PREFACE

A spectrum survey often depends upon significant efforts by personnel not directly involved in

the measurements. We wish to thank the following people who made the spectrum survey at San

Diego, California a success: Commander H. Hugo of the Naval Command, Control and Ocean

Surveillance Center (NCCOSC), who granted us permission to use the Battery Ashbum area on

Pt. Loma for the survey; T. DiMattio of the Cabrillo National Monument, who granted us access

to Monument property; F. Kirtman of the NCCOSC spectrum management office, who provided

us with information on individual transmitters on the Point; L. Kilgore of the Naval Research and

Development (NRaD) security division, who made physical security arrangements at the site; and

H, Grigsby of the San Diego Federal Communications Commission office for providing valuable

background information on spectrum activities in the San Diego area.

Certain commercial equipment and software are identified in this report to adequately describe

the measurements. In no case does such identification imply recommendation or endorsement

by the National Telecommunications and Information Administration, nor does it imply that the

equipment or software identified are necessarily the best available for the application.

This report, along with other ITS reports, is available on the World Wide Web through the ITS

home page. The home page address is: http://ntia/home. html. The ITS online document page

address is: http://ntia/pub/pubs. html.

. . .

111

CONTENTS

PREFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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

1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.2 Authority . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.3 Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.4 Extrapolation of Spectrum Occupancy Data . . . . . . . . . . . . . . . . . . . . . . .

2. OVERVIEW OF BROADBAND SPECTRUM SURVEYS . . . . . . . . . . . . . . . .

2.1

2.2

2.3

3. SAN

3.1

3.2

3.3

3.4

3.5

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Survey Site Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Spectrum Survey Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DIEGO SPECTRUM SURVEY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Measurement Site Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Data Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Measured Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Observations on Measured Data and Spectrum Use . . . . . . . . . . . . . . . . .

4. REFERENCES

A. APPENDIX A:

B. APPENDIX B:

C. APPENDIX C:

D. APPENDIX D:

RADIO SPECTRUM MEASUREMENT SYSTEM (RSMS) . . .

DATA ACQUISITION SOFTWARE . . . . . . . . . . . . . . . . . . .

INTERPRETATION OF SPECTRUM SURVEY DATA . . . . . .

CALIBRATION OF THE MEASUREMENT SYSTEM . . . . . .

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3

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3

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79

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99

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FIGURES

Figure 1.

Figure 2.

Figure 3.

Figure 4.

Figure 5.

Figure 6.

Figure 7.

Figure 8.

Figure 9.

Figure 10.

Figure 11.

Figure 12.

Figure 13.

Figure 14.

Area map of San Diego, California showing the location of the RSMS

measurement site on Point Loma . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Area map of San Diego, California showing line-of-sight areas from the

RSMS measurement site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ITS Radio Spectrum Measurement System at Point Loma, San Diego,

California . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Spectrum survey graph summarizing swept/m3 measurements in the

108-138 MHz frequency range. . . . . . . . . . . . . . . . . . . . . . . . . .

Spectrum survey graph summarizing swept/m3 measurements in the

138-162 MHz frequency range. . . . . . . . . . . . . . . . . . . . . . . . . . . .

Spectrum survey graph summarizing swept/m3 measurements in the

162-174 MHz frequency range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Spectrum survey graph summarizing swept/m3 measurements in the

174-216 MHz frequency range. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Spectrum survey graph summarizing swept/m3 measurements in the

216-225 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Spectrum survey graph summarizing swept/m3 measurements in the

225-400 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Spectrum survey graph summarizing swept/m3 measurements in the

400-406 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Spectrum survey graph summarizing swept/m3 measurements in the

406-420 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . .

Spectrum survey graph summarizing stepped measurements in the

420-450 MHz frequency range . . . . . . . . . . . . . . . . . . . . .

Spectrum survey graph summarizing swept/m3 measurements

450-470 MHz frequency range . . . . . . . . . . . . . . . . . . . . .

Spectrum survey graph summarizing swept/m3 measurements

470-512 MHz frequency range . . . . . . . . . . . . . . . . . . . . .

in the

. . . . . . . . .

in the

. . . . . . . . .

