NTIA Report TR-15-514

Effect of Broadband Radio Service 

Reallocation on 2900–3100 MHz Band 

Marine Radars: Base Station 

Unwanted Emissions 

Robert Achatz

Paul McKenna 

Roger Dalke

Frank Sanders

John Carroll

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

report series
NTIA Report TR-15-514

Effect of Broadband Radio Service 

Reallocation on 2900–3100 MHz Band 

Marine Radars: Base Station 

Unwanted Emissions 

Robert Achatz

Paul McKenna 

Roger Dalke

Frank Sanders

John Carroll

U.S. DEPARTMENT OF COMMERCE

April 2015

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.

iii

CONTENTS

List of Figures............................................................................................................................... vii

List of Tables ...................................................................................................................................x

Acronyms....................................................................................................................................... xi

Executive Summary.......................................................................................................................xv

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

1.1 Previous Background Work...................................................................................................4

1.2 Report Organization...............................................................................................................6

2 Unwanted Emissions.....................................................................................................................7

3 Method ..........................................................................................................................................9

4 Mathematical Foundation ...........................................................................................................13

4.1 Powers, Power Ratios, and IPC ...........................................................................................13

4.2 Distance Separation with Spurious Attenuation ..................................................................14

4.2.1 Constant SNR.............................................................................................................14

4.2.2 Variable SNR .............................................................................................................15

4.3 Distance Separation with FDR ............................................................................................16

5 Results.........................................................................................................................................18

5.1 Parameters............................................................................................................................18

5.2 Interference Protection Criteria ...........................................................................................18

5.3 Interference Power Distributions.........................................................................................20

5.4 Distance separation with spurious attenuation.....................................................................21

5.4.1 Constant SNR.............................................................................................................21

5.4.2 Variable SNR .............................................................................................................23

5.4.3 Comparison of constant SNR to variable SNR results...............................................25

5.5 Distance and frequency separation with FDR .....................................................................27

6 Conclusion ..................................................................................................................................30

7 Acknowledgements.....................................................................................................................32

8 References...................................................................................................................................33

Appendix A : Unwanted Signal Power..........................................................................................35

A.1 Basic Frequency Dependent Interference Model................................................................35

A.2 Transmitted Unwanted Signal Power .................................................................................36

A.3 Received Unwanted Signal Power......................................................................................38

A.4 Received Unwanted Signal Power in Terms of the Transmitted Unwanted Signal 

Power .........................................................................................................................................39

A.5 References...........................................................................................................................39

v
Appendix B : Fast Method For Computing Segmented, LogNormal- Distribution Integral.........41

B.1 References...........................................................................................................................43

Appendix C : Rise in Noise Power ................................................................................................44

Appendix D : Emission Limits ......................................................................................................45

D.1 ITU-R Spurious Emission Limit.........................................................................................45

D.2 ETSI Spectrum Emission Mask..........................................................................................46

D.3 References...........................................................................................................................47

Appendix E : Variable SNR Data Examples .................................................................................48

Appendix F : WiMAX Measured PSD and Filtered PSD..............................................................51

F.1 PSD Measurement ...............................................................................................................51

F.2 Filtered PSD Measurement..................................................................................................51

F.3 References ...........................................................................................................................53

Appendix G : Radar IF Filter Frequency Responses.....................................................................54

G.1 References...........................................................................................................................55

Appendix H : Results For Other INR ............................................................................................56

H.1 Results for -9 dB INR .........................................................................................................56

H.2 Results for -12 dB INR .......................................................................................................58

Appendix I : Probability.................................................................................................................60

vi
LIST OF FIGURES

Figure 1. Marine radar slotted array antenna (white bar) mounted on motor which spins it...........3

Figure 2. BRS base station...............................................................................................................3

Figure 3. Radio spectrum from 2500 to 3700 MHz with current allocations for air traffic control 

(ATC), weather, marine, and various Department of Defense (DOD) radar services. ....4

Figure 4. Physical layout showing a network of BRS base stations contributing to the interfering 

signal power. The interference can cause the radar to not detect the target. Antenna 

pattern attenuation is not represented in this figure. ........................................................6

Figure 5. ITU power spectral density domains................................................................................7

Figure 6. Interfering power spectral density (centered around ffff) unwanted emissions are within 

the radar detection IF bandwidth (inner dashed line). Radar is vulnerable to unwanted 

emissions. .........................................................................................................................8

Figure 7. Interfering power spectral density (centered around ffff) after transmitter filter 

mitigation. Radar is protected from unwanted emissions. ...............................................8

Figure 8. General block diagram of BRS transmitters and radar system. TX represents the 

transmitter, TF represents the transmitter filter, TX ANT represents the transmitter 

antenna, ANT represents the radar antenna, FEF represents the front-end filter, LNA 

represents the low-noise amplifier, IFF represents the IF filter, and DET represents the 

threshold detector. ............................................................................................................8

Figure 9. Short radar to target ranges as in (a) and (b) are analyzed with a constant SNR while 

long radar to target ranges as in (c) are analyzed with a variable SNR. ........................11

Figure 10. RCS and range for 10 IEC 62388 standard clutter free test cases with pulse range 

limits. Short and long pulses are separated by solid blue line at 5.6 km. Medium pulse 

ranges are between dashed red lines at 1.4 and 22.2 km................................................12

Figure 11. Radar performance with GN interfering signal, Swerling 1 target, non-coherent 

integration performance, and baseline performance of 0.8 PPPP, 10-4 PP PP. The long and 

short pulses were integrated 6 and 14 times, respectively. ............................................19

Figure 12. Radar performance degradation with GN interfering signal, Swerling 1 target, noncoherent integration, and baseline performance of 0.8 PPPP, 10-4 PPff . The long and short 

pulses were integrated 6 and 14 times, respectively. .....................................................20

Figure 13. INR distributions at various distances to the closest base station when there is 60 dB 

spurious attenuation........................................................................................................21

Figure 14. Separation distance versus reliability for -6 dB INR. 95 dB attenuation produces 

separation distances less than the 1 km propagation model limit and is not shown. .....22

vii
Figure 15. SNR distributions for 10 IEC 62388 standard clutter free test cases with power margin 

removed. Only seven curves are visible because cases 2 and 5, 6 and 7, and 8 and 9 

have similar target parameters........................................................................................24

Figure 16. INR distributions for 10 IEC 62388 clutter free test cases with spurious attenuation set 

to 60 dB. The separation distance between the radar and the closest base station is set 

to the radar to target range plus a 1 km base station to target distance. Only seven 

curves are visible because cases 2 and 5, 6 and 7, and 8 and 9 have similar target 

distances. ........................................................................................................................24

Figure 17. Comparison of constant and variable SNR results for -6 dB INR and 90% reliability.26

Figure 18. Measured PSD, filtered measured PSD, and SEM.......................................................28

Figure 19. FDR for ideal short pulse, 20 MHz bandwidth, IF filter..............................................28

Figure 20. Separation distance versus frequency separation for 50 and 90% reliability with short 

pulse 20 MHz radar detection IF bandwidth when INR is -6 dB...................................29

Figure A-1. Basic interference model. TX represents the transmitter source, TX Filter represents 

the transmitter filter, ANT represents the antenna, and RX filter represents the receiver 

filter. ...............................................................................................................................35

Figure A-2. Hypothetical PSD with ITU domains.........................................................................36

Figure C-1. Rise in noise power relative to receiver noise power for interfering signal with 

Gaussian noise characteristics........................................................................................44

Figure D-1. 3GPP spectrum emission mask in 30.0 kHz bandwidth.............................................47

Figure E-1. Case 1 reliability as a function of separation distance. The thick vertical black line at 

38.0 km is the separation distance used in our analysis. Reliabilities for spurious 

attenuations above 85 dB are approximately 1.0 for all separation distances................48

Figure E-2. Case 6 reliability as a function of separation distance. The thick vertical black line at 

7.8 km is the separation distance used in our analysis. Reliabilities for spurious 

attenuations above 90 dB are approximately 1.0 for all separation distances................49

Figure E-3. Case 1 reliability as a function of radar to target range. The thick vertical black line 

at 37.0 km is the radar to target range used in our analysis. All spurious attenuation 

curves lie on top of each other........................................................................................49

Figure E-4. Case 6 reliability as a function of radar to target range. The thick vertical black line 

at 6.8 km is the radar to target range used in our analysis. Spurious attenuation curves 

from 80 to 105 lie on top of each other. Reliability anomalies from 1 to 2 km are due to 

numerical integration error.............................................................................................50

Figure F-1. PSD measurement.......................................................................................................51

Figure F-2. Transmitter filter frequency response. ........................................................................52

viii
Figure F-3. Measured and filtered PSDs........................................................................................53

Figure G-1. Radar A measured and ideal, long and short pulse IF filter frequency responses. ....54

Figure G-2. Radar C measured and ideal, long and short pulse IF filter frequency responses......55

Figure H-1. Separation distance versus reliability for -9 dB INR. 95 dB attenuation produces 

separation distances less than the 1 km propagation model limit and is not shown. .....56

Figure H-2. Spurious attenuation for IEC 62388 standard clutter free test cases with -9 dB INR 

using constant and variable SNR for 90% reliability. ....................................................57

Figure H-3. Separation distance versus frequency separation for 50 and 90% reliability -9 dB 

INR with 20 MHz radar detection IF bandwidth. ..........................................................57

Figure H-4. Separation distance versus reliability for -12 dB INR. ..............................................58

Figure H-5. Spurious attenuation for IEC 62388 standard clutter free test cases with -12 dB INR 

using constant and variable SNR for 90% reliability. ....................................................59

Figure H-6. Separation distance versus frequency separation for 50 and 90% reliability -12 dB 

INR with 20 MHz radar detection IF bandwidth. ..........................................................59

ix
LIST OF TABLES

Table 1. IEC 62388 standard clutter free test cases.......................................................................11

Table 2. Radar and BRS parameters used for analysis. .................................................................18

Table 3. Baseline ideal SNR for a 1.9 degree beam-width antenna at baseline performance 

0.8 PPPP and 10 − 4 PP PP. PW is pulse width, PRF is pulse repetition frequency, BW is 

IF filter bandwidth, RR is rotation rate, and nnnn is the number of pulses integrated......18

Table 4. Relevant IPC parameters for baseline 0.8 PPPP, 10-4 PP PP with long and short pulse 

widths. S, I, and N are evaluated at the receiver input...................................................20

Table 5. Analysis results for -6.0 dB allowable INR.....................................................................22

Table 6. Separation distances for all INR at 90% reliability. ........................................................23

Table 7. Spurious attenuation for IEC 62388 standard clutter free test cases for 90% reliability.25

Table 8. Spurious attenuation for IEC 62388 standard clutter free test cases using constant SNR 

(C) and variable SNR (V) for 90% reliability. Case 1 difference is not available (NA) 

because the required spurious attenuation is below the minimum tested.......................26

Table 9. Spurious attenuation, Lspur, FDR, Lfdr, and frequency separation, ∆ff, needed for 90% 

reliability for 20 MHz bandwidth short pulse at 1 km distance separation....................29

Table B-1. Probability, qqqq, and corresponding standard normal deviate, zz , for the each of the 26 

segments in the aggregate distribution function.............................................................42

Table D-1. ITU-R Spurious emission power limit for BRS base station. .....................................46

Table D-2 Spectrum emission mask breakpoints...........................................................................46

Table F-1. Transmitter filter specifications. ..................................................................................52

Table H-1. Separation distance results for -9.0 dB allowable INR and 2.7% allowable 

degradation. ....................................................................................................................56

Table H-2. Separation distance results for -12.0 dB allowable INR and 1.4% allowable 

degradation. ....................................................................................................................58

x
ACRONYMS

3GPP 3rd Generation Partnership Project

APD Amplitude probability distribution

AWGN Additive white Gaussian noise

BPF Bandpass filter

BRS Broadband radio service

BW Bandwidth

CFAR Constant false alarm rate

CW Continuous wave

dB Decibel

dBi Decibels relative to the gain of an isotropic antenna

dBm Decibels relative to a milliwatt

dBsm Decibels relative to a square meter

dBW Decibels relative to a watt

DOD Department of Defense

EIRP Effective isotropic radiated power

ETSI European Telecommunications Standards Institute

FDD Frequency division duplex

FDR Frequency dependent rejection

FE Front-end

FEF Front-end filter

FS Free space

GHz Gigahertz

GN Gaussian noise

Hz Hertz

IEC International Electrotechnical Committee

IEEE Institute of Electrical and Electronics Engineers

xi
IF Intermediate frequency

INR Interference to noise power ratio

IPC Interference protection criteria

ITM Irregular terrain model

ITS Institute for Telecommunication Sciences

ITU International Telecommunication Union

ITU-R ITU Radiocommunication Sector

km Kilometer

kHz kilohertz

LNA Low-noise amplifier

LNFE Low-noise front-end

LTE Long Term Evolution

MHz Megahertz

MIMO Multiple-input multiple-output

MSC Maritime Safety Committee

nmi Nautical mile

ns Nanosecond

NTIA National Telecommunications and Information Administration

OFDM Orthogonal frequency division multiplexing

OFDMA Orthogonal frequency division multiple access

OOB Out-of-band

PRF Pulse repetition frequency

PRI Pulse repetition interval

PSD Power spectral density

RCS Radar cross section

RF Radio frequency

RPM Revolutions per minute

xii
SA Spectrum analyzer

SEM Spectrum emission mask

SINR Signal to interference plus noise ratio

SNR Signal to noise ratio

SOLAS Safety of life at sea

STC Sensitivity time control

TDD Time division duplex

UMTS Universal Mobile Telecommunications System

UN United Nations

UN/MSC United Nations Maritime Safety Committee

USCG United States Coast Guard

VSA Vector signal analyzer

WGN White Gaussian noise

WiMAX Worldwide interoperability for microwave access

xiii

EXECUTIVE SUMMARY

Spectrum reallocation is often necessary to accommodate new services which can potentially 

increase business productivity and enhance the lives of private citizens. However, reallocating 

services to bands near those used by incumbent services—or, in some cases, to those same 

bands—can cause interference to the incumbent service.

