NTIA Report 97-335 

FM Subcarrier Corridor Assessment for 

the Intelligent Transportation System 

Robert O. DeBolt 

Nicholas DeMinco 

U.S. DEPARTMENT OF COMMERCE 

Mickey Kantor, Secretary 

Larry Irving, Assistant Secretary 

for Communications and Information 

January 1997 

iii

PREFACE 

The propagation studies and analysis described in this report were sponsored by the Federal 

Highway Administration (FHWA), U.S. Department of Transportation, McLean, Virginia. The 

guidance and advice provided by J. Arnold of FHWA are gratefully acknowledged. 

v 

CONTENTS 

Page 

1. INTRODUCTION .....................................................................................................................1 

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

 1.2 Objective...........................................................................................................................2 

 1.3 Study Tasks.......................................................................................................................3 

 1.4 Study Approach ................................................................................................................3 

 1.5 FM Subcarrier Systems.....................................................................................................4 

2. ANALYSIS OF CORRIDOR 1 - Interstate 95 from Richmond, Virginia, 

 to Portland, Maine......................................................................................................................5 

3. ANALYSIS OF CORRIDOR 2 - Gary, Indiana, to Chicago, Illinois, and Milwaukee, 

 Wisconsin, along Interstates 80, 90, and 94...............................................................................7 

4. ANALYSIS OF CORRIDOR 3 - The Atlanta, Georgia, Metropolitan Area ............................8 

5. CONCLUSIONS........................................................................................................................9 

 

6. REFERENCES ........................................................................................................................20 

APPENDIX: COMMUNICATION SYSTEM PERFORMANCE MODEL ................................21 

1

FM SUBCARRIER CORRIDOR ASSESSMENT FOR THE INTELLIGENT 

TRANSPORTATION SYSTEM 

Robert O. DeBolt and Nick DeMinco∗

This report documents the assessment of FM subcarrier performance for 

Intelligent Transportation Systems (ITS) applications in three areas of interest in 

the United States. These areas are: 1) The Interstate 95 corridor from 

Richmond, Virginia, to Portland, Maine; 2) The Midwest corridor from Gary, 

Indiana, to Chicago, Illinois, and Milwaukee, Wisconsin, along Interstates 80, 

90, and 94; and 3) The Atlanta, Georgia, Metropolitan Area. This study 

indicates that subcarrier systems of carefully chosen FM stations can provide 

good performance for ITS applications. 

Key words: FM subcarrier; Intelligent Transportation System; ITS; IVHS 

1. INTRODUCTION 

The Federal Highway Administration (FHWA) provided funding to the MITRE Corporation 

to investigate the use of FM subcarriers for the broadcast of traffic data to vehicles on 

highways to support the Intelligent Transportation System (ITS) program. In response to this 

contract, MITRE developed the prototype hardware called the Subcarrier Traffic Information 

Channel (STIC) System. The National Telecommunications and Information 

Administration/Institute for Telecommunication Sciences (NTIA/ITS) independently 

evaluated, both in the laboratory and in the field, the performance of an FM subcarrier-based 

traveler information broadcast system. This report describes the results of the FM subcarrier 

coverage predictions for three areas in the United States. The geographic plots of the areas 

of coverage by the FM subcarrier systems are presented along with descriptions of potential 

problem areas with this approach to the traveler information system services for ITS. 

1.1 Background 

The United States Department of Transportation (DOT) established the ITS program to use 

advanced computer, electronics, and communications technologies to improve the 

effectiveness of the nation’s highway system. ITS uses these technologies to provide a group 

of functions that include information processing, navigation, communications, and control. 

Once it is fully functional, ITS will provide information to travelers about road and transit

 

∗

 The authors are with the Institute for Telecommunication Sciences, National 

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

CO 80303. 
2

travel conditions and will monitor, guide, and assist in the control and operation of vehicles. 

ITS can enable travelers to make more informed choices about routes, times, and modes of 

travel. It will also allow authorities to manage transportation systems and control traffic more 

efficiently. Authorities will be able to respond rapidly to road accidents to restore traffic flow, 

redirect traffic away from the most congested routes, provide informational ridesharing, 

control traffic at intersections and on street networks, meter ramps on freeways, reserve lanes 

for buses and high-occupancy vehicles, and provide automatic in-transit commercial vehicle 

weigh-in and toll collection. In the future, ITS will assist drivers and reduce accidents through 

automation of vehicle control. 

