NTIA Report 99-359

Electromagnetic Compatibility Testing

of a Dedicated Short-Range

Communication (DSRC) System that

Conforms to the Japanese Standard

John J. Lemmon

Frank H. Sanders

Brent L. Bedford

U.S. DEPARTMENT OF COMMERCE

William M. Daley, Secretary

Larry Irving, Assistant Secretary

for Communications and Information

November 1998
This Page Intentionally Left Blank

This Page Intentionally Left Blank
iii

PREFACE

This work was sponsored by the Federal Highway Administration (FHWA), McLean, Virginia,

under the direction of J.A. Arnold, FHWA Contracting Officer Technical Representative.

Certain commercial companies, equipment, instruments, 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

necessarily the best available for the purpose.
iv

CONTENTS

Page

PREFACE ................................................................ iii

EXECUTIVE SUMMARY .................................................... v

1.0 INTRODUCTION ....................................................... 1

1.1 Background ...................................................... 1

1.2 Approach ........................................................ 2

1.3 Experimental Configuration ........................................... 3

2.0 DSRC SOFTWARE DESCRIPTION ......................................... 4

3.0 MEASUREMENT RESULTS AND DATA ANALYSIS .......................... 5

3.1 System Performance Measurements ..................................... 5

3.2 Statistical Measurements of DSRC System Performance in the

 Presence of Pulsed Radar Interference ................................... 7

3.3 Frequency Offset Measurements ....................................... 8

3.4 Analysis of Results ................................................. 9

4.0 SUMMARY ........................................................... 13

5.0 REFERENCES ......................................................... 14
v

EXECUTIVE SUMMARY

The Department of Transportation is investigating the feasibility of deploying dedicated shortrange communication (DSRC) systems at locations across the United States in the 5850 to 5925

MHz band. This is part of a larger band, 5250-5925 MHz, which is currently allocated to radar

services. Deployment of DSRC systems depends upon the electromagnetic compatibility of their

operations with radar systems operating in the 5-GHz portion of the spectrum.

Electromagnetic compatibility tests of a DSRC system that conforms to Japanese standards were

performed by the Institute for Telecommunication Sciences. The purpose of the tests was to

determine to what extent the DSRC system may experience electromagnetic compatibility

problems when in close proximity to high-power radars in the 5-GHz spectrum. The tests were

performed by injecting simulated radar signals into a DSRC receiver. The radar signals are

representative of the range of parameters used by existing and possible future radars.

Thresholds at which the radar signals caused degradations of DSRC system performance were

measured for each set of radar signal parameters. These measured interference thresholds were

then used to determine the received signal levels at which existing 5-GHz radars would be

expected to interfere with DSRC systems deployed in the United States. For each type of radar,

the distance at which the radar system would be expected to cause interference to the DSRC

system was computed for various conditions of electromagnetic isolation between the two

systems. This analysis indicates that for typical conditions of isolation and nominal operating

conditions of the DSRC system that was tested, 5-GHz radars are not expected to interfere with

DSRC operations for any realistic separations between the systems (greater than several meters).
This Page Intentionally Left Blank

This Page Intentionally Left Blank
The authors are with the Institute for Telecommunication Sciences, National 1

Telecommunications and Information Administration, U.S. Department of Commerce, Boulder,

CO 80303.

ELECTROMAGNETIC COMPATIBILITY TESTING OF A DEDICATED

SHORT-RANGE COMMUNICATION (DSRC) SYSTEM 

THAT CONFORMS TO THE JAPANESE STANDARD

John J. Lemmon, Frank H. Sanders, and Brent L. Bedford1

Dedicated short-range communication (DSRC) systems, designed to enhance the

efficiency of highway travel, have been proposed for operation in the 5850- to

5925-MHz band. The successful operation of these communication systems

depends upon their compatibility with high-power search and tracking radars that

operate at or near this frequency band and are a potential source of interference.

This report presents the methods and results of a series of interference tests

performed by the Institute for Telecommunication Sciences to determine the

electromagnetic compatibility of a DSRC system and high-power 5-GHz radars.

Key words: dedicated short-range communication (DSRC) systems; high-power radars;

electromagnetic compatibility; interference

1.0 INTRODUCTION

1.1 Background

As part of the planning of an intelligent transportation system, the Department of Transportation

is evaluating the performance of dedicated short-range communication (DSRC) systems. DSRC

systems are wireless communication systems designed for operation in highway environments.

