

(b) Received power for scenario S02-15.1 for

ht = 100.0 m and hr = 20.0 m – Radiosonde to VSS.

Figure 12. Near and far details of interference effects –

high transmitter antenna height – high receiver antenna height.

Distance (km)

Received Power (dBm)

0 1 2 3 4 5 6 7 8 -100

-90

-80

-70

-60

-50

-40

ITM

FS-6

FS

0 10 20 30 40 50 60 70 80 90 100

Distance (km)

-180

-170

-160

-150

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

Received Power (dBm)

ITM

FS-6

Distance (km)

Received Power (dBm)

0 1 2 3 4 5 6 7 8

-110

-100

-90

-80

-70

-60

-50

-40

ITM

FS-6

FS

0 10 20 30 40 50 60 70 80 90 100

Distance (km)

-180

-170

-160

-150

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

Received Power (dBm)

FS-6

FS
27

(a) Received power for scenario S02-15.1 for

ht = 3000.0 m and hr = 2.0 m – Radiosonde to VSS.

(b) Received power for scenario S02-15.1 for

ht = 3000.0 m and hr = 2.0 m – Radiosonde to VSS.

Figure 13. Near and far details of interference effects –

very high transmitter antenna height – low receiver antenna height.

(a) Received power for scenario S02-15.1 for

ht = 3000.0 m and hr = 20.0 m – Radiosonde to VSS.

(b) Received power for scenario S02-15.1 for

ht = 3000.0 m and hr = 20.0 m – Radiosonde to VSS.

Figure 14. Near and far details of interference effects –

very high transmitter antenna height – high receiver antenna height.

The largest power level from the radiosonde interference source into the VSS receiver occurred 

for the scenario where the radiosonde transmitter was at a height of 100 meters and the VSS 

receiver was at a height of 20 meters. Curves were generated over two distance ranges to provide 

resolution at short distances and a greater dynamic range for long distances. These curves appear 

in Figures 12(a) and 12(b) respectively.

The VSS transmitter to VSS receiver separations used during normal operation range from 0.01 

to 1 km, with the antenna heights both at 2.0 meters. Figure 15 is a computation of the received 

power versus the distance between the VSS transmitter and the VSS receiver with both antenna 

heights at 2 m.

Distance (km)

Received Power (dBm)

0 1 2 3 4 5 6 7 8 -110

-100

-90

-80

-70

-60

ITM

FS-6

FS

-120

-110

-100

-90

-80

-70

-60

Received Power (dBm)

0 10 20 30 40 50 60 70 80 90 100

Distance (km)

ITM

FS-6

Distance (km)

Received Power (dBm)

0 1 2 3 4 5 6 7 8 -90

-80

-70

-60

ITM

FS-6

FS

0 10 20 30 40 50 60 70 80 90 100

Distance (km)

Received Power (dBm) -110

-100

-90

-80

-70

-60

-50

-40

-30

-20

FS-6

FS
28

Figure 15. Received power for VSS to VSS with ht = 2.0 m and hr = 2.0m.

For incremental separation distances between the VSS transmitter and receiver, the allowed 

interference level was calculated for three S/I ratios of 20, 18, and 15 dB. For each VSS 

transmitter to VSS receiver separation distance, the allowed interference signal level was 

determined using the equation I = S –S/I, where I, S, and S/I are all in decibels for all three S/I

ratios. Figures 12 and 15 can then be used to determine the separation distance between the 

radiosonde and VSS at which these interference levels are attained. These values can then be 

used to plot the radiosonde to VSS separation distance versus the VSS transmitter to VSS 

receiver separation distance for three different S/I ratios (Figure 16). These are on-tune plots (cochannel) and represent the situation for a strong desired and strong interference signal as long as 

the S/I ratios are maintained.

Figure 16. Distance from interference source required to avoid interference as a

function of VSS transmitter to VSS receiver separation distance.

Distance (km)

Received Power (dBm)

-80

-70

-60

-50

-40

-30

-20

-10

0

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

FS-6

FS

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

0

10

20

30

40

50

60

70

S/I = 15.0 dB

S/I = 18.0 dB

S/I = 20.0 dB

Distance from Interference Source Required to Avoid Interference (km)

VSS Transmitter to VSS Receiver Separation Distance (km)
29

For situations where the signal is much weaker and near the noise level, the interference 

computation is performed using the minimum S/N in decibels, which is determined from the 

Eb/N0 for a required BER. The I/N ratios required to maintain the S/I and S/N ratios are given by:

0

0

0

log

b

b

b

I SS

NNI

S R E

NNB

E R K where K

N B

I SS S E K

NNI N I

= −

= ×

=+ =

= −= +−

The Eb/N0 required to obtain proper operation of the VSS was determined using the methods of 

Section 3.0 and computations of BER versus Eb/N0 with S/I as a parameter shown in Figures 

17(a1), 17(a2), and 17(a3) for each of the three modulations: QPSK, 16QAM, and 64QAM.

Figures 17(b1), 17(b2), and 17(b3) are plots of the I/N in dB as a function of Eb/N0 with S/I as a 

parameter for each of the three modulations. It should be noted that based on the above definition 

of I/N, none of the variables (S, N, or I) are dependent on the type of modulation used or the BER

to Eb/N0 relationship. I/N only is dependent on the values of R and B which are the same for all 

three modulations. Therefore, the three plots are identical.
30

(a1) BER versus Eb/N0 curves for scenario S02-15.3 for 

BPSK & QPSK (PSK M≤4) receivers.

(b1) I/N vs. Eb/N0 curves for scenario S02-15.3 for 

BPSK & QPSK (PSK M≤4) receivers.

(a2) BER versus Eb/N0 curves for scenario S02-15.4 for 

a 16 QAM receiver.

(b2) I/N vs. Eb/N0 curves for scenario S02-15.4 for a 16 

QAM receiver.

(a3) BER versus Eb/N0 curves for scenario S02-15.5 for 

a 64 QAM receiver.

(b3) I/N vs. Eb/N0 curves for scenario S02-15.5 for a 64 

QAM receiver.

Figure 17. Victim VSS receiver with noise-like interferer

(radiosonde and GOES satellites).

The required Eb/N0, S/N, interference level (I), and signal level (S) for the 7.5 MHz bandwidth 

are listed in Tables 6(a), 6(b), and 6(c) for S/I ratios of 20, 18 and 15 dB. The plots with noise0 5 10 15 20 25 30 10-6

10-5

10-4

10-3

10-2

E /N (dB) b 0

No Interfence

S/I = 20 (dB)

S/I = 18 (dB)

S/I = 15 (dB)

S/I = 10 (dB)

BER (dB)

0 5 10 15 20 25 30 35 40 -50

-40

-30

-20

-10

0

10

20

30

40

E /N (dB) b 0

No Interference

S/I = 20 (dB)

S/I = 18 (dB)

S/I = 15 (dB)

S/I = 10 (dB)

I/N (dB)

0 5 10 15 20 25 30 10-6

10-5

10-4

10-3

10-2

10-1

No Interference

S/I = 20 (dB)

S/I = 18 (dB)

S/I = 15 (dB)

S/I = 10 (dB)

BER (dB)

0 5 10 15 20 25 30 35 4 -50

-40

-30

-20

-10

0

10

20

30

E /N (dB) b 0

No Interference

S/I = 20 (dB)

S/I = 18 (dB)

S/I = 15 (dB)

S/I = 10 (dB)

I/N (dB)

0 5 10 15 20 25 30 10-6

10-5

10-4

10-3

10-2

10-1

E /N (dB) b 0

No Interference

S/I = 20 (dB)

S/I = 18 (dB)

S/I = 15 (dB)

S/I = 10 (dB)

BER (dB)

0 5 10 15 20 25 30 35 40 -50

-40

-30

-20

-10

0

10

20

30

40

E /N (dB) b 0

No Interference

S/I = 20 (dB)

S/I = 18 (dB)

S/I = 15 (dB)

S/I = 10 (dB)

I/N (dB)
31

like interference were calculated using the algorithms in [2]. The information regarding Eb/N0

using CW noise was obtained from plots in [2]. From Tables 6(a), 6(b), and 6(c), it can be seen 

that there is a small difference between noise-like interference and CW interference.

Table 6(a). Required Eb/N0 and S/N for a BER of 1.0 × 10-3

for noise-like and CW interference for S/I = 20 dB.

Modulation

Eb/N0 (dB)

S/N (dB) I (dBm) I/N (dB) S (dBm) Eb/N0 (dB)S/N (dB) I (dBm) I/N (dB) S (dBm)

Noise Int. Noise Int. Noise Int. Noise Int. CW Int. CW Int. CW Int. CW Int.

QPSK

7.5 MHz

7.0

7.28 -113.97 -12.72 -93.97 7.0

7.28 -113.97 -12.72 -93.97

16QAM

7.5 MHz

11.2

11.5 -109.5 -8.5 -89.5 11.2

11.5 -109.5 -8.5 -89.5

64QAM

7.5 MHz

16.6

16.9 -104.65 -3.1 -84.65 15.215.5 -105.75 -4.25 -85.75

Table 6(b). Required Eb/N0 and S/N for a BER of 1.0 × 10-3

for noise-like and CW interference for S/I = 18 dB.

Modulation

Eb/N0 (dB)

S/N (dB) I (dBm) I/N (dB) S (dBm) Eb/N0 (dB)S/N (dB) I (dBm) I/N (dB) S (dBm)

Noise Int. Noise Int. Noise Int. Noise Int. CW Int. CW Int. CW Int. CW Int.

QPSK

7.5 MHz

7.1

7.38 -111.87 -10.62 -93.87 7.77.98 -111.27 -10.02 -93.27

16QAM

7.5 MHz

11.4

11.68 -107.57 -6.32 -89.57 11.5

11.78 -107.47 -6.22 -89.47

64QAM

7.5 MHz

18.0

18.28 -100.97 0.28 -82.97 16.0

16.28 -102.97 -1.72 -84.97

Table 6(c). Required Eb/N0 and S/N for a BER of 1.0 × 10-3

for noise-like and CW interference for S/I = 15 dB.

Modulation

Eb/N0 (dB)

S/N (dB) I (dBm) I/N (dB) S (dBm) Eb/N0 (dB)S/N (dB) I (dBm) I/N (dB) S (dBm)

Noise Int. Noise Int. Noise Int. Noise Int. CW Int. CW Int. CW Int. CW Int.

QPSK

7.5 MHz

7.5

7.78 -108.47 -7.22 -93.47 8.2

8.48 -107.77 -6.52 -92.77

16QAM

7.5 MHz

12.9

13.18 -103.07 -1.82 -88.07 12.7

12.98 -103.27 -2.02 -88.97

64QAM

7.5 MHz

----

---- ---- ---- ---- 16.8

17.08 -99.17 2.08 -84.17

Frequency dependent rejection between a transmitter and receiver depends on the operating 

center frequency and the in and out of band emission characteristics of the transmitter. It also 

depends on the center frequency and the in and out of band rejection characteristics of the 

receiver. Computation of frequency dependent rejection was covered in Section 3.5.
32

The FDR required to bring the interference signal down to a power level that would satisfy I/N

and S/N ratios is:

FDR dB P dBm N dBm I N dB ( ) = −+ rec ( ) ( ( ) / . ( ))

The plots of required FDR are plotted for each of the three modulations. Figure 18 is a plot of the 

FDR attainable between the radiosonde transmitter and the VSS receiver for the 7.5 MHz 

bandwidth. It is calculated based on the wanted signal’s emission characteristics, the interference 

signal’s emission characteristics, and the receiver’s IF bandwidth characteristics.

Figure 18. FDR versus Df for the VSS transmitter to radiosonde receiver.

0

10

20

30

40

50

60

70

0 2 4 6 8 10 12 14 16 18 20

Frequency Dependent Rejection (dB)

Df (MHz)
33

4.1.1 Scenario S02 (QPSK)

Figures 19(a) and 19(b) show the long and short distance range frequency dependent rejection, 

respectively, that is necessary to achieve electromagnetic compatibility for case S02 (QPSK)

with a 7.5 MHz bandwidth and QPSK modulation.

(a) Long distance (b) Short distance

Figure 19. FDR for scenario S02-15.3

for ht = 100 m and hr = 20 m – radiosonde to VSS (QPSK).

Figure 20 shows the Df in frequency versus radiosonde transmitter to VSS receiver separation 

required to provide electromagnetic compatibility with a 7.5 MHz bandwidth and QPSK 

modulation. Figure 20 was obtained by combining the FDR attainable for a 7.5 MHz bandwidth 

of Figure 18 with the required frequency dependent rejection of Figures 19(a) and 19(b).

Figure 20. Df versus separation distance for scenario S02-15.3

for ht = 100 m and hr = 20 m –radiosonde to VSS (QPSK).

0

10

20

30

40

50

60

70

80

90

0 10 20 30 40 50 60 70 80 90 100

Distance (km)

Frequency Dependent Rejection (dB)

30

40

50

60

70

80

90

0 1 2 3 4 5 6 7 8

Distance (km)

Frequency Dependent Rejection (dB)

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

0 10 20 30 40 50 60 70 80 90 100

Df (MHz)

Distance (km)
34

4.1.2 Scenario S02 (16QAM)

Figures 21(a) and 21(b) show the long and short distance range frequency dependent rejection, 

respectively, that is necessary to achieve electromagnetic compatibility for case S02 (16QAM)

with a 7.5 MHz bandwidth and 16QAM modulation.

(a) Long distance (b) Short distance

Figure 21. FDR for scenario S02-15.4

for ht = 100 m and hr = 20 m – radiosonde to VSS (16QAM).

Figure 22 shows the Df in frequency versus radiosonde transmitter to VSS receiver separation 

required to provide electromagnetic compatibility with a 7.5 MHz bandwidth and 16QAM 

modulation. Figure 22 was obtained by combining the FDR attainable for a 7.5 MHz bandwidth 

of Figure 18 with the required frequency dependent rejection of Figures 21(a) and 21(b).

Figure 22. Df versus separation distance for scenario S02-15.4

for ht = 100 m and hr = 20 m –radiosonde to VSS (16QAM).

0

10

20

30

40

50

60

70

80

90

0 10 20 30 40 50 60 70 80 90 100

Distance (km)

Frequency Dependent Rejection (dB)

30

40

50

60

70

80

90

0 1 2 3 4 5 6 7 8

Distance (km)

Frequency Dependent Rejection (dB)

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

0 10 20 30 40 50 60 70 80 90 100

Df (MHz)

Distance (km)
35

4.1.3 Scenario S02 (64QAM)

Figures 23(a) and 23(b) show the long and short distance range required frequency dependent 

rejection, respectively, that is necessary to achieve electromagnetic compatibility for case S02

(64QAM) with a 7.5 MHz bandwidth and 64QAM modulation.

(a) Long Distance. (b) Short Distance.

Figure 23. FDR for scenario S02-15.5

for ht = 100 m and hr = 20 m – radiosonde to VSS (64QAM).

Figure 24 shows the Df in frequency versus radiosonde transmitter to VSS receiver separation 

required to provide electromagnetic compatibility with a 7.5 MHz bandwidth and 64QAM 

modulation. Figure 24 was obtained by combining the FDR attainable for a 7.5 MHz bandwidth 

of Figure 18 with the required frequency dependent rejection of Figures 23(a) and 23(b).

Figure 24. Df versus separation distance for scenario S02-15.5

for ht = 100 m and hr = 20 m –radiosonde to VSS (64QAM).

0

10

20

30

40

50

60

70

80

90

0 10 20 30 40 50 60 70 80 90 100

Distance (km)

Frequency Dependent Rejection (dB)

20

30

40

50

60

70

80

0 1 2 3 4 5 6 7 8

Distance (km)

Frequency Dependent Rejection (dB)

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

0 10 20 30 40 50 60 70 80 90 100

Df (MHz)

Distance (km)
36

4.1.4 Summary for Analysis of Results for Scenarios S02 (QPSK), S02 (16QAM), & S02

(64QAM)

Figures 20, 22, and 24 represent the amount in frequency separation that the victim receiver must 

be off-tuned from the interfering transmitter versus separation distance in order to avoid 

interference. Small amounts of off-tuning are required if the separation distance is large, and 

large amounts of off-tuning are required for small separation distances. For the 7.5 MHz 

bandwidth operation of the VSS, a separation distance of 10 km requires an approximate 

separation in frequency of 10 MHz to avoid interference.