A potential method for providing traveler information services in some demonstration projects 

and possibly the final ITS architecture is via an FM subcarrier on an existing channel of the 

FM broadcast band. FM subcarriers have long been used for a variety of applications. More 

recently, FM subcarriers have been used to transmit road warnings and conditions, traveler 

advisories, emergency situations, and navigation information; these ITS applications have 

shown great promise. 

NTIA/ITS developed computer programs to assist in the assessment of FM subcarrier 

performance for ITS applications. These programs assist the engineer in choosing the best FM 

stations that could provide subcarrier coverage over a desired corridor by predicting the area 

coverage of stations deploying ITS subcarrier systems. 

NTIA/ITS also measured the STIC system performance when installed in the subcarrier 

channel of a commercial FM broadcast station. STIC performance was evaluated in a variety 

of reception environments in order to assist in the verification of the prediction of subcarrier 

coverage in three specific areas of the United States that differ dramatically in terrain and 

population density. These regions may implement the FM subcarrier form of Advanced 

Traveler Information System (ATIS). The primary goal of the field test program was to 

correlate the STIC performance with received signal level in a variety of reception 

environments. The test results were used to establish a threshold for minimum detectable 

signal in a variety of propagation environments and then verify the coverage predictions that 

were made. After these thresholds for acceptable performance were established, reliable 

predictions were made for other areas of the country. 

1.2 Objective 

The objective of this study was to evaluate the area coverage capabilities of FM stations that 

may be used in ITS applications in three areas of the United States and determine if a particular 

set of FM stations could provide adequate subcarrier coverage for ITS applications. This 

assessment focused on three areas of the United States: 1) The Interstate 95 corridor from 

Richmond, Virginia, to Portland, Maine; 2) The Midwest corridor from Gary, Indiana, to 

Chicago, Illinois, and Milwaukee, Wisconsin, along Interstates 80, 90, and 94; and 3) The 

Atlanta, Georgia, Metropolitan area. 
3

1.3 Study Tasks 

The assessment study incorporated the following tasks: 

1) Define the corridor bounds and extract reference points from within these bounds. These 

include points along interstate highways and points around major metropolitan areas that 

define the analysis area. These points were chosen to be at approximately 1-km intervals 

along interstates and within 80 km of the center of downtown Atlanta for corridor 3. 

2) Search through the Federal Communications Commission (FCC) FM database to extract 

those stations within a specified distance from the reference points determined above. 

3) Import the selected set of FM stations into the Communication System Performance 

Model (CSPM) to predict the FM subcarrier coverage for each station. For a description 

of the CSPM program, see Appendix A. 

4) Evaluate the coverage for each station to determine if the coverage is insufficient or 

redundant. Develop a set of stations that could provide the desired coverage most 

efficiently. This selection was based upon location and power only. Cost and contractual 

arrangements were not considered. 

5) Produce a composite coverage map of the selected corridors using this chosen set of FM 

stations. 

1.4 Study Approach 

The Telecommunications Analysis Services Group of NTIA/ITS developed software and databases 

that provide users with the means to find, extract, and analyze FM station parameters and 

performance. This software was used to develop new software that allows the ITS user to specify 

a geographic block by latitude and longitude and a target interstate highway or city within that 

block. These programs extract reference points for this target area, search the FCC FM database, 

extract all FM stations within a specified distance from the targets, and import these FM stations 

and their equipment parameters into the CSPM program. 

The results of the CSPM analyses can then be examined to determine the quality of coverage of the 

target area for each FM station. Those that provide poor coverage or redundant coverage are 

removed from the set of “best” stations leaving a minimum set of FM stations that can provide the 

desired target coverage. The coverage of these FM stations are combined to produce a composite 

coverage map of the target area. 
4

1.5 FM Subcarrier Systems 

The STIC system is a proof-of-concept prototype developed by the MITRE Corporation under the 

sponsorship of the ITS program. The prototype is intended to demonstrate the ability to broadcast 

high-speed digital data using the existing commercial FM broadcast radio infrastructure. 