Page

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15

16

19

20

21

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23

24

25

26

27

28

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vi
FIGURES (Continued)

Page

Figure 15. Spectrum survey graph summarizing swept/m3 measurements in the

512-806 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Figure 16. Spectrum survey graph summarizing swept/m3 measurements in the

806-902 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Figure 17. Spectrum survey graph summarizing swept measurements in the

902-928 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Figure 18. Spectrum survey graph summarizing stepped measurements in the

902-928 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Figure 19. Spectrum survey graph summarizing swept/m3 measurements in the

928-960 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Figure 20. Spectrum survey graph summarizing swept/m3 measurements in the

960-1215 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Figure 21. Spectrum survey graph summarizing stepped measurements in the

1215 -1400 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Figure 22. Spectrum survey graph summarizing swept/m3 measurements in the

1350- 1400 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Figure 23. Spectrum survey graph summarizing swept/m3 measurements in the

1400- 1530 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Figure 24. Spectrum survey graph summarizing swept/m3 measurements in the

1530- 1710 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Figure 25. Spectrum survey azimuth-scan graph of measurements in the

1710-2300 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Figure 26. Spectrum survey graph summarizing swept measurements in the

2300-2500 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Figure 27. Spectrum survey azimuth-scan graph of measurements in the

2500-2700 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Figure 28. Spectrum survey graph summarizing stepped measurements in the

2700-2900 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

vii
FIGURES (Continued)

Figure 29.

Figure 30.

Figure 31.

Figure 32.

Figure 33.

Figure 34.

Figure 35.

Figure 36.

Figure 37.

Figure 38.

Figure 39.

Figure 40.

Figure 41.

Figure 42.

Spectrum survey graph summarizing stepped measurements in the

2900-3100 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Spectrum survey graph summarizing stepped measurements in the

3100-3700 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Spectrum survey azimuth-scan graph of measurements in the

3700-4200 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Spectrum survey graph summarizing swept/m3 measurements in the

4200-4400 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Spectrum survey azimuth-scan graph of measurements in the

4400-5000 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Spectrum survey graph summarizing swept/m3 measurements in the

5000-5250 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Spectrum survey graph summarizing stepped measurements in the

5250-5925 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Spectrum survey azimuth-scan graph of measurements in the

5925 -7125 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Spectrum survey azimuth-scan graph of measurements in the

7125 -8500 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Spectrum survey graph summarizing stepped measurements in the

8500-10550 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . .

Spectrum survey azimuth-scan graph of measurements in the

10550-13250 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . .

Spectrum survey graph summarizing stepped measurements in the

13250-14200 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . .

Spectrum survey azimuth-scan graph of measurements in the

14200- 15700 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . .

Spectrum survey graph summarizing stepped measurements in the

15700- 17700 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . .

Page

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45

46

47

48

49

50

51

52

53

54

55

56

57

viii
FIGURES (Continued)

Figure 43. Spectrum survey azimuth-scan graph of measurements in the

17700-19700 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure A-1. Top and side view drawings of the RSMS . . . . . . . . . . . . . . . . . . . . . .

Figure A-2. Front panel of the RSMS instrument racks . . . . . . . . . . . . . . . . . . . . . .

Figure A-3. Block diagram of the RSMS receiver . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure C-1. Functional diagram of the RSMS signal-processing path for

cumulated data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure D-1. Example calibration graph of noise figure and correction factor curves . .

Figure D-2. Typical noise diode solid state noise source . . . . . . . . . . . . . . . . . . . . .

Figure D-3. Lumped-component noise diode calibration schematic . . . . . . . . . . . . . .

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ix

BROADBAND SPECTRUM SURVEY AT

SAN DIEGO, CALIFORNIA

Frank H. Sanders, Bradley J, Ramsey, and Vincent S. Lawrencel

The National Telecommunications and Information Administration (NTIA) is

responsible for managing the Federal Government’s use of the radio spectrum. In

discharging this responsibility, NTIA uses the Radio Spectrum Measurement System

to collect data for spectrum utilization assessments. This report details such a data

collection effort spanning all of the spectrum from 108 MHz to 19.7 GHz in the

metropolitan area of San Diego, California during February and March of 1995.