4.2 Interactions for Scenarios S03 to S15, GOES-N and GOES-R Interference to 

VSS Victim Receiver

4.2.1 Computation of Interference Levels

Computations of the interference levels into the VSS receiver from the GOES-N and GOES-R 

satellite transmissions toward Earth were made to determine if this type of interference was an 

issue. The antenna gains of the VSS receiver (2.15 dBi) are very low in comparison to the 

antenna gains of the satellite receiver links (39.6 dBi for GOES-N and 47.2 dBi for GOES-R). 

The satellite links also have a low gain margin to conserve satellite power. As a result, the 

satellite signal levels, which are adequate for the design of the GOES-N and GOES-R links, do 

not cause interference into the low gain antennas on the VSS receivers.

The following equation calculates the received signal level from the GOES satellites into the 

VSS receiver. Free-space loss is used to compute the propagation loss from the satellites to the 

VSS receiver and is equal to 188 dB.

P dBm P dBm G dBi G dBi L dB rec ( ) = ++ t ( ) t ( ) r ( ) – p ( )

where

Prec is the received interference power at the VSS receiver (dBm)

Pt is the satellite transmitter power of the GOES satellite transmitter (dBm)

Gt is the satellite transmitter antenna gain (dBi)

Gr is the VSS receiver antenna gain (2.15 dBi)

Lp is the free-space propagation loss from the satellite to the VSS receiver (188 dB).

Using the values in Table 6, the above equation produces the received signal level values 

contained in Table 7.
37

Table 7. Computation of received interference power from the GOES satellites into the 

VSS receiver.

Scenario GOES Satellite

Series

GOES 

Transmitter

Function

Pt

(dBm)

Gt

(dBi)

Pr (dBm)

Interferer

I/N (dB) 

Narrowband

1.25 MHz

I/N (dB) 

Wideband

7.5 MHz

S03 GOES-N SD 36.9 15.6 -133.35 -24.35 -32.1

S04 GOES-N PDR 44.5 15.6 -125.75 -16.75 -24.5

S05 GOES-N LRIT-WEFAX 40.2 15.6 -130.05 -21.05 -28.8

S06 GOES-N EMWIN 31.2 15.6 -139.05 -30.05 -37.8

S07 GOES-N MDL 38.2 15.6 -132.05 -23.05 -30.08

S08 GOES-N DCPR 38.0 15.6 -132.25 -23.25 -31.0

S09 GOES-N CDA/TLM 34.5 15.6 -135.75 -26.75 -34.5

S10 GOES-R GRB#1 46.0 17.3 -122.55 -13.6 -21.35

S11 GOES-R GRB#2 46.0 17.3 -122.55 -13.6 -21.35

S12 GOES-R HRIT 43.8 16.5 -125.55 -16.55 -24.30

S13 GOES-R DCPR#1 37.0 16.5 -132.35 -23.35 -31.10

S14 GOES-R DCPR#2 37.0 16.5 -132.35 -23.35 -31.10

S15 GOES-R CDA/TLM 31.8 3.1 -150.95 -41.95 -49.70

4.2.2 Summary for the Interactions for Scenarios S03 to S15, GOES-N and GOES-R 

Interference to VSS Victim Receiver

All of the calculated interference levels in Table 7 are well below the noise levels for both the 

1.25 MHz (-109.0 dBm) worst case and 7.5 MHz (-101.25 dBm) best case operating bandwidths 

of the VSS receiver. Interference from the GOES satellites into the VSS receiver antenna is 

therefore not a problem. The wide bandwidth of 7.5 MHz was assumed for this analysis, since 

VSSs run in wideband mode most of the time. No frequency dependent rejection is needed and 

as a result, no off-tuning of these systems is required to avoid this type of interference from the 

GOES satellites. The satellites maintain an almost constant separation distance from the VSS 

receivers of 35,786 km. The highest level of interference from GOES-N or GOES-R satellites is 

from the GOES-R Rebroadcast links (GRB#1 and GRB#2) at a signal level of -122.5 dBm,

which results in a worst case I/N of -13.6 dB.

4.3 Interactions for Scenarios S16 to S28, VSS Interference to GOES-N and GOES-R 

Victim Receiver

The remainder of this section analyzes interference of the VSS transmitter into the GOES 

satellite earth station receivers (Scenarios S16 to S28). This is important since the sensitivity of 

the GOES receivers and the very large gains of the earth station satellite receiver antennas make 

the earth station satellite receiver very susceptible to interference from the VSS. The separation 

distance versus Df relationships for all of these VSS transmitter to GOES receiver interactions 

have been calculated based on transmitter and receiver parameters, the received interference 
38

levels necessary to maintain compatibility, and the FDR to Df and FDR to separation distance 

relationships.

Eight to twelve plots were generated for each scenario, based on interferer and victim antenna 

heights and antenna alignment. The scenarios specify two antenna heights for the VSS and two 

or three antenna heights for the GOES receiver. The relative alignment of the two antennas is 

important because it demonstrates the need to tailor the analysis for each potential deployment 

situation. In a worse case situation, the VSS would be located on the GOES antenna’s axis, or 

boresight (on-axis). While an on-axis arrangement is improbable (but physically possible), a 

more likely scenario involves the VSS unit positioned on the ground (antenna height = 2 m) or 

on a rooftop (antenna height = 20 m) in the vicinity of the GOES receiver (off-axis).

Appendix C lists all 26 GOES receiver sites operated by the U.S. Government and their 

orientation towards the two GOES satellites. Not all sites receive signals from both satellites 

(due to local needs and the physical alignment with each satellite) and not all sites monitor all of 

the signals that GOES satellites transmit. In addition, the terrain around each GOES receiver site 

can vary greatly. This must be taken into account when calculating the separation distance.

Appendix D contains all of the separation distance versus Df plots generated for the last 13 

scenarios. The plots are laid out in the following manner: the first page for each scenario shows 

the plots for a VSS antenna height of 2 m, and the second page for a VSS antenna height of 20 

m. The left-hand column of each page shows the results of the on-axis calculations, the righthand column the results of the off-axis calculations. From top to bottom, the plots show the 

differences due to increasing GOES receiver antenna heights. Reading across (left-to-right), one 

can see the improvement (closer separation distances and smaller Df) a more realistic 

configuration makes over the worst-case on-axis configuration.

Based on the Appendix D plots, an estimation of the required separation distance and Df can be 

obtained and adjusted against each other to arrive at a solution for operation on a noninterference 

basis.
39

5. MEASUREMENTS

The primary goal of the test design was to define the environment that would result in 

detrimental interference to the VSS signal (Section 5.1). The tests also had to identify where, 

when, and if the VSS causes interference to the incumbent services in the band (Section 5.2). 

From an engineering perspective, the tests must verify and validate any assumptions made about

the unknowns in the interference environment. Testing for such a complex problem meant that 

the number and range of potential test parameters had to be reduced to a manageable number.

Analyzing all potential combinations of equipment settings, propagation channel conditions, and 

physical relationships between the various communication systems would be impractical. The 

following sections describe the measurements selected to form a manageable and meaningful set 

to test comprehensively the potential interference in this band.

5.1 Interference of the Radiosonde to the VSS

5.1.1 Actual Frequency Relationships Between the Radiosonde and the VSS

Figure 25 shows possible positions of the radiosonde (red line) and VSS signals (blue region)

within the 1675–1695 MHz band. The radiosonde signal is limited to the 1675–1683 MHz range

(gray region). Figures 25(a) and 25(b) are the extreme cases where the two signals are 

immediately adjacent to each other, with the radiosonde lying on the lower edge of the VSS 

signal; Figure 25(c) shows the singular case with the radiosonde lying on the upper edge of the 

VSS signal. Figures 25(d) and 25(e) are the extreme cases where the radiosonde and VSS signals 

are co-located. Figure 25(f) shows that the maximum frequency separation between the two 

signals is 16 MHz.

Figure 25. VSS-Radiosonde location extremes in the 1675–1695 MHz band.

VSS

16951679

16831675 (a) VSS-Radiosonde Adjacent Channel #1

VSS

1695

16791683

1675 (c) VSS-Radiosonde Adjacent Channel #2

VSS

1695

1675

16911687

1683

(b) VSS-Radiosonde Adjacent Channel #3

VSS

1695

167916831675

(d) VSS-Radiosonde Co-Channel #1

VSS

16951675

16791687

1683

(e) VSS-Radiosonde Co-Channel #2

VSS

168716911683

16951675 (f) VSS-Radiosonde Maximum Separation
40

5.1.2 VSS Configuration Space

The VSS COFDM transmitter can transmit in narrowband and wideband modes. In wideband 

mode, the device uses the DVB-T waveform. There are four parameters available to the user: 

FEC rate, guard interval, modulation, as well as a choice of three bandwidths (6, 7, and 8 MHz). 

Initial testing revealed that the choice of configuration parameters was limited by the selected 

bandwidth (for example, when the device is configured to transmit with a 6 MHz bandwidth,

64QAM is unavailable).

To obtain a detailed understanding of the VSS’s failure-point and more thoroughly examine the 

interference environment, the configuration parameters were bracketed (i.e., ranges of VSS input 

parameters were selected such that the configurations would represent extremes in performance). 

The goal of selecting the appropriate configuration brackets is to reduce the number of required 

measurements without diminishing the significance of the results and assure that the most critical 

interference environments in a public safety setting are examined thoroughly. This process led to 

the creation of 20 potential configurations of the VSS as shown in Table 8.

Table 8. VSS configurations.

Configuration Bandwidth FEC Rate Guard Interval Modulation

6 MHz 8 MHz 1/2 3/4 2/3 1/4 1/32 QPSK 16QAM 64QAM

1    

2    

3    

4    

5    

6    

7    

8    

9    

10    

11    

12    

13    

14    

15    

16    

17    

18    

19    

20    
41

The remainder of the VSS parameters, such as Spectrum Inversion, and 4 kHz Offset (which are 

used to correct for transmission anomalies), were kept fixed for all configurations (Table 9). 

Preliminary tests showed that these parameters did not affect the VSS’s sensitivity to 

interference.

Table 9. Non-critical VSS parameters.

Device Parameter Value

Transmitter

Spectrum Inversion Inverted

4 kHz Offset None

Video Input NTSC

MPEG Mode MPEG2

Horizontal Resolution 704

Video Sharpness Normal

Receiver

Down-converter LO 1050 MHz

Down-converter LO Side Low

OFDM Polarity Normal

MPEG4 De-blocking Filter Off

Descrambling Off

LNB Power Yes

Other parameters are used by the system’s audio channel. Audio quality failure-points were not 

tested relative to the video quality failure-points because the video signal is more susceptible to 

interference than the audio signal and represents worst-case usage. As a result, the audio 

component was not taken into consideration in these tests and no specific audio content was sent 

between the VSS devices (save for ambient noise picked up by the microphones).

In addition, there are a number of “housekeeping” parameters used by both hardware and 

configuration software that do not affect the RF signal and are not addressed here.

Although the VSS transmitter can be adjusted to operate over a range of center frequencies, 

adjustment requires the device to be reprogrammed and the center frequency is not easily 

changed without the proper equipment. Consequently, the VSS was left to transmit at the preprogrammed frequency it was supplied with (1687 MHz) and the frequency of the simulated 

interference signals was varied instead.

5.1.3 Test Qualifiers

The test setup represents a communication circuit in a controlled interference environment. This 

concept is used to determine the interaction between the desired signal and the interferer. These 

interactions can be one-to-one, many-to-one, or one-to-many; the initial tests addressed a one-toone interaction. Ideally, an objective measurement is used to determine the degree of 

performance degradation due to interference; for example, BER, receiver selectivity, or perhaps 
42

FDR could be used as the receiver’s figure of merit if such parameters could be measured. The 

most straightforward measurement to make is BER in the presence of interference. However, the 

interactions between modulation type, forward-error-correction methods, video codec, and the 

overall robustness of the underlying protocol (COFDM), make any correlation between BER and 

video quality complex. In situations where the communication content is primarily video, 

informal subjective measures are used. It is important that the test design use a simple video 

failure mode as a figure of merit for a particular interference environment.

What follows is a description of the tests that were conducted. Also included are tests that 

verified assumptions that were made to limit the search space. These tests were conducted in a 

laboratory environment only. Field tests should be performed when a target incumbent receiver 

is available. More significantly, field-testing the VSS is not possible without special exemptions 

for transmitting in the existing band; a VSS operating in the existing band can interfere with the 

active, mission-critical incumbents. In addition, field-testing that produces results that are not 

readily interpretable (because relevant propagation parameters cannot be controlled as well as in 

the lab and cannot be accurately measured) would not be a good use of time and resources. Fieldtesting should be limited to interference scenarios that exactly match actual, proposed 

deployments for assurance testing (validation and verification). Since the scenarios themselves 

are under evaluation, as much effort as possible went towards a thorough laboratory 

examination. This gives all potential users data that can be used to develop methods for peaceful

coexistence.

5.1.4 Basic Test Setup

Figure 26 shows the basic test setup that was used to calibrate and test the VSS in a flat fading 

environment, which was simulated with variable and fixed attenuators. Flat fading occurs when 

the coherence bandwidth of the channel is greater than the bandwidth of the signal and, as a 

result, all frequency components of the signal will experience the same amount of fading. The 

fixed losses associated with the various circuit elements are shown in red text.
43

Figure 26. VSS baseline test setup.

Figure 27 shows the setup used to inject interference into the VSS propagation channel. Isolators 

were necessary in this setup to ensure that the signal generator was not exposed to input power 

levels beyond its designed limits. Note that the power splitter closest to the VSS transmitter was 

used as a power combiner.

These two tests served different purposes. The basic setup (Figure 26) was used to verify the 

proposed test design and to uncover any potential for equipment damage. The spectrum analyzer

in both circuits confirmed that the intended interference environment was being created

correctly. Since these tests were not designed to address the effects that receiver space diversity 

may have on the interference, the signal was fed to the dual inputs of the VSS receiver via a final 

power splitter.
44

Figure 27. VSS interference injection test setup.

5.1.5 VSS Video Failure Mode

The video signal transmitted by the VSS originated from a desktop computer playing a 12 

second long looped video clip (Figure 28). A surveillance video clip that shows an aerial view of 

a crowded parking lot from a helicopter was used in all tests. This clip was chosen because it 

reflected the intended use of the VSS (surveillance) and because of the high visual complexity of 

the scene. The clip satisfies the engineering requirement for a scene that has both high pixel-topixel dynamic range and motion that stresses the video codec and provides abrupt failure-points.
45

Figure 28. Sample frames from the video clip used for testing.

A series of preliminary tests determined that the VSS video link fails abruptly with a

monotonically decreasing signal level. The video failure-point was consistently repeatable within 

a 1 dB value of attenuation. In this context, the video failure-point is defined as the last 

attenuation value (in 1 dB increments) that allows the video link to operate. Video failure is 

defined as the observed freeze of the video stream or the point at which the receiver is unable to 

decode the transmitted video. This consistent and well-defined failure mode was used as a 

performance metric to determine the lowest signal level of operation of the VSS.

Although it is beyond the scope of these tests, it must be mentioned that that video stream 

exhibited performance hysteresis. That is, when this measurement was conducted in the opposite 

direction (monotonically increasing signal level), the 1 dB point before the video stream 

recovered from failure was not the same as the failure-point. This is because the underlying 

complexity of initiating a video stream is greater than that when it fails. It was observed also that 

the recovery point was less repeatable than the failure-point; the recovery point could vary from 

3 to 6 dB between tests.

5.1.6 VSS Configuration Baseline Tests

The baseline tests were conducted to assure that the concept of VSS configuration bracketing 

was valid. For these tests, all of the 20 configurations in Table 8 were examined. Using the basic 

circuit configuration (Figure 26), a variable attenuator was used to represent a simple flat-fading 

channel to determine the operational failure-point of the VSS. The results in Table 10 were then 

used to gauge the performance variability of the VSS for each of the 20 configurations.

Table 10. Results from VSS baseline tests.

Configuration 

Number

Transmitter Receiver VSS Measured 

Power at Failure 

(dBm)

Video Bit Rate 

(Mb/sec)

Input Lev. 

A (dBm)

Input Lev. 