The STIC system is an FM subcarrier-based data transmission and reception system. It is designed 

to achieve reliable communications in the multipath and fading environment associated with very 

high frequency (VHF) mobile receivers. To achieve that end, the STIC system uses high levels of 

signal processing and error correction. The key characteristics of the waveform are: 

• 72.2-kHz center frequency; 

• 20-kHz bandwidth; 

• π/4 DQPSK with square root raised cosine filtering; 

• 1⁄2-rate convolutional code (to mitigate random errors); 

• Reed-Solomon (228,243) block code (to provide error detection and mitigate errors); 

• convolutional interleaving (to randomize burst errors); and 

• 18.05-kbps channel data rate and >8-kbps information data rate. 

The prototype STIC system consists of a transmitter subsystem and receiver subsystem. The STIC 

transmitter subsystem consists of the STIC subcarrier generator and a personal computer (PC). The 

PC is used to control and configure the subcarrier generator and generate messages for 

transmission. The subcarrier generator is enclosed in a single rack-mounted chassis. It connects 

directly to the subcarrier input port of an FM broadcast exciter. The STIC receiver subsystem 

consists of an FM car stereo receiver (modified to demodulate the subcarrier signal), a Global 

Positioning System (GPS) antenna, the STIC receiver (which also functions as a GPS receiver), a 

hand-held data terminal, a data collection PC, and the STIC power supply and harness. 

Coverage predictions were made for two different FM subcarrier systems: the FM Subcarrier 

Traffic Information Channel System and the Radio Broadcast Data System (RBDS). It was first 

necessary to determine the operating threshold of these systems. The operating threshold is the 

minimum field strength at the receiver required for operation. 

The signal thresholds, which gave a specified level of performance for the STIC system, were 

determined from a measurement task “FM Subcarrier Coverage Measurement and Verification,” also 

performed for the Federal Highway Administration. The results of the measurement task will be 

included in an NTIA/ITS report [1]. Two operating thresholds were used to characterize different 

propagation environments. The rural plains environment was characterized as an area having few 

significant natural or man-made obstacles and having virtually line-of-sight propagation paths. The 

urban low-rise environment was characterized as an area having significant man-made obstacles and 

obstructions typically one or two stories tall. The urban high-rise environment was characterized as 

an area typical of the downtown portion of a large city: city streets and urban canyons formed by 

long rows of buildings greater than two stories including high-rise buildings. An operating threshold
5

for the rural and urban low-rise environments was determined by measurement to be 54 dBuV/m. 

The operating threshold for the urban high-rise environment was determined by measurement to be 

74 dBuV/m. 

The operating thresholds for the RBDS were determined from [2], which contains an exhaustive 

description of the testing of the Radio Data System (RDS) in Europe; this system is very similar to 

the RBDS used in the United States. An operating threshold of 60 dBuV/m for an urban high-rise 

environment was obtained from [2]. An operating threshold of 29 dBuV/m was obtained from [3] 

for the rural and urban low-rise environment. 

2. ANALYSIS OF CORRIDOR 1 

Interstate 95 from Richmond, Virginia, to Portland, Maine 

The analysis area was bounded by a rectangle whose north and west boundaries were 41 degrees 

15 minutes north, 78 degrees 30 minutes west and whose south and east boundaries were 36 

degrees 45 minutes north, 73 degrees west. 

Reference points along Interstate 95 were extracted from the U.S. Geological Survey digital 

database of interstates. The FCC FM database was searched to select those FM stations within 80 

km of each of these reference points. The list of candidate FM stations is shown in Table 1. 

The area coverage for each of the stations listed in Table 1 was predicted using the CSPM model. 

To predict STIC reception, the operating thresholds of 74 dBuV/m for urban high-rise areas and 54 

dBuV/m for urban low-rise areas were plotted by the CSPM. To predict RBDS reception, the 

operating thresholds of 60 dBuV/m for urban high-rise areas and 29 dBuV/m for urban low-rise 

areas were plotted by the CSPM. The results of these CSPM analyses were then visually examined 

to determine a minimum set of stations to cover this corridor. The selected set of stations was 

based upon location and power. Those stations that had the maximum amount of predicted 

coverage along the corridor were selected. Those stations that provided either minimal coverage 

along the interstate or that provided redundant coverage with one of the selected stations were not 

selected. The selected set of stations is shown in Table 2. 