Spectrum reallocation can cause interference in radar systems in a number of ways. A system 

reallocated to a nearby band can introduce unwanted signals into the radar detection bandwidth. 

Also, a system reallocated to a nearby band can overload the radar receiver front-end and cause 

gain compression, increased noise power, and intermodulation in the radar detection bandwidth. 

The U.S. Coast Guard (USCG) asked the National Telecommunications and Information 

Administration Institute for Telecommunication Sciences (NTIA/ITS) to investigate effects of 

reallocation on the 2900–3100 MHz band marine radar service by determining interference 

protection criteria (IPC) and analyzing strategies for mitigating the interference.

Here we investigate the effects of reallocation to accommodate the broadband radio services 

(BRS) on the 2900–3100 MHz band marine radar service. The BRS is the next generation of 

personal communications services which will provide wideband Internet communications to 

mobile users. Results of our investigations have been assembled into three reports subtitled 

“Background,” “Unwanted Emissions,” and “Front-end Overload.”

This report analyzes the effect of unwanted emissions from a broadband radio service (BRS) 

base station on magnetron radar receiver performance. This report builds upon the interference 

model developed in the previous background report where we demonstrated that unwanted 

emissions were Gaussian distributed and aggregated. Results include distance separation and 

frequency separation that meet IPC. Baseline radar system performance was set at a 0.8 

probability of detection and 10-4 probability of false alarm. Interference to noise ratios (INR) of -

6, -9, and -12 dB were investigated. 

Distance separation was computed from expressions for radar link reliability. Reliability in this 

context is dependent solely on radio wave propagation path loss variability. So that anomalous 

radio wave propagation ducting conditions do not influence results, 90% reliability is used. Two 

expressions for reliability were provided. One expression assumed constant radar signal to noise 

ratio (SNR) corresponding to short radar to target ranges. This method does not require knowing 

the radar to target link budget.

The other expression assumed variable SNR which is valid over any radar to target range. This 

method requires complete knowledge of the radar to target link budget. We used targets from the 

IEC 62388 standard clutter free test cases to set radar to target link budget parameters. Base 

station to radar path length was set to the radar to target range plus 1 km.

The constant SNR case is important because it can be easily applied to the most demanding case 

where the ship with the radar is close to the target and the base station. The expression for 

variable SNR is the most general and useful for situations where close radar to base station 

distances are not likely.

xv
Distance separation calculations for constant SNR showed that 90 dB spurious attenuation could 

provide 90% reliability at a separation distance of 1.2 km when INR is -6 dB. The separation 

distance decreased below 1 km with 95 dB spurious attenuation. For reference, the ETSI -52 

dBm/MHz unwanted emissions limit outside the BRS operating band corresponds to 95 dB 

spurious attenuation.

Results for variable SNR agreed with those using constant SNR at short radar to target ranges. 

However, as radar to target range increased, less spurious attenuation was needed. The largest 

difference was with case 4, a SOLAS ship 21.4 km away from the radar, where 7.1 dB less 

spurious attenuation was needed when INR is -6 dB. Consequently the constant SNR reliability 

expression can be considered worst case.

We also showed how frequency separation could be computed by replacing spurious attenuation 

by an expression for FDR. The FDR were calculated from measured PSD, filtered PSD, 

spectrum emission mask, and idealized IF filter frequency responses that corresponded with 

measured filter frequency responses. SNR was assumed to be constant so results are worst case. 

The results showed that 90 % reliability IPC could be met at 1.2 km separation distance with 

92.8 MHz and 99.7 MHz for the filtered PSD and SEM when INR is -6 dB. We found that 

filtered PSD frequency separation can be reduced from 92.8 MHz to 54.6 MHz when the 

distance separation is increased to 32.8 km.

Results for the -9 dB and -12 dB INR cases differed in most cases. For example, the separation 

distance for the constant SNR case increased to 1.7 and 2.7 km with 90 dB spurious attenuation 

for INR of -9 and -12 dB, respectively. For variable SNR, case 4 required 8.7 and 11.2 dB less 

spurious attenuation than constant SNR for INR of -9 and -12 dB, respectively. Frequency 

separation did not increase when the INR was decreased to -9. However it did increase to 99.3 

MHz when INR was decreased to -12 dB.

The results in this report are encumbered with two caveats. First, the results are for a frequency 

division duplexing (FDD) BRS base station signal that occupies one 10 MHz BRS channel. 

Results need to be adjusted to accommodate more channels. Second, these results are based on 

magnetron radar signal processing. Additional analysis is needed to assess the impact to solidstate radar receivers because their signal processing is very different from that in the magnetron 

radar receiver. The signal processing affects receiver sensitivity and IF selectivity and estimates 

of separation distance and frequency separation need to take this into account.

xvi
EFFECT OF BROADBAND RADIO SERVICE REALLOCATION ON 2900–3100 BAND 

MARINE RADARS: BASE STATION UNWANTED EMISSIONS

Robert Achatz, Paul McKenna, Roger Dalke, Frank Sanders, John Carroll1

Spectrum reallocations may place broadband radio services (BRS) near spectrum used by 

2900–3100 MHz band marine radars. Signals from the BRS base stations can potentially

introduce unwanted emissions in the radar detection bandwidth and cause interference.

Interference protection criteria (IPC) are needed to mitigate this effect. The primary IPC of 

concern are the interference to noise power ratio (INR) and the reliability of the radar link at 

a specified radar signal to noise power ratio (SNR). Reliability is determined by radio wave 

propagation path loss variability which increases with distance. Distance separation between 

base stations and radar for various spurious attenuations were calculated using reliability 

expressions for short radar to target ranges with constant SNR and for longer radar to target 

ranges with variable SNR. For a magnetron radar under clutter free conditions, 90 dB of 

spurious attenuation is needed to obtain 90% radar operational reliability at1.2 km when the 

INR is -6 dB and the SNR is constant. Reducing the INR to -9 and -12 dB increased the 

separation distance to 1.7 and 2.7 km, respectively. At longer base station to radar separation 

distances, variable SNR required less spurious attenuation than constant SNR. Consequently, 

constant SNR analysis can be considered worst case. Distance and frequency separation were 

calculated using frequency dependent rejection (FDR). These calculations showed that for 

constant SNR 92.8 MHz of frequency separation is required to meet the 90% reliability IPC

at 1.2 km separation distance when the INR is -6 dB. Only 54.6 MHz frequency separation is 

needed when the separation distance is increased to 32.8 km. 

Keywords: broadband radio service, frequency dependent rejection, interference, interference 

protection criteria, marine radar, radar, radio wave propagation, radio spectrum

engineering, spurious emissions, unwanted emissions

1 INTRODUCTION

Spectrum reallocation is often necessary to accommodate new services which can potentially

increase business productivity and enhance the lives of private citizens. However, reallocating 

services to bands near those used by incumbent services—or, in some cases, to those same 

bands—can cause interference to the incumbent service.

Spectrum reallocation can cause interference in radar systems in a number of ways [1], [2], [3], 

[4]. For example, a system moved to a nearby band can introduce unwanted emissions into the 

radar detection bandwidth. Also, emissions from a system reallocated to a nearby band can 

overload the radar receiver front-end (receiver circuits operating at the carrier frequency) and 

cause gain compression, increased noise power, and intermodulation in the radar detection 

bandwidth.

1

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

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

 
The U.S. Coast Guard (USCG) asked the National Telecommunications and Information 

Administration Institute for Telecommunication Sciences (NTIA/ITS) to investigate effects of 

spectrum reallocation on the 2900–3100 MHz band marine radar service by determining 

interference protection criteria (IPC) and analyzing strategies for mitigating the interference.

Results of these investigations are expected to be useful to regulatory and standards bodies which 

are responsible for developing IPC including the NTIA [5]; the International Telecommunication 

Union (ITU) [6]; the International Electrotechnical Commission (IEC) [7], which is currently 

devising IPC tests on behalf of the United Nations Maritime Safety Committee (UN/MSC) [8]; 

and the Institute of Electrical and Electronics Engineers (IEEE) [9].

In this series of reports we analyze the effects of reallocation to accommodate broadband radio 

services (BRS) on the 2900–3100 MHz band marine radar service. The BRS is the next 

generation of personal communications services which will provide wideband Internet 

communications to mobile users. Spectrum regulators are currently investigating various 

reallocation strategies to accommodate BRS growth.

Marine radars are used by ships to avoid collisions with objects while traveling in oceans, seas, 

lakes, and rivers. An example of a marine radar antenna mounted on a ship is shown in Figure 1. 

Detection of objects, referred to as targets, is often difficult. Even on calm seas, the target can 

have significant radar cross section (RCS) variation and corresponding reductions in signal 

power. The target can also be obscured by signal reflections or clutter from waves and 

precipitation.

These 2900–3100 MHz band radars are often referred to as S-band marine radars. Similar radars 

that operate in the 9200–9500 MHz band are often referred to as X-band marine radars. The 

primary advantage of S-band radar signals is that they have less precipitation attenuation than Xband radar signals. This allows S-band radars to detect smaller objects at longer distances in 

adverse weather conditions. Large ships subject to international safety of life at sea (SOLAS) 

regulations generally operate with radars in both bands.

BRS providers promise to deliver fast, reliable Internet service to users wherever they are. An 

example of a BRS base station is shown in Figure 2. Potential unwanted emissions and front-end 

overload problems in 2900–3100 MHz band marine radars from BRS base stations were brought 

to the attention of the International Telecommunication Union in November 2009 by the United 

Kingdom [10]. 

Significant amounts of spectrum are needed for widespread BRS use. BRS systems are already 

operating in the 2500–2690 MHz band. The 3500–3650 MHz band has been evaluated for 

reallocation [11]. Other reallocations in the 2700–3700 band, currently allocated to a number of 

radar services as shown in Figure 3, could also affect 2900–3100 MHz band marine radars.

BRS and radar system characteristics are derived from those used by internationally recognized 

groups. The BRS system is modeled after systems devised by the European Technical Standards 

Institute (ETSI) Universal Mobile Telecommunications System (UMTS) committee/3rd 

Generation Partnership Project (3GPP) [12], ITU [13], and the WiMAX Forum [14]. The radar 

2
system is modeled after a system devised by the IEC 62388 standard shipborne radar committee 

[7] for industry acceptance testing.

Figure 1. Marine radar slotted array antenna (white bar) mounted on motor which spins it.

Figure 2. BRS base station.

3
Figure 3. Radio spectrum from 2500 to 3700 MHz with current allocations for air traffic control 

(ATC), weather, marine, and various Department of Defense (DOD) radar services.

1.1 Previous Background Work 

The IPC, scenario, and models needed for interference analysis are provided in the previous 

background report [15] and briefly summarized here. IPC are needed to reduce the probability of 

collision while not placing onerous burdens on other systems using the radio spectrum. Our 

objective is to determine IPC and factors such as distance and frequency separation that can 

mitigate the effects of the interfering signal so IPC can be met. IPC for base station interference 

in the marine radar receiver include:

• Radar baseline performance level, signal to noise ratio (SNR), and reliability

• Radar allowable degraded performance level, interference power level, and reliability

The physical scenario used for interference analysis is shown in Figure 4. We assume a radar 

target is located between a network of BRS base stations and a ship with a 2900–3100 MHz band 

magnetron marine radar. Weather conditions are assumed to be benign so that there is no signal 

“clutter” from reflections off precipitation or waves.

Radar targets include shorelines, ships, boats, and navigational buoys. The target RCS, which 

varies or fluctuates with time, is modeled with a statistical distribution. The mean of the 

distribution is dependent on target aspect angle, shape, and materials.

The base stations are modeled after those described by ETSI UMTS, 3GPP, ITU, and WiMAX 

groups. BRS signals use orthogonal frequency division multiple access (OFDMA) and are 

transmitted within BRS channels characterized by their center frequency and bandwidth.