Key words: land mobile radio (LMR); radar emission spectrum; radio frequency environment;

Radio Spectrum Measurement System (RSMS); spectrum resource assessment;

spectrum survey.

1. INTRODUCTION

1.1 Background

The National Telecommunications and Information Administration (NTIA) is responsible for

managing the Federal Government’s use of the radio spectrum. Part of this responsibility is to

establish policies concerning spectrum assignment, allocation, and use; and to provide the various

departments and agencies with guidance to ensure that their conduct of telecommunications

activities is consistent with these policies [1, part 8.3], In discharging this responsibility, NTIA

1) assesses spectrum utilization, 2) identifies existing and/or potential compatibility problems

among the telecommunication systems that belong to various departments and agencies,

3) provides recommendations for resolving any compatibility conflicts that may exist in the use

of the frequency spectrum, and 4) recommends changes to promote spectrum efficiency and

improve spectrum management procedures.

Since 1973, NTIA has been collecting data on Federal use of the radio frequency spectrum in

support of the NTIA Spectrum Analysis Program. The Radio Spectrum Measurement System

(RSMS) is used by NTIA to provide technical support for 1) Spectrum Resource Assessments

(SRAs), 2) U.S. participation in the International Telecommunication Union (ITU) conferences

and ITU Radiocommunication Sector (ITU-R) activities, 3) analysis of electromagnetic

compatibility (EMC) problems, 4) interference resolution, and 5) systems review activity related

to new Federal Government systems.

l

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

and Information Administration, U.S. Department of Commerce, Boulder, CO 80303-3328.
1.2 Authority

The RSMS is under the administrative control of the Director of the Institute for Telecommunication Sciences (ITS), The Deputy Associate Administrator of the Office of Spectrum

Management (OSM) is responsible for meeting the spectrum management requirements of NTIA,

as transmitted to him by the Associate Administrator of OSM. RSMS measurement activities

are authorized by the Deputy Associate Administrator of OSM in consultation with the Director

of ITS. Federal agencies with spectrum management problems can request support of the RSMS

through the Deputy Associate Administrator of OSM.

1.3 Purpose

Under Departmental Organizational Order 25-7, issued October 5, 1992 and amended

December 3, 1993, the Office of Spectrum Management is responsible for identifying and

conducting measurements necessary to provide NTIA and the various departments and agencies

with information to ensure effective and efficient use of the spectrum. As part of this NTIA

measurement program, spectrum occupancy measurements are conducted using the RSMS. The

spectrum occupancy data presented in this report do not include identification of specific emitters.

The measured data are provided for the spectrum management community to:

 enable a better understanding of how telecommunication systems use the allocated

spectrum;

 provide timely information on variations in frequency-band usage, e.g., identify

frequency bands becoming heavily used;

 support the NTIA system review process by providing information on the availability of spectrum for new systems; and

 assess the feasibility of promoting alternative types of services or systems that

result in more effective and efficient use of the spectrum.

1.4 Extrapolation of Spectrum Occupancy Data

The spectrum survey measurements contained in this report cannot be solely used to assess the

feasibility of using alternate services or systems in a band. Extrapolation of data in this report

to general spectrum occupancy for alternative spectrum uses requires consideration of additional

factors. These include spectrum management procedures, types of missions performed in the

bands, and new spectrum requirements in the development and procurement stages. Also,

measurement area, measurement site, and measurement system parameters should be considered.

The area chosen for a spectrum survey will affect measured spectrum occupancy. For example,

measurements made in Denver, Colorado [2] are probably representative of many major

metropolitan areas that do not have any maritime radionavigation or heavy military activity.

2
Other cities, such as San Diego, California, show higher levels of usage in bands that support

such activities.