B (dBm)

SNR A 

(dB)

SNR B 

(dB)

1 3.502 -91 -96 7.7 - -98.2

2 5.7159 -92 -98 7 - -98.6

3 2.7271 -90 -95 0 6.8 -98.7

4 4.5536 -90 -96 7.3 - -98.7

5 12.3576 -87 -92 9.7 - -96.1

6 18.9993
46

Configuration 

Number

Transmitter Receiver VSS Measured 

Power at Failure 

(dBm)

Video Bit Rate 

(Mb/sec)

Input Lev. 

A (dBm)

Input Lev. 

B (dBm)

SNR A 

(dB)

SNR B 

(dB)

7 10.033 -84 -89 12 - -95.5

8 15.5124

9 4.978 -117 -117 4 - -103.2

10 7.9298 -102 -117 5.8 0 -101.8

11 3.9448 -117 -117 1 0.7 -103.7

12 6.3801 -99 -112 4.4 3.9 -102.7

13 16.7854 -89 -96 12.1 11.2 -98.4

14 25.6411

15 13.686 -88 -93 10.3 9.6 -98.7

16 20.9919

17 16.7854 -83 -88 11.8 10.4 -93.8

18 13.686 -82 -87 12.4 11.3 -90.9

19 22.6892 -85 -91 13.1 14.2 -91.2

20 18.5566 -83 -88 13.1 11.6 -90.8

The four receiver columns of Table 10 (input level A and B, SNR A and B) are values generated 

by the VSS receiver and displayed on the output video monitor. The methods by which they are 

measured or calculated is unknown. Although the same signal is fed into both of the receiver’s

inputs (through a splitter), the reported input levels are rarely the same and the difference is 

inconsistent. Similarly, the reported SNRs do not correspond with each other. Consequently, 

these values are not used in the analysis and are included here just for the sake of completeness.

These preliminary tests demonstrated that four of the proposed configurations (6, 8, 14, and 16)

could not be tested because the receiver would not link to the transmitted signal. These four 

configurations involved an FEC of 3/4 with both 16QAM and 64QAM modulations; an FEC of 

3/4 with QPSK modulation was not a problem. This appears to be a limitation in the VSS design.

It was decided to concentrate further testing on three (5, 9, and 13) of the remaining

configurations because they represented the performance extremes for the VSS (FEC = 1/2 and 

Guard Interval = 1/32 for each of the three modulations).

5.1.7 Interference Testing

Figures 29, 30, and 31 display the VSS receiver power at the failure-point versus the interferer 

center frequency offset. In each graph, the dotted line indicates the average VSS failure-point 

power in the absence of interference.

Using the test setup shown in Figure 27, interference at five different power levels was injected 

into the VSS transmission path at varying frequency offsets relative to the VSS’s center 
47

frequency. The VSS’s failure-point was then determined and the various signal powers were 

measured. The interfering signal (supplied by the signal generator) was a simulated radiosonde 

signal, 150 kHz wide, driven by a base-band random sequence. The interference-free failurepoint was also measured for each test. When the failure-point could not be identified without 

changing the test configuration then no data was recorded. This assures that all plotted points 

were measured with a consistent test configuration.

In the case of configuration 13, the graphs of the VSS failure-points (Figures 31(a) and 31 (b)) 

are compared to a plot of the theoretical calculation of FDR (Figure 31(c)). It is apparent that 

there is a significant change in slope at the band edge (4 MHz) in both plots. However, there are 

unique features in each plot. There is an inflection point between 4.5 and 5 MHz in the 

measurements that does not appear in the calculated values, while two points at 10 and 15 MHz 

that exist in the calculated values are not reflected in the measurements. The overall total 

rejection is comparable between the plots over the range of offset frequencies. The calculated 

values take 16 MHz from the band edge to achieve approximately 60 dB of rejection, while the 

measurements achieve the same rejection range over 1 MHz from the band edge. As can be seen 

from Figure 31(b), there is no significant improvement in interference rejection once the 

interferer (radiosonde in this case) is outside of the victim’s bandwidth.

Since the failure-point is a performance-based measure, it includes several error-mitigation 

techniques, such as FEC and packet re-transmission. The calculated data in Figure 31(c) does not 

take these methods into account. It is assumed that the difference in interference rejection 

behavior between the calculated and measured data is due to the presence of error-correction 

methods used in the VSS.

An examination of the measured data shows that actual equipment achieves interference 

rejection in a significantly shorter offset range than the calculated FDR would indicate. Some of 

this difference can be attributed to interference and error reduction techniques (such as FEC, 

retransmission requests, scrambling, and interleaving) that are not taken into account in the FDR

calculations Therefore, the FDR values reflect a more conservative estimation of interference 

rejection with increasing frequency offset than what actual fielded equipment presumably will 

experience.

It is best to base planning decisions on conservative estimates of interference. However, due to

the mission-critical nature of these communication systems, it would be prudent to perform 

additional measurements of the interference potential before the VSS is deployed in the shared 

band. This would involve measuring the interference rejection potential with different 

bandwidths, FEC levels, guard intervals, etc. This could be easily accomplished since the test 

methodologies have already been established, as described in Sections 5.1.4 and 5.1.6.
48

Figure 29. VSS failure-points with a simulated radiosonde interferer – configuration 5.

Figure 30. VSS failure-points with a simulated radiosonde interferer – configuration 9.

-110

-100

-90

-80

-70

-60

-50

-40

-7 -6 -5 -4 -3 -2 -1 0

VSS Power at Failure Point (dBm)

Interferer Center Frequency Offset (MHz)

-40 dBm

-35 dBm

-30 dBm

-25 dBm

-20 dBm

No interference

-110

-100

-90

-80

-70

-60

-50

-40

-7 -6 -5 -4 -3 -2 -1 0

VSS Power at Failure Point (dBm)

Interferer Center Frequency Offset (MHz)

-40 dBm

-35 dBm

-30 dBm

-25 dBm

-20 dBm

No interference
49

Figure 31(a). VSS failure-points with a simulated radiosonde interferer – configuration 13.

Figure 31(b). VSS failure-points with a simulated radiosonde interferer –

configuration 13 (large frequency separation).

-110

-100

-90

-80

-70

-60

-50

-40

-7 -6 -5 -4 -3 -2 -1 0

VSS Power at Failure Point (dBm)

Interferer Center Frequency Offset (MHz)

-40 dBm

-35 dBm

-30 dBm

-25 dBm

-20 dBm

No interference

-110

-100

-90

-80

-70

-60

-50

-40

-17 -16 -15 -14 -13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0

VSS Power at Failure Point (dBm)

Interferer Center Frequency Offset (MHz)

-25 dBm

-20 dBm

No interference
50

Figure 31(c). Calculated FDR for scenario S02 (radiosonde to VSS interference).

5.1.8 Narrowband vs. Wideband Interference Comparison

The characteristics of narrowband and wideband interference are quite different. Typically, it is 

assumed that wideband interference represents the worst-case scenario since it occupies the 

victim’s entire receiver passband. To simplify the interference calculation, wideband interference 

is used since it is easier to describe. To perform a similar interference calculation using a 

narrowband interferer, the actual demodulation technique must be modeled. Since there is no 

consistency of demodulation techniques between receivers, generalizing the effects of 

narrowband interference is impossible.

In the analysis described in an earlier section, broadband interference was assumed to be the 

worst-case situation. In light of the difficulty in calculating the effect of narrowband interference, 

tests were performed to verify that this assumption was valid.

The three graphs below (Figures 32, 33, and 34) show the S/I power at the VSS failure-point

versus the interference bandwidth for two levels of interference power that are 10 dB apart, for

each of the three modulations used by the VSS. A co-channel interference situation (the center 

frequencies of the VSS and the interferer are identical) was used, which represents the most 

extreme interference case. The VSS was configured for its widest possible bandwidth (8 MHz), 

making it most susceptible to interference.

When the bandwidth of the interferer is less than half of the victim’s (VSS) bandwidth, then 

there appears to be a complex relationship between the two signals. For very narrow interferer 

bandwidths, the S/I value approaches that of a broadband interferer, in which case a broadbandbased interference estimate would be adequate. When the interferer bandwidth is between 1⁄4 and 

0

10

20

30

40

50

60

70

20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

Rejection Level (dB)

Δf (MHz)
51

1⁄2 of the VSS bandwidth, then the victim receiver appears to be less susceptible to the interferer 

than to a broader-band interferer. Once the interferer’s bandwidth is greater than half of the 

victim receiver’s bandwidth, then the effect of interference is essentially constant (to within the 

accuracy of the measurement equipment).

These measurements indicate that broadband interference is the worst-case situation. In a 

spectrum-sharing scenario where the interferer bandwidth is approximately 1⁄4 to 1⁄2 of the victim 

receiver’s bandwidth, these graphs indicate that an assumption based on broadband interference 

will over-estimate the effect of interference. In such a case, further measurements would be 

valuable to determine the level of interference rejection more accurately.

Figure 32. Signal-to-interference ratio versus interference bandwidth – QPSK.

-75

-70

-65

-60

-55

-50

0 2 4 6 8 10 12 14 16 18 20

Signal-to-Interference Ratio (dB)

Interference Bandwidth (MHz)

Interference Power Level A

Interference Power Level B
52

Figure 33. Signal-to-interference ratio versus interference bandwidth - 16QAM.

Figure 34. Signal-to-interference ratio versus interference bandwidth - 64QAM.

-75

-70

-65

-60

-55

-50

0 2 4 6 8 10 12 14 16 18 20

Signal-to-Interference Ratio (dB)

Interference Bandwidth (MHz)

Interference Power Level A

Interference Power Level B

-75

-70

-65

-60

-55

-50

0 2 4 6 8 10 12 14 16 18 20

Signal-to-Interference Ratio (dB)

Interference Bandwidth (MHz)

Interference Power Level A

Interference Power Level B
53

5.2 Interference of the VSS to the GOES

5.2.1 Considerations for GOES Receiver Testing

From an engineering perspective, an objective measure of service performance would involve 

evaluating metrics such as BER and throughput. Data streams would be tested in various 

interference environments to determine the degree to which the stream has been degraded. This 

assumes that all evaluated data streams have similar parametric characteristics and are used in a 

similar manner.

In the case of the GOES systems, the data “stream” is not monolithic. It actually consists of an 

aggregate of multiple data services, seven of which are wholly or partially within the 1675–1695 

MHz band for the GOES-N/O/P case (Figures 35–37). Each of these has distinct user 

characteristics (Table 11). For instance, the telemetry channel (CDA Telem) requires highpriority, real-time data access, while a channel such as LRIT is used to download archived, lowrate meteorological information that could be perceived to be a lower priority. All channels have 

different downstream processing methods that require different levels of signal quality and time 

availability. A single data stream quality metric cannot cover all of the possible GOES data use 

scenarios.

Figure 35 shows the GOES RF signal received by an off-the-shelf five-foot diameter dish with 

an integral pre-amplifier installed at ITS’s site in Boulder. Figure 36 shows the GOES IF signal 

received, amplified, filtered, and down-converted at NOAA’s receiver located 400 meters (onequarter mile) from ITS’s site.

Figure 35. GOES RF signals.
54

Figure 36. GOES IF signals received at the Boulder site.

Figure 37. GOES-N/O/P frequency plan (downlinks).

Table 11. Characteristics of GOES-N/O/P channels in the 1675–1695 MHz band.

Link Designation SD MDL PDR LRIT EMWIN CDA Telem DCPR

Function Name Sensor 

Data

Multiuse 

Data Link

Processed 

Data Relay

Low Rate 

Information 

Transmission

Emergency 

Managers 

Weather 

Information 

Network

Command and 

Data Acquisition & 

Telemetry

Data Collection 

Platform Report

Frequency (MHz) 1676.0 1681.478 1685.7 1691.0 1692.7 1694.0 1694.5, 1694.8

(1694.4474 – 26)

Modulation UQPSK QPSK BPSK PCM/NRZ-L/

BPSK OQPSK PCM/BiØ-L/PM 8PSK
55

Link Designation SD MDL PDR LRIT EMWIN CDA Telem DCPR

Symbol Rate 

(ksps) TBD TBD TBD 293.0 35.94 TBD

i) 300 bps 

certification the 

output symbol rate 

shall be 150 

symbols per second 

±0.025%

ii) 1200 bps 

certification the 

output symbol rate 

shall be 600 

symbols per second

Data Rate (kbps) 2660 400 2110 128.0 19.2

4000 bps 

operational

1000 bps 

contingency

0.1/0.3/1.2

Data format notes GVAR CCSDS coding

i) 200 FDMA 

channels @ 1500 

Hz- 100 and 300 bps

ii) 33 FDMA 

channels @ 3000 Hz 

- 1200 bps

Rx Max BER (bps) 10-8 10-8 10-6 10-8 10-8 10-6

Tx filter

-3 dB

2.2 MHz 150 kHz 2.2 MHz 200 kHz 18 kHz 12 kHz 507 kHz

Tx Filter

-20 dB

8.0 MHz 400 kHz 6.2 MHz 600 kHz 26 kHz 40 kHz 650 kHz

Tx Filter

-60 dB

11.2 MHz 4.0 MHz 11.0 MHz 4.5 MHz 200 kHz 2.0 MHz 5.6 MHz

Tx Antenna

EOC Gain (dBi)

14.5 14.5 14.5 (± 9°) 14.5 (± 9°) 14.5 (± 9°) -14.0 14.5 (± 9°)

To design an effective suite of tests to cover each data use scenario, the required data throughput, 

reliability, and integrity need to be determined. Conversations with staff at the NOAA/NWS 

Space Weather Prediction Center in Boulder have led to an understanding of how the aggregate 

RF signal is received, demodulated, and pre-processed before each service is distributed to 

various Federal users. However, once the data services are distributed locally and nationally, it is 

not known how they are further processed. Without actual specifications of minimum 

performance requirements for each service, the results of the tests will be based on assumed 

performance requirements.

Because the GOES N/O/P is a live, mission-critical system, in-situ testing is not possible;

laboratory testing is the only option. Several alternative test procedures were considered:

• Playback simulation. This involves recording a portion of an actual GOES signal and 

playing it back in the presence of varying degrees of interference while measuring the 

level of data degradation. The problem with this method is the difficulty in accurately 

recording an RF signal for a long-enough period. Such a recording would contain 

propagation channel effects that would be difficult to remove.

• Software-defined radio (SDR) simulation. This involves simulating one or more of the 

GOES data services with an SDR. This allows for full control of the data content and 
56

measurement of the data quality. Problems with this method include the need to replicate 

the entire signal, including the data protocol, error correction schemes, equalization, etc.

• Live signal interference test. This involves injecting a live signal into a controlled 

interference environment. The live signal would come from an earth station with similar 

characteristics to the incumbent receiver. Problems with this method include the inability 

to match the signal-to-noise ratio of an actual earth station and the fact that the dynamic 

characteristics of the propagation channel cannot be removed.

• Replication of an actual GOES earth station in the laboratory. This involves the 

acquisition of the actual hardware used in an earth station. It allows for the testing in a 

controlled interference environment. Problems with this method include replicating the 

RF front-end equipment used by the actual earth station; configuration of the equipment 

to match that of an earth station; and difficulty in receiving comparable RF levels and 

SNR values.

All of these potential methods share a common drawback: although throughput can be measured 

easily, BER cannot be measured in a receive-only configuration without a priori knowledge of 

the signal. The lack of a quality metric such as BER makes the determination of a service failurepoint impossible. The GOES service failure-point would be equivalent to the VSS video failurepoint at which the required data throughput, reliability, and integrity are considered inadequate. 

Without determining a GOES service failure-point, the effect of interference cannot be 

determined.

5.2.2 Test Plan

Given the time constraints the project had to meet, the fourth method (replica of a GOES earth 

station) was chosen. However, all GOES earth stations are not identically configured. Different 

sites use different modems, depending on the signals being received. The RF front-end at the 

Boulder site is a custom design, using custom-built filters. Replicating any RF front-end, much 

less one that would be representative of all GOES earth stations (see Appendix C) would be 

extremely impractical. So it was decided to try measuring the system’s parameters at the IF level. 

One major drawback to this approach is that the contribution of the RF electronics to the 

system’s FDR is missing.

5.2.3 Test Setup

The satellite modems that were tested are general-use modems with a wide range of configurable 

settings. They also have limitations in various areas, notably the types of modulations and data 

rates they can handle. This also points out the inequality among the various GOES earth stations. 