Transmit and receive signals use frequency division duplexing (FDD) so that transmissions can 

occur at all times. The signals are transmitted from antennas that typically cover 60 degree 

azimuth sectors with slant, 45 degree polarization. Although more than one BRS channel can be 

transmitted from the same antenna, we assume only one 10 MHz BRS channel is transmitted.

The radar is modeled after the magnetron radar in the IEC 62388 standard for shipborne radars. 

The radar transmits periodic pulses from a rotating antenna with a narrow antenna beam width

and horizontal polarization. Typically short, medium, and long pulse widths are used to detect 

targets at different ranges and range resolution. Pulses arriving within the time it takes the 

antenna to traverse its beam width are integrated to enhance SNR. 

4
The interfering radio wave propagation path is the path from the base station to the radar. The 

desired propagation path is the path from the radar to the target and back to the radar. These 

paths can have path loss variation depending on atmospheric conditions, which produces power 

fading and enhancement. Path loss variability occurs at longer distances from hour to hour and is 

characterized with a statistical distribution. The ITS Irregular Terrain Model (ITM) radio wave 

propagation model is used because it is able to predict power fading and enhancement caused by 

path loss variability.

Besides establishing IPC, scenario, and models, the previous background report addressed three 

fundamental interference analysis issues including

• BRS signal characteristics: BRS emissions from a single base station can be reasonably 

modeled with Gaussian noise. Since its statistics are Gaussian it follows that emissions from 

an aggregate of base stations will also be Gaussian.

• Aggregate interfering emissions: The interfering signal is the sum of signals from an 

aggregate of base stations, the mean power and distribution of the aggregate emissions can be 

determined using ITM and Monte Carlo analysis, and the aggregate emissions from 10 base 

stations spaced 3 km apart could have as much as 6 dB more power at some distances as 

compared to a single base station.

• Variable SNR: Interference analysis for scenarios with long radar to target ranges need to 

account for a variable radar SNR caused by atmospheric conditions that vary from hour to 

hour. While devising a method for incorporating variable SNR we found that there was a 

considerable amount of excess power in radar to target link budgets used in acceptance tests. 

Although this excess SNR could potentially mitigate interference we found that it is needed 

to accommodate reductions in target mean RCS due to different target aspects, shapes, and 

materials. We recommended removing the excess power prior to interference analysis by 

reducing the mean RCS.

5
Figure 4. Physical layout showing a network of BRS base stations contributing to the interfering 

signal power. The interference can cause the radar to not detect the target. Antenna pattern 

attenuation is not represented in this figure.

1.2 Report Organization

This report determines allowable INR IPC and the distance and frequency separations needed to 

meet the allowable IPC. Distance separation is analyzed with constant and variable SNRs 

corresponding to short and long radar to target ranges, respectively. Results are compared to 

determine worst case conditions. Frequency separation is analyzed using frequency dependent 

rejection (FDR) which takes the transmitted power spectral density (PSD) and the radar receiver 

IF filter frequency responses into account. We also show how interference can be mitigated by 

the combination of distance and frequency separation. The general problem is discussed Section 

2. Our approach to solving the problem is provided in Section 3. A mathematical description of 

the method is given in Section 4. Results are provided in Section 5. The Appendices provide 

additional information for the interested reader. 

6
2 UNWANTED EMISSIONS

Unwanted emissions are precisely defined by the ITU-R [16], which recognizes three transmitted 

signal power spectral density (PSD) domains referred to as necessary bandwidth, out-of-band 

(OOB), and spurious. Collectively, OOB and spurious emissions are referred to as unwanted 

emissions. Figure 5 illustrates these domains.

In general the OOB domain begins at the edge of the necessary bandwidth and ends at ± 2.5 

times the necessary bandwidth from the transmitter center frequency. The spurious domain 

follows the OOB domain. The necessary bandwidth contains most of the modulated signal 

power, the spurious region contains unwanted signals incidental to transmission, and the OOB 

region between them contains both modulated and incidental signals.

Effects of unwanted emissions are mitigated by decreasing transmitter power, increasing the 

distance separating the base stations from the radar, and increasing the frequency separation 

between base station and radar center frequencies.

Unwanted emissions can also be mitigated by transmitter filtering. An example of unwanted 

emissions before and after transmitter filtering is shown in Figures 6 and 7. As Figure 8 shows,

the transmitter filter is located between the transmitter and the transmitter antenna. Although the 

IF filter in the radar signal processing block can attenuate unwanted emissions, it is constrained

by its requirement to maximize radar signal power. Nevertheless, we will see that its design has a 

significant effect on frequency separation.

Figure 5. ITU power spectral density domains.

7
Figure 6. Interfering power spectral density (centered around ffii) unwanted emissions are within 

the radar detection IF bandwidth (inner dashed line). Radar is vulnerable to unwanted emissions.

Figure 7. Interfering power spectral density (centered around ffii) after transmitter filter 

mitigation. Radar is protected from unwanted emissions.

Figure 8. General block diagram of BRS transmitters and radar system. TX represents the 

transmitter, TF represents the transmitter filter, TX ANT represents the transmitter antenna, ANT 

represents the radar antenna, FEF represents the front-end filter, LNA represents the low-noise 

amplifier, IFF represents the IF filter, and DET represents the threshold detector.

8
3 METHOD

The previous background report [15] showed that the aggregate base station interference was 

Gaussian distributed. This finding is very advantageous because it allows us to repurpose 

theoretical expressions for predicting marine radar performance in Gaussian receiver noise for 

analyzing effects of aggregate base station unwanted emissions on marine radar receivers [17].

Consequently our analytic method establishes baseline SNR from baseline probability of 

detection, PPdd, and probability of false alarm, PPffff. Allowable interference to noise ratio (INR) is 

then determined from the signal to interference plus noise ratio (SINR) corresponding to the 

allowable PPdd and PPffff. Note that the unwanted emissions do not have to be “white” Gaussian 

noise with a constant PSD. This approach can be used even for unwanted OOB emissions where 

the PSD is not constant but sloped.

Having established the SNR and INR IPC, we proceed to determine distance and frequency 

separation with two methods that have distinctly different transmitter and receiver filtering

assumptions. Our first method assumes that frequency separation places the unwanted emissions 

in the spurious domain and the spurious emission PSD is constant. Because the PSD is constant

the emissions can be specified by one spurious attenuation parameter defined as 

llssssssss = tt

ψ rrff

(1)

where tt is the total power at the transmit antenna input and ψ rr is the spurious power 

measured in an ITU reference equivalent noise bandwidth, bb rr . More details regarding spurious 

attenuation can be found in Appendix A.

The second method replaces spurious attenuation with frequency dependent rejection (FDR). 

Frequency dependent rejection (FDR) is the fraction of transmitted power that is received at any 

frequency separation

∆ff = fftt − ff (2)

where fftt and ff are the transmitter center frequency and received frequency, respectively. FDR is 

computed from an actual PSD and IF filter frequency response

llff (∆ff) = ̂

tt

∫ ̂

tt (ff)�hii (ff + ∆ff)�

2 ∞

−∞

(3)

where ̂

tt (ff) is the BRS base station PSD at the transmit antenna input, hii (ff) is the radar IF 

filter frequency response, and 

̂

tt = � ̂tt (ff)

∞

−∞

(4)

is the total power at the transmit antenna input.

9
Propagation path loss variability caused by atmospheric conditions further complicates our 

method. We address this by including radar link reliability in the separation distance calculation. 

In this context link reliability is determined solely by propagation path loss variability and is 

independent of electrical or mechanical malfunction. To avoid including the effects of radio 

wave propagation ducting we use a 90% reliability goal.

Reliability is included into the analysis in two ways. First, the interfering path from the base 

station to the radar is allowed to have path loss variability but the desired radar to target link is 

not. The underlying assumption in this approach is that the radar to target distance is short and 

SNR is constant. This is shown in Figures 9(a) and 9(b). With constant SNR only the aggregate 

interference power distribution is needed to compute reliability and separation distance.

The second way is to allow both interfering and desired path loss to vary. This is valid for any 

radar to target distance including the long radar to target range in Figure 9(c) where path loss and 

SNR variability can be high. With variable SNR, the radar power probability distribution is 

needed in addition to the aggregate interference distribution function to compute reliability and 

separation distance.

The radar power probability distribution is derived from targets given in the IEC 62388 standard. 

The set of targets, summarized in Table 1, is diverse in that it includes distributed targets such as 

shorelines, complex targets such as ships and boats, and point targets such as channel markers 

and buoys. The incongruity between the descriptive shoreline height and the height used in 

calculations is assumed to be due to terrain irregularity. Figure 10 displays the targets with 

respect to their RCS and range. Range limits for each pulse width based on manufacturer 

literature are also shown. The short pulse is limited to ranges up to 5.6 km (3 nmi) and the long 

pulse from 5.6 to 44.4 km (3 to 24 nmi). The medium pulse range from 1.4 to 22.2 km (0.75 to 

12 nmi) overlaps short and long pulse ranges. The RCS of these targets are reduced to remove 

excess power needed to accommodate different target aspect angles, shapes, and materials by

σσ� aa = σσ aa�mm (5)

where σσ aa is the mean RCS and mm is the excess power margin.

10
Figure 9. Short radar to target ranges as in (a) and (b) are analyzed with a constant SNR while 

long radar to target ranges as in (c) are analyzed with a variable SNR.

Table 1. IEC 62388 standard clutter free test cases.

Case Target

Height 

(m)

Range RCS 

(m2 nmi km )

1 60m high shoreline 50.0 20.0 37.0 50000.0

2 6 m high shoreline 5.0 8.0 14.8 5000.0

3 3 m high shoreline 2.5 6.0 11.1 2500.0

4 SOLAS ship > 5000gt 10.0 11.0 20.4 30000.0

5 SOLAS ship > 500gt 5.0 8.0 14.8 1000.0

6 Small boat with reflector 4.0 3.7 6.8 0.5

7 Buoy with reflector 3.5 3.6 6.7 1.0

8 Buoy 3.5 3.0 5.6 0.5

9 Small 10 m long boat 2.0 3.0 5.6 1.4

10 Channel marker 1.0 1.0 1.9 0.1

11
Figure 10. RCS and range for 10 IEC 62388 standard clutter free test cases with pulse range 

limits. Short and long pulses are separated by solid blue line at 5.6 km. Medium pulse ranges are 

between dashed red lines at 1.4 and 22.2 km.

12
4 MATHEMATICAL FOUNDATION

This section provides the mathematical description of our method to determine distance 

separation between the base stations and radar positions and frequency separation between the 

base stations and radar center frequencies required to mitigate unwanted out-of-band and 

spurious emissions so that IPC are met.

4.1 Powers, Power Ratios, and IPC

Signal, noise, and interference powers are referenced to the receiver input. The signal power is 

ss = 1

TT � ss2(tt)

TT

2�

−TT

2�

(6)

where TT is the pulse period.

The receiver noise power is

nn = E ��� nn(ττ)hii (tt − ττ)

∞

−∞

�

2

� (7)

where E{∙} is the expectation operator. When the noise power spectral density is constant,

nn = TT0ff rrbbii (8)

where is Boltzman’s constant, TT0 is the ambient temperature in degrees K, ff rr is the receiver 

noise factor, and bbii is the IF filter equivalent noise bandwidth.

The interference power is

= E ��� (ττ)hii (tt − ττ)

∞

−∞

�

2

� (9)

The relationships between SNR, INR, and SINR power ratios are derived as follows:

ss

+ nn =

ss⁄nn

nn� + 1 (10)

nn� =

ss⁄nn

ss

( + nn) � − 1 (11)

For notational convenience we let ww = ss

nn represent SNR, uu = iinn represent INR, and vv = ssii+nn

represent SINR. WW, UU, and VV are ww, uu, vv respectively in dB. The ww can be thought of as wanted 

13
signal power normalized by the noise power and uu as unwanted interfering signal power 

normalized by the noise power. Hence, (11) can be rewritten as

uu = ww

vv − 1 (12)

or

vv = ww

uu + 1 (13)

and IPC baseline SNR, wwbb, allowable INR, uu , and allowable SINR, vv , are related by

uu = wwbb

vv − 1 (14)

or 

vv = wwbb

uu + 1 (15)

4.2 Distance Separation with Spurious Attenuation

4.2.1 Constant SNR

Distance separation analysis for constant SNR is dependent on expressions for the received 

aggregate spurious emissions power and radar link reliability. SNR is assumed to be set to the 

baseline level, wwbb. The expression for aggregate spurious emission power is a combination of the 

interference link budget in the previous background report [15] and the definition of spurious 

attenuation discussed in Appendix A

( 1,llssssssss) = � ss ssss ( nn) = � ̂

tt gg�ttgg

�llddllbbbbll pp llcc

∙ 1

ll

̃ ,nn( nn)

NN

nn=1

NN

nn=1

∙ bbii

llssssssssbb rr

(16)

where 1is the distance to the closest base station of the aggregate, nnis the distance from the 

radar to the nn-th base station, NN is the number of base stations in the aggregate, ̂

tt is the signal 

power in at the transmit antenna input, gg�tt is the gain of the base station antenna in the direction 

of the radar, gg is the gain of the radar antenna in the direction of the base station, lldd is the 

radome loss, llbbbb is the integration beam shape loss, ll pp is the polarization loss between the base 

station and radar antennas, llcc is the radar receiver circuit loss, ll

̃ is the path loss from the base 

station to the radar, llssssssss is the spurious attenuation, bb rr is the equivalent noise bandwidth of 

the reference filter, and bbii is the equivalent noise bandwidth of the radar IF filter.