Their purpose is to enhance the efficiency of highway travel by providing various vehicle-toroadside services such as wireless interrogation stations that would collect tolls electronically as

vehicles pass through the stations without stopping.

The portion of the spectrum between 5850 MHz and 5925 MHz has been identified as a likely

band for deployment of DSRC systems in the United States. This band is part of a larger band

(5250-5925 MHz) that is allocated on a primary basis for radiolocation (radar) systems. The band

is occupied in the United States by high-power radar systems that could potentially interfere with

DSRC systems in highway environments.

The Institute for Telecommunication Sciences (the Institute) recently tested a DSRC system for

its response to high incident field strengths in the 5250-5925 MHz band. Tests were performed to

determine the interference thresholds at which DSRC performance was degraded. The results of

these tests in conjunction with previous measurements of emissions from high-power radars in
2

the 5250-5925 MHz portion of the spectrum [1-5] were used to determine the extent of

electromagnetic compatibility problems the DSRC device under test may encounter if deployed in

the proposed 5850- to 5925-MHz band. The methodology and results of these tests have been

discussed in a report by Dalke, Sanders, and Bedford [6].

The DSRC system described in [6] is based on European standards, and will hereafter be referred

to as the European DSRC. More recently the Institute performed analogous tests on a DSRC

system that conforms to Japanese standards. The purpose of this report is to describe the methods

and results of these latter tests.

1.2 Approach

The tests were performed in a laboratory at the Institute for Telecommunication Sciences in

Boulder, CO. The basic approach to the tests was to inject simulated radar signals into the DSRC

and to determine the interference levels, for various radar signal modulations, at which

performance degradations of the DSRC would occur for both co-channel interference and offfrequency interference.

As discussed in [6], radar beams typically scan across any given point in space repetitively,

approximately every 3 to 10 seconds, and illuminate any given point (such as a DSRC station) for

about 20 ms during a given beam-scan period. The signals consist of a repetitive series of pulses

that are characterized by the pulse width and pulse repetition interval. Two related parameters are

the duty cycle (pulse width divided by pulse repetition interval) and the pulse repetition frequency

(reciprocal of the pulse repetition interval). The pulse parameter combinations that were selected

for the interference testing are representative of the parameters for 5-GHz radars in the United

States and are shown in Table 1. For each combination of duty cycle and pulse repetition

frequency (or pulse repetition interval), the corresponding pulse width is shown in the table.

Table 1. Radar Parameters Used for DSRC Interference Signal Testing (prf = pulse repetition

frequency and pri = pulse repetition interval)

prf = 300 Hz prf = 1000 Hz prf = 3000 Hz

pri = 3.3 ms pri = 1 ms pri = 330 μs

Duty cycle = -20 dB 33.3 μs 10 μs 3.3 μs

(1%)

Duty cycle = -30 dB 3.3 μs 1 μs 0.33 μs

(0.1%)

Duty cycle = -40 dB 0.33 μs 0.1 μs 0.03 μs

(0.01%)
3

For each interference signal modulation that was tested, the interference level was initially

adjusted to a very low amplitude, well below the level that adversely affects DSRC performance.

The amplitude was then gradually increased until an adverse effect on DSRC performance was

noted.

1.3 Experimental Configuration

The hardware configuration used for the testing is shown schematically in Figure 1. The units

under test, a DSRC roadside unit (RSU) and a DSRC on-board unit (OBU), were mounted in an

Institute laboratory and were separated by approximately 2.8 m. The RSU was operated from a

Proto H10 computer via a fiber optic link. The RSU transmitted to the OBU at a frequency of

5860 MHz. The OBU responded to the RSU at 5900 MHz. The OBU operated autonomously, its

only external connection being for power.

As pointed out in [6], the uplink (signal transmitted by the OBU and received by the RSU) of the

European DSRC is more susceptible than the downlink (signal transmitted by the RSU and

received by the OBU) to interference signals, so that interference signals were coupled into the

RSU receiver. Similar considerations apply to the Japanese system. As in the tests of the

European DSRC, the signals were coupled via coaxial cable, rather than via RF radiation, to

better control the amplitudes at which the interfering signals were injected into the receiver. A

broadband RF combiner was utilized between the RSU antenna and the RSU receiver, as shown

in Figure 1.

Interference signals were generated using a pulse-waveform generator. That output was then

routed to the input of a signal generator to generate pulsed RF energy at the proper amplitudes

and frequencies for the tests. The interfering signal was then coupled into the RSU receiver via

the broadband combiner, along with the desired signal from the RSU antenna.