Choice of measurement site within an area can also affect measured spectrum occupancy. An

area such as Seattle-Tacoma, Washington (rough terrain, heavy forestation, and widely dispersed

transmitters) may require multiple measurement sites to adequately characterize usage.

Spectrum management procedures such as band allotments for functions and missions affect

spectrum utilization. For example, channels used for taxi dispatch might show heavy use

whereas channels allocated for law enforcement or public safety may show less use. Regardless

of usage, dedicated channels for these safety-of-life functions remain a spectrum requirement.

Special occurrences such as olympic games, natural disasters, and Presidential inaugurations also

create unique spectrum requirements.

Spectrum measurements provide data on expected signal levels and probability of occurrences

that are essential for assessing alternate uses of the spectrum. Such information cannot be

obtained from band allocation databases or an understanding of spectrum management

procedures.

2. OVERVIEW OF BROADBAND SPECTRUM SURVEYS

2.1 Introduction

Procedures for conducting a broadband spectrum survey using the RSMS are outlined in this

section. Site selection factors, significant measurement system parameters, and hardware and

software configurations developed for the surveys are described. Detailed information on the

system hardware (including the vehicle, instrumentation, antennas, and receiver front-end),

measurement software, and other measurement capabilities are provided in Appendices A and B.

Measurement system response to various types of signals is described in Appendix C. RSMS

calibration theory and application are described in Appendix D.

2.2 Survey Site Selection

A successful spectrum survey (also called a site survey) requires careful selection of a

measurement site. Maximum signal intercept probability and minimum logistic problems are the

first considerations when locating a site for an RSMS spectrum survey.

The primary signal intercept factors are 1) maximum line-of-sight coverage to increase the

probability of weak signal reception such as transmissions from mobile units; 2) limited numbers

of nearby transmitters to prevent intermodulation or saturation problems that can arise even

though preelection and/or filtering is used for survey measurements; and 3) limited man-made

noise such as impulsive noise from automobile ignition systems and electrical machinery that can

add to the received signals of interest and give misleading results.

3
The primary logistic factors are 1) commercial power to increase the probability of completing

the spectrum survey (typically two weeks of 24-hr operation) without power interruptions;

2) commercial telephone for relatively inexpensive reliable communications, compared to the

RSMS cellular telephone that could possibly contaminate the measurements when transmitting;

and 3) security of personnel, vehicle, and electronic hardware.

The ideal site is a well-illuminated, fenced, and patrolled area that satisfies all of the primary site

selection factors above and has reasonable access to lodging for the operating personnel.

2.3 Spectrum Survey Measurements

Spectrum surveys are normally conducted for two weeks using the RSMS in an automatic mode.

The measurement system is preprogrammed to continuously run software algorithms tailored to

the characteristics of the radio emitters that typically occupy measured frequency sub-bands.

Two decades of making such measurements in cities across the United States suggest that general

patterns of spectrum occupancy tend to be repeated from site to site. Emissions from the

following sources are commonly observed during RSMS spectrum surveys:

 land-mobile, marine-mobile and air-mobile communication radios;

 terrestrial, marine and airborne radars, and airborne radio altimeters;

 radionavigation emitters, such as TACAN and VOR;

 cellular and trunked communication systems;

 broadcasting transmitters such as UHF and VHF television, and multipoint distribution systems (wireless cable TV);

 industrial, scientific and medical (ISM) sources, including vehicular tracking

systems, welders, and microwave ovens; and

 common carrier (point-to-point) microwave signals.

Emissions that are not normally receivable during spectrum surveys are:

satellite downlink emissions;

 galactic and solar noise;

 some types of spread spectrum signals; and

 radio transmitters that are turned off.

4
Although the last category is self-evident, questions exist regarding the extent to which users who

have assignments in the radio spectrum either do not operate, or operate very rarely, with those

assignments. Appendix C discusses factors related to probability of intercept and addresses

matters of measurement time vs. statistical significance of data.