14
The expression for reliability is 

PPPP�UU( 1,llssssssss) < U � = � ff(UU( 1, llssssssss)) UU

Uaa

−∞

(17)

i.e., the probability that INR is less than the allowable INR. The right side of this equation is the 

aggregate interference distribution function derived by Monte Carlo analysis in the previous 

background report.

4.2.2 Variable SNR

Distance separation analysis for variable SNR is dependent on expressions for the received 

aggregate spurious emissions power shown above, received radar signal power derived in the 

previous background report, and radar link reliability.

The received radar signal power is

ss( ) = tt gg2σσ aaλλ2

(4ππ)3 4 2( )llddllbbbbllcc llcc mm

(18)

where tt is the radar source power, gg is the radar antenna gain, σσ aa is the target mean RCS, λλ is 

the wavelength, is the radar to target range, ( ) is the radar to target excess path loss 

which varies with distance, lldd is the radome loss, llbbbb is the integration beam shape loss, llcc is the 

radar transmitter circuit loss, llcc is the radar receiver circuit loss, and mm is the excess power

margin.

The expression for radar link reliability is 

PPPP�WW( ) ≥ WWbb,VV( 1,llssssssss) ≥ VV � (19)

i.e., the joint probability that the SNR is greater than or equal to the base line SNR and the SINR 

is greater than or equal to the allowable SINR. An expression for the practical computation of 

this probability is derived as follows. For notational convenience, the independent variables ,

1, and llssssssss are not explicitly stated.

The joint probability can be written in integral form as

PPPP{ww ≥ wwbb, vv ≥ vv } = � � ff(ww, vv)

∞

aa

∞

wwbb

(20)

But ff(ww, vv) = ff(vv|ww)ff(ww) and the upper limit of the inner integral is ww when interference is 

not present, i.e. uu = 0, so

PPPP{ww ≥ wwbb, vv ≥ vv } = � �� ff(vv|ww)

ww

aa

�

∞

wwbb

ff(ww) (21)

15
We now want to express the inner integral in terms of uu. Since 

ff(vv|ww) = ff(uu|ww) (22)

and uu is independent of ww we have

� ff(vv|ww) =

ww

aa

� ff(uu)

ww

aa

−1

0

(23)

In other words the complementary cumulative distribution function of vv is equal to the 

cumulative distribution function of uu

PPPP{vv > vv |ww} = PPPP �uu <

ww

vv − 1� (24)

Finally

PPPP{ww ≥ wwbb, vv ≥ vv } = � �� ff(uu)

ww

aa

−1

0

� ff(ww)

∞

wwbb

(25)

In addition we can write this in terms of decibels since 

ff(uu) = ff(UU) (26)

and

ff(ww) = ff(WW) (27)

Consequently, reliability is also

PPPP{WW ≥ WWbb,VV ≥ VV } = � �� ff(UU)

10 log10�100.1WW

100.1VVaa−1�

−∞

�

∞

WWbb

ff(WW) (28)

Inner and outer integrals are computed with segmented log normal distribution functions. The 

method for computing the outer integral is documented in the description of the ITM in the 

previous background report. A fast method for computing the inner integral is provided in 

Appendix B.

4.3 Distance Separation with FDR

The expression for aggregate unwanted emission power is a combination of the interference link 

budget in the previous background report and the definition of frequency dependent rejection 

discussed in Appendix A

16
( 1, ∆ff) = � ss ssss ( nn) = � ̂

tt gg�ttgg

�llddllbbbbll pp llcc

∙ 1

ll

̃ ,nn( nn)

NN

nn=1

NN

nn=1

∙ 1

llff (∆ff) (29)

This is the same expression as that used for spurious emissions with the substitution 

llff (∆ff) = llssssssssbb rr

bbii

(30)

Consequently we can convert spurious attenuation distance separation results to frequency 

separation results by finding the ∆ff which satisfies (30).

17
5 RESULTS

5.1 Parameters

Parameters for these scenarios are explained in detail in the previous background report [15]. 

Table 2 summarizes relevant radar and BRS parameters.

Table 2. Radar and BRS parameters used for analysis.

Parameter Value Note

̂

tt 13.0 dBW 20 W for 10 MHz bandwidth signal at antenna

gg�tt 15.0 dB

lldd 1.0 dB Transmission and reception

llbbbb 1.6 dB Transmission and reception

llssss 1.8 dB

llcc 2.7 dB

llcc 2.7 dB

llss 9.8 dB

ll pp 3.0 dB Radar is horizontally polarized. BRS is slant polarized.

tt 44.8 dBW 30 kW at source

gg 27.0 dB

ff rr 5.0 dB Referred to limiter input

5.2 Interference Protection Criteria

IPC were determined for the IEC 62388 long and short pulses at a 40 rpm antenna rotation rate. 

As shown in Table 3, the long and short pulses were integrated 6 and 14 times, respectively.

Table 3. Baseline ideal SNR for a 1.9 degree beam-width antenna at baseline performance 0.8 PPdd

and 10−4 PPffff. PW is pulse width, PRF is pulse repetition frequency, BW is IF filter bandwidth, 

RR is rotation rate, and nn is the number of pulses integrated.

Pulse

PW 

(ns)

PRF 

(Hz) BW (MHz) RR (rpm) nnpp

Ideal SNR (dB)

Swerling 0 Swerling 1

Short 50 1800 20 40 14 2.31 7.58

Long 800 785 3 40 6 4.83 10.03

The INR are determined from the GN interference radar performance curves in Figures 11 and 

12. Conditions used to create the curves include Swerling 1 RCS fluctuation, baseline 

performance of PPdd = 0.8 and PPffff = 10−4, and non-coherent integration. The equations used to 

create the plot are

18
uu = wwbb�nn , PPdd,bb, PPffff�

vv(nn , PPdd, , PPffff) − 1 (31)

based on (12) and,

degraded performance percentage = �

PPdd,bb − PPdd

PPdd,bb

� ∙ 100% (32)

where PPdd,bb is the baseline performance probability of detection, PPdd, is the allowable probability 

of detection, nn is the number of pulses integrated, and wwbbis the baseline performance SNR. 

The curves show INRs of -6, -9, and -12 dB have approximately 5.5%, 2.8%, and 1.4% 

degradation, respectively. Differences between long and short pulses are negligible. These INRs 

raised the radar receiver noise floor of approximately1.0, 0.5, and 0.25 dB, respectively, as 

shown in Appendix C. Baseline and degraded conditions for the long and short pulse widths are 

shown in Table 4. 

Figure 11. Radar performance with GN interfering signal, Swerling 1 target, non-coherent 

integration performance, and baseline performance of 0.8 PPdd, 10-4 PPffff. The long and short pulses 

were integrated 6 and 14 times, respectively.

19
Figure 12. Radar performance degradation with GN interfering signal, Swerling 1 target, noncoherent integration, and baseline performance of 0.8 PPdd, 10-4 PPffff. The long and short pulses 

were integrated 6 and 14 times, respectively.

Table 4. Relevant IPC parameters for baseline 0.8 PPdd, 10-4 PPffff with long and short pulse widths.

S, I, and N are evaluated at the receiver input.

Pulse 

width

Baseline 

SNR (dB)

Allowable

INR (dB)

Allowable degradation 

(PPdd/%)

Allowable

SINR (dB) S (dB) I (dB) N (dB)

Long 11.83 -6 0.76/5.5 10.87 -92.40 -110.23 -104.23

Long 11.83 -9 0.78/2.8 11.32 -92.40 -113.23 -104.23

Long 11.83 -12 0.79/1.4 11.57 -92.40 -116.23 -104.23

Short 9.38 -6 0.76/5.6 8.41 -86.61 -101.99 -95.99

Short 9.38 -9 0.78/2.8 8.87 -86.61 -104.99 -95.99

Short 9.38 -12 0.79/1.4 9.12 -86.61 -107.99 -95.99

5.3 Interference Power Distributions

The aggregate interference power distribution is determined by Monte Carlo analysis using the 

ITM propagation model as shown in the previous background report. Figure 13 shows the results 

of this analysis for distances to the closest base station, 1, at 1 km and then at 5 km steps 

starting at 5 km. These results are for 60 dB of spurious attenuation. The most distinctive feature 

of these curves is how variability increases with distance. The INR for the 1 and 5 km curves is

relatively constant.

20
Figure 13. INR distributions at various distances to the closest base station when there is 60 dB 

spurious attenuation.

5.4 Distance separation with spurious attenuation

5.4.1 Constant SNR

Results were calculated for single 10 MHz bandwidth signal with spurious attenuations ranging 

from 56 dB to as much as 100 dB, where 56 dB is the ITU minimum amount of spurious 

attenuation for the U.S. These results are valid for both long and short pulses. Methods for 

converting between spurious attenuation, LLssssssss, transmitted power density in the reference 

bandwidth, Ψ rr , and effective isotropic radiated power in the reference bandwidth, ZZ rr , are 

provided in Appendix D.

The separation distances between the base station and the radar at various reliabilities and 

spurious attenuations for a -6 dB INR are presented in Table 5 and shown in Figure 14. Results 

for -9 and -12 dB INR are provided in Appendix H. In the tables, separation distances < 1 km 

occur when the allowable INR was not reached at the 1 km ITM distance limit because of high

spurious attenuation. Greater spurious attenuation resolution, perhaps 1 dB instead of the current 

5dB, is needed to determine a better estimate of spurious attenuation needed at 1 km. 

The results show that greater separation distances are needed for higher reliabilities and lower 

spurious attenuations when all other parameters are held constant. Close separation distances 

with little or no change in reliability can be achieved with increased spurious attenuation.

21
Results for 90% reliability are provided for all INR in Table 6. The results show that more than 

90 dB spurious attenuation is required to achieve 90% reliability at a 1 km separation distance at 

-6 and -9 dB INR. More than 95 dB spurious attenuation is needed at -12 dB INR.

The ETSI spurious emission requirement outside the BRS operating band is -52 dBm/MHz. This 

limit corresponds to 95 dB spurious attenuation when 20 W of power is at the transmit antenna 

input, which is adequate for -6 and -9 dB INR but not for -12 dB.

Table 5. Analysis results for -6.0 dB allowable INR.

Parameter Separation distance, ddmmmm (km)

LLss ssss ΨΨ rrrr ΖΖ rrrr Reliability

dB dBm/MHz dBm/MHz 50% 60% 70% 80% 90% 95% 99%

56 -13 2 33.6 33.9 34.2 34.7 35.5 36.4 38.8

60 -17 -2 31.2 31.5 31.8 32.1 32.8 33.6 35.4

65 -22 -7 27.7 28.10 28.6 29.1 29.6 30.2 31.6

70 -27 -12 20.4 20.7 21.1 21.7 22.9 23.7 26.4

75 -32 -17 11.1 11.2 11.4 11.6 11.9 12.2 13.0

80 -37 -22 5.0 5.0 5.0 5.1 5.1 5.2 5.3

85 -42 -27 2.3 2.3 2.3 2.3 2.3 2.3 2.3

90 -47 -32 1.1 1.2 1.2 1.2 1.2 1.2 1.2

95 -52 -37 < 1 <1 < 1 < 1 < 1 < 1 < 1

Figure 14. Separation distance versus reliability for -6 dB INR. 95 dB attenuation produces 

separation distances less than the 1 km propagation model limit and is not shown.

22
Table 6. Separation distances for all INR at 90% reliability.

Parameter Separation distance, ddmmmm (km)

LLss ssss ΨΨ ΖΖ rrrr INR (dB)

dB dBm/MHz dBm/MHz -6 -9 -12

56 -13 2 35.5 37.7 40.1

60 -17 -2 32.8 34.8 37.0

65 -22 -7 29.6 31.5 33.5

70 -27 -12 22.9 27.6 30.3

75 -32 -17 11.9 18.3 24.6

80 -37 -22 5.1 8.5 14.0

85 -42 -27 2.3 3.7 6.0

90 -47 -32 1.2 1.7 2.7

95 -52 -37 < 1 < 1 1.3

100 -57 -42 < 1 < 1 < 1

5.4.2 Variable SNR

Variable SNR analysis requires knowledge of radar target height, range, and RCS characteristics. 