Some stations do not monitor all of the downlink signals in the 1675–1695 MHz band. For 

example, the Boulder site does not monitor the raw sensor data (SD) and therefore does not need 

an additional modem that can handle the modulation and data rate of the SD signal. To minimize 

the amount of testing required, the two extreme signals, in terms of modulation and data rate, 

that the on-hand modems could handle, were tested. These are Processed Data Relay (PDR) and 

Emergency Managers Weather Information Network (EMWIN), shown highlighted in Table 11.

In the case of the PDR signal, the modem’s maximum data rate of 512 kbps was less than that 

required (2110 kbps). To exercise the extremes, we settled for the 512 kbps data rate.
57

Besides the parameters shown in Table 11, the modems can be configured to use a number of 

other functions that may or may not affect the received signal quality. These include Viterbi 

FEC, FEC rate, different types of automatic power modes, data framing, data scrambling, and 

clocking source (embedded, internal, or external). Of these, only FEC and data scrambling were 

tested to see if they made a difference on the received data quality.

The modems can display the BER and Eb/N0 of the received signal. These values were recorded 

during the measurements when required, although an outboard BER measuring setup was 

developed in case better accuracy was required.

Since the tests were to be performed at the IF level, the VSS signal needed to be downconverted. This was accomplished by using a component mixer/down-converter and a vector 

signal generator (VSG) operating as a local oscillator (LO). The modems’ output center 

frequency (IF) could be reconfigured and varied between 104 and 176 MHz; it was set to the 

midpoint of 140 MHz. The modems’ frequency was left fixed for convenience sake since it was 

easier to change the LO’s frequency for off-frequency testing.

The resultant test setup is shown in Figure 38. It was determined that the VSS’s RF output was 

not affected by the presence (or lack) of an input video signal. Consequently, the tests were 

performed with no input video signal.
58

Figure 38. Test setup - VSS interference injection into GOES.

5.2.4 Test Procedure

The following tests were performed for the two GOES signals (PDR and EMWIN).

5.2.4.1 Calibration Test

An initial test was performed to determine if the RF output level of the VSS would have any 

effect on the measured values. A 30 dB fixed attenuator was inserted between the VSS’s output 
59

and the mixer’s RF input to avoid overloading (and possibly damaging) the test components and 

the satellite modems. This test resulted in the plots shown in Figures 39 and 40. Values were 

measured for two signal-to-interference ratios (15 and 20 dB). The modems were configured to 

operate with QPSK modulation and the maximum 512 kbps data rate.

Figure 39. Results of calibration test – fixed attenuator at VSS output = 20 dB.

Figure 40. Results of calibration test – fixed attenuator at VSS output = 30 dB.

As can be seen, there is, at the most, a couple of dB difference between the two plots, but the 

difference is not significant.
60

5.2.4.2 Test 1 – A Procedure to Demonstrate the Baseline Failure Point

1. With the satellite modems connected back to back through the variable attenuator, start 

out with the attenuator adjusted such that data is transferred without errors.

2. Increase the attenuation in 1 dB steps until the signal is too weak for the two modems to 

maintain a connection. The results of this test are shown in Table 12.

Table 12. Results from GOES baseline tests.

Signal Viterbi FEC Scrambling Attenuator Value (dB)

EMWIN

1/2 ON 61

1/2 OFF 58

7/8 ON 58

PDR

1/2 OFF 52

1/2 ON 52

OFF OFF 55

OFF ON 55

5.2.4.3 Test 2 – Coincident Signal Interference

1. Set up the test configuration as shown in Figure 38.

2. Set the LO frequency to 1547.0 MHz so that the down-converted VSS signal is centered 

at 140 MHz.

3. With the RF output of the vector signal generator OFF, adjust the variable attenuator at 

the output of the transmitting modem such that the receiving modem starts reporting 

errors, then lower the attenuator by 1 dB (so that the receiving modem reports no errors 

but the signal is immediately preceding the failure point). The results of this test are 

shown in Table 13.

Table 13. Results from Test 2, Step 3.

Signal Viterbi FEC Scrambling Attenuator Value (dB)

EMWIN

1/2 ON 40

1/2 OFF 39

7/8 ON 36

PDR

1/2 OFF 31

1/2 ON 31

OFF OFF 33

OFF ON 33

4. Set the attenuator at the output of the down converter to max (95 dB), turn the RF output 

of the vector signal generator ON, then decrease the attenuation in 1 dB steps, recording 
61

both BERs and the Eb/N0 at each step, until the modems can no longer connect to each 

other. The results of this test are shown in Figures 41 through 45.

Figure 41. Results of Test 2, Step 4 – EMWIN, FEC = 1/2, Scrambling = ON.

Figure 42. Results of Test 2, Step 4 – EMWIN, FEC = 1/2, Scrambling = OFF.

Figure 43. Results of Test 2, Step 4 – EMWIN, FEC = 7/8, Scrambling = ON.
62

Figure 44. Results of Test 2, Step 4 – PDR, FEC = 1/2,

Scrambling = OFF (left), ON (right).

Figure 45. Results of Test2, Step 4 – PDR, FEC = OFF,

Scrambling = OFF (left), ON (right).

5.2.4.4 Test 3 – Out-of-Band Interference

1. Repeat Test 2 while changing the center frequency of the down-converted VSS signal (by 

changing the LO frequency). Start out with the down-converted VSS at 140 MHz, and 

then decrease the frequency by 0.5 MHz steps until the interfering signal no longer has 

any effect on the modems (i.e., change the LO frequency from 1547.0 MHz to 1546.5 

MHz and so on).

2. Repeat a single test, but increase the LO (raising the VSS’s frequency) in a similar 

manner to prove that the offset interference effect is symmetrical.

We could not discern any effect of the VSS on the satellite modem’s failure point until we 

reached an I/N of 25 dB and further increasing the I/N to 35 dB changed the failure point only by 

1 dB.
63

5.2.5 VSS to GOES Interference Test Conclusions

Test 1 showed that for EMWIN, data scrambling can improve the satellite modem’s performance 

by 3 dB, but increasing the FEC from 1/2 to 7/8 reverses that improvement. For PDR, data 

scrambling has no effect, but simply turning FEC on can cause a 3 dB improvement. This could 

be significant in an interfering environment. However, it is unknown how any deployed modems 

are configured. One would assume that the modems would be optimally configured, considering 

the low signal levels that are received at the earth stations (which are only 4–5 dB above the 

noise floor), but this should be looked into if interference becomes a problem. Note that,

depending on the modulation selected, the modems will limit the levels of FEC available, which

accounts for the difference in settings between the two signals.

Test 2 was a proof-of-concept to confirm the validity of the test design, and to confirm that the 

modems performed as intended. It shows that the Eb/N0 and BER reported by the receiving 

modem vary relatively smoothly (within the measurement’s ranges) as interference is gradually 

increased, except in the last case (PDR, FEC = OFF, Scrambling = ON) where the presumed loss 

of synchronization results in large variations of BER.

The failure of Test 3 showed the limits of trying to measure the FDR of a device at IF. This test 

was performed in lieu of having access to a complete GOES receiver system. Without the RF 

front end, the total system FDR cannot be measured. We had hoped to gain some qualitative 

insight into the total system FDR by measuring the IF portion. We learned that the IF section’s 

contribution to the total system FDR is negligible.

The purpose of testing interference into the satellite modems was to try to validate the 

assumptions made during the analysis stage. The fact that testing the modems at IF did not 

produce usable results did not disprove those assumptions. The assumptions were already 

confirmed by the results of the tests described in Section 5.1 (Interference of the Radiosonde to 

the VSS). What was confirmed was that the entire system (RF, IF, and the down-stream 

processing gain) needs to be tested as a single entity to obtain an accurate understanding of FDR

behavior.
64

6. CONCLUSIONS

6.1 The Interference Between the Incumbent and Entrant Systems

It is not the intent of this report to make pronouncements on how to achieve coexistence within a 

shared band. The intent is to examine and illuminate the engineering questions that need to be 

answered so that those who are responsible for Federal services in a band may negotiate and 

cooperate with their colleagues who are responsible for other Federal services in the same band.

Four classes of interaction were examined: VSS-to-radiosonde, radiosonde-to-VSS, GOES-toVSS, and VSS-to-GOES. Of these interactions, interference from the GOES-N/O/P and GOES-R 

satellites into the VSS receiver was determined not to be a problem. The interfering signal levels 

from the satellites into the VSS receiver are so low because the levels of the satellite’s signals are 

very low and the VSS receiver has a very low gain antenna.

On the other hand, interference from the VSS transmitter into the GOES earth stations can be a 

significant problem given the fact that the GOES receiver antennas have extremely high gains to 

receive the satellite signals. As a result, Df versus separation distance plots for all VSS-intoGOES interactions were calculated (Appendix D) and can be used to plan the deployment of 

VSS devices near GOES earth stations.

Interference from the radiosondes into the VSS receiver is best described by Figures 20, 22, and 

24 in Section 4, which define the Df needed versus radiosonde-to-VSS separation distance. These 

figures provide protection distance and off-tuning information for compatible operation for 

coexistence in the 1675–1695 MHz band. The analysis and measurement data included in this 

report can be used to create a coexistence plan by specifying protection distances and frequency 

arrangements compatible with the findings.

Interference from the VSS transmitter into the radiosonde receiver resulted in plots such as 

Figure 8, which specify the Df versus the separation distance between the VSS transmitter and 

the radiosonde receiver. Figure 8 is a worst-case scenario where the VSS transmitter antenna and 

the radiosonde receiver antenna are pointed directly at each other. This is not always the case, 

but is possible. Figures 4 through 7 plot Df versus separation distance for other cases where the 

antennas of each system are not pointing directly at each other. Further investigation of this 

interaction between the VSS transmitter and the radiosonde receiver would involve a statistical 

analysis with probability considerations.

All of the interference scenarios have been analyzed to determine the calculated FDR. In the 

absence of additional corroborating information from testing, these graphs can form the basis for 

the development of a detailed sharing plan. A clear understanding of the FDR for these scenarios 

forms an engineering basis for establishing protection zones and frequency plans. The required 

S/I values still need to be determined for the equipment used for each service; this may not be 

possible until the users determine their minimum data performance requirements. Determining 

these performance requirements will require an understanding of how the data is both acquired 

and used.
65

Defining the problem and the search space for this proposed shared communication service band 

is complete at this point. Tests based on the methods given here have been verified and can now 

be applied to other receivers for validation or the raw analysis data can be used to move forward 

to develop frequency channel plans and protection zones.

6.2 The Importance of Using the Correct Propagation-Loss Prediction Model

It is critical to an EMC analysis of any digital communication system that the correct 

propagation-loss prediction models are used and that the specific digital receiver modulation is 

accurately modeled. The correct propagation model must be used in specific geometric scenarios 

to determine the signal strength of the interfering signal. A suitably selected propagation model 

will accurately represent the effects of input parameters such as frequency, antenna heights, 

antenna characteristics, and communication distance on predicted signal strength. Failure to 

account for the implicit range of input parameters in the selection of a propagation model will 

produce erroneous results. Consequently, the use of a model outside its designed range will lead 

to inevitable misinterpretation of the interference potential. Based on such misinterpretation, 

interference mitigation techniques could be proposed that either over- or under-compensate. This 

could result in either an unnecessarily expensive mitigation solution or unexpected interference, 

both of which could be catastrophic to mission critical communication systems.

An example of potential misinterpretation is incorrect use of the free-space loss model. 

Principally, this model does not include physical phenomena such as the surface wave, the 

effects of ground on the antenna performance, and the propagation effects of diffraction and 

troposcatter in the prediction of transmission loss. In applying the free-space model to an 

interference scenario, the analyst must be vigilantly aware of these limitations. Use of the correct 

propagation model provides cost savings by eliminating ineffective mitigation techniques from 

consideration and assuring that interference is effectively estimated.

This report shows where and why the correct propagation model is used in all 28 of the 

interference scenarios. Using the correct propagation models allows for the accurate and 

appropriate levels of interference to be identified, thus eliminating misinterpretation of the 

results. In this fashion, this complex analysis has been streamlined and simplified. This is 

possible because many of the radio-wave propagation models used in this investigation have 

been developed at ITS.

6.3 The Method for Identifying Interference Potential

Although the method described here was developed for a specific frequency band, it could be 

used for any pair of systems sharing any frequency band. This document can act as a template for 

determining the Df and separation distances necessary to achieve a required level of interference 

rejection for potential interference scenarios (such as those listed in Appendix B). The best way 

to illustrate how to use this document is through a generalized example.

To begin with, all of the potential interference scenarios must be defined. Then the operating 

parameters for both devices under consideration must be identified; for instance, transmitter and 

receiver filter characteristics, the receiver noise figure, the calculated receiver sensitivity, and the 
66

calculated acceptable interference level at the receiver. Using these parameters, the following 

steps can be performed to determine the FDR, Df, and separation distances necessary to maintain 

required performance levels:

1. Once the acceptable BER of the victim system is determined, the BER versus Eb/N0

plot (e.g. Figure 17 in Section 4.1) is used to determine the Eb/N0 for a given S/I. An 

S/I of 20 dB is a generally accepted value.

2. Using these Eb/N0 and S/I values, I/N is determined from the I/N versus Eb/N0 plot 

(e.g. Figure 17 in Section 4.1).

3. For a given distance between the interfering transmitter and the victim receiver, the 

received interference power is derived from the received interference power versus 

distance plot (e.g. Figure 1 in Section 3.2).

4. Using the interference power and I/N values, the FDR can be derived from the FDR

versus distance plot (e.g. Figure 2 in Section 3.5). If the I/N differs from that used to 

generate an existing plot, then the FDR equation in Section 3.5 can be used to scale 

the FDR.

5. The FDR can be used to determine either the Df or the separation distance from the 

FDR versus Df plot (e.g. Figure 3 in Section 3.5) and the FDR versus separation 

distance plot (e.g. Figure 2 in Section 3.5). Those two relationships can be combined 

into a Df versus separation distance plot (e.g. Figure 4 in Section 3.5).

6.4 Miscellaneous Conclusions

The interference effects on digital communication systems have been addressed by taking into 

account the specific digital modulation of the incumbent receiver. Consideration of the digital 

modulation permits specific S/I and I/N ratios based on Eb/N0 to provide a more precise 

determination of interference thresholds.

It has been shown that broadband and narrowband interference are similar enough that the 

broadband interference assumptions used in the calculations do not affect the predictions of the 

effect of interference.

It was determined that the video failure method described in this report can be used as a 

surrogate for objective measures since it appears to correlate well with assumptions made 

regarding video behavior in the presence of interference.
67

7. REFERENCES

[1] Fast-Track Report “An Assessment of the Near-Term Viability of Accommodating 

Wireless Broadband Systems in the 1675–1710 MHz, 1755–1780 MHz, 3500–3650 MHz, 

and 4200–4220 MHz, 4380–4400 MHz Bands,” U.S. Department of Commerce, October 

2010. Available http://www.ntia.doc.gov/files/ntia/publications/

fasttrackevaluation_11152010.pdf.

[2] ITT Corporation, “Communications Receiver Performance Degradation Handbook,” 

Document Control No. JSC-CR-10-004, Defense Information Systems Agency, Defense 

Spectrum, Organization, Joint Spectrum Center, August 11, 2010. Available 

http://www.ntia.doc.gov/report/2010/communications-receiver-performance-degradationhandbook.

[3] John G. Proakis, Digital Communications, New York: McGraw-Hill, 1989.

[4] ITU-R Recommendation SM.337-6 (2008), “Frequency and distance separations,” 

International Telecommunication Union, Geneva, Switzerland. Available 

http://www.itu.int/rec/R-REC-SM.337-6-200810-I/en.

[5] W. Kuebler, “The Definition of Frequency-Dependent Rejection,” IEEE Transactions on 

Electromagnetic Capability, Vol. EMC-21, No. 4, Nov 1979.

[6] N. DeMinco, “Propagation Loss Prediction Considerations for Close-In Distances and 

Low-Antenna Height Applications,” NTIA Technical Report TR-07-449, July 2007.

Available http://www.its.bldrdoc.gov/publications/2486.aspx.

[7] P. L. Rice et. al., “Transmission Loss Predictions for Tropospheric Communication 

Circuits,” National Bureau of Standards Technical Note 101 (TN-101), Volumes 1 and 2, 

January 1, 1967. Available http://www.its.bldrdoc.gov/publications/2726.aspx and 

http://www.its.bldrdoc.gov/publications/2727.aspx.