The coverage plots for the selected stations in Table 2 were then combined to produce the coverage 

composites shown in Figures 1 and 2. This analysis, and Figure 1 showed that in the case of 

predicted STIC coverage, there is a section of Interstate 95 in southeast Connecticut that has 

adequate urban low-rise coverage but inadequate urban high-rise coverage. Since this area of 

Connecticut is urban low-rise in nature, subcarrier coverage is adequate in this area. Predictions 

indicate that RBDS coverage would be adequate for the entire corridor. 
6

Table 1. FM Stations within 80 km of Interstate 95 

 

WVST WETA WWMX WBLS WRTN WCHR WFLN WQGN WMPG 

WKHK WAVA WERQ WQHT WRRH WWFM W204AD WBMW WMGX 

WDYL WGMS WQSR WNCN WFAS WTSR W300AD WTYD WBQQ 

WRVQ WAMU WEAA WBAI WXPS WRRC WMMR WERS WZZE 

WVGO WMMJ WBJC WPLJ WEDW W220AG WKDN WCTK WCME 

WMXB WPFW WXYV WMXV WKHL WNJTFM WEEE WNYE WPORFM 

WHCE WKYS WTMD WHTZ W211AI WKX WFM WKDU WRQX 

W221AA WWDC WKJY WPOB WMGQ WEAZ WJBRFM WCVE WKHS 

WXZL WSKQF W276AV WPRB WPEB WTVR WHUR WNEW WWDB 

WARY WWPH WHHS WDCE WJZE WLIF WXRK WRPR WDVR 

WXVU WRXL WASH WBSB WQXR WNYK WCVH WYBF WCDX 

WFME WDCU WHFC WRKS WOSS W289AA WDBK WYFJ WGLSFM 

WXCY WCBS WVIP WNTI WRSD WPLC WLTT WGRX WGAY 

WLTW W232AL WRDV WSRN WJYJ WMUC WRCY WDRE WKNJ 

WBJB WBMR WKSZ WRTI WFLS WGTS WKRB WMNJ WFSI 

WCNJ WEGX WDNR WBQB WHFS WSIA WFMU W220AA W221AH 

WLSA WSMD WNYE WKWZ WVHP WMGK WSTW W280CP WLIU 

WGRQ WMJS WQCD WCWP WVPH WXTU WMPH WDHAFM WCSO 

WCUL WACC WKCR WHCR WAWZ WIBF WVLT WNYUFM WNPR 

WQRA WINFM WPAT WJSV WHTG WHYY WHEB WEDW WKCI 

WPLZ WRBS WNYC WHPH WMCX WYSP WNNN WNPR WHYR 

WDCK WPOC WYNY W27AQ WZVU WYXR WVUD WXTR W261CD 

WRHU WBGD WDAS WPGC WBYQ WBAU WADB WUSL WCXR 

WHPS WHPC WFUV WJLK WOGL WOELFM WJFK WJHU WBGO 

W244AS WMSC WPST WXPN WDAC WMZQ WIYY WSOU WFDU 

WIOQ WHJY WHRB WHTZ WKHL WPLR WVVE WSVSFM WBRU 

WICN WSKQ WEFX WKSS WSNE WSSH WNEW WEBE WYSR 

WWBB WXLO WXRK WWEM WPKT WPLM WLYT WQXR WHUD 

WZMX WHUS WKCR WGBH WZEA WRKS WMNR WWYZ WWRX 

WMEA WCDJ WERZ WCBS WPKN WDRC WBLQ WBLM WBOS 

WPAT WLTW WSHU WHCN WPJB WTHT WBMX WNYC WBAB 

WEZN WKJY WRIU WKZS WODS WYNY WMJC WALK WIHS 

WOTB WCLZ WBUR WBGO WOKQ WRKI WRCH WPRO WKRH 

WCRB WBLS WFRS WBLI WWHB WWLI WXGL WZLX WQHT 

WNYU WNHU WLNG WMXV WRTN WMN WXKS WBAI WFUV 

WYBC WBAZ WQCD WABK WBCN WPLJ WUSB WCQL WHFM 

WJFD WKCG WMJX 

Table 2. Selected FM Stations That Provide Maximum Coverage along Interstate 95 

WABK WKRH WCLZ WPOR WBQQ WHEB WLYT WTYD WBMW 

WSSH WGBH WHJY WPRO WWRX WVVE WQGN WJYJ WKCI 

WEBE WKHL WQCD WMGQ WAWZ WKXW WTVR WWDB WJBR 

WXCY WYOC WHFS WGAY WBQB WTVR 
7

3. ANALYSIS OF CORRIDOR 2 

Gary, Indiana, to Chicago, Illinois, and Milwaukee, Wisconsin, along 

Interstates 80, 90, and 94. 

The analysis area was bounded by a rectangle whose north and west boundaries were 45 degrees 