As shown in Figure 1, a calibrated horn antenna was also used in the RSU-OBU propagation path

to observe time-domain and frequency domain emissions from the RSU and OBU. The horn

antenna output was connected to a spectrum analyzer. Data from the spectrum analyzer were

recorded via a GPIB bus interface.

Calibration of the measurement system and of the DSRC performance parameters was discussed

in [6], and will not be repeated here.
Fiber Optic

Proto H10

Computer

Circulator

Tx/Rx

RSU

transmitter

RSU

Receiver

Control and data

collection computer

Pulse

input Pulse

generator

Signal

generator

2.8 m

Oscilloscope

OBU

LNA

GPIB

Separation

Spectrum

analyzer

Calibrated

horn antenna

RF power

combiner

4

Figure 1. Block diagram of interference testing arrangement.

2.0 DSRC SOFTWARE DESCRIPTION

The DSRC system could not be operated under manual control. The RSU operations were

controlled by the software, and the OBU operated autonomously. Test results were obtained

through outputs from the DSRC software.

The protocol for communication between the RSU and OBU is based on a synchronous adaptive

slotted ALOHA system. This is a time-division multiple access system in which the number of

slots in a frame can be varied; for the interference tests the DSRC was operated in an automatic

toll collection mode with a frame structure consisting of four slots. Each slot comprises 800 bits

at a bit rate of 1 Mb/s. Thus, each frame had a time duration of 3.2 ms. Measurements of timedomain waveforms indicated that signals were not continuously transmitted during each frame.

Also, the time between frames is variable and can be specified by the user; however, during the

tests the frames were transmitted continuously to minimize the possibility of interference pulses

being injected into the DSRC receiver during ‘dead time’.
5

As explained in [6], the performance parameter that was measured during the tests of the

European DSRC is a quantity called wait time, which is essentially the time required for a

transaction to take place. In the case of the Japanese DSRC, the wait time is not an output of the

software. Instead, the number of frame errors on the DSRC uplink was measured for a userspecified number of transactions. The maximum number of transactions that the system will

automatically conduct is 999, which is the number that was used for the tests.

The software also enables the user to specify a maximum number of frames that may be

retransmitted during each transaction when one or more frames are in error. The number chosen

for the DSRC tests was ten, which is the system default value. The experimenters discovered that

the number of uplink “frame errors” is strongly dependent upon the number of retransmitted

frames. For example, it was noted that when the number of retransmitted frames was set to zero,

the number of uplink frame errors increased to a large value even when no interference was

injected into the RSU receiver. Thus, the interference thresholds at which DSRC system

performance is adversely affected depend upon the value selected for the number of retransmitted

frames. The system default value of ten was selected, because it was concluded that this is

representative of actual system deployment.

3.0 MEASUREMENT RESULTS AND DATA ANALYSIS

3.1 System Performance Measurements

Figures 2 and 3 show RSU and OBU spectra measured with a 10 dBi horn antenna located 1.7 m

from the DSRC antennas. Institute engineers also measured the effective isotropic radiated

powers (EIRP) of the RSU and OBU transmitters and the frequency response of the preselection

bandpass filter in the RSU receiver unit. The measured EIRPs are consistent with the values of

transmitter output powers and antenna gains specified by the manufacturer. The frequency

response of this filter and the RSU antenna gain (approximately 15 dB) are of particular

importance, because they are used in the analysis discussed in Section 3.4 below.
-75

-60

-45

-30

-15

5850 5855 5860 5865 5870

Frequency (MHz)

dB

-75

-60

-45

-30

-15

5890 5895 5900 5905 5910

Frequency (MHz)

dB

6

Figure 2. Emission spectrum of the RSU.

Figure 3. Emission spectrum of the OBU.
7

3.2 Statistical Measurements of DSRC System Performance in the Presence of Pulsed

Radar Interference

The time and phase of a pulsed radar signal are random with respect to the DSRC transmissions.

Thus, the number of frame errors is a random variable. Determination of the interference

thresholds at which DSRC system performance is degraded therefore requires a statistical

characterization. Using the measurement equipment and methods described above, uplink frame

error statistics were measured for each of the nine radar signal modulations in Table 1 based on

999 independent transactions.

The interference thresholds at which uplink frame errors were generated are shown in Table 2.

The maximum interference signal level that was output from the signal generator was 10 dBm.