[8] A. G. Longley and P.L. Rice, “Prediction of Tropospheric Radio Transmission Loss Over

Irregular Terrain, A Computer Method-1968”, ESSA Technical Report ERL-79-ITS-67, 

July 1968. Available http://www.its.bldrdoc.gov/publications/2784.aspx.

[9] Carl T. A. Johnk, Engineering Electromagnetic Fields & Waves, New York: John Wiley & 

Sons, 1975.

[10] R. L. Freeman, Radio System Design for Telecommunications, Third Edition, New York, 

Wiley-Interscience, 2007.
68

ACKNOWLEDGEMENTS

ITS was tasked to conduct an exit evaluation to evaluate the feasibility of coexistence of Federal 

communications services. This work was performed under the funding and direction of the DHS 

lead task group charged with examining an exit strategy for the 1755–1850 MHz band.
69

APPENDIX A. FREQUENCY DEPENDENT REJECTION VERSUS OFFSET 

FREQUENCY CURVES FOR ALL SCENARIOS

Figure A-1. Frequency dependent rejection

versus offset frequency – scenario S01.

Figure A-2. Frequency dependent rejection

versus offset frequency – scenario S02.

Figure A-3. Frequency dependent rejection

versus offset frequency – scenario S03.

Figure A-4. Frequency dependent rejection

versus offset frequency – scenario S04.

Figure A-5. Frequency dependent rejection

versus offset frequency – scenario S05.

Figure A-6. Frequency dependent rejection

versus offset frequency – scenario S06.

0

10

20

30

40

50

60

0 1 2 3 4 5 6 7 8 9 10

Rejection Level (dB)

Δf (MHz)

0

10

20

30

40

50

60

70

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Rejection Level (dB)

Δf (MHz)

0

5

10

15

20

25

0 1 2 3 4 5 6 7 8 9 10

Rejection Level (dB)

Δf (MHz)

0

5

10

15

20

25

0 1 2 3 4 5 6 7 8 9 10

Rejection Level (dB)

Δf (MHz)

0

5

10

15

20

25

0 1 2 3 4 5 6 7 8 9 10

Rejection Level (dB)

Δf (MHz)

0

5

10

15

20

25

0 1 2 3 4 5 6 7 8 9 10

Rejection Level (dB)

Δf (MHz)
70

Figure A-7. Frequency dependent rejection

versus offset frequency – scenario S07.

Figure A-8. Frequency dependent rejection

versus offset frequency – scenario S08.

Figure A-9. Frequency dependent rejection

versus offset frequency – scenario S09.

Figure A-10. Frequency dependent rejection

versus offset frequency – scenario S10.

Figure A-11. Frequency dependent rejection

versus offset frequency – scenario S11.

Figure A-12. Frequency dependent rejection

versus offset frequency – scenario S12.

0

5

10

15

20

25

0 1 2 3 4 5 6 7 8 9 10

Rejection Level (dB)

Δf (MHz)

0

5

10

15

20

25

0 1 2 3 4 5 6 7 8 9 10

Rejection Level (dB)

Δf (MHz)

0

5

10

15

20

25

0 1 2 3 4 5 6 7 8 9 10

Rejection Level (dB)

Δf (MHz)

0

2

4

6

8

10

12

14

16

18

0 1 2 3 4 5 6 7 8 9 10

Rejection Level (dB)

Δf (MHz)

0

2

4

6

8

10

12

14

16

18

0 1 2 3 4 5 6 7 8 9 10

Rejection Level (dB)

Δf (MHz)

0

5

10

15

20

25

0 1 2 3 4 5 6 7 8 9 10

Rejection Level (dB)

Δf (MHz)
71

Figure A-13. Frequency dependent rejection

versus offset frequency – scenario S13.

Figure A-14. Frequency dependent rejection

versus offset frequency – scenario S14.

Figure A-15. Frequency dependent rejection

versus offset frequency – scenario S15.

Figure A-16. Frequency dependent rejection

versus offset frequency – scenario S16.

Figure A-17. Frequency dependent rejection

versus offset frequency – scenario S17.

Figure A-18. Frequency dependent rejection

versus offset frequency – scenario S18.

0

5

10

15

20

25

0 1 2 3 4 5 6 7 8 9 10

Rejection Level (dB)

Δf (MHz)

0

5

10

15

20

25

0 1 2 3 4 5 6 7 8 9 10

Rejection Level (dB)

Δf (MHz)

0

2

4

6

8

10

12

14

16

18

20

0 1 2 3 4 5 6 7 8 9 10

Rejection Level (dB)

Δf (MHz)

0

5

10

15

20

25

30

35

40

45

50

0 1 2 3 4 5 6 7 8 9 10

Rejection Level (dB)

Δf (MHz)

0

5

10

15

20

25

30

35

40

45

50

0 1 2 3 4 5 6 7 8 9 10

Rejection Level (dB)

Δf (MHz)

0

10

20

30

40

50

60

0 1 2 3 4 5 6 7 8 9 10

Rejection Level (dB)

Δf (MHz)
72

Figure A-19. Frequency dependent rejection

versus offset frequency – scenario S19.

Figure A-20. Frequency dependent rejection

versus offset frequency – scenario S20.

Figure A-21. Frequency dependent rejection

versus offset frequency – scenario S21.

Figure A-22. Frequency dependent rejection

versus offset frequency – scenario S22.

Figure A-23. Frequency dependent rejection

versus offset frequency – scenario S23.

Figure A-24. Frequency dependent rejection

versus offset frequency – scenario S24.

0

10

20

30

40

50

60

70

0 1 2 3 4 5 6 7 8 9 10

Rejection Level (dB)

Δf (MHz)

0

10

20

30

40

50

60

0 1 2 3 4 5 6 7 8 9 10

Rejection Level (dB)

Δf (MHz)

0

5

10

15

20

25

30

35

40

45

50

0 1 2 3 4 5 6 7 8 9 10

Rejection Level (dB)

Δf (MHz)

0

10

20

30

40

50

60

70

0 1 2 3 4 5 6 7 8 9 10

Rejection Level (dB)

Δf (MHz)

0

5

10

15

20

25

30

35

40

0 1 2 3 4 5 6 7 8 9 10

Rejection Level (dB)

Δf (MHz)

0

5

10

15

20

25

30

35

40

45

0 1 2 3 4 5 6 7 8 9 10

Rejection Level (dB)

Δf (MHz)
73

Figure A-25. Frequency dependent rejection

versus offset frequency – scenario S25.

Figure A-26 Frequency dependent rejection

versus offset frequency – scenario S26

Figure A-27. Frequency dependent rejection

versus offset frequency – scenario S27.

Figure A-28. Frequency dependent rejection

versus offset frequency – scenario S28.

0

10

20

30

40

50

60

0 1 2 3 4 5 6 7 8 9 10

Rejection Level (dB)

Δf (MHz)

0

10

20

30

40

50

60

0 1 2 3 4 5 6 7 8 9 10

Rejection Level (dB)

Δf (MHz)

0

10

20

30

40

50

60

0 1 2 3 4 5 6 7 8 9 10

Rejection Level (dB)

Δf (MHz)

0

10

20

30

40

50

60

70

0 1 2 3 4 5 6 7 8 9 10

Rejection Level (dB)

Δf (MHz)
74

APPENDIX B. SCENARIOS

The VSS provided by DHS operates on three discrete channels: 1679, 1687, and 1695 MHz and 

can be re-programmed to operate on other frequencies within the 1675-1695 MHz band. For the 

purposes of determining worst-case interference levels in the following scenarios, the VSS will 

operate in a co-channel configuration, independent of bandwidth. During actual testing, the VSS 

channel closest to the paired transceiver frequency will be used.
75

Scenario: S01

Transmitter: VSS Receiver: Radiosonde

ht = 2m and greater hr =5m

Pt = 24 dBm

Polarization = linear Polarization = LHCP

Gt = 2.15 dBi Gr = 7 dBi (wide angle, close to ground)

= 28 dBi (otherwise)

Cable loss = 0 dB Cable loss = 0 dB

f = 1676, 1678, 1680, 1682 MHz f = 1676, 1678, 1680, 1682 MHz

Filter characteristics Filter characteristics

Attenuation (dB) Frequency offset (MHz) Attenuation (dB) Frequency offset (MHz)

3

20

33

34

36

37

39

41

43

45

46

48

50

51

53

54

55

3.75

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

3

20

60

66

72

78

0.075

0.270

0.600

1.200

2.400

4.800

3dB emission bandwidth = 7.5 MHz 3dB receiver bandwidth = 0.150 MHz

Noise Figure = 6.5 dB

Sensitivity = -174 dBm/Hz + NF (dB) + 10logBW(Hz)

= -174 dBm/Hz + 6.5 dB + 10log(0.150x106

)

= -115.74 dBm

I/N = -6 dB

I = -121.74 dBm

Tuning range = 1668.4 to 1700 MHz
76

Scenario: S02

Transmitter: Radiosonde Receiver: VSS

ht = 1 to 33,000m hr = 2m and greater

Pt = 23.8 dBm

Polarization = LHCP Polarization = linear

Gt = 4.3 dBi Gr = 2.15 dBi

Cable loss = 0 dB Cable loss = 0.5 dB

f = 1676, 1678, 1680, 1682 MHz f = 1676, 1678, 1680, 1682 MHz

Filter characteristics Filter characteristics

Attenuation (dB) Frequency offset (MHz) Attenuation (dB) Frequency offset (MHz)

3

36

48

52

56

58

0.0675

0.2000

0.4000

0.6000

0.8000

1.0000

3

20

60

3.751

10.000

≥15.000

3dB emission bandwidth = 0.135 MHz 3dB receiver bandwidth = 7.502 MHz

Noise Figure = 4.0 dB

Receiver sensitivity:

-89 dBm @ QPSK

-83 dBm @ 16QAM

-77 dBm @ 64QAM

Sensitivity = -174 dBm/Hz + NF (dB) + 10logBW(Hz)

= -174 dBm/Hz + 4.0 dB + 10log(7.5021x106

)

= -101.25 dBm

I/N = -6 or -10 dB

I = -107.25 or -111.25 dBm

Tuning range = 1675 to 1695 MHz
77

Scenario: S03

Transmitter: GOES-N Sensor Data (SD) Receiver: VSS

ht = 35,786 Km hr = 2m and greater

Pt = 6.9 dBW

Polarization = linear (N-S)

3 dB vertical beamwidth = 32°

3 dB horizontal beamwidth = 32°

Polarization = linear

Gt = 15.6 dBi (-6 dBi @ 60°) Gr = 2.15 dBi

Cable loss = 0.5 dB

f = 1676.0 MHz f = 1676.0 MHz

Filter characteristics Filter characteristics

Attenuation (dB) Frequency offset (MHz) Attenuation (dB) Frequency offset (MHz)

3

20

60

1.1

4.0

5.6

3

20

60

3.751

10.000

≥15.000

3dB emission bandwidth = 2.2 MHz 3dB receiver bandwidth = 7.502 MHz

Spurious emissions = -70 dB

2nd harmonic = -60 dB

3rd harmonic = -60 dB

Higher harmonics = -80 dB

Noise Figure = 4.0 dB

Receiver sensitivity:

-89 dBm @ QPSK

-83 dBm @ 16QAM

-77 dBm @ 64QAM

Sensitivity = -174 dBm/Hz + NF (dB) + 10logBW(Hz)

= -174 dBm/Hz + 4.0 dB + 10log(7.5021x106

)

= -101.25 dBm

I/N = -6 or -10 dB

I = -107.25 or -111.25 dBm

Tuning range = 1675 to 1695 MHz
78

Scenario: S04

Transmitter: GOES-N Processed Data Relay 

(PDR) Receiver: VSS

ht = 35,786 Km hr = 2m and greater

Pt = 14.5 dBW (28.0 W)

Polarization = linear (N-S)

3 dB vertical beamwidth = 32°

3 dB horizontal beamwidth = 32°

Polarization = linear

Gt = 15.6 dBi (-6 dBi @ 60°) Gr = 2.15 dBi

Cable loss = 0.5 dB

f = 1685.7 MHz f = 1685.7 MHz

Filter characteristics Filter characteristics

Attenuation (dB) Frequency offset (MHz) Attenuation (dB) Frequency offset (MHz)

3

20

60

1.1

3.1

5.5

3

20

60

3.751

10.000

≥15.000

3dB emission bandwidth = 2.2 MHz 3dB receiver bandwidth = 7.502 MHz

Spurious emissions = -75 dB

2nd harmonic = -67 dB

3rd harmonic = -67 dB

Higher harmonics = -80 dB

Noise Figure = 4.0 dB

Receiver sensitivity:

-89 dBm @ QPSK

-83 dBm @ 16QAM

-77 dBm @ 64QAM

Sensitivity = -174 dBm/Hz + NF (dB) + 10logBW(Hz)

= -174 dBm/Hz + 4.0 dB + 10log(7.5021x106

)

= -101.25 dBm

I/N = -6 or -10 dB

I = -107.25 or -111.25 dBm

Tuning range = 1675 to 1695 MHz
79

Scenario: S05

Transmitter: GOES-N Low Rate Info 

Transponder (LRIT) WEFAX Receiver: VSS

ht = 35,786 Km hr = 2m and greater

Pt = 10.2 dBW (10.4 W)

Polarization = linear (N-S)

3 dB vertical beamwidth = 32°

3 dB horizontal beamwidth = 32°

Polarization = linear

Gt = 15.6 dBi (-6 dBi @ 60°) Gr = 2.15 dBi

Cable loss = 0.5 dB

f = 1691.0 MHz f = 1691.0 MHz

Filter characteristics Filter characteristics

Attenuation (dB) Frequency offset (MHz) Attenuation (dB) Frequency offset (MHz)

3

20

60

0.10

0.30

2.25

3

20

60

3.751

10.000

≥15.000

3dB emission bandwidth = 0.2 MHz 3dB receiver bandwidth = 7.502 MHz

Spurious emissions = -75 dB

2nd harmonic = -63 dB

3rd harmonic = -63 dB

Higher harmonics = -80 dB

Noise Figure = 4.0 dB

Receiver sensitivity:

-89 dBm @ QPSK

-83 dBm @ 16QAM

-77 dBm @ 64QAM

Sensitivity = -174 dBm/Hz + NF (dB) + 10logBW(Hz)

= -174 dBm/Hz + 4.0 dB + 10log(7.5021x106

)

= -101.25 dBm

I/N = -6 or -10 dB

I = -107.25 or -111.25 dBm

Tuning range = 1675 to 1695 MHz
80

Scenario: S06

Transmitter: GOES-N Emergency 

Management Weather Info Network (EMWIN) Receiver: VSS

ht = 35,786 Km hr = 2m and greater

Pt = 1.2 dBW (1.3 W)

Polarization = linear (N-S)

3 dB vertical beamwidth = 32°

3 dB horizontal beamwidth = 32°

Polarization = linear

Gt = 15.6 dBi (-6 dBi @ 60°) Gr = 2.15 dBi

Cable loss = 0.5 dB

f = 1692.7 MHz f = 1692.7 MHz

Filter characteristics Filter characteristics

Attenuation (dB) Frequency offset (MHz) Attenuation (dB) Frequency offset (MHz)

3

20

60

0.009

0.013

0.100

3

20

60

3.751

10.000

≥15.000

3dB emission bandwidth = 0.018 MHz 3dB receiver bandwidth = 7.502 MHz

Spurious emissions = -65 dB

2nd harmonic = -69 dB

3rd harmonic = -69 dB

Higher harmonics = -80 dB

Noise Figure = 4.0 dB

Receiver sensitivity:

-89 dBm @ QPSK

-83 dBm @ 16QAM

-77 dBm @ 64QAM

Sensitivity = -174 dBm/Hz + NF (dB) + 10logBW(Hz)

= -174 dBm/Hz + 4.0 dB + 10log(7.5021x106

)

= -101.25 dBm

I/N = -6 or -10 dB

I = -107.25 or -111.25 dBm

Tuning range = 1675 to 1695 MHz
81

Scenario: S07

Transmitter: GOES-N Multiuse Data Link 

(MDL) Receiver: VSS

ht = 35,786 Km hr = 2m and greater

Pt = 8.2 dBW (6.7 W)

Polarization = linear (N-S)

3 dB vertical beamwidth = 32°

3 dB horizontal beamwidth = 32°

Polarization = linear

Gt = 15.6 dBi (-6 dBi @ 60°) Gr = 2.15 dBi

Cable loss = 0.5 dB

f = 1681.478 MHz f = 1681.478 MHz

Filter characteristics Filter characteristics

Attenuation (dB) Frequency offset (MHz) Attenuation (dB) Frequency offset (MHz)