north, 91 degrees 30 minutes west and whose south and east boundaries were 39 degrees, 30 

minutes north, 84 degrees, 20 minutes west. 

Reference points along Interstates 80, 90, and 94 were extracted from the U.S. Geological 

Survey digital database of interstates. The FCC FM database was searched to select those FM 

stations within 80 km of each of these reference points. The list of candidate FM stations is 

shown in Table 3. 

Table 3. FM Stations within 80 km of Interstates 80, 90, and 94 

 

WOND WONC WCRX WKQX WCBR WHKQ WFMR WDND WHSD 

WCKG WZVN WYLL WKKV WTKM WKBM WDGC WJMK WGVE 

WVVX WMYX WGLB WBUS WLTL WTMX WZRD WMXM WVCY 

WBWI WCFL WDCB WLSFM WWJY WEPS WCCX WIIL WJCY 

WETN WLIT WLUW WABT WHAD WNIZ WCCQ WRSE WBBM 

WDSO WXLC WMSE WSJY WCSF WKOT WGCI WVUR WZSR 

WLZR WSUW WLLI WRKX WNIB WLJE WDEK WQFM WHO 

WJTW WSTQ WPNT WCOE WDKB WUWM WMAD WHFH WKKC 

WOJO WEFM WNIU WMWK WYKY USN WNTH WBSD WLTQ 

WLRA WCYC WBEZ WKVI W289AB WYMS WXRO WSPY WMBI 

WNUA WGTC WZOK WZTR WLRT WXAV WYCA WXRT WJKL 

WQFL WKTI WTKC WBHI WRRG WLUP WMTH WGSL WEZW 

WYSY WSSD WVAZ WNUR WXRX WKLH WHKD WHPK WFMT 

WMWA WGTD WLUM WARG WOUI 

The area coverage for each of the stations listed in Table 3 was predicted using the CSPM model. 

To predict STIC reception, the operating thresholds of 74 dBuV/m for urban high-rise areas and 54 

dBuV/m for urban low-rise areas were plotted by the CSPM model. To predict RBDS reception, 

the operating thresholds of 60 dBuV/m for urban high-rise areas and 29 dBuV/m for urban low-rise 

areas were plotted by the CSPM model. The results of these CSPM analyses were then visually 

examined to determine a minimum set of stations to cover this corridor. The selected set of stations 

was based upon location and power. Those stations that had the maximum amount of predicted 

coverage along the corridor were selected. Those stations that provided either minimal coverage 

along the Interstate or that provided redundant coverage with one of the selected stations were not 

selected. The selected set is shown in Table 4. This analysis indicated that there are more than 

enough stations to provide adequate coverage of the Interstates 80, 90, and 94 corridor. 
8

Table 4. Selected FM Stations that Provide Maximum Coverage along 

Interstates 80, 90, and 94 

WEFM WCOE WLJE WGVE WJMK WMBI WXLC WIIL WKKV WMYX WZTR 

The coverage plots for the selected stations in Table 4 were then combined to produce the coverage 

composites shown in Figures 3 and 4. Both STIC and RBDS coverage predictions indicate that 

there would be adequate coverage for the entire corridor. 

4. ANALYSIS OF CORRIDOR 3 

The Atlanta, Georgia, Metropolitan Area 

The city of Atlanta, Georgia, was the host of the 1996 Summer Olympic Games and FM 

subcarriers were used for facilitating traffic management during the Olympic Games. For this 

reason, Atlanta was chosen as corridor 3. 