We used the targets of the ten IEC 62388 standard clutter free test cases because of their 

importance to maritime radar designers. The SNR distributions for the test cases are shown in 

Figure 15. Cases 1–9 and case 10 were analyzed with the long and short pulses, respectively. The 

99% excess power margin, used to compensate for variations in RCS because of target aspect, 

materials, and shape, has been removed by reducing the RCS as discussed in the previous 

background report. With the excess power margin removed the 99% SNR quantile is equal to the 

baseline SNR.

Figure 16 shows the INR for the 10 test cases at these separation distances with spurious 

attenuation set to 60 dB. The separation distance between the radar and the closest base station is 

set to the radar to target range plus a 1 km base station to target distance. 

Table 7 summarizes final results. The least spurious attenuation, 56 dB, was required by the 

furthest target, Case 1. The most spurious attenuation, 85.1 dB, was required by the closest 

target, Case 10. Appendix E shows examples of the raw data from which these results are drawn.

23
Figure 15. SNR distributions for 10 IEC 62388 standard clutter free test cases with power margin 

removed. Only seven curves are visible because cases 2 and 5, 6 and 7, and 8 and 9 have similar

target parameters.

Figure 16. INR distributions for 10 IEC 62388 clutter free test cases with spurious attenuation set 

to 60 dB. The separation distance between the radar and the closest base station is set to the radar 

to target range plus a 1 km base station to target distance. Only seven curves are visible because 

cases 2 and 5, 6 and 7, and 8 and 9 have similar target distances.

24
Table 7. Spurious attenuation for IEC 62388 standard clutter free test cases for 90% reliability.

Case Description

Height 

(m)

Range RCS

(m2)

LLss ssss (dB)

nmi km -6 dB INR -9 dB INR -12 dB INR

1 60 m high shoreline 50.0 20.0 37.0 50000.0 <56 <56 <56

2 6 m high shoreline 5.0 8.0 14.8 5000.0 68.6 69.9 70.9

3 3 m high shoreline 2.5 6.0 11.1 2500.0 72.2 73.7 74.7

4 SOLAS ship > 5000gt 10.0 11.0 20.4 30000.0 63.6 64.7 65.3

5 SOLAS ship > 500gt 5.0 8.0 14.8 1000.0 68.6 69.9 70.9

6 Small boat with reflector 4.0 3.7 6.8 0.5 77.9 70.6 83.6

7 Buoy with reflector 3.5 3.6 6.7 1.0 77.1 79.2 81.1

8 Buoy 3.5 3.0 5.6 0.5 78.4 80.4 83.1

9 Small 10 m long boat 2.0 3.0 5.6 1.4 78.3 80.3 82.9

10 Channel marker 1.0 1.0 1.9 0.1 85.1 87.5 90.1

5.4.3 Comparison of constant SNR to variable SNR results

Here we compare spurious attenuation levels obtained using variable SNR against those obtained 

using constant SNR. The constant SNR results have a short radar to target range regardless of the 

separation distance.

Results of the comparison for -6 dB INR, 90% reliability are shown in Figure 17. Corresponding 

comparisons for -9 and -12 dB INR are provided in Appendix H. Variable SNR cases can be 

identified by their separation distances which are 1 km more than the radar to target distance. 

Case 1 is not shown because the required spurious attenuation is below the minimum tested. 

Cases 8 and 9 at 6.6 km and Cases 2 and 5 at 15.8 km are indistinguishable because they have 

nearly identical spurious attenuation requirements due to similarities in target height and range.

The methods disagree the most at longer radar to target ranges. As an example, Case 4 at 

21.4 km required 7 dB less attenuation with variable SNR than constant SNR. This difference 

increased even more with decreasing INR, as shown in Table 8. From this we can conclude that 

the constant SNR method, where radar to target range is short regardless of separation distance, 

provides an upper bound on the amount of spurious attenuation needed.

25
Figure 17. Comparison of constant and variable SNR results for -6 dB INR and 90% reliability.

Table 8. Spurious attenuation for IEC 62388 standard clutter free test cases using constant SNR 

(C) and variable SNR (V) for 90% reliability. Case 1 difference is not available (NA) because 

the required spurious attenuation is below the minimum tested.

Case Description

Range 

(km)

-6 dB INR -9 dB INR -12 dB INR

LLss ssss (dB) Diff 

(dB)

LLss ssss (dB) Diff 

(dB)

LLss ssss (dB) Diff 

V C V C V C (dB)

1 60 m high 

shoreline

37.0 NA NA NA NA NA NA NA NA NA

2 6 m high 

shoreline

14.8 68.6 73.2 -4.6 69.9 76.3 -6.4 70.9 79.2 -8.3

3 3 m high 

shoreline

11.1 72.2 74.9 -2.7 73.7 78.1 -4.5 74.7 81.2 -6.5

4 SOLAS ship > 

5000gt

20.4 63.6 70.7 -7.1 64.7 73.4 -8.7 65.3 76.5 -11.2

5 SOLAS ship > 

500gt

14.8 68.6 73.2 -4.6 69.9 76.3 -6.4 70.9 79.2 -8.3

6 Small boat with 

reflector

6.8 77.9 78.0 -0.1 80.6 80.8 -0.2 83.6 83.9 -0.3

7 Buoy with 

reflector

6.7 77.1 78.1 -1.0 79.2 80.9 -1.7 81.1 84.0 -2.9

8 Buoy 5.6 78.4 78.9 -0.5 80.4 82.0 -1.6 83.1 84.7 -1.6

9 Small 10 m long 

boat

5.6 78.3 78.9 -0.6 80.3 82.0 -1.7 82.9 84.7 -1.8

10 Channel marker 1.9 85.1 84.0 1.1 87.5 87.1 0.4 90.1 89.7 0.4

26
5.5 Distance and frequency separation with FDR

FDR is calculated from the transmitted PSD and receiver IF filter frequency response. In this 

report we use measured, filtered, and spectrum emission mask (SEM) PSDs. The measured PSD 

was discussed in the previous background report. The filtered PSD, described in Appendix F is 

designed to reduce unwanted emissions in the 2700–2900 MHz radar band. The SEM PSD is 

described in Appendix D.2. Justification for using an ideal short pulse, 20 MHz bandwidth, IF 

filter frequency response which falls off at 80 dB/decade outside the 3 dB bandwidth is provided 

in Appendix G.

Figure 18 shows the measured, filtered, and SEM PSDs used for calculating FDR. The measured 

and filtered PSD powers are adjusted with the assumption of a 26 dBm/100 kHz or 46 dBm/10 

MHz signal power. The SEM is adjusted to a 100 kHz bandwidth.

Figure 19 shows the results of the FDR calculations. Because frequency separation is defined as 

the difference between the transmitted and received center frequencies, the positive separation 

frequencies are due to radar center frequencies below the 2683.5 MHz BRS center frequency and 

the negative separation frequencies are due to radar center frequencies above the 2683.5 MHz

BRS center frequency. Our interest is in the negative separation frequencies, where the filtered 

PSD has the most FDR, followed by the SEM and the measured PSD.

Frequency separation needed to satisfy allowable INR is determined from the constant SNR 

spurious attenuation requirements in Table 6, which we have already established as worst case. 

First, the spurious attenuation is converted to FDR using (30). Then, frequency separation is 

determined from the FDR. As an example, converting the -6 dB INR, 90% reliability, greater 

than 90 dB spurious attenuation requirement at 1 km separation distance from Table 6 yields a 

greater than 77 dB FDR requirement. Figure 19 shows that this FDR corresponds to 92.8 MHz

for the filtered PSD and 99.7 MHz for the SEM.

Frequency separation results for all INR are summarized in Table 9. Those that never obtain the 

FDR required to meet IPC are labeled NA. The SEM requires slightly more frequency separation 

than the filtered PSD at -6 and -9 dB INR. SEM and filtered PSD results do not change 

between -6 and -9 dB INR. The filtered PSD is the only one that meets the IPC at -12 dB INR,

where it shows a slight increase compared to -9 dB INR.

The combined separation distance and frequency separation needed for the allowable IPC can 

also be determined. We do this by converting separation distance versus reliability curves for 

various spurious attenuations to various FDR. We can then plot any combination of separation 

distance and frequency separation that meets a specified reliability. Results of this analysis using 

the -6 dB INR case in Figure 14 are shown in Figure 20. The results show that frequency 

separation can be reduced from 92.8 MHz to 54.6 MHz when the separation distance is increased 

from 1.2 km to 32.8 km.

27
Figure 18. Measured PSD, filtered measured PSD, and SEM.

Figure 19. FDR for ideal short pulse, 20 MHz bandwidth, IF filter.

28
Table 9. Spurious attenuation, Lspur, FDR, Lfdr, and frequency separation, ∆ff, needed for 90% 

reliability for 20 MHz bandwidth short pulse at 1 km distance separation.

INR (dB) LLss ssss (dB) LL (dB)

∆ (MHz)

Unfiltered Filtered SEM

-6 >90 >77 NA >92.8 99.7

-9 >90 >77 NA >92.8 99.7

-12 >95 >82 NA >99.3 NA

Figure 20. Separation distance versus frequency separation for 50 and 90% reliability with short 

pulse 20 MHz radar detection IF bandwidth when INR is -6 dB.

29
6 CONCLUSION

This report analyzes the effect of unwanted emissions from a broadband radio service (BRS) 

base station on magnetron radar receiver performance. This report builds upon the interference 

model developed in the previous background report [15] where we demonstrated that unwanted 

emissions were Gaussian distributed and aggregated. Results include distance separation and 

frequency separation that meet interference protection criteria (IPC). Baseline radar system 

performance was set at a 0.8 probability of detection and 10-4 probability of false alarm. 

Interference to noise ratios (INR) of -6, -9, and -12 dB were investigated.

Distance separation was computed from expressions for radar link reliability. Reliability in this 

context is dependent solely on radio wave propagation path loss variability. So that anomalous 

radio wave propagation ducting conditions do not influence results, 90% reliability is used. Two 

expressions for reliability were provided. One expression assumed constant radar signal to noise 

ratio (SNR) corresponding to short radar to target ranges. This method does not require knowing 

the radar to target link budget.

The other expression assumed variable SNR which is valid over any radar to target range. This 

method requires complete knowledge of the radar to target link budget. We used targets from the 

IEC 62388 standard clutter free test cases to set radar to target link budget parameters. Base 

station to radar path length was set to the radar to target range plus 1 km.

The constant SNR case is important because it can be easily applied to the most demanding case 

where the ship with the radar is close to the target and the base station. The expression for 

variable SNR is the most general and useful for situations where close radar to base station 

distances are not likely.

Distance separation calculations for constant SNR showed that 90 dB spurious attenuation could 

provide 90% reliability at a separation distance of 1.2 km when INR is -6 dB. The separation

distance decreased below 1 km with 95 dB spurious attenuation. For reference, the ETSI -52 

dBm/MHz unwanted emissions limit outside the BRS operating band corresponds to 95 dB 

spurious attenuation.

Results for variable SNR agreed with those using constant SNR at short radar to target range. 

However, as radar to target range increased, less spurious attenuation was needed. The largest 

difference was with case 4, a SOLAS ship 21.4 km away from the radar, where 7.1 dB less 

spurious attenuation was needed when INR is -6 dB. Consequently the constant SNR reliability 

expression can be considered worst case.

We also showed how frequency separation could be computed by replacing spurious attenuation 

by an expression for FDR. The FDR were calculated from measured PSD, filtered PSD, 

spectrum emission mask, and idealized IF filter frequency responses that corresponded with 

measured filter frequency responses. SNR was assumed to be constant so results are worst case. 

The results showed that 90 % reliability IPC could be met at 1.2 km separation distance with 

92.8 MHz and 99.7 MHz for the filtered PSD and SEM when INR is -6 dB. We found that 

filtered PSD frequency separation can be reduced from 92.8 MHz to 54.6 MHz when the 

distance separation is increased to 32.8 km.

30
Results for the -9 dB and -12 dB INR cases differed in most cases. For example, the separation 

distance for the constant SNR case increased to 1.7 and 2.7 km with 90 dB spurious attenuation 

for INR of -9 and -12 dB, respectively. For variable SNR, case 4 required 8.7 and 11.2 dB less 

spurious attenuation than constant SNR for INR of -9 and -12 dB, respectively. Frequency 

separation did not increase when the INR was decreased to -9. However it did increase to 99.3

MHz when INR was decreased to -12 dB.

The results in this report are encumbered with two caveats. First, the results are for a frequency 

division duplexing (FDD) BRS base station signal that occupies one 10 MHz BRS channel. 

Results need to be adjusted to accommodate more channels. Second, these results are based on 

magnetron radar signal processing. Additional analysis is needed to assess the impact to solidstate radar receivers because their signal processing is very different from that in the magnetron 

radar receiver. The signal processing affects receiver sensitivity and IF selectivity and estimates 

of separation distance and frequency separation need to take this into account.