3

20

60

0.075

0.200

2.000

3

20

60

3.751

10.000

≥15.000

3dB emission bandwidth = 0.150 MHz 3dB receiver bandwidth = 7.502 MHz

Spurious emissions = -70 dB

2nd harmonic = -60 dB

3rd harmonic = -60 dB

Higher harmonics = -80 dB

Noise Figure = 4.0 dB

Receiver sensitivity:

-89 dBm @ QPSK

-83 dBm @ 16QAM

-77 dBm @ 64QAM

Sensitivity = -174 dBm/Hz + NF (dB) + 10logBW(Hz)

= -174 dBm/Hz + 4.0 dB + 10log(7.5021x106

)

= -101.25 dBm

I/N = -6 or -10 dB

I = -107.25 or -111.25 dBm

Tuning range = 1675 to 1695 MHz
82

Scenario: S08

Transmitter: GOES-N Data Collection 

Platform Report (DCPR) Receiver: VSS

ht = 35,786 Km hr = 2m and greater

Pt = 8.0 dBW (6.3 W)

Polarization = linear (N-S)

3 dB vertical beamwidth = 32°

3 dB horizontal beamwidth = 32°

Polarization = linear

Gt = 15.6 dBi (-6 dBi @ 60°) Gr = 2.15 dBi

Cable loss = 0.5 dB

f = 1694.5 and 1694.8 MHz f = 1694.5 and 1694.8 MHz

Filter characteristics Filter characteristics

Attenuation (dB) Frequency offset (MHz) Attenuation (dB) Frequency offset (MHz)

3

20

60

0.254

0.325

2.800

3

20

60

3.751

10.000

≥15.000

3dB emission bandwidth = 0.507 MHz 3dB receiver bandwidth = 7.502 MHz

Spurious emissions = -65 dB

2nd harmonic = -61 dB

3rd harmonic = -61 dB

Higher harmonics = -80 dB

Noise Figure = 4.0 dB

Receiver sensitivity:

-89 dBm @ QPSK

-83 dBm @ 16QAM

-77 dBm @ 64QAM

Sensitivity = -174 dBm/Hz + NF (dB) + 10logBW(Hz)

= -174 dBm/Hz + 4.0 dB + 10log(7.5021x106

)

= -101.25 dBm

I/N = -6 or -10 dB

I = -107.25 or -111.25 dBm

Tuning range = 1675 to 1695 MHz
83

Scenario: S09

Transmitter: GOES-N Command and Data 

Acquisition (CDA) Telemetry Receiver: VSS

ht = 35,786 Km hr = 2m and greater

Pt = 4.5 dBW (2.8 W)

Polarization = RHCP

3 dB vertical beamwidth = 56°

3 dB horizontal beamwidth = 56°

Polarization = linear

Gt = 0 dBi (-1.5 dBi @ 122°) Gr = 2.15 dBi

Cable loss = 0.5 dB

f = 1694.0 MHz f = 1694.0 MHz

Filter characteristics Filter characteristics

Attenuation (dB) Frequency offset (MHz) Attenuation (dB) Frequency offset (MHz)

3

20

60

0.006

0.020

1.000

3

20

60

3.751

10.000

≥15.000

3dB emission bandwidth = 0.012 MHz 3dB receiver bandwidth = 7.502 MHz

Spurious emissions = -65 dB

2nd harmonic = -65 dB

3rd harmonic = -65 dB

Higher harmonics = -80 dB

Noise Figure = 4.0 dB

Receiver sensitivity:

-89 dBm @ QPSK

-83 dBm @ 16QAM

-77 dBm @ 64QAM

Sensitivity = -174 dBm/Hz + NF (dB) + 10logBW(Hz)

= -174 dBm/Hz + 4.0 dB + 10log(7.5021x106

)

= -101.25 dBm

I/N = -6 or -10 dB

I = -107.25 or -111.25 dBm

Tuning range = 1675 to 1695 MHz
84

Scenario: S10

Transmitter: GOES-R Rebroadcast Data 

Transponder (GRB1 and GRB2) QPSK Receiver: VSS

ht = 35,786 Km hr = 2m and greater

Pt = 16.0 dBW (40 W)

Polarization = RHCP and LHCP

3 dB vertical beamwidth = 26°

3 dB horizontal beamwidth = 26°

Polarization = linear

Gt = 17.3 dBi Gr = 2.15 dBi

Cable loss = 0.5 dB

f = 1686.6 MHz f = 1686.6 MHz

Filter characteristics Filter characteristics

Attenuation (dB) Frequency offset (MHz) Attenuation (dB) Frequency offset (MHz)

3

20

40

60

4.35

5.45

6.10

54.00

3

20

60

3.751

10.000

≥15.000

3dB emission bandwidth = 8.7 MHz 3dB receiver bandwidth = 7.502 MHz

Spurious emissions = -60 dB

2nd harmonic = -60 dB

3rd harmonic = -60 dB

Higher harmonics = -60 dB

Noise Figure = 4.0 dB

Receiver sensitivity:

-89 dBm @ QPSK

-83 dBm @ 16QAM

-77 dBm @ 64QAM

Sensitivity = -174 dBm/Hz + NF (dB) + 10logBW(Hz)

= -174 dBm/Hz + 4.0 dB + 10log(7.5021x106

)

= -101.25 dBm

I/N = -6 or -10 dB

I = -107.25 or -111.25 dBm

Tuning range = 1675 to 1695 MHz
85

Scenario: S11

Transmitter: GOES-R Rebroadcast Data 

Transponder (GRB1 and GRB2) 8PSK Receiver: VSS

ht = 35,786 Km hr = 2m and greater

Pt = 16.0 dBW (40 W)

Polarization = RHCP and LHCP

3 dB vertical beamwidth = 26°

3 dB horizontal beamwidth = 26°

Polarization = linear

Gt = 17.3 dBi Gr = 2.15 dBi

Cable loss = 0.5 dB

f = 1686.6 MHz f = 1686.6 MHz

Filter characteristics Filter characteristics

Attenuation (dB) Frequency offset (MHz) Attenuation (dB) Frequency offset (MHz)

3

20

40

60

3.95

4.90

5.40

50.00

3

20

60

3.751

10.000

≥15.000

3dB emission bandwidth = 7.90 MHz 3dB receiver bandwidth = 7.502 MHz

Spurious emissions = -60 dB

2nd harmonic = -60 dB

3rd harmonic = -60 dB

Higher harmonics = -60 dB

Noise Figure = 4.0 dB

Receiver sensitivity:

-89 dBm @ QPSK

-83 dBm @ 16QAM

-77 dBm @ 64QAM

Sensitivity = -174 dBm/Hz + NF (dB) + 10logBW(Hz)

= -174 dBm/Hz + 4.0 dB + 10log(7.5021x106

)

= -101.25 dBm

I/N = -6 or -10 dB

I = -107.25 or -111.25 dBm

Tuning range = 1675 to 1695 MHz
86

Scenario: S12

Transmitter: GOES-R High Resolution 

Information Transponder (HRIT, EMWIN) Receiver: VSS

ht = 35,786 Km hr = 2m and greater

Pt = 13.8 dBW (24.0 W)

Polarization = linear (N-S)

3 dB vertical beamwidth = 26°

3 dB horizontal beamwidth = 26°

Polarization = linear

Gt = 16.5 dBi Gr = 2.15 dBi

Cable loss = 0.5 dB

f = 1694.1 MHz f = 1694.1 MHz

Filter characteristics Filter characteristics

Attenuation (dB) Frequency offset (MHz) Attenuation (dB) Frequency offset (MHz)

3

20

40

60

0.475

0.715

0.750

1.250

3

20

60

3.751

10.000

≥15.000

3dB emission bandwidth = 0.950 MHz 3dB receiver bandwidth = 7.502 MHz

Spurious emissions = -60 dB

2nd harmonic = -60 dB

3rd harmonic = -60 dB

Higher harmonics = -60 dB

Noise Figure = 4.0 dB

Receiver sensitivity:

-89 dBm @ QPSK

-83 dBm @ 16QAM

-77 dBm @ 64QAM

Sensitivity = -174 dBm/Hz + NF (dB) + 10logBW(Hz)

= -174 dBm/Hz + 4.0 dB + 10log(7.5021x106

)

= -101.25 dBm

I/N = -6 or -10 dB

I = -107.25 or -111.25 dBm

Tuning range = 1675 to 1695 MHz
87

Scenario: S13

Transmitter: GOES-R Data Collection 

Platform Report (DCPR #1) Receiver: VSS

ht = 35,786 Km hr = 2m and greater

Pt = 7.0 dBW (5.0 W)

Polarization = linear (N-S)

3 dB vertical beamwidth = 26°

3 dB horizontal beamwidth = 26°

Polarization = linear

Gt = 16.5 dBi Gr = 2.15 dBi

Cable loss = 0.5 dB

f = 1679.9 MHz f = 1679.9 MHz

Filter characteristics Filter characteristics

Attenuation (dB) Frequency offset (MHz) Attenuation (dB) Frequency offset (MHz)

3

20

40

60

0.2000

0.2010

0.20125

2.0000

3

20

60

3.751

10.000

≥15.000

3dB emission bandwidth = 0.400 MHz 3dB receiver bandwidth = 7.502 MHz

Spurious emissions = -60 dB

2nd harmonic = -60 dB

3rd harmonic = -60 dB

Higher harmonics = -60 dB

Noise Figure = 4.0 dB

Receiver sensitivity:

-89 dBm @ QPSK

-83 dBm @ 16QAM

-77 dBm @ 64QAM

Sensitivity = -174 dBm/Hz + NF (dB) + 10logBW(Hz)

= -174 dBm/Hz + 4.0 dB + 10log(7.5021x106

)

= -101.25 dBm

I/N = -6 or -10 dB

I = -107.25 or -111.25 dBm

Tuning range = 1675 to 1695 MHz
88

Scenario: S14

Transmitter: GOES-R Data Collection 

Platform Report (DCPR #2) Receiver: VSS

ht = 35,786 Km hr = 2m and greater

Pt = 7.0 dBW (5.0 W)

Polarization = linear (N-S)

3 dB vertical beamwidth = 26°

3 dB horizontal beamwidth = 26°

Polarization = linear

Gt = 16.5 dBi Gr = 2.15 dBi

Cable loss = 0.5 dB

f = 1680.2 MHz f = 1680.2 MHz

Filter characteristics Filter characteristics

Attenuation (dB) Frequency offset (MHz) Attenuation (dB) Frequency offset (MHz)

3

20

40

60

0.2000

0.2010

0.20125

2.0000

3

20

60

3.751

10.000

≥15.000

3dB emission bandwidth = 0.400 MHz 3dB receiver bandwidth = 7.502 MHz

Spurious emissions = -60 dB

2nd harmonic = -60 dB

3rd harmonic = -60 dB

Higher harmonics = -60 dB

Noise Figure = 4.0 dB

Receiver sensitivity:

-89 dBm @ QPSK

-83 dBm @ 16QAM

-77 dBm @ 64QAM

Sensitivity = -174 dBm/Hz + NF (dB) + 10logBW(Hz)

= -174 dBm/Hz + 4.0 dB + 10log(7.5021x106

)

= -101.25 dBm

I/N = -6 or -10 dB

I = -107.25 or -111.25 dBm

Tuning range = 1675 to 1695 MHz
89

Scenario: S15

Transmitter: GOES-R Command and Data 

Acquisition (CDA) Telemetry Receiver: VSS

ht = 35,786 Km hr = 2m and greater

Pt = 1.8 dBW (1.5 W)

Polarization = RHCP

3 dB vertical beamwidth = 160°

3 dB horizontal beamwidth = 160°

Polarization = linear

Gt = 3.1 dBi Gr = 2.15 dBi

Cable loss = 0.5 dB

f = 1693.0 MHz f = 1693.0 MHz

Filter characteristics Filter characteristics

Attenuation (dB) Frequency offset (MHz) Attenuation (dB) Frequency offset (MHz)

3

20

40

60

22 or 2.2

40 or 4.0

42.5 or 4.25

125.0

3

20

60

3.751

10.000

≥15.000

3dB emission bandwidth =44 or 4.4 kHz 3dB receiver bandwidth = 7.502 MHz

Spurious emissions = -60 dB

2nd harmonic = -60 dB

3rd harmonic = -60 dB

Higher harmonics = -60 dB

Noise Figure = 4.0 dB

Receiver sensitivity:

-89 dBm @ QPSK

-83 dBm @ 16QAM

-77 dBm @ 64QAM

Sensitivity = -174 dBm/Hz + NF (dB) + 10logBW(Hz)

= -174 dBm/Hz + 4.0 dB + 10log(7.5021x106

)

= -101.25 dBm

I/N = -6 or -10 dB

I = -107.25 or -111.25 dBm

Tuning range = 1675 to 1695 MHz
90

Scenario: S16

Transmitter: VSS Receiver: GOES-N Sensor Data (SD)

ht = 2m and greater hr =20, 25, 33m

Pt = 24 dBm

Polarization = linear Polarization = linear

Gt = 2.15 dBi Gr = 39.6 dBi

Cable loss = 0 dB Cable loss = 0 dB

f = 1676.0 MHz f = 1676.0 MHz

Filter characteristics Filter characteristics

Attenuation (dB) Frequency offset (MHz) Attenuation (dB) Frequency offset (MHz)

3

20

33

34

36

37

39

41

43

45

46

48

50

51

53

54

55

3.75

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

3

20

60

1.1

4.0

5.6

3dB emission bandwidth = 7.5 MHz 3dB receiver bandwidth = 2.2 MHz

Noise Figure = 2.85 dB

Sensitivity = -174 dBm/Hz + NF (dB) + 10logBW(Hz)

= -174 dBm/Hz + 2.85 dB + 10log(2.2x106

)

= -107.73 dBm

I/N = -6 dB

I = -113.73 dBm
91

Scenario: S17

Transmitter: VSS Receiver: GOES-N Processed Data Relay 

(PDR)

ht = 2m and greater hr =20, 25, 33m

Pt = 24 dBm

Polarization = linear Polarization = linear

Gt = 2.15 dBi Gr = 39.6 dBi

Cable loss = 0 dB Cable loss = 0 dB

f = 1685.7 MHz f = 1685.7 MHz

Filter characteristics Filter characteristics

Attenuation (dB) Frequency offset (MHz) Attenuation (dB) Frequency offset (MHz)

3

20

33

34

36

37

39

41

43

45

46

48

50

51

53

54

55

3.75

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

3

20

60

1.1

3.1

5.5

3dB emission bandwidth = 7.5 MHz 3dB receiver bandwidth = 2.2 MHz

Noise Figure = 2.85 dB

Sensitivity = -174 dBm/Hz + NF (dB) + 10logBW(Hz)

= -174 dBm/Hz + 2.85 dB + 10log(2.2x106

)

= -107.73 dBm

I/N = -6 dB

I = -113.73 dBm
92

Scenario: S18

Transmitter: VSS Receiver: GOES-N Low Rate Info 

Transponder (LRIT WEFAX)

ht = 2m and greater hr =20, 25, 33m

Pt = 24 dBm

Polarization = linear Polarization = linear

Gt = 2.15 dBi Gr = 39.6 dBi

Cable loss = 0 dB Cable loss = 0 dB

f = 1691.0 MHz f = 1691.0 MHz

Filter characteristics Filter characteristics

Attenuation (dB) Frequency offset (MHz) Attenuation (dB) Frequency offset (MHz)

3

20

33

34

36

37

39

41

43

45

46

48

50

51

53

54

55

3.75

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

3

20

60

0.10

0.30

2.25

3dB emission bandwidth = 7.5 MHz 3dB receiver bandwidth = 0.2 MHz

Noise Figure = 2.85 dB

Sensitivity = -174 dBm/Hz + NF (dB) + 10logBW(Hz)

= -174 dBm/Hz + 2.85 dB + 10log(0.20x106

)

= -118.14 dBm

I/N = -6 dB

I = -124.14 dBm
93

Scenario: S19

Transmitter: VSS Receiver: GOES-N Emergency Management 

Weather Information Network (EMWIN)

ht = 2m and greater hr =20, 25, 33m

Pt = 24 dBm

Polarization = linear Polarization = linear

Gt = 2.15 dBi Gr = 39.6 dBi

Cable loss = 0 dB Cable loss = 0 dB

f = 1692.7 MHz f = 1692.7 MHz

Filter characteristics Filter characteristics

Attenuation (dB) Frequency offset (MHz) Attenuation (dB) Frequency offset (MHz)