As mentioned above, there are many different types of radio signals within the measurement

frequency range, Each is measured with a hardware configuration and measurement algorithm

specifically selected to give the most useful description of the particular type of signal(s)

expected in a frequency sub-band. The measurement system parameters specially configured for

each signal type include: antennas, signal conditioning, tuning speed, measurement bandwidth,

detector mode, and measurement repetitions. The RSMS measurement software automatically

switches the measurement system to the proper configuration for each sub-band. The measurements are repeated in various sub-bands according to specifications established by consideration

of signal intercept probability, signal variability, measurement significance, and expenditure of

system resources.

For spectrum surveys, the RSMS normally performs measurements of general spectrum

occupancy across a frequency range of 108 MHz to 19,7 GHz. To accomplish this task,

measurements are conducted in an automatic mode with the RSMS configured as two measurement systems, identified as “System-1” for frequency measurements below 1 GHz, and

“System-2” for simultaneous measurements above 1 GHz.

The data acquisition (DA) measurement software provides instructions to configure each receiver

system, execute measurement routines, record measured data, and maintain a real-time log of the

measurements and key parameters. The measurement system configuration parameters used by

the software are called “band events” and the automated band event execution procedures are

called “band-event schedules.” Unattended operation of the measurement system for extended

periods of time is made possible through this use of computer control. Remote control of the

RSMS is also possible via a telephone modem linked to the computer. Standardized measurement schedules are used for

measurement processing.

2.3.1 Survey Band Events

each spectrum survey, with the measured data stored for postThe spectrum measured by the RSMS is divided into selected frequency ranges (survey bands)

that are measured according to a computer-stored list of measurement parameters and instrument

settings called a band event. Each band event combines a measurement algorithm (“Swept/m3”

for example) with a particular set of signal input ports, front-end configurations, spectrum

analyzer (SA) modes and settings, and data-recording options. Band-event parameters and

options are detailed in Appendix B. The factors considered when selecting frequency sub-bands,

receiver algorithms, and other parameters for the band events are discussed in Appendix C.

Spectrum survey “standard” band-event parameters for System- 1 and System-2 are shown in

Tables 1 and 2, respectively.

5
Table 1. Spectrum Survey Band Events for RSMS System-1


Each row in the tables, beginning with an event number, shows the measurement parameters for

a specific receiver configuration in the RSMS. Instruction to run the event can come from an

operator or from a computer-loaded band-event schedule as explained in Section 2.3.2. The DA

software, when instructed, sends the command parameters for an event to the system hardware

and initiates measurements for the event. The tables (Table 1 and Table 2) are subdivided into

four parts: 1) “Standard Events” identifies the event number and exact frequency range of

interest, 2) “DA Receiver Parameters” shows input values for receiver configuration subroutines,

3) “DA Spectrum Analyzer Parameters” lists configuration command values sent to the spectrum

analyzer, and 4) “Antenna” identifies the type and gain of the antenna selected for the event.

Appendix B describes DA software configuration routines and the associated table parameters

found in 2) and 3) above.

2.3.2 Band-Event Schedules

Using RSMS measurement control software, any band event can be executed by an operator at

any time. For spectrum surveys, many band events are used to span several gigahertz of

spectrum and each event requires a different amount of time to execute. DA software also

includes an automated band-event execution mode where any of the band events may be

programmed (scheduled) to execute in any sequence for any amount of time (within hardware

limits on continuous operation of the measurement system).

There are two types of schedules used for spectrum surveys with the RSMS: a standard bandevent schedule of all the survey bands, or a special band-event schedule for a few selected survey

bands. For example, if a survey was conducted in a port city, a special schedule might include

only survey bands with assignments for maritime communications (this was not, however, done

in San Diego). Any number of special schedules can be run during a survey.

Tables 3 and 4 show the standard band-event schedules for RSMS System-1 and System-2,

respectively. Tables 5 and 6 show special band-event schedules for measurements in survey

bands expected to show altered usage during adverse weather. The tables include: 1) schedule

number; 2 2) band-event number (specifies which band event to “run” in the schedule); 3) priority

number (value assigned to the band-event data, with (1) being the highest priority); 4) event time

(approximate time in minutes needed to run the event); and 5) accumulative time (approximate

time in hours that the sequence has run).