Subtracting 6 dB for combiner loss and an additional 6 dB for cable loss, a maximum signal level

of -2 dBm was injected into the RSU receiver. A possible concern is that this is not a sufficiently

high value for the maximum interference level since uplink frame errors were not generated for

five of the nine radar signal modulations (this is why five of the interference power levels are

designated as >-2 dBm in Table 2). However, as will be seen below, if interference signal levels of

-2 dBm do not generate frame errors, the radars in the 5-GHz band and the DSRC system are

electromagnetically compatible even at extremely small physical separations (several meters or

less). Thus, it was not considered necessary to inject larger interference signal levels for the

purposes of these tests.
8

Table 2. Peak Pulsed Interference Power Levels Resulting in Uplink Frame Errors for Various

Radar Parameters (pw = pulse width, dc = duty cycle, and prf = pulse repetition frequency)

Radar Parameters Interference Power Level (dBm)

prf = 300 Hz

pw = 33.3 μs > -2

dc = 1% 

prf = 300 Hz

pw = 3.3 μs > -2

dc = 0.1%

prf = 300 Hz

pw = 0.33 μs > -2

dc = 0.01%

prf = 1 kHz

pw = 10 μs -2

dc = 1%

prf = 1 kHz

pw = 1 μs -2

dc = 0.1%

prf = 1 kHz

pw = 0.1 μs > -2

dc = 0.01%

prf = 3 kHz

pw = 3.3 μs -52

dc = 1%

prf = 3 kHz

pw = 0.33 μs -12

dc = 0.1%

prf = 3 kHz

pw = 0.033 μs >-2

dc = 0.01%

3.3 Frequency Offset Measurements

The measurements described above, in which the interference center frequency is equal to the

center frequency of the RSU receiver (co-channel interference) is the worst case scenario, since

the RSU receiver has a preselection bandpass filter. To determine the DSRC performance when

the interference signal is offset in frequency, the number of uplink frame errors was measured at

various frequency offsets. Allowing up to ten retransmitted frames per transaction (as was done
-75

-45

-15

15

5700 5800 5900 6000 6100

Frequency (MHz)

dB

9

Figure 4. Receiver preselection bandpass filter frequency response.

for the co-channel testing) resulted in no uplink frame errors for offsets of more than a few

megahertz. Therefore, the frequency response of the preselection filter in the RSU receiver was

measured to ascertain system performance with frequency offsets. The frequency response is

shown in Figure 4. The attenuation of the filter (as a function of frequency) relative to the center

frequency provides additional isolation between the DSRC and an interferer that is offset in

frequency.

3.4 Analysis of Results

Using the measurement results described above, the required isolations between the DSRC and an

interfering radar have been determined for a variety of cases. High-power radars operating in the

5-GHz band typically have peak effective isotropic radiated power (EIRP) in the range of 113 to

133 dBm. The worst case interference degrades DSRC system performance at power levels as

low as -52 dBm, as indicated in Table 2. Assuming an RSU antenna gain of 15 dB, at least 180-

200 dB of isolation is required. The best case interference (from Table 2) occurs at power levels

greater than -2 dBm, requiring 130 to 150 dB of isolation.

The physical separation between the DSRC system and the interfering radar necessary to achieve

the best and worst case isolation is shown in Table 4. These separations correspond to those

distances at which the basic transmission loss equals the required isolation. The basic transmission

loss as a function of distance was calculated using the ITS Irregular Terrain Model [7] for a

typical environment with the parameters shown in Table 3.
10

Table 3. ITM Parameters Used to Calculate Basic Transmission Loss

Parameter Value

Frequency 5850 MHz

Polarization Vertical

Antenna heights 13 m (radar), 6.1 m (DSRC)

Terrain irregularity 90 m

Surface refractivity 301 N-units (4/3 earth)

Climate Continental temperate

Electrical ground constants F = 0.005 S/m, ,r = 15

Time reliability, location reliability, 90%, 90%, 50%

and confidence level

The above estimates of required isolations assume co-channel interference and peak directivity for

both the radar transmit antenna and the DSRC receive antenna. Additional isolation can be

achieved when the DSRC is installed so that the interferer is out of the receiver antenna main

beam. As pointed out in [6], it is estimated that an additional 15 dB of isolation can be achieved

for such an installation. It is also estimated that when the DSRC system is well out of the main

beam of the radar, an additional 25 dB of isolation may be obtained. Thus, an additional 40 dB of

isolation may be realized by antenna alignment.