The analysis area was bounded by a rectangle whose north and west boundaries were 35 degrees 

north, 86 degrees west, and whose south and west boundaries were 32 degrees 30 minutes north, 

82 degrees 30 minutes west. 

A search of the FCC FM database was conducted to select those FM stations within 100 km of the 

city of Atlanta. The list of candidate FM stations is shown in Table 5. 

Table 5. All FM Stations within 100 km of Atlanta, Georgia 

WQUL WBTR WSTR WABE WALR WFOX WAFM WRAS WSB W221AW WKHX 

WYAY WCCV WJZF WCLK WVEE WKLS WGHR WGST WMKJ WGLSFM WREK 

W298AA WPCH WYFW WWGC WZGC WNNX WLKQ WWEV WTSH W208AA WRFG 

The area coverage for each of the stations listed in Table 5 was predicted using the CSPM model. 

To predict STIC reception, the operating thresholds of 74 dBuV/m for urban high-rise areas and 54 

dBuV/m for urban low-rise areas were plotted by the CSPM model. To predict RBDS reception, 

the operating thresholds of 60 dBuV/m for urban high-rise areas and 29 dBuV/m for urban low-rise 

areas were plotted by the CSPM model. The results of these CSPM analyses were then visually 

examined to determine a minimum set of stations to cover the Atlanta area. The selected set of 

stations was based upon location and power. Those stations that had the maximum amount of 

predicted area coverage throughout Atlanta were selected. Those stations that provided either 

minimal coverage or that provided redundant coverage with one of the selected stations were not 

selected. The selected set is shown in Table 6. 
9

Table 6. Selected FM Stations for Atlanta, Georgia 

WWEV WTSH WGST WFOX WALR WNNX WJZF WQUL WJGA 

The coverage plots for the selected stations in Table 6 were then combined to produce the coverage 

composites shown in Figures 5 and 6. Coverage predictions indicate that there would be adequate 

coverage for both STIC and RBDS systems. 

There were two FM stations in the Atlanta area that are of particular interest since they were used 

in special coverage of the Olympic Games. These stations are WKLS and WRFG. Plots of the 

predicted STIC and RBDS coverage for each of these stations is shown in Figures 7 through 10. 

5. CONCLUSIONS 

Predictions indicate that both STIC and RBDS can provide good area coverage for ITS 

applications using the FM subcarriers of carefully chosen FM stations. STIC and RBDS coverage 

predictions shown in Figures 1 and 2 indicate that for the interstate corridor from Richmond, 

Virginia, to Portland, Maine, there is a section of Interstate 95 in southeast Connecticut that has 

adequate rural/urban low-rise STIC coverage but inadequate urban high-rise STIC coverage. Since 

this is a rural area of Connecticut, subcarrier coverage is adequate in this area. Predictions indicate 

that RBDS coverage would be adequate for the entire corridor. For the corridor from Gary, 

Indiana, to Chicago, Illinois, and Milwaukee, Wisconsin, along Interstates 80, 90, and 94 (Figures 

3 and 4), both STIC and RBDS coverage predictions indicate that there would be adequate 

coverage for the entire corridor. Figures 5 and 6 show the predicted STIC and RBDS coverage for 

the Atlanta area. Coverage predictions indicate that there would be adequate coverage for both 

STIC and RBDS systems. Figures 7 and 8 show the predicted STIC and RBDS coverage for 

station WKLS in Atlanta. These predictions indicate that there would be adequate coverage of the 

Atlanta area using WKLS from both STIC and RBDS systems. Figures 9 and 10 show the 

predicted STIC and RBDS coverage for station WRFG in Atlanta. These predictions indicate that 

there would be adequate coverage of the Atlanta area using WRFG, but that the coverage is not 

quite as good as that for station WKLS. 
10
11
12
13
14
15
16
17
18
19
20

6. REFERENCES 

[1] J.F. Mastrangelo and W.R. Rust, “Subcarrier traffic information channel testing and 

evaluation,” NTIA Report 96-333, Jul. 1996. 

[2] G. Klein, “Digital traffic information using the radio data system,” PhD Thesis, 

University of Nottingham, Nottingham, United Kingdom, pp. 170-209, May 1995. 