3

20

33

34

36

37

39

41

43

45

46

48

50

51

53

54

55

3.75

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

3

20

60

0.009

0.013

0.100

3dB emission bandwidth = 7.5 MHz 3dB receiver bandwidth = 0.018 MHz

Noise Figure = 2.85 dB

Sensitivity = -174 dBm/Hz + NF (dB) + 10logBW(Hz)

= -174 dBm/Hz + 2.85 dB + 10log(0.018x106

)

= -128.6 dBm

I/N = -6 dB

I = -134.6 dBm
94

Scenario: S20

Transmitter: VSS Receiver: GOES-N Multiuse Data Link (MDL)

ht = 2m and greater hr =20, 25, 33m

Pt = 24 dBm

Polarization = linear Polarization = linear

Gt = 2.15 dBi Gr = 39.6 dBi

Cable loss = 0 dB Cable loss = 0 dB

f = 1681.478 MHz f = 1681.478 MHz

Filter characteristics Filter characteristics

Attenuation (dB) Frequency offset (MHz) Attenuation (dB) Frequency offset (MHz)

3

20

33

34

36

37

39

41

43

45

46

48

50

51

53

54

55

3.75

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

3

20

60

0.075

0.200

2.000

3dB emission bandwidth = 7.5 MHz 3dB receiver bandwidth = 0.150 MHz

Noise Figure = 2.85 dB

Sensitivity = -174 dBm/Hz + NF (dB) + 10logBW(Hz)

= -174 dBm/Hz + 2.85 dB + 10log(0.150x106

)

= -119.39 dBm

I/N = -6 dB

I = -125.39 dBm
95

Scenario: S21

Transmitter: VSS Receiver: GOES-N Data Collection Platform 

Report (DCPR)

ht = 2m and greater hr =20, 25, 33m

Pt = 24 dBm

Polarization = linear Polarization = linear

Gt = 2.15 dBi Gr = 39.6 dBi

Cable loss = 0 dB Cable loss = 0 dB

f = 1694.5 and 1694.8 MHz f = 1694.5 and 1694.8 MHz

Filter characteristics Filter characteristics

Attenuation (dB) Frequency offset (MHz) Attenuation (dB) Frequency offset (MHz)

3

20

33

34

36

37

39

41

43

45

46

48

50

51

53

54

55

3.75

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

3

20

60

80

92

NOTE: use slope of 

-20 to -60 to get to -

80 dB, then use 40 

dB/decade.

0.750

2.250

5.040

6.435

12.890

3dB emission bandwidth = 7.5 MHz 3dB receiver bandwidth = 1.50 MHz

Noise Figure = 2.85 dB

Sensitivity = -174 dBm/Hz + NF (dB) + 10logBW(Hz)

= -174 dBm/Hz + 2.85 dB + 10log(1.50x106

)

= -109.39 dBm

I/N = -6 dB

I = -115.39 dBm
96

Scenario: S22

Transmitter: VSS Receiver: GOES-N Command and Data 

Acquisition (CDA) Telemetry

ht = 2m and greater hr =20, 25, 33m

Pt = 24 dBm

Polarization = linear Polarization = RHCP

Gt = 2.15 dBi Gr = 39.6 dBi

Cable loss = 0 dB Cable loss = 0 dB

f = 1693.0 MHz f = 1693.0 MHz

Filter characteristics Filter characteristics

Attenuation (dB) Frequency offset (MHz) Attenuation (dB) Frequency offset (MHz)

3

20

33

34

36

37

39

41

43

45

46

48

50

51

53

54

55

3.75

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

3

20

60

0.006

0.020

1.000

3dB emission bandwidth = 7.5 MHz 3dB receiver bandwidth = 0.012 MHz

Noise Figure = 2.85 dB

Sensitivity = -174 dBm/Hz + NF (dB) + 10logBW(Hz)

= -174 dBm/Hz + 2.85 dB + 10log(0.012x106

)

= -130.36 dBm

I/N = -6 dB

I = -136.36 dBm
97

Scenario: S23

Transmitter: VSS Receiver: GOES-R Rebroadcast Data 

Transponder (GRB1 and GRB2) QPSK

ht = 2m and greater hr =9m

Pt = 24 dBm

Polarization = linear

Polarization = RHCP and LHCP

3 dB vertical beamwidth = 0.66°

3 dB horizontal beamwidth = 0.66°

Gt = 2.15 dBi Gr = 47.2 dBi

Cable loss = 0 dB Cable loss = 0 dB

f = 1686.6 MHz f = 1686.6 MHz

16.4 m dish BER = 1x10-10

Filter characteristics Filter characteristics

Attenuation (dB) Frequency offset (MHz) Attenuation (dB) Frequency offset (MHz)

3

20

33

34

36

37

39

41

43

45

46

48

50

51

53

54

55

3.75

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

3

20

60

4.35

5.45

6.50

3dB emission bandwidth = 7.5 MHz 3dB receiver bandwidth = 8.7 MHz

Noise Figure = 1.45 dB

Max bitrate = 17.332Mbps N Temp = 115°K

Sensitivity = -103.15 dBm

I/N = -6 dB

I = -109.15 dBm
98

Scenario: S24

Transmitter: VSS Receiver: GOES-R Rebroadcast Data 

Transponder (GRB1 and GRB2) 8PSK

ht = 2m and greater hr =9m

Pt = 24 dBm

Polarization = linear

Polarization = RHCP and LHCP

3 dB vertical beamwidth = 0.66°

3 dB horizontal beamwidth = 0.66°

Gt = 2.15 dBi Gr = 47.2 dBi

Cable loss = 0 dB Cable loss = 0 dB

f = 1686.6 MHz f = 1686.6 MHz

16.4 m dish BER = 1x10-10

Filter characteristics Filter characteristics

Attenuation (dB) Frequency offset (MHz) Attenuation (dB) Frequency offset (MHz)

3

20

33

34

36

37

39

41

43

45

46

48

50

51

53

54

55

3.75

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

3

20

60

3.95

4.90

6.00

3dB emission bandwidth = 7.5 MHz 3dB receiver bandwidth = 7.9 MHz

Noise Figure = 1.45 dB

Max bitrate = 23.480 Mbps N Temp = 115°K

Sensitivity = -103.57 dBm

I/N = -6 dB

I = -109.57 dBm
99

Scenario: S25

Transmitter: VSS Receiver: GOES-R High Resolution 

Information Transponder (HRIT, EMWIN)

ht = 2m and greater hr =20, 25, 33m

Pt = 24 dBm

Polarization = linear

Polarization = linear (N-S)

3 dB vertical beamwidth = 0.66°

3 dB horizontal beamwidth = 0.66°

Gt = 2.15 dBi Gr = 47.2 dBi

Cable loss = 0 dB Cable loss = 0 dB

f = 1694.1 MHz f = 1694.1 MHz

16.4 m dish BER = 1x10-8

Filter characteristics Filter characteristics

Attenuation (dB) Frequency offset (MHz) Attenuation (dB) Frequency offset (MHz)

3

20

33

34

36

37

39

41

43

45

46

48

50

51

53

54

55

3.75

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

3

20

60

0.475

0.715

2.000

3dB emission bandwidth = 7.5 MHz 3dB receiver bandwidth = 0.95 MHz

Noise Figure = 1.45 dB

Max bitrate = 927 Kbps N Temp = 115°K

Sensitivity = -112.77 dBm

I/N = -6 dB

I = -118.77 dBm
100

Scenario: S26

Transmitter: VSS Receiver: GOES-R Data Collection Platform 

Report (DCPR #1)

ht = 2m and greater hr =9m

Pt = 24 dBm

Polarization = linear

Polarization = RHCP

3 dB vertical beamwidth = 0.66°

3 dB horizontal beamwidth = 0.66°

Gt = 2.15 dBi Gr = 47.2 dBi

Cable loss = 0 dB Cable loss = 0 dB

f = 1679.9 MHz f = 1679.9 MHz

16.4 m dish BER = 1x10-6

Filter characteristics Filter characteristics

Attenuation (dB) Frequency offset (MHz) Attenuation (dB) Frequency offset (MHz)

3

20

33

34

36

37

39

41

43

45

46

48

50

51

53

54

55

3.75

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

3

20

40

60

0.20000

0.20100

0.20125

2.0000

3dB emission bandwidth = 7.5 MHz 3dB receiver bandwidth = 0.4 MHz

Noise Figure = 1.45 dB

Max bitrate = 1.8 Kbps N Temp = 115°K

Sensitivity = -116.53 dBm

I/N = -6 dB

I = -122.53 dBm
101

Scenario: S27

Transmitter: VSS Receiver: GOES-R Data Collection Platform 

Report (DCPR #2)

ht = 2m and greater hr =9m

Pt = 24 dBm

Polarization = linear

Polarization = RHCP

3 dB vertical beamwidth = 0.66°

3 dB horizontal beamwidth = 0.66°

Gt = 2.15 dBi Gr = 47.2 dBi

Cable loss = 0 dB Cable loss = 0 dB

f = 1680.2 MHz f = 1680.2 MHz

16.4 m dish BER = 1x10-6

Filter characteristics Filter characteristics

Attenuation (dB) Frequency offset (MHz) Attenuation (dB) Frequency offset (MHz)

3

20

33

34

36

37

39

41

43

45

46

48

50

51

53

54

55

3.75

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

3

20

40

60

0.2000

0.2010

0.20125

2.0000

3dB emission bandwidth = 7.5 MHz 3dB receiver bandwidth = 0.4 MHz

Noise Figure = 1.45 dB

Max bitrate = 45 Kbps N Temp = 115°K

Sensitivity = -116.53 dBm

I/N = -6 dB

I = -122.53 dBm
102

Scenario: S28

Transmitter: VSS Receiver: GOES-R Command and Data 

Acquisition (CDA) Telemetry

ht = 2m and greater hr =9m

Pt = 24 dBm

Polarization = linear

Polarization = RHCP

3 dB vertical beamwidth = 0.66°

3 dB horizontal beamwidth = 0.66°

Gt = 2.15 dBi Gr = 47.2 dBi

Cable loss = 0 dB Cable loss = 0 dB

f = 1693.0 MHz f = 1693.0 MHz

16.4 m dish BER = 1x10-7

Filter characteristics Filter characteristics

Attenuation (dB) Frequency offset (MHz) Attenuation (dB) Frequency offset (MHz)

3

20

33

34

36

37

39

41

43

45

46

48

50

51

53

54

55

3.75

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

3

20

60

0.0225

0.0400

0.1750

3dB emission bandwidth = 7.5 MHz 3dB receiver bandwidth = 0.045 MHz

Noise Figure = 1.45 dB

Max bitrate = 64 Kbps N Temp = 115°K

Sensitivity = -126.02 dBm

I/N = -6 dB

I = -132.02 dBm
103

APPENDIX C. GOES EARTH STATION LOCATIONS AND ALIGNMENTS

In all of the United States and its territories, there are 26 Geostationary Operational 

Environmental Satellite (GOES) earth stations owned and operated by the Federal Government. 

This Appendix lists the stations by name, location, and the antenna bearings (azimuth and 

elevation) for the two operational GOES satellites. Since the 1675–1695 MHz band only 

contains downlink channels, all of these sites receive one or more channels from one or both of 

the operational satellites (GOES-West and GOES-East). Due to the extreme angles involved, 

some of the sites receive channels from only one satellite (at the sites in Hawaii and Alaska, 

GOES-East is below the horizon, and GOES-West is close to the horizon for the Puerto Rico 

site).

Due to their extremely differing positions, each site requires a separate antenna for each satellite, 

so not all sites monitor both satellites. Any site monitoring both satellites would need two 

antennas; physical constraints would require the antennas to be separated by some distance. 

However, this distance would be small enough compared to the overall distance to the satellites, 

that they could be considered co-located and still maintain reasonable accuracy regarding any 

geometric calculations.
104

Location Latitude Longitude GOES-E (75°W) GOES-W (135.4°W) Antenna

Elevation Azimuth Elevation Azimuth Height (m)

Wallops Island, 

VA

37°56'45"N

37.9458°

075°27'45"W

75.4625° 46.000 179.300 14.900 250.116 20.0

Fairbanks, AK 64°48'14"N

64.8039°

147°52'34"W

147.8761° - - 16.170 165.822 33.0

Suitland, MD 38°49'00"N

38.8167°

076°51'00"W

76.8500° 45.010 177.050 15.917 248.724 33.0

Boulder, CO 40°00'54"N

40.0150°

105°16'14"W

105.2706° 34.218 137.746 34.543 221.587 9.0

Sioux Falls, SD 43°44'06"N

43.7350°

096°37'32"W

96.6256° 35.091 150.168 26.743 228.878 33.0

Boise, ID 46°36'53"N

46.6147°

116°15'08"W

116.2522° 23.098 129.646 33.317 205.034 33.0

Knoxville, TN 35°57'58"N

35.9661°

083°55'13"W

83.9203° 47.192 165.037 22.534 244.628 33.0

Guaynabo, PR 18°25'44"N

18.4289°

066°06'85"W

66.1000° 66.088 206.352 11.448 263.045 33.0

Greenbelt, MD 39°05'00"N

39.0833°

076°46'00"W

76.7667° 44.715 177.199 15.753 248.675 33.0

Huntsville ,AL 34°38'42"N

34.6450°

086°40'29"W

86.6747° 47.852 160.025 25.306 243.158 33.0

Cincinnati, OH 39°06'08"N

39.1022°

084°30'36"W

84.5100° 43.659 165.125 21.498 242.521 20.0

Rock Island, IL 41°31'04"N

41.5178°

090°33'46"W

90.5628° 39.458 157.210 24.404 235.941 25.0

St. Louis, MO 38°35'26"N

38.5906°

090°12'25"W

90.2069° 42.567 156.453 25.870 237.860 20.0

Vicksburg, MS 32°21'23"N

32.3564°

090°51'29"W

90.8581° 48.612 152.041 29.774 241.125 20.0

Sacramento, CA 38°34'59"N

38.5831°

121°29'39"W

121.4942° 18.971 125.371 32.905 197.804 20.0

Omaha, NB 41°15'32"N

41.2589°

095°55'20"W

95.9222° 37.734 149.898 28.032 230.920 20.0

Elmendorf AFB, 

AK

61°08'59"N

61.1497°

149°28'12"W

149.4700° - - 19.668 163.584 33.0

Hickam AFB, HI 21°19'07"N

21.3186°

157°55'21"W

157.9225° - - 53.994 130.686 33.0

Norfolk, VA 36°53'59"N

36.8997°

076°17'59"W

76.2997° 47.182 177.836 16.199 249.945 33.0

Monterey, CA 36°36'00"N

36.6000°

121°54'00"W

121.9000° 25.418 119.159 45.336 201.321 33.0

Stennis Space 

Center, MS

30°23'59"N

30.3997°

089°35'59"W

89.5997° 51.137 152.763 29.728 243.480 33.0

Twenty Nine 

Palms, CA

34°17'46"N

34.2961°

116°09'44"W

116.1622° 31.013 122.802 45.332 211.194 33.0

Camp Pendleton, 

CA

33°18'04"N

33.3011°

117°21'19"W

117.3553° 30.672 121.057 46.861 210.085 33.0

Yuma, AZ 32°39'24"N

32.6567°

114°36'22"W

114.6061° 33.169 123.109 46.086 214.566 33.0

Bogue Field, NC 34°41'26"N

34.6906°

077°01'47"W

77.0297° 51.939 176.242 18.265 251.347 33.0

Beaufort, SC 32°28'50"N

32.4806°

080°43'09"W

80.7192° 51.697 169.436 21.412 248.886 33.0
105

APPENDIX D. FREQUENCY SEPARATION VS. SEPARATION DISTANCE CURVES

FOR VSS-INTO-GOES SCENARIOS

Plots of the frequency separation versus separation distance required for minimum performance

were generated for scenarios of VSS interference to GOES-N and GOES-R victim receivers

(Scenarios 16 through 28) for varying antenna heights.

VSS heights of 2 m (ground location) and 20 m (roof-top location) were used, as well as GOES 

heights of 20 m, 25 m, and 33 m (Scenarios 16– 22), or GOES heights of 9 m and 21 m 

(Scenarios 23–28).