The measurement of the frequency response of the preselection bandpass filter in the RSU

receiver, shown in Figure 4, indicates that about 70 dB of additional isolation may be achieved for

frequency offsets of a few hundred megahertz. This attenuation in combination with antenna

sidelobe attenuation provides adequate isolation for effective operation of the DSRC system that

was tested.

To compare these possibilities, Table 4 gives the required best case and worst case isolations and

the corresponding physical separations between the radar and the DSRC system for the following

cases:

Case 1, isolation is achieved via physical separation only.

Case 2, isolation is achieved via physical separation and antenna alignment, which

provides an additional 40 dB of isolation.

Case 3, isolation is achieved via physical separation and frequency offset, which provides 

an additional 70 dB of isolation.
11

Case 4, isolation is achieved via physical separation, frequency offset, and antenna

alignment, which provides an additional 110 dB of isolation.

Table 4. Required Separation Between an Interfering Radar and the DSRC System to Achieve

Best and Worst Case Isolation

Required isolation Case 1: Isolation by Case 2: Isolation by Case 3: Isolation by Case 4: Isolation by

physical separation physical separation physical separation physical separation,

only and antenna and frequency offset frequency offset, and

alignment antenna alignment

< 130 dB < 7.1 km < 0.133 km < 0.004 km < 0.001 km

< 150 dB < 24.8 km < 1.1 km < 0.040 km < 0.001 km

 180 dB 64.4 km 14.0 km 1.1 km < 0.013 km

 200 dB 203.5 km 39.8 km 7.1 km 0.133 km

These results indicate that when the DSRC and radar antennas are aligned so that the radar is

viewed with minimum directive gain for both antennas, and the center RF frequencies are offset

by a few hundred megahertz, the two systems should be compatible at separation distances of

approximately 0.1 km for the worst case required isolation of 200 dB (EIRP = 133 dBm). If 180

dB of isolation is required (EIRP = 113 dBm), the systems should be compatible at distances of

approximately 10 m. At these extemely small separation distances, the condition for minimum

directive gain should be realized for both antennas.

Table 5 shows the results of interference calculations for specific existing radars that could

potentially interfere with DSRC systems in the 5-GHz band. The radars and their operating

characteristics were taken from the Government Master File.
12

Table 5. Required Separation Distances Between Specific Interfering Radars and the DSRC

System for Different Isolation Cases

Specific radar Case 1: Isolation by Case 2: Isolation by Case 3: Isolation by Case 4: Isolation by Case 5: Isolation by

physical separation physical separation physical separation physical separation, physical separation,

only and 40 dB from and frequency offset frequency offset, and frequency offset, and

antenna alignment 40 dB from antenna 15 dB from antenna

alignment alignment

RIR-778C/FRS-16 24.8 km 1.1 km 0.007 km <0.001 km <0.001 km

1 μs, 1 kHz )f=50 MHz

MIP*=4 dBm 150 dB 110 dB 65 dB 25 dB 50 dB

Test radar 16.8 km 0.54 km <0.001 km <0.001 km <0.001 km

10 μs, 1 kHz )f=180 MHz

MIP=4 dBm 143 dB 103 dB 33 dB -7 dB 18 dB

Test radar <16.8 km <0.54 km <0.001 km <0.001 km <0.001 km

3.3 μs, 303 Hz )f=180 MHz

MIP>4 dBm <143 dB <103 dB <33 dB <-7 dB <18 dB

SPS-10 7.1 km 0.133 km 0.009 km <0.001 km <0.002 km

1 μs, 1 kHz )f=25 MHz

MIP=4dBm 130 dB 90 dB 67 dB 27 dB 52 dB

SPS-10 <7.1 km <0.133 km <0.009 km <0.001 km <0.002 km

3.3 μs, 303 Hz )f=25 MHz

MIP>4dBm <130 dB <90 dB <67 dB <27 dB <52 dB

SPS-67 8.2 km 0.166 km 0.011 km <0.001 0.002 km

1 μs, 1 kHz )f=25 MHz

MIP=4dBm 132 dB 92 dB 69 dB 29 dB 54 dB

SPS-67 15.8 km 0.485 km 0.036 km <0.001 km 0.006 km

0.33 μs, 3.03 kHz )f=25 MHz

MIP=-6 dBm 142 dB 102 dB 79 dB 39 dB 64 dB

WSR-74C 14.9 km 0.435 km <0.001 km <0.001 km <0.001 km

1 μs, 1 kHz )f=200 MHz

MTP=4dBm 141 dB 101 dB 29 dB -11 dB 14 dB

WSR-74C <14.9 km <0.435 km <0.001 km <0.001 km <0.001 km

3.3 μs, 303 Hz )f=200 MHz

MIP>4dBm <141 dB <101 dB <29 dB <-11 dB <14 dB

*Minimum interference power (MIP)

In the first column we give the specific radar identification, the radar pulse parameters (pulse

width and pulse repetition frequency), and the measured minimum interference power (MIP) for

the pulse parameters. The pulse parameters were matched as closely as possible to the

measurement results in Table 2 to estimate the MIP for each radar. For most of the radars there is

a range of possible pulse widths and repetition frequencies, resulting differences in the required

isolation. In these cases we have shown the best and worst cases associated with each radar.