31
7 ACKNOWLEDGEMENTS

This work was sponsored by the U.S. Coast Guard Spectrum Management Telecommunications 

Policy Division, U.S. Coast Guard CG-652, 2100 2nd St. SW Stop 7101, Washington DC 20593-

7101. The authors would like to acknowledge Fred Mistichelli (former Division Chief), Joseph 

Hersey (former Division Chief), and Daniel Freedman (former Spectrum Engineer) for their 

sponsorship.

The authors would also like to acknowledge David Turnage, Research and Development 

Manager, Kelvin Hughes Ltd.; Lawrence Cohen, Electronics Engineer, U.S. Naval Research 

Laboratory; Jon Higham, Program Coordinator, United Kingdom Office of Communication

(OFCOM); David G. Money, consultant to the OFCOM; and Richard Rees, Spectrum Policy and 

Technical Standards Manager, United Kingdom Maritime and Coastal Agency for sharing their 

insights into this issue.

Finally, the authors would also like to acknowledge Al Romero, Visual Information Specialist, of

the National Oceanic and Atmospheric Administration (NOAA) for creating the illustrative 

figures.

32
8 REFERENCES

[1] International Telecommunication Union, “Procedures for determining the potential for 

interference between radars operating in the radiodetermination service and systems in 

other services,” Recommendation ITU-R M.1461-1, July 2003.

[2] International Telecommunication Union, “Tests illustrating the compatibility between 

maritime radionavigation radars and emissions from radiolocation radars in the band 2900–

3100 MHz,” Report ITU-R M.2032, 2003.

[3] F. Sanders et. al., “Effects of RF interference on radar receivers,” NTIA Report TR-06-444, 

September 2006, http://www.its.bldrdoc.gov/publications/2481.aspx.

[4] J.E. Carroll, G.A. Sanders, F.H. Sanders, and R.L. Sole, “Case study: Investigation of 

interference into 5 GHz weather radars from unlicensed national information infrastructure 

devices, Part I,” NTIA Technical Report TR-11-473, November 2010, 

http://www.its.bldrdoc.gov/publications/2548.aspx.

[5] A. Paul et. al., “Interference protection criteria,” NTIA Report 05-432, October 2005, 

http://www.its.bldrdoc.gov/publications/2462.aspx.

[6] International Telecommunication Union, “Studies on frequency-related matters on 

International Mobile Telecommunications and other terrestrial mobile broadband 

applications”, Resolution 233 (WRC-12),The World Radiocommunication Conference 

(Geneva, 2012)

[7] International Electrotechnical Commission, “Maritime navigation and radiocommunication 

equipment and systems – Shipborne radar – Performance requirements, methods of testing 

and required test results,” IEC 62388, Edition 1.0, 2007-12.

[8] International Maritime Organization, “Adoption of the revised performance standards for 

radar equipment,” Annex 34, Resolution MSC.192(79), December 6, 2004.

[9] Institute for Electrical and Electronic Engineer, “IEEE recommended practice for the 

analysis of in-band and adjacent band interference and coexistence between radio systems,” 

IEEE Std 1900.2-2008, July 29, 2008.

[10] United Kingdom of Great Britain and Northern Ireland, “Radar adjacent band selectivity,” 

Recommendation ITU-R 5b/389-E, November 18, 2009.

[11] U.S. Department of Commerce, National Telecommunications and Information 

Administration, “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,” October 2010, http://www.ntia.doc.gov/files/ntia/

publications/fasttrackevaluation_11152010.pdf.

[12] European Telecommunications Standards Institute, “Technical Specification, Digital 

cellular telecommunications system (Phase 2+); Universal Mobile Telecommunications 

33
System (UMTS); LTE; E-UTRA,UTRA, and GSM/Edge; Multi-Standard Radio (MSR) 

Base Station (BS) radio transmission and reception,” ETSI TS 137 104 version 11.2.1 

Release 11, October 2012.

[13] International Telecommunication Union Joint Task Group 4-5-6-7, Appendix 1 

“Characteristics of terrestrial IMT-Advanced systems for frequency sharing/interference 

analyses” in Attachment 1, “Protection criteria, system characteristics, related materials on 

modelling considerations and sharing studies already performed or underway in ITU-R 

related to the terrestrial services” in Annex 2 “Compilation of material maintained by the 

Joint Task Group 4-5-6-7 working groups” of Report on the Fourth meeting of the Joint 

Task Group 4-5-6-7, Document 4-5-6-7/393-E, October 30, 2013.

[14] WiMAX Forum, “Mobile WiMAX – Part 1: A Technical Overview and Performance 

Evaluation,” WiMAX Forum white paper, August 2006.

[15] R. Achatz, P. McKenna, R. Dalke, N. DeMinco, F. Sanders, and J. Carroll, “Effect of 

broadband radio service reallocation on 2900–3100 MHz band marine radars: 

Background,” NTIA Report TR-15-513, April 2015. http://www.its.bldrdoc.gov/

publications/2795.aspx

[16] International Telecommunication Union, “Unwanted emissions in the spurious domain,” 

Recommendation ITU-R SM.329-10, February 2003.

[17] A. Piotrowski, “In band interference to radar for Swerling targets,” in Proc. of the 2008 

IEEE International Conference on Radar, September 2008, pp. 379–385.

34
APPENDIX A: UNWANTED SIGNAL POWER

A.1 Basic Frequency Dependent Interference Model

A basic frequency dependent interference model is shown in Figure A-1. The transmitter is on 

the left beginning with the transmitter source (TX) and ending with an antenna (TX ANT). The 

transmitter source and filter are separated by transmission loss. Unwanted emissions can be 

mitigated with the transmitter filter (TX filter). The receiver in another system begins with an 

antenna (RX ANT) and ends with a receiver filter (RX Filter). The receiver antenna and filter are 

separated by receiver loss. The transmitter and receiver antennas are assumed to be pointed 

directly at each other. The transmitter and receiver antennas are separated by path and 

polarization loss.

Figure A-1. Basic interference model. TX represents the transmitter source, TX Filter represents 

the transmitter filter, ANT represents the antenna, and RX filter represents the receiver filter.

The parameters in the Figure are defined as

• tt (ff) source power spectral density

• llcc transmitter circuit loss

• htt(ff) transmitter filter transfer function

• tt (ff) transmitted power spectral density

• ggtt transmitter antenna gain 

• ll ( ) propagation path loss and is path distance

• ll pp polarization loss

• gg receiver antenna gain

• llcc receiver circuit loss

• h (ff) receiver filter transfer function

• (ff) received power spectral density

The frequency dependent parameters are expressed as low-pass complex-baseband signals 

centered at 0 Hz.

35
A.2 Transmitted Unwanted Signal Power

The ITU divides the transmitted signal power spectral density (PSD) into necessary bandwidth, 

out-of-band (OOB), and spurious domains [A-1] [A-2]. Power in the OOB and spurious domains 

are collectively referred to as unwanted. Figure A-2 shows a PSD with ITU domains.

The OOB domain lies between the necessary bandwidth and spurious domains. In general, the 

out-of-band domain extends from the edge of the necessary bandwidth to 250% of the necessary 

bandwidth from the center frequency. Mathematically the necessary bandwidth domain is

|∆ff| < 0.5bbnn (A-1)

the OOB domain is 

0.5bbnn ≤ |∆ff| ≤ 2.5bbnn (A-2)

and the spurious domain is 

|∆ff| > 2.5bbnn (A-3)

where the difference between the transmit frequency, fftt, and any other frequency is defined as

∆ff = fftt − ff.

Figure A-2. Hypothetical PSD with ITU domains.

The necessary bandwidth domain contains most of the modulated signal power. Power in the 

spurious domain is due to effects incidental to transmission such as amplification, frequency 

conversion, and parasitic resonance. Power in the OOB domain is a mixture of modulated and 

incidental signals.

36
The ITU limits unwanted power with a spectrum emission mask (SEM). The mask is referenced

by the total transmitted power or the maximum spectral density in the necessary bandwidth. In 

decibel units these are dBc and dBsd, respectively. The mask referenced by total transmitted 

power is

ll (∆ff)(cc) = tt

ψ (∆ff) = tt

∫ tt (ff)�h rr (ff + ∆ff)�

2 ∞

−∞

(A-4)

where ∆ff is the difference between the transmit frequency, fftt, and the measurement frequency, 

ff , tt is the total power at the antenna terminal, tt (ff) is the power spectral density at the 

antenna terminal, and ψ is the unwanted power measured with a reference filter whose 

baseband impulse response is h rr (ff).

Spurious attenuation is a special case of this mask. It is defined as the total power divided by the 

unwanted power measured with the reference filter centered at any frequency in the spurious 

domain

llssssssss = tt

ψ rr

(A-5)

The mask referenced by spectral density is 

ll (∆ff)(ss ) = ψψnn

ψψ (∆ff) = ∫ tt (ff)�h rr (ff)�

2 ∞

−∞

∫ tt (ff)�h rr (ff + ∆ff)�

2 ∞

−∞

(A-6)

where ψψnn is the maximum power in the necessary bandwidth measured with the same reference 

filter as was used for the unwanted emissions.

The reference filter bandwidth is not necessarily the same in the OOB and spurious domains.

Smaller bandwidths are necessary to accurately measure steep OOB attenuation. The OOB 

reference filter bandwidth is suggested to be on the order of 1% of the necessary bandwidth. The 

spurious reference filter bandwidth is dependent on carrier frequency. A 10 MHz bandwidth 

signal at 3000 MHz would use 100 kHz and 1 MHz for OOB and spurious measurement 

bandwidths, respectively.

The unwanted emission power can also be expressed in terms of effective isotropic radiated 

power (EIRP) in units of watts in the reference bandwidth

ζζ(∆ff) = ggttψ (∆ff) (A-7)

or in dB

Ζ (∆ff)(dB) = GGtt + Ψ (∆ff) (A-8)

where Ζ = 10 log10 ζζ, GGtt = 10 log10 ggtt, and Ψ = 10 log10 ψ .

37
A.3 Received Unwanted Signal Power

The received power is

= � (ff)

∞

−∞

. (A-9)

Assuming antenna gains and propagation path loss are constant over the bandwidth of interest 

this expands to

( , ∆ff) = ggttgg

llcc ll pp ll ( )

� tt (ff)|htt(ff)|

2|h (ff + ∆ff)|2

llcc

∞

−∞

. (A-10)

Since

tt (ff) = tt (ff)|htt(ff)|

2

llcc

(A-11)

then

( , ∆ff) = ggttgg

llcc ll pp ll ( )

� tt (ff)|h (ff + ∆ff)|

2

∞

−∞

(A-12)

Defining frequency dependent rejection (FDR) [A-3] as the total power divided by the power 

after receiver filtering

llff (∆ff) = tt

∫ tt (ff)|h (ff + ∆ff)|2 ∞

−∞

(A-13)

where

tt = � tt (ff)

∞

−∞

(A-14)

then 

( , ∆ff) = tt ggttgg

llcc ll pp ll ( )llff (∆ff) (A-15)

In decibels the corresponding equation is

PP (∆ff) ( dd) = PPtt + GGtt + GG − LLcc − LL pp − LL ( ) − LLff (∆ff) (A-16)

38
A.4 Received Unwanted Signal Power in Terms of the Transmitted Unwanted Signal 

Power

The received power can also be written in terms of transmitted unwanted signal power. Dividing 

(A-13) by (A-4) and rearranging terms we find

llff (∆ff) = ll (∆ff)

∫ tt (ff)�h rr (ff + ∆ff)�

2 ∞

−∞

∫ tt (ff)|h (ff + ∆ff)|2 ∞

−∞

(A-17)

which can then be substituted in (A-16).

Furthermore if we assume ∆ff is in the spurious region and tt (ff) is constant across reference 

and radar filter bandwidths then

llff (∆ff) = llssssssss

bb rr

bb (A-18)

where bb rr and bb are the noise equivalent bandwidths defined as

bb rr = � �h rr (ff)�

2 ∞

−∞

(A-19)

bb = � |h (ff)|

2

∞

−∞

(A-20)

or in dB 

LLff (∆ff) = LLssssssss + rr − (A-21)

where LLff = 10 log10 llff , LLssssssss = 10 log10 llssssssss, rr = 10 log10 bb rr , and = 10 log10 bb .

Hence, the received power in the spurious region can be written in terms of spurious attenuation 

by

= tt ggttgg bb

llcc ll pp ll ( )llssssssssbb rr

(A-22)

or in dB

PP ( dd) = PPtt + GGtt + GG − LLcc − LL pp − LL ( ) − LLssssssss − rr + (A-23)

A.5 References

[A-1] International Telecommunication Union, “Unwanted emissions in the out-of-band 

domain,” Recommendation ITU-R SM.1541-4, September 2011.

39
[A-2] International Telecommunication Union, “Unwanted emissions in the spurious domain,” 

Recommendation ITU-R SM.329-10, February 2003.

[A-3] International Telecommunication Union, “Frequency and distance separations,” 

Recommendation ITU-R SM.337-6, 2008.