In each figure, the left-hand column was calculated by assuming that the antennas of the 

interfering source (VSS) and the victim receiver (GOES) were pointed at each other for 

maximum interference transfer.

The plots in the right-hand column were calculated by assuming that both antennas have 

directional characteristics and the scenario geometry was taken into account; this assumption 

factors in the off-axis gains of both antennas. Separate antennas were used for GOES-N/O/P and 

GOES-R.

The plot ranges cover the most critical portions of the frequency-distance relationships and 

extend out to where the required frequency separation drops to zero.
106

(a) GOES antenna height = 20 m

antennas on axis.

(b) GOES antenna height = 20 m

antennas off axis.

(c) GOES antenna height = 25 m

antennas on axis.

(d) GOES antenna height = 25 m

antennas off axis.

(e) GOES antenna height = 33 m

antennas on axis.

(f) GOES antenna height = 33 m

antennas off axis.

Figure D-1. Frequency separation versus separation distance curves for scenario 16 –

VSS transmitter into GOES-N Sensor Data (SD)

for VSS antenna height = 2 m.
107

(a) GOES antenna height = 20 m

antennas on axis.

(b) GOES antenna height = 20 m

antennas off axis.

(c) GOES antenna height = 25 m

antennas on axis.

(d) GOES antenna height = 25 m

antennas off axis.

(e) GOES antenna height = 33 m

antennas on axis.

(f) GOES antenna height = 33 m

antennas off axis.

Figure D-2. Frequency separation versus separation distance curves for scenario 16 –

VSS transmitter into GOES-N Sensor Data (SD)

for VSS antenna height = 20 m.
108

(a) GOES antenna height = 20 m

antennas on axis.

(b) GOES antenna height = 20 m

antennas off axis.

(c) GOES antenna height = 25 m

antennas on axis.

(d) GOES antenna height = 25 m

antennas off axis.

(e) GOES antenna height = 33 m

antennas on axis.

(f) GOES antenna height = 33 m

antennas off axis.

Figure D-3. Frequency separation versus separation distance curves for scenario 17 –

VSS transmitter into GOES-N Processed Data Relay (PDR)

for VSS antenna height = 2 m.
109

(a) GOES antenna height = 20 m

antennas on axis.

(b) GOES antenna height = 20 m

antennas off axis.

(c) GOES antenna height = 25 m

antennas on axis.

(d) GOES antenna height = 25 m

antennas off axis.

(e) GOES antenna height = 33 m

antennas on axis.

(f) GOES antenna height = 33 m

antennas off axis.

Figure D-4. Frequency separation versus separation distance curves for scenario 17 –

VSS transmitter into GOES-N Processed Data Relay (PDR)

for VSS antenna height = 20 m.
110

(a) GOES antenna height = 20 m

antennas on axis.

(b) GOES antenna height = 20 m

antennas off axis.

(c) GOES antenna height = 25 m

antennas on axis.

(d) GOES antenna height = 25 m

antennas off axis.

(e) GOES antenna height = 33 m

antennas on axis.

(f) GOES antenna height = 33 m

antennas off axis.

Figure D-5. Frequency separation versus separation distance curves for scenario 18 –

VSS transmitter into GOES-N Low Rate Info Transponder (LRIT WEFAX)

for VSS antenna height = 2 m.
111

(a) GOES antenna height = 20 m

antennas on axis.

(b) GOES antenna height = 20 m

antennas off axis.

(c) GOES antenna height = 25 m

antennas on axis.

(d) GOES antenna height = 25 m

antennas off axis.

(e) GOES antenna height = 33 m

antennas on axis.

(f) GOES antenna height = 33 m

antennas off axis.

Figure D-6. Frequency separation versus separation distance curves for scenario 18 –

VSS transmitter into GOES-N Low Rate Info Transponder (LRIT WEFAX)

for VSS antenna height = 20 m.
112

(a) GOES antenna height = 20 m

antennas on axis.

(b) GOES antenna height = 20 m

antennas off axis.

(c) GOES antenna height = 25 m

antennas on axis.

(d) GOES antenna height = 25 m

antennas off axis.

(e) GOES antenna height = 33 m

antennas on axis.

(f) GOES antenna height = 33 m

antennas off axis.

Figure D-7. Frequency separation versus separation distance curves for scenario 19 –

VSS transmitter into GOES-N Emergency Management Weather Information Network 

(EMWIN)

for VSS antenna height = 2 m.
113

(a) GOES antenna height = 20 m

antennas on axis.

(b) GOES antenna height = 20 m

antennas off axis.

(c) GOES antenna height = 25 m

antennas on axis.

(d) GOES antenna height = 25 m

antennas off axis.

(e) GOES antenna height = 33 m

antennas on axis.

(f) GOES antenna height = 33 m

antennas off axis.

Figure D-8. Frequency separation versus separation distance curves for scenario 19 –

VSS transmitter into GOES-N Emergency Management Weather Information Network 

(EMWIN)

for VSS antenna height = 20 m.
114

(a) GOES antenna height = 20 m

antennas on axis.

(b) GOES antenna height = 20 m

antennas off axis.

(c) GOES antenna height = 25 m

antennas on axis.

(d) GOES antenna height = 25 m

antennas off axis.

(e) GOES antenna height = 33 m

antennas on axis.

(f) GOES antenna height = 33 m

antennas off axis.

Figure D-9. Frequency separation versus separation distance curves for scenario 20 –

VSS transmitter into GOES-N Multiuse Data Link (MDL)

for VSS antenna height = 2 m.
115

(a) GOES antenna height = 20 m

antennas on axis.

(b) GOES antenna height = 20 m

antennas off axis.

(c) GOES antenna height = 25 m

antennas on axis.

(d) GOES antenna height = 25 m

antennas off axis.

(e) GOES antenna height = 33 m

antennas on axis.

(f) GOES antenna height = 33 m

antennas off axis.

Figure D-10. Frequency separation versus separation distance curves for scenario 20 –

VSS transmitter into GOES-N Multiuse Data Link (MDL)

for VSS antenna height = 20 m.
116

(a) GOES antenna height = 20 m

antennas on axis.

(b) GOES antenna height = 20 m

antennas off axis.

(c) GOES antenna height = 25 m

antennas on axis.

(d) GOES antenna height = 25 m

antennas off axis.

(e) GOES antenna height = 33 m

antennas on axis.

(f) GOES antenna height = 33 m

antennas off axis.

Figure D-11. Frequency separation versus separation distance curves for scenario 21 –

VSS transmitter into GOES-N Data Collection Platform Report (DCPR)

for VSS antenna height = 2 m.
117

(a) GOES antenna height = 20 m

antennas on axis.

(b) GOES antenna height = 20 m

antennas off axis.

(c) GOES antenna height = 25 m

antennas on axis.

(d) GOES antenna height = 25 m

antennas off axis.

(e) GOES antenna height = 33 m

antennas on axis.

(f) GOES antenna height = 33 m

antennas off axis.

Figure D-12. Frequency separation versus separation distance curves for scenario 21 –

VSS transmitter into GOES-N Data Collection Platform Report (DCPR)

for VSS antenna height = 20 m.
118

(a) GOES antenna height = 20 m

antennas on axis.

(b) GOES antenna height = 20 m

antennas off axis.

(c) GOES antenna height = 25 m

antennas on axis.

(d) GOES antenna height = 25 m

antennas off axis.

(e) GOES antenna height = 33 m

antennas on axis.

(f) GOES antenna height = 33 m

antennas off axis.

Figure D-13. Frequency separation versus separation distance curves for scenario 22 –

VSS transmitter into GOES-N Command and Data Acquisition (CDA) Telemetry

for VSS antenna height = 2 m.
119

(a) GOES antenna height = 20 m

antennas on axis.

(b) GOES antenna height = 20 m

antennas off axis.

(c) GOES antenna height = 25 m

antennas on axis.

(d) GOES antenna height = 25 m

antennas off axis.

(e) GOES antenna height = 33 m

antennas on axis.

(f) GOES antenna height = 33 m

antennas off axis.

Figure D-14. Frequency separation versus separation distance curves for scenario 22 –

VSS transmitter into GOES-N Command and Data Acquisition (CDA) Telemetry

for VSS antenna height = 20 m.
120

(a) GOES antenna height = 9 m

antennas on axis.

(b) GOES antenna height = 9 m

antennas off axis.

(c) GOES antenna height = 21 m

antennas on axis.

(d) GOES antenna height = 21 m

antennas off axis.

Figure D-15. Frequency separation versus separation distance curves for scenario 23 –

VSS transmitter into GOES-R Rebroadcast Data Transponder (GRB1 and GRB2) QPSK

for VSS antenna height = 2 m.
121

(a) GOES antenna height = 9 m

antennas on axis.

(b) GOES antenna height = 9 m

antennas off axis.

(c) GOES antenna height = 21 m

antennas on axis.

(d) GOES antenna height = 21 m

antennas off axis.

Figure D-16. Frequency separation versus separation distance curves for scenario 23 –

VSS transmitter into GOES-R Rebroadcast Data Transponder (GRB1 and GRB2) QPSK

for VSS antenna height = 20 m.
122

(a) GOES antenna height = 9 m

antennas on axis.

(b) GOES antenna height = 9 m

antennas off axis.

(c) GOES antenna height = 21 m

antennas on axis.

(d) GOES antenna height = 21 m

antennas off axis.

Figure D-17. Frequency separation versus separation distance curves for scenario 24 –

VSS transmitter into GOES-R Rebroadcast Data Transponder (GRB1 and GRB2) 8PSK

for VSS antenna height = 2 m.
123

(a) GOES antenna height = 9 m

antennas on axis.

(b) GOES antenna height = 9 m

antennas off axis.

(c) GOES antenna height = 21 m

antennas on axis.

(d) GOES antenna height = 21 m

antennas off axis.

Figure D-18. Frequency separation versus separation distance curves for scenario 24 –

VSS transmitter into GOES-R Rebroadcast Data Transponder (GRB1 and GRB2) 8PSK

for VSS antenna height = 20 m.
124

(a) GOES antenna height = 9 m

antennas on axis.

(b) GOES antenna height = 9 m

antennas off axis.

(c) GOES antenna height = 21 m

antennas on axis.

(d) GOES antenna height = 21 m

antennas off axis.

Figure D-19. Frequency separation versus separation distance curves for scenario 25 –

VSS transmitter into GOES-R High Resolution Information Transponder (HRIT, EMWIN)

for VSS antenna height = 2 m.
125

(a) GOES antenna height = 9 m

antennas on axis.

(b) GOES antenna height = 9 m

antennas off axis.

(c) GOES antenna height = 21 m

antennas on axis.

(d) GOES antenna height = 21 m

antennas off axis.

Figure D-20. Frequency separation versus separation distance curves for scenario 25 –

VSS transmitter into GOES-R High Resolution Information Transponder (HRIT, EMWIN)

for VSS antenna height = 20 m.
126

(a) GOES antenna height = 9 m

antennas on axis.

(b) GOES antenna height = 9 m

antennas off axis.

(c) GOES antenna height = 21 m

antennas on axis.

(d) GOES antenna height = 21 m

antennas off axis.

Figure D-21. Frequency separation versus separation distance curves for scenario 26 –

VSS transmitter into GOES-R Data Collection Platform Report (DCPR #1)

for VSS antenna height = 2 m.
127

(a) GOES antenna height = 9 m

antennas on axis.

(b) GOES antenna height = 9 m

antennas off axis.

(c) GOES antenna height = 21 m

antennas on axis.

(d) GOES antenna height = 21 m

antennas off axis.

Figure D-22. Frequency separation versus separation distance curves for scenario 26 –

VSS transmitter into GOES-R Data Collection Platform Report (DCPR #1)

for VSS antenna height = 20 m.
128

(a) GOES antenna height = 9 m

antennas on axis.

(b) GOES antenna height = 9 m

antennas off axis.

(c) GOES antenna height = 21 m

antennas on axis.

(d) GOES antenna height = 21 m

antennas off axis.

Figure D-23. Frequency separation versus separation distance curves for scenario 27 –

VSS transmitter into GOES-R Data Collection Platform Report (DCPR #2)

for VSS antenna height = 2 m.
129

(a) GOES antenna height = 9 m

antennas on axis.

(b) GOES antenna height = 9 m

antennas off axis.

(c) GOES antenna height = 21 m

antennas on axis.

(d) GOES antenna height = 21 m

antennas off axis.

Figure D-24. Frequency separation versus separation distance curves for scenario 27 –

VSS transmitter into GOES-R Data Collection Platform Report (DCPR #2)

for VSS antenna height = 20 m.
130

(a) GOES antenna height = 9 m

antennas on axis.

(b) GOES antenna height = 9 m

antennas off axis.

(c) GOES antenna height = 21 m

antennas on axis.

(d) GOES antenna height = 21 m

antennas off axis.

Figure D-25. Frequency separation versus separation distance curves for scenario 28 –

VSS transmitter into GOES-R Command and Data Acquisition (CDA) Telemetry

for VSS antenna height = 2 m.
131

(a) GOES antenna height = 9 m

antennas on axis.

(b) GOES antenna height = 9 m

antennas off axis.

(c) GOES antenna height = 21 m

antennas on axis.

(d) GOES antenna height = 21 m

antennas off axis.

Figure D-26. Frequency separation versus separation distance curves for scenario 28 –

VSS transmitter into GOES-R Command and Data Acquisition (CDA) Telemetry

for VSS antenna height = 20 m.

NTIA FORM 29 U.S. DEPARTMENT OF COMMERCE 

(4-80) NATIONAL TELECOMMUNICATIONS AND INFORMATION ADMINISTRATION

BIBLIOGRAPHIC DATA SHEET

1. PUBLICATION NO.

TR-15-516

2. Government Accession No. 3. Recipient’s Accession No.

4. TITLE AND SUBTITLE

A Spectrum Sharing Case Study Leading to the Development of a Method for 

Identifying Interference Potential

5. Publication Date

April 2015

6. Performing Organization Code

ITS.E

7. AUTHOR(S)

Christopher Behm, Nicholas DeMinco, Timothy Riley, Linh Vu

9. Project/Task/Work Unit No.

3109011-300

8. PERFORMING ORGANIZATION NAME AND ADDRESS

Institute for Telecommunication Sciences

National Telecommunications & Information Administration

U.S. Department of Commerce

325 Broadway

Boulder, CO 80305

10. Contract/Grant Number.

11. Sponsoring Organization Name and Address

Department of Homeland Security

12th & C Street SW

Washington, DC 20024

12. Type of Report and Period Covered

14. SUPPLEMENTARY NOTES

15. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant bibliography or 

literature survey, mention it here.)

This report details a method that was developed to identify all potential forms of interference that could occur with a 

proposed collocation of three Federal systems in the 1675–1695 MHz frequency band. The incumbents are the National 

Oceanographic and Atmospheric Administration’s (NOAA) Geostationary Operational Environmental Satellites (GOES) 

receivers and radiosonde systems. The entrant is the Department of Homeland Security’s (DHS) Video Surveillance System 

(VSS). The primary objective is that the quality of the mission-critical communications for each service is maintained.

A detailed electromagnetic compatibility (EMC) analysis is used to identify both the highest potential interference scenarios

and those scenarios that have little to no effect. Two primary interference mitigation techniques can be implemented to 

achieve electromagnetic compatibility: frequency offset (Df) and separation distance. Based on the frequency dependent 

rejection (FDR) between the interference source and the victim receiver, the Df and separation distance necessary for a 

desired level of interference rejection can be calculated. For all potential interference interactions, the Df nd the separation 

distance can be adjusted to arrive at a solution for operation on a non-interference basis. It is not the intent of this report to 

make pronouncements on how to achieve coexistence within a shared band. It is intended to examine and illuminate the 

engineering questions that need to be answered so that those who are responsible for Federal services in a band may negotiate

and cooperate with their colleagues who are responsible for other Federal services in the same band.

16. Key Words (Alphabetical order, separated by semicolons)

spectrum sharing; FDR; frequency dependent rejection; frequency offset; separation distance; electromagnetic compatibility; 

interference mitigation

17. AVAILABILITY STATEMENT

 UNLIMITED.

 FOR OFFICIAL DISTRIBUTION.

18. Security Class. (This report)

Unclassified

20. Number of pages

155

19. Security Class. (This page)

Unclassified

21. Price:

N/A

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