In the following columns of Table 5, we give the results for each of the four previously defined

cases and for a fifth case, where the DSRC antenna is in the main beam of the radar antenna, and

the additional isolation due to antenna alignment is 15 dB. There are two table entries for all

cases: the required isolation and the physical separation required to achieve that isolation. For

Case 3, there is an additional entry showing the value of the frequency offset ()f) that was used
13

to estimate the value of isolation due to frequency offset (from Figure 4). These frequency offsets

are the minimum offsets based on the radar RF frequency range and the proposed DSRC system

RF frequency range.

Cases 4 and 5 have extremely small separation distances (several meters or less). As pointed out

in [6], Case 4 should be achievable in most cases. Case 5 could occur if, for example, a nonrotating radar is pointed at the DSRC antenna sidelobe, and requires 25 dB more isolation than

Case 4. However, even for this case the required separations are several meters or less.

Case 1 only occurs when the radar and the DSRC are co-channel and when additional isolation

due to antenna alignment cannot be achieved. However, even for this worst case scenario, the

maximum separation distance is less than 25 km (for the RIR-778C tracking radars).

4.0 SUMMARY

The operation of the DSRC system that was tested was found to be affected by co-channel radars

with pulse parameters that are representative of high-power radars operating in the 5-GHz band.

To achieve the necessary isolation between the radars and the DSRC system, separation distances

of tens of kilometers or less are required. Our results also indicate that significant additional

isolation can be achieved when the RF frequencies are offset by more than 25 MHz. When

combined with the additional isolation achieved by antenna alignment (estimated to be 40 dB), the

engineers found that all of the existing 5-GHz radars should be compatible with the DSRC system

that was tested for extremely small separation distances (several meters or less).

One should be cautious in making any quantitative comparison between the results of the tests of

the Japanese DSRC system described here and the test results of the European system discussed

in [6]. In the tests described here, the performance quantity that was measured was the number of

uplink frame errors, whereas wait time was measured in [6]. Without more information than the

software of these two systems provided, the engineers were unable to measure the relationship

between wait time and uplink frame errors. Thus, a direct comparison of the electromagnetic

compatibility of the Japanese and European systems does not appear possible at this time.

It should also be realized that the number of uplink frame errors that was measured is dependent

upon the number of retransmitted frames per transaction. For these tests, the system default

(maximum of ten retransmitted frames per transaction) was chosen, because this is representative

of actual deployment of the DSRC that was tested.
14

5.0 REFERENCES

[1] F.H. Sanders and V.S. Lawrence, “Broadband spectrum survey at Denver, Colorado,” NTIA

Report 95-321, Sep. 1995.

[2] F.H. Sanders, B.J. Ramsey, and V.S. Lawrence, “Broadband spectrum survey at San Diego,

California,” NTIA Report 97-334, Dec. 1996.

[3] F.H. Sanders, B.J. Ramsey, and V.S. Lawrence, “Broadband spectrum survey at Los Angeles,

California,” NTIA Report 97-336, May 1997.

[4] F.H. Sanders, R.L. Hinkle, and B.J. Ramsey, “Analysis of electromagnetic compatibility

between radar stations and 4 GHz fixed-satellite earth stations,” NTIA Report 94-313, Jul.

1994.

[5] R.J. Matheson, J.D. Smiley, G.D. Falcon, and V.S. Lawrence, “Output tube emission

characteristics of operational radars,” NTIA Report 82-92, Jan. 1992.

[6] R. A. Dalke, F. H. Sanders, and B. L. Bedford, “Electromagnetic compatibility testing of a

dedicated short-range communication system,” NTIA Report 98-352, July 1998.

[7] G.A. Hufford, A.G. Longley, and W.A. Kissick, “A guide to the use of the ITS Irregular

Terrain Model in the area prediction mode,” NTIA Report 82-100, Apr. 1982.