40
APPENDIX B: FAST METHOD FOR COMPUTING SEGMENTED, LOGNORMALDISTRIBUTION INTEGRAL

Interfering power from a cellular network is the sum of the powers or aggregate power of a set of 

base stations. If the power from each base station is log-normally distributed it can be 

demonstrated that the aggregate power of a moderate number of base stations is also lognormally distributed, especially in the range of 1 to 99 percent [B-1]. This is a pleasing result as 

it allows the use of the standard normal function or some variation of it such as the Q function to 

efficiently determine probabilities as follows. Let

II = μμ + YY = μμ + σσ (B-1)

where II is the aggregate quantile in dBW, μμ is the mean or median in dBW, YY is the deviation, σσ

is the standard deviation in dBW, and zz is the standard normal deviate

zz = II − μμ

σσ

(B-2)

Then the probability density for II is 

ff(II) = 1

√2ππσσ

eeee �

−(II − μμ)2

2σσ2 � (B-3)

The cumulative distribution function is

FF(II) = PPPP{I < II} = 1

√2ππσσ

� eeee �

−(XX − μμ)2

2σσ2 �

II

−∞

(B-4)

and the complementary cumulative distribution function is

1 − FF(II) = PPPP{I ≥ II} = 1

√2ππσσ

� eeee �

−(XX − μμ)2

2σσ2 �

∞

II

(B-5)

Written in terms of zz we have 

PPPP{ZZ < zz} = qq = 1 − QQ(zz) (B-6)

and 

PPPP{ZZ ≥ zz} = 1 − qq = QQ(zz) (B-7)

where

QQ(zz) = 1

√2ππ

� ee−tt2

2� ∞

zz

(B-8)

41
However, if the power from each base station is not log-normal, as is the case for the maritime 

propagation channel, the aggregate power may not be log-normal and we must look for another 

method to efficiently determine probabilities.

Inspired by the method used by ITM to model the propagation loss distribution with fading, 

enhancement, and ducting regions using 3 log-normal segments we divide the aggregate power 

distribution acquired through Monte Carlo analysis into 2K log-normal segments. The segments 

and their parameters are designated by the subscript . Parameters associated with the median 

are designated by the subscript mm .

In the case of the -th linear segment with probabilities qqkk−1 < qq < qqkk the aggregate power is 

II = μμkk + σσkkzz (B-9)

The segment standard deviations are

σσkk = IIkk − II

zzkk − zz = IIkk − IIzzkk

(B-10)

The segment means for the fading side of the distribution are computed from K to 2 with the 

approximation μμKK+1 = μμ

μμkk = μμkk+1 + zzkk(σσkk − σσkk−1). (B-11)

The segment means for the enhancement side of the distribution are computed from K+3 to 

2K+1 with the approximation μμKK+2 = μμ

μμkk = μμkk−1 + zzkk−2(σσkk−2 − σσkk−1). (B-12)

The resulting mean vector indices are then decremented by one, yielding the vector

μμkk, ∈ {1,2, ⋯ 2KK}. (B-13)

We can now characterize the aggregate distribution function with σσkk and μμkk calculated at 

specific probabilities, qqkk, and the corresponding standard normal deviates, zzkk. Through trial and 

error, we found satisfactory agreement with K = 13. The 2K = 26 segments are delineated in 

Table B-1.

Table B-1. Probability, qqkk, and corresponding standard normal deviate, zzkk, for the each of the 26 

segments in the aggregate distribution function.

k qqkk zzkk k qqkk zzkk

1 0.001 -3.090 14 0.60 0.253

2 0.002 -2.878 15 0.70 0.524

3 0.005 -2.576 16 0.80 0.841

4 0.01 -2.327 17 0.85 1.036

5 0.02 -2.054 18 0.90 1.282

42
k qqkk zzkk k qqkk zzkk

6 0.04 -1.751 19 0.93 1.476

7 0.05 -1.645 20 0.95 1.645

8 0.07 -1.476 21 0.96 1.751

9 0.1 -1.282 22 0.98 2.054

10 0.15 -1.036 23 0.99 2.327

11 0.20 -0.841 24 0.995 2.576

12 0.30 -0.524 25 0.998 2.878

13 0.40 -0.253 26 0.999 3.090

B.1 References

[B-1] S. C. Schwartz and Y. S. Yeh, “On the Distribution Function and Moments of Power 

Sums With Log-Normal Components,” Bell System Technical Journal, Vol. 61, #7, pp. 

1441-1462, Sept. 1982.

43
APPENDIX C: RISE IN NOISE POWER

In this section we calculate the rise in noise power relative to receiver noise power when an 

interferer with Gaussian noise characteristics is received. 

Let the rise in noise power relative to receiver noise power be

y = + nn

nn = nn� + 1 (C-1)

where is the interfering signal power and n is the receiver noise power.

Let uu = nn� and UU = 10 log10 uu then

y = 10UU

10 � + 1 (C-2)

so that the rise in dB is

Y = log10 �10UU

10 � + 1� ( dd) (C-3)

Results are plotted below. INR of -6, -9, and -12 corresponds to an approximate 1, 0.5, and 0.25 

dB rise in power.

Figure C-1. Rise in noise power relative to receiver noise power for interfering signal with 

Gaussian noise characteristics.

44
APPENDIX D: EMISSION LIMITS

D.1 ITU-R Spurious Emission Limit

The following analysis calculates the BRS maximum spurious emission attenuation and spurious 

effective isotropic radiated power (EIRP) according to ITU-R guidelines which are summarized 

in [D-1]. Related documents are [D-2] and [D-3].

Spurious emissions are defined by the ITU-R as “emissions in the spurious domain which 

consists of frequencies separated from the center frequency of the emission by 250% or more of 

the necessary bandwidth”.

General spurious emission limits are specified as attenuation below the power supplied to the 

antenna transmission line in Category A tables. More restrictive emission limits for the United 

States are specified in Category C tables. If the service is not addressed in Category C, limits in 

Category A are used. 

Spurious emission attenuation is

llssssssss = tt

ψ rr (D-1)

where tt is the total transmitted power and ψ rr is the spurious power at the transmitter antenna 

input measured in the ITU reference equivalent noise bandwidth, bb rr . In dB we have

LLssssssss( dd) = PPtt − Ψ rr (D-2)

where LLssssssss = 10 log10 llssssssss, PPtt = 10 log10 tt ,Ψ rr = 10 log10 ψ rr .

Spurious EIRP is 

ζ rr = ψ rr gg (D-3)

where gg is the transmitting antenna gain. In dB we have

Ζ rr ( dd) = Ψ rr + GG (D-4)

where Ζ rr = 10 log10 ζ rr and GG = 10 log10 gg.

Combining the two expressions we have

Ζ rr ( dd) = PPtt − LLssssssss + GG (D-5)

Category C does not address the limit for the BRS service. Consequently the limit in Category A 

is used, i.e., 

45
LLssssssss( dd) = 43 + PPtt (D-6)

where PPtt is in dBW or 70 dBc, whichever is less stringent. In this case, the former is less 

stringent. The bb rr is 1 MHz for frequencies greater than 1 GHz.

Table D-1. ITU-R Spurious emission power limit for BRS base station.

Parameter Value Calculation

PPtt 20 watts for 10 MHz bandwidth signal 43 dBm

LLssssssss 56 dB -56

Ψ rr -13 dBm/1 MHz

GG 15 dB +15

ΖΖ rrrr +2 dBm/1 MHz

D.2 ETSI Spectrum Emission Mask

Table D-2 shows the ETSI SEM limits [D-4] for the BRS emissions in the operating band. The 

operating band is the spectrum 10 MHz above and below the allocated spectrum lower and upper 

edges, respectively. The SEM is defined terms of ∆ff and f_offset. These are defined as:

• f_offset is the separation between the allocated spectrum edge and the measurement filter 

center frequency

• f_offsetmax is the separation between the allocated spectrum edge and the operating band edge

• ∆ff is separation between the allocated spectrum edge and the closest measurement filter -3 

dB point

• ∆ff is f_offsetmax minus one-half the measurement filter 3 dB bandwidth

Figure D-1 displays these limits in a 30 kHz bandwidth for the 2500–2700 MHz allocated 

spectrum along with the -52 dBm/MHz (or -67.2 dBm/30 kHz) limit outside the allocated 

spectrum [D-5]. The limits assume a 10 MHz bandwidth signal next to the band edge with 20 W 

transmission power.

Table D-2 Spectrum emission mask breakpoints.

∆ (MHz) f_offset (MHz) SEM SEM units

0 ≤ ∆ff < 0.200 0.15 ≤ f_offset < 0.215 -14 dBm/30 kHz

0.200≤ ∆ff < 1.0 0.215≤f_offset < 1.015 -14 -15(∆ff − 0.200) dBm/30 kHz

Not needed 1.015≤f_offset < 1.5 -26 dBm/30 kHz

1≤ ∆ff ≤ Min(∆ff ,10) 1.5≤ f_offset < Min(f_offsetmax,10.5) -13 dBm/1 MHz

10≤ ∆ff ≤ ∆ff 10.5≤f_offset < f_offsetmax -15 dBm/1 MHz

46
Figure D-1. 3GPP spectrum emission mask in 30.0 kHz bandwidth.

D.3 References 

[D-1] International Telecommunication Union, “Unwanted emissions in the spurious domain,” 

Recommendation ITU-R SM.329-10, February 2003.

[D-2] International Telecommunication Union, “Generic unwanted emission characteristics of 

base stations using the terrestrial radio interfaces of IMT-2000,” Recommendation ITU-R 

M.1580-3, October 2009.

[D-3] International Telecommunication Union, “Generic unwanted emission characteristics of 

mobile stations using the terrestrial radio interfaces of IMT-2000,” Recommendation 

ITU-R M.1581-3, October 2009.

[D-4] European Telecommunications Standards Institute 3rd Generation Partnership Project, 

ETSI TS 137 104 V11.2.1 (2012-10), “Digital Cellular Telecommunications System 

(Phase 2+); Universal Mobile Telecommunications System (UMTS); LTE; E-UTRA, 

UTRA, and GSM/EDGE; Multistandard Radio Base Station (BS) radio transmission and 

reception (3GPP TS 37.104 version 11.2.1 Release 11),” Table 6.6.2.1-1, p. 37.

[D-5] European Telecommunications Standards Institute 3rd Generation Partnership Project, 

ETSI TS 137 104 V11.2.1 (2012-10), “Digital Cellular Telecommunications System 

(Phase 2+); Universal Mobile Telecommunications System (UMTS); LTE; E-UTRA, 

UTRA, and GSM/EDGE; Multistandard Radio Base Station (BS) radio transmission and 

reception (3GPP TS 37.104 version 11.2.1 Release 11),” Table 6.6.1.3.1-1, pp. 30-33.

47
APPENDIX E: VARIABLE SNR DATA EXAMPLES

This Appendix shows raw variable SNR reliability data for two IEC 62388 standard cases. Case 

1 is a 60 m high shoreline 37 km away. Case 6 is a small boat with a reflector 6.8 km away. Case 

1 signal and interference powers have a considerable amount of variability. Case 6 signal and 

interference powers are relatively constant.

Reliability is a function of radar to target range and separation distance. Figures E-1 and E-2

show reliability over a range of separation distances when radar to target range is fixed. Figures

E-3 and E-4 show reliability over radar to target ranges when the separation distance is fixed. All 

calculations are done with an INR of -6 dB and an RCS that has been reduced by the 99% power 

margin.

Figure E-1 shows that Case 1 needs less than 56 dB spurious attenuation at 90% reliability when 

the separation distance is 38 km and the radar to target range is 37 km. This corresponds with 

Figure E-3 which shows reliability close to 1 when spurious attenuation is 56 dB or more at these 

same distances. Figure E-2 shows that Case 6 needs 77.9 dB spurious attenuation at 90% 

reliability when the separation distance is 7.8 km and the radar to target range is 6.8 km. This 

corresponds to Figure E-4 which shows that 90% reliability can be obtained with spurious 

attenuations greater than 75 dB at these same distances.

Figure E-1. Case 1 reliability as a function of separation distance. The thick vertical black line at 

38.0 km is the separation distance used in our analysis. Reliabilities for spurious attenuations 

above 85 dB are approximately 1.0 for all separation distances.

48
Figure E-2. Case 6 reliability as a function of separation distance. The thick vertical black line at 

7.8 km is the separation distance used in our analysis. Reliabilities for spurious attenuations 

above 90 dB are approximately 1.0 for all separation distances.

Figure E-3. Case 1 reliability as a function of radar to target range. The thick vertical black line 

at 37.0 km is the radar to target range used in our analysis. All spurious attenuation curves lie on 

top of each other.

49
Figure E-4. Case 6 reliability as a function of radar to target range. The thick vertical black line 

at 6.8 km is the radar to target range used in our analysis. Spurious attenuation curves from 80 to 

105 lie on top of each other. Reliability anomalies from 1 to 2 km are due to numerical 

integration error.