[3] International Telecommunications Union (ITU-R), “System for automatic tuning and 

other applications in FM radio receivers for use with the pilot-tone system,” vol. X-1, 

ITU-R Recommendation 643-1 (Dusseldorf, Germany), 1990. 
21

APPENDIX: COMMUNICATION SYSTEM PERFORMANCE MODEL 

The Communication System Performance Model (CSPM) program creates detailed shaded or 

contour plots of basic transmission loss, field strength, power density, available power, or signalto-interference ratios from one or more transmitters in a given geographical area. CSPM allows the 

user to select the propagation model desired for predictions. The default model is the Institute for 

Telecommunication Sciences Irregular Terrain Model (ITM) in the point-to-point mode. The 

model chosen by the user determines path loss along radials of about one degree azimuthal 

intervals around each transmitter. The ITM is applicable to analyze mobile, broadcast, or radar 

coverage and interference problems in the 20-MHz to 20-GHz band. The model uses the U.S. 

Geological Survey 3-arc second terrain database and the Defense Mapping Agency terrain 

database. These databases provide an elevation point approximately every 90 m. The model also 

uses the 1990 U.S. Census information and frequently updated FCC databases. 

CSPM calculates path losses in a user-defined geographic area. This area is divided into a grid of 

up to 200 x 200 points for a maximum number of calculated values of 40,000. These path losses 

are used in the generation of a plot and are converted to the desired output type (e.g., field strength 

and power) at plot time. The user either imports station information directly from the FCC database 

or hand enters information about the station. This information includes: transmitter location, 

power, antenna pattern, tower height, gains and losses of the system, and desired contours of signal 

coverage. The model plots the desired contours of signal strength and determines the number of 

households and population that lie within the specified contours. CSPM plots can be combined to 

produce predicted area coverage of a group of stations. Each cell value of the 200 x 200 grid is set 

to the maximum signal strength from the group of stations. A sample of the summary of input data 

is shown in the following table. 
22

Communications System Performance Model Input Summary 

21 Nov 95 - 15:43:52 

Process Filename: CS000Nov2195E.ques 

1) Model: Point-to-point irregular terrain model 

2) Output option: Field intensity 

3) Length units: English (mi and ft) 

4) Service application: Broadcast 

5) Results option: Mail only 

 FAX number: 000-000-0000 

6) Location variability: 50.00 % 

7) Time availability: 50.00 % 

8) Situation variability: 50.00 % 

10) Frequency: 89.30 MHz 

11) Polarization: Vertical 

12) Conductivity: .005 S/m 

13) Dielectric constant: 15.00 

14) Climate zone: Continental temperate 

20) Transmitter name: WRFG 

21) Transmitter location: Latitude Longitude 

 Deg N Deg W 

 33.7489 33,44,56.00 84.4072 84,24,26.00 

22) Xmtr site elevation: 309.70 m 1016.00 ft 

23) Xmtr ant ht AMSL: 361.00 m 1184.38 ft 

23) Xmtr ant ht AGL: 51.33 m 168.41 ft 

24) Transmitter radiation option: ERP 

24) Effective radiated power: 24500.00 W 

 Effective isotropic radiated power: 40196.90 W 

30) Transmitter ant horiz pattern: Omnidirectional 

32) Transmitter ant vert pattern: Omnidirectional 

40) Rcvr ant ht above ground: 9.10 m 29.86 ft 

56) Corporate name: ITS-TA Services 

57) Color option: Color 

58) Scale option: No Scale 

59) Quality option: High 

60) Plot name: Atlanta, GA 

62) Plot center: Latitude Longitude 

 Deg N Deg W 

 33.7489 33,44,56.00 84.4072 84,24,26.00 

63) Plot size: 350.00 km 217.48 mi 

64) Plot Roads option: No Roads 

66) Field intensity contour levels: 

 1) 54.00 dBuV/m 

 2) 74.00 dBuV/m 

66) Contour legend label: Field Intensity (dBuV/m) 

66) Contour labels and colors: 

 Contour levels Labels Colors 

 1 Less than 54.00 Less than 54.00 Blue 

 2 54.00 to 74.00 54.0000 to 74.00 Green 

 3 Greater than 74.00 Greater than 74.00 Clear 

67) Political boundaries: County and State 

68) Landmarks: None