Band-event priority is an important consideration when scheduling standard band events; i.e.,

some frequency bands in a spectrum survey are of more interest to spectrum managers than

others. In fact, an important part of the preparation for a spectrum survey is a review of local

frequency assignments and allocations. From this preliminary information, measurement

parameters may be modified and band-event priority numbers (1, 2, or 3, with 1 being highest

priority) adjusted to optimize survey data.

2

This is a sequence number used by the scheduling subroutine. Only 64 band events may be

sequenced, but there is no limit on how many times the sequence runs during a survey.

9
.

Table 3. Standard Band-Event Schedule for RSMS System-1

Schedule Band Event Priority Event Time Accumulative

Number Number Number (minutes) Time (hours)

1 12 1 16.3 0.27

2 10 2 1.7 0.30

3 11 2 8.6 0.44

4 17 1 10.8 0.62

5 14 2 5.1 0.71

6 13 3 5.8 0.81

7 19 1 10.8 0.99

8 22 2 10.8 1.17

9 9 1 5.5 1.26

10 20 1 8.3 1.40

11 23 2 5.3 1.48

12 25 1 20.0 1.82

13 18 2 6.7 1.93

14 12 1 16.3 2.20

15 16 3 3.4 2.26

16 17 1 10.8 2.44

17 24 2 6.7 2.55

18 19 1 10.8 2.73

19 10 2 1.7 2.76

20 11 2 8.6 2.90

21 9 1 5.5 2.99

22 20 1 8.3 3.13

23 14 2 5.1 3.22

24 25 1 20.0 3.55

25 21 3 7.3 3.67

26 12 1 16.3 3.94

27 22 2 10.8 4.12

28 17 1 10.8 4.30

29 23 2 5.3 4.39

30 15 3 8.3 4.53

31 19 1 10.8 4.71

32 18 2 6.7 4.82

33 9 1 5.5 4.91

34 20 1 8.3 5.05

35 24 2 6.7 5.16

36 25 1 20.0 5.50

10
Table 4. Standard Band-Event Schedule for RSMS System-2

11
Table 5. Adverse Weather Band-Event Schedule for RSMS System-1

Schedule Band Event Priority Event Time Accumulative

Number Number Number (minutes) Time (hours)

1 12 1 16,3 0.27

2 11 2 10,3 0.44

3 12 1 16.3 0.72

4 14 2 5.1 0.80

Table 6. Adverse Weather Band-Event Schedule for RSMS System-2

Schedule Band Event Priority Event Time Accumulative

Number Number Number (minutes) Time (hours)

1 09 1 37.2 0.62

2 23 2 49,0 1.44

3 05 3 5.6 1.53

4 17 3 5.6 1.62

5 20 2 49.0 2.44

6 14 2 42.0 3.14

7 13 3 18.0 3.44

Highly dynamic bands (where occupancy changes rapidly) include those used by mobile radios

(land, marine, and airborne) and airborne radars. These bands preassigned a high priority and

measured often during a spectrum survey in order to maximize opportunities for signal detection.

Bands that are not very dynamic in their occupancy (such as those occupied by commercial radio

and television signals or fixed emitters such as air traffic control radars) need not be observed

as often, because the same basic occupancy picture will be generated every time. Such bands

are given a low priority and less measurement time. An extreme case is that of the common

carrier bands, which are essentially nondynamic. Generally, these are only measured once during

a survey and are not included in the band-event schedules.

The standard band-event schedules are usually arranged to execute priority 1 events three times

more often than priority 3 events. However, some adjustment to this arrangement may be

necessary to accommodate total time required to complete the sequenced band-event schedule.

For example, if less than two weeks of measurement time were available, a time-consuming

priority 1 event (such as Band Event 27; 15.7-17.7 GHz) might not be run three times as often

as priority 3 events to ensure that all bands would be measured.

12
Because of the many land mobile radio (LMR) bands below 1 GHz, System-1 scheduling reflects

some preplanning for time-of-day analysis. The sequenced schedule is prepared so that all events

will be run within an 8-hr period; such that, after a few days of 24-hr data collection certain

LMR bands will be measured at least once during each hour.

3. SAN DIEGO SPECTRUM SURVEY

3.1 Introduction

This section 1) describes the measurement site selected for a spectrum survey in the San Diego,

California area; 2) briefly describes the data processing used to characterize spectrum occupancy

across the 108-MHz to 19.7-GHz frequency range; and 3) presents the measured data.

3.2 Measurement Site Description

The RSMS was parked on Point Loma, west of Catalina Drive, about 40 m southwest of the

Cabrillo National Monument upper maintenance building and directly above Battery Ashburn.

The location was about 9.5 km (6 mi) west-by-southwest of downtown San Diego, on property

owned by the U.S. Navy. The site coordinates were 117°14’38.2” W, 32°40’39.8” N. Base

altitude was 116 m MSL. The only structure at the site that was higher than the RSMS antennas

was a mast (made of metal and approximately 2 ft in diameter) about 15 m high and about 80 m

from the RSMS.

The site was well removed from fixed RF transmitters and man-made noise sources such as

vehicular traffic. Mobile communications originating on Point Loma were primarily associated

with the Cabrillo Monument maintenance staff, the Navy Public Works Center, and security

patrols. Figure 1 shows the location of the RSMS in the San Diego area. Figure 2 shows areas

that were line-of-sight (white) to the RSMS from 2 m above ground (typical mobile antenna

height) and those areas that were obstructed (shaded with plus (+) signs) from the RSMS due to

terrain. Figure 3 shows the RSMS deployed at Point Loma.

The San Diego metropolitan area occupies a low coastal zone that is bounded by high mountains

to the east, and rough but lower terrain to the north. It adjoins the city of Tijuana, Mexico on

the southern side of the U.S./Mexico border. Prominent physical features in the area include

Mission Bay, San Diego Bay, and a large peninsula, named North Island, forming one side of

San Diego Bay. North Island and the bays support extensive naval, commercial shipping, and

aviation activities that contribute to spectrum usage. (For example, America’s Cup qualifying

races were being held near Point Loma; during one race, a rescue operation requiring radio

communications occurred). Urban development in the area is extensive. Figure 2 shows that the

RSMS survey location on Pt. Loma afforded mostly unbroken line-of-sight coverage of the San

Diego metropolitan area. Line-of-sight coverage over the ocean extended to a radius of about

40 km (24 mi) from the RSMS location on the Point.

13
Figure 1. Area map of San Diego, California showing the location of the RSMS on Point

Loma. Map produced with MapExpertTM software from DeLorme Mapping.

14
Figure 2. Area map of San Diego, California showing regions that are line-of-sight (white) and

nonline-of-sight (terrain shadowed) from the RSMS raised antennas. Terrain

shadowing overlay provided by ITS Telecommunications Analysis Services.

15
Figure 3. ITS Radio Spectrum Measurement System at Point Loma, San Diego, California.

16
Also shown in Figure 2, RSMS coverage included much of the Tijuana area. Most spectrum

usage in Tijuana is thought to occur below 1 GHz. The RSMS measurements in this frequency

range were performed with a 6-dBi gain log periodic antenna pointed toward downtown San

Diego, thus enhancing RSMS reception of San Diego-area signals relative to signals from

Tijuana. However, the spectrum occupancy data from San Diego

also contain some Tijuana usage, particularly below 1 GHz.

3.3 Data Considerations

undoubtedly (and unavoidably)

The San Diego survey was performed as outlined in Section 2. The band-event tables (Table 1

for System- 1 and Table 2 for System-2) in Section 2.3.1 list the measurement system parameters

used for each survey band. Appendix C contains explanations of the measurement algorithm

selections. All survey bands for System- 1 were measured with a 100-MHz to 1-GHz log periodic

antenna (LPA) mounted at a 45° angle (for slant polarization) on the small mast and aimed

toward downtown San Diego. The System-2 survey bands (except for azimuth-scanning bands3

)

were measured with a 500-MHz to 18-GHz slant polarized biconical omni antenna mounted on

the large mast. For the azimuth-scanning survey bands (event numbers 10, 12, 16, 18, 21, 22,

24, 26, and 28) a rotating l-m Tecom dish (dual horizontal/vertical feed) antenna was used. See

Appendix A for more on antennas and RF front-end hardware configurations.

All of the measured data, except the azimuth-scanning measurements previously mentioned,

underwent an additional cumulative processing (cuming) step before being displayed. Every

frequency data point recorded for Swept/m3 measurements was cumulated (cumed) such that the

graphed data points (received signal levels; RSLS) show the maximum of maximum RSLS, mean

of mean RSLS, and minimum of minimum RSLS (see Section C.3.1 of Appendix C for a

discussion of Swept/m3 cumulative processing). Cuming of Stepped and Swept measurements

results in graphs showing maximum, mean, and minimum RSLs of all scans. On all graphs of

cumed data, maximum and minimum curves are drawn with solid lines and mean curves with

dashed lines.

The data collection rate for the San Diego survey was increased by decreasing the number of

steps used to measure some survey bands (specifically, band events 20, 23, 25, and 27). This

change was made to assess the trade-off between reduced steps and accelerated measurement rate.

The reduced-step results are comparable to those of RSMS surveys performed in these bands

during the last twenty years.

Strong received signal levels from FM radio broadcast stations below 108 MHz generated

intermodulation products in the normally configured RSMS front-end. To eliminate such

responses, 40 dB of attenuation was inserted at the RF front-end for measurements below

114 MHz. This desensitized the RSMS measurements by 40 dB at these frequencies.

3

The azimuth-scanning measurement routine is a special operator-interactive technique using a

rotating dish antenna with the DA Swept measurement algorithm. See Sections B.2 and C.8 in

Appendices B and C for more about scanning.

17
Consequently, the possibility of receiving measurable signals in this range (such as instrumentlanding system glideslope transmissions) was greatly reduced. However, a signal at 109.8 MHz

was still detected. Similarly, commercial television broadcast signals forced the addition of

20 dB attenuation in the 174-216 MHz range and 30 dB additional attenuation in the 470-

490 MHz range.

3.4 Measured Data

Each survey band of measured data is graphically displayed on a single page along with

corresponding frequency allocations and assignment information (Figures 4-43). Each surveyband figure has an identical format. The principal band-event parameters and measurement

location are included in the figure caption. The survey-band graphs in the middle of the page

show frequency in megahertz on the x-axis vs. received signal level marked at 5-dBm increments

on the y-axis. Noise level tick marks on the y-axis of some graphs (e.g., “avg sample noise” and

“rein sample noise” on Figure 4) show measurement noise limits. Measurement system noise and

system response to various types of signals are described in Appendix C.

The text above each graph (delimited by horizontal and vertical lines) shows the applicable U.S.

Government and non-Govemment frequency allocations and corresponding typical user

information (general utilization) for the survey band. The vertical lines delimit, by frequency,

both the allocations and the measured survey-band graph on the same page.

The frequency allocations (services) are entered according to convention just as they appear in

the “U.S. Government Table of Frequency Allocations” [1, part 4. 1.3]. Briefly summarized: the

names of primary services are printed in capital letters; secondary services are printed in normal

upper and lower case; and where the allocated service is followed by a function in parenthesis,

the allocation is limited to the function shown.

The vertical lines are placed according to frequency separations in the allocation tables. The

frequencies are written at the lower end of the vertical lines and are always in megahertz. Any

service entry that does not fit within the line-delimited space above the graph is given a number

referencing the complete allocation text below the graph on the same page. If there is additional

information pertinent to a specific Government or non-Govemment allocation, it is indicated by

a number referencing a note below the graph. General utilization, i.e., typical assignment usage

notes (for the Government or non-Government allocations that fall between the same vertical line

delimiters) also have a reference number if insufficient space is available. All notes are written

in simple text format distinguishable from the allocated service entries that are entered according

to convention as explained above.

It should be noted that the appearance of survey