50
APPENDIX F: WIMAX MEASURED PSD AND FILTERED PSD

F.1 PSD Measurement 

The PSD of a BRS WiMAX BS operating in the 2500–2700 MHz band was measured in a 

laboratory with a spectrum analyzer as described in the previous background report [F-1]. Figure 

F-1 shows the results of this measurement in terms of power at the measurement system input. 

The measurement was performed with a 1 MHz frequency step and 100 kHz resolution 

bandwidth. The center frequency and bandwidth are estimated to be 2683.5 MHz and 9.3 MHz, 

respectively. The measurement system noise figure was 15.2 dB. A horizontal line has also been 

added at -108.8 dBm to demark the measurement system noise floor.

The signal is occupying a 10 MHz BRS channel adjacent to the lower edge of the 2700–2900 

radar band and has unwanted emissions above and below the BRS channel. The unwanted 

emissions below the BRS channel fall to approximately -90 dBm by 2640 MHz then level off 

until 2450 MHz where they reach the measurement system noise floor. Unwanted emissions 

above the BRS channel fall to the noise floor by 2760 MHz.

Figure F-1. PSD measurement

F.2 Filtered PSD Measurement

The filtered PSD was created by filtering the measured PSD. The filter was designed to be 

attached at the BRS base station antenna input and attenuate unwanted emissions in adjacent 

bands. Filter specifications are provided in Table F-1. Filtering was done analytically in the 

51
frequency domain. Figure F-2 shows the measured filter frequency response. Figure F-3 shows 

the measured PSD before and after filtering.

Table F-1. Transmitter filter specifications.

Specification Value Note

Manufacturer K&L Microwave Inc. Salisbury, MD USA

Part Number WSF-00543

Passband 2500-2692 MHz

Insertion Loss 1.50 dB max

Return Loss 18.0 dB min

Amplitude Flatness +/- 0.75 dB max

Stop Bands 0-2375 and 2704-4000 MHz

Rejection 55 dB min

Figure F-2. Transmitter filter frequency response.

52
Figure F-3. Measured and filtered PSDs.

F.3 References

[F-1] R. Achatz, P. McKenna, R. Dalke, N. DeMinco, F. Sanders, and J. Carroll, “Effect of 

broadband radio service reallocation on 2900–3100 MHz band marine radars: 

Background,” NTIA Report TR-15-513, April 2015. http://www.its.bldrdoc.gov/

publications/2795.aspx

53
APPENDIX G: RADAR IF FILTER FREQUENCY RESPONSES

Radar IF filter frequency response measurements of two magnetron 2900–3100 MHz band 

maritime radars, identified as Radar A and Radar C, are described in this Appendix. The filters 

were measured to characterize radars during interference tests [G-1]. Each radar had two IF 

filters corresponding to short and long pulse widths.

The measurement configuration consisted of a signal generator that provided a continuous wave 

test signal, the radar, and a spectrum analyzer that measured the response to the test signal. The 

signal was injected into the radar front-end input rather than the IF input. This restricted the 

measurement dynamic range to approximately 60 dB. The spectrum analyzer was attached to 

receiver IF filter output. Radar A measurement consisted of 600 points measured with a 150 kHz 

spacing, 100 kHz bandwidth, and 0.3 s dwell time. Radar C measurement consisted of 1000 

points measured with a 164 kHz spacing, 100 kHz bandwidth, and 0.0492 s dwell time.

Figures G-1 and G-2 show the results of these measurements along with the frequency responses 

of ideal filters that roll off at a rate of 80 dB/decade below the -3 dB points [G-2]. While the 

ideal filter frequency response does not match that of the long pulse, it does match that of the 

short pulse in all but the higher frequencies of Radar C, which falls off at approximately 

40 dB/decade. Since 80 dB/decade is achievable in most circumstances, we conclude that the 

frequency response of the short pulse filter can be reasonably replaced by an ideal filter that falls 

off at a rate of 80 dB/decade.

Figure G-1. Radar A measured and ideal, long and short pulse IF filter frequency responses.

54
Figure G-2. Radar C measured and ideal, long and short pulse IF filter frequency responses.

G.1 References

[G-1] F. Sanders et. al., “Effects of RF interference on radar receivers,” NTIA Report TR-06-

444, September 2006, http://www.its.bldrdoc.gov/publications/2481.aspx.

[G-2] International Telecommunication Union, “Procedures for determining the potential for 

interference between radars operating in the radio determination service and systems in 

other services,” ITU-R Recommendation M.1461-1, June 2003, p. 9.

55
APPENDIX H: RESULTS FOR OTHER INR

H.1 Results for -9 dB INR

Table H-1. Separation distance results for -9.0 dB allowable INR and 2.7% allowable

degradation.

Parameter Separation distance, ddmmmm (km)

LLss ssss ΨΨss ssss ΖΖ ii ITM 

50%

ITM 

60%

ITM 

70%

ITM 

80%

ITM 

90%

ITM 

95%

ITM 

dB dBm/MHz dBm/MHz 99%

56 -13 2 35.4 35.7 36.2 36.7 37.7 38.8 42.2

60 -17 -2 33.0 33.3 33.6 34.0 34.8 35.7 37.9

65 -22 -7 30.0 30.3 30.6 30.9 31.5 32.2 33.9

70 -27 -12 25.4 25.9 26.2 26.7 27.6 28.9 30.2

75 -32 -17 16.6 16.9 17.2 17.6 18.3 19.1 20.9

80 -37 -22 8.1 8.2 8.3 8.4 8.5 8.7 9.0

85 -42 -27 3.6 3.6 3.6 3.7 3.7 3.7 3.7

90 -47 -32 1.7 1.7 1.7 1.7 1.7 1.7 1.7

95 -52 -37 < 1 <1 < 1 < 1 < 1 < 1 < 1

Figure H-1. Separation distance versus reliability for -9 dB INR. 95 dB attenuation produces 

separation distances less than the 1 km propagation model limit and is not shown.

56
Figure H-2. Spurious attenuation for IEC 62388 standard clutter free test cases with -9 dB INR 

using constant and variable SNR for 90% reliability.

Figure H-3. Separation distance versus frequency separation for 50 and 90% reliability -9 dB 

INR with 20 MHz radar detection IF bandwidth.

57
H.2 Results for -12 dB INR

Table H-2. Separation distance results for -12.0 dB allowable INR and 1.4% allowable

degradation.

Parameter Separation distance, ddmmmm (km)

LLss ssss ΨΨss ssss ΖΖ ii ITM 

50%

ITM 

60%

ITM 

70%

ITM 

80%

ITM 

90%

ITM 

95%

ITM 

dB dBm/MHz dBm/MHz 99%

56 -13 2 37.3 37.7 38.2 38.8 40.1 41.7 46.0

60 -17 -2 34.8 35.1 35.5 36.0 37.0 38.0 41.0

65 -22 -7 31.8 32.0 32.4 32.8 33.5 34.3 36.2

70 -27 -12 28.8 29.1 29.4 29.7 30.3 30.9 32.4

75 -32 -17 22.2 22.2 23.1 23.6 24.6 26.0 28.3

80 -37 -22 12.8 13.0 13.2 13.5 14.0 14.4 15.5

85 -42 -27 5.9 5.9 5.9 6.0 6.0 6.1 6.3

90 -47 -32 2.7 2.7 2.7 2.7 2.7 2.7 2.7

95 -52 -37 1.3 1.3 1.3 1.3 1.3 1.3 1.3

100 -57 -42 < 1 <1 < 1 < 1 < 1 < 1 < 1

Figure H-4. Separation distance versus reliability for -12 dB INR.

58
Figure H-5. Spurious attenuation for IEC 62388 standard clutter free test cases with -12 dB INR 

using constant and variable SNR for 90% reliability.

Figure H-6. Separation distance versus frequency separation for 50 and 90% reliability -12 dB 

INR with 20 MHz radar detection IF bandwidth.

59
APPENDIX I: PROBABILITY

The cumulative distribution function is 

FF( ) = Pr{XX < } = � ff(zz) −∞

(I-1)

where XXis a random variable. A specific probability between 0 and 1 is expressed as Pr{XX <

0}.

The inverse of the cumulative distribution function is the complementary cumulative distribution 

function

FF′

( ) = Pr{XX ≥ } = 1 − FF( ) (I-2)

The probability density function is 

ff( ) = ( ) (I-3)

If a change in variables is made such as yy = gg( )the following relation is true

ff( ) = ff(yy) (I-4)

The joint cumulative distribution of two random variables is

FF( , yy) = Pr{XX < , YY < yy} (I-5)

The joint probability density function is

ff( , yy) = ∂∂2FF( , yy)

∂∂ ∂∂ (I-6)

which can also be expressed in terms of the product of the conditional probability density 

function and the probability density function of the other random variable

ff( , yy) = ff( |yy)ff(yy) = ff(yy| )ff( ) (I-7)

60
FORM NTIA-29 U.S. DEPARTMENT OF COMMERCE 

(4-80) NAT’L. TELECOMMUNICATIONS AND INFORMATION ADMINISTRATION

BIBLIOGRAPHIC DATA SHEET

1. PUBLICATION NO.

TR-15-514

2. Government Accession No. 3. Recipient’s Accession No.

4. TITLE AND SUBTITLE

Effect of Broadband Radio Service Reallocation on 2900–3100 MHz Band Marine 

Radars: Unwanted Emissions

5. Publication Date

April 2015

6. Performing Organization Code

NTIA/ITS.T

7. AUTHOR(S)

Robert Achatz, Paul McKenna, Roger Dalke, Frank Sanders

9. Project/Task/Work Unit No.

8. PERFORMING ORGANIZATION NAME AND ADDRESS 3105011-300

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

U.S. Coast Guard Spectrum Management Telecommunications Policy Division

U.S. Coast Guard CG-652,

2100 2nd St. SW Stop 7101

Washington, DC 20593-7101

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.)

Spectrum reallocations may place broadband radio services (BRS) near spectrum used by 2900–3100 MHz band marine 

radars. Signals from the BRS base stations can potentially introduce unwanted emissions in the radar detection bandwidth 

and cause interference. Interference protection criteria (IPC) are needed to mitigate this effect. The primary IPC of concern 

are the interference to noise power ratio (INR) and the reliability of the radar link at a specified radar signal to noise power 

ratio (SNR). Reliability is determined by radio wave propagation path loss variability which increases with distance. Distance 

separation between base stations and radar for various spurious attenuations were calculated using reliability expressions for 

short radar to target ranges with constant SNR and for longer radar to target ranges with variable SNR. For a magnetron radar 

under clutter free conditions, 90 dB of spurious attenuation is needed to obtain 90% radar operational reliability at1.2 km 

when the INR is -6 dB and the SNR is constant. Reducing the INR to -9 and -12 dB increased the separation distance to 1.7 

and 2.7 km, respectively. At longer base station to radar separation distances, variable SNR required less spurious attenuation 

than constant SNR. Consequently, constant SNR analysis can be considered worst case. Distance and frequency separation 

were calculated using frequency dependent rejection (FDR). These calculations showed that for constant SNR 92.8 MHz of 

frequency separation is required to meet the 90% reliability IPC at 1.2 km separation distance when the INR is -6 dB. Only 

54.6 MHz frequency separation is needed when the separation distance is increased to 32.8 km. 

16. Key Words (Alphabetical order, separated by semicolons)

broadband radio service, interference, interference protection criteria, marine radar, radar, radio wave propagation, radio 

spectrum engineering, spurious emissions

17. AVAILABILITY STATEMENT

UNLIMITED.

FOR OFFICIAL DISTRIBUTION.

18. Security Class. (This report)

Unclassified

20. Number of pages

19. Security Class. (This page)

Unclassified

21. Price:
NTIA FORMAL PUBLICATION SERIES

NTIA MONOGRAPH (MG) 

A scholarly, professionally oriented publication dealing with state-of-the-art research or 

an authoritative treatment of a broad area. Expected to have long-lasting value.

NTIA SPECIAL PUBLICATION (SP)

Conference proceedings, bibliographies, selected speeches, course and instructional 

materials, directories, and major studies mandated by Congress.

NTIA REPORT (TR)

Important contributions to existing knowledge of less breadth than a monograph, such as 

results of completed projects and major activities.

JOINT NTIA/OTHER-AGENCY REPORT (JR)

This report receives both local NTIA and other agency review. Both agencies’ logos and 

report series numbering appear on the cover. 

NTIA SOFTWARE & DATA PRODUCTS (SD)

Software such as programs, test data, and sound/video files. This series can be used to 

transfer technology to U.S. industry.

NTIA HANDBOOK (HB)

Information pertaining to technical procedures, reference and data guides, and formal 

user's manuals that are expected to be pertinent for a long time.

NTIA TECHNICAL MEMORANDUM (TM)

Technical information typically of less breadth than an NTIA Report. The series includes 

data, preliminary project results, and information for a specific, limited audience.

For information about NTIA publications, contact the NTIA/ITS Technical Publications Office at 

325 Broadway, Boulder, CO, 80305 Tel. (303) 497-3572 or e-mail info@its.bldrdoc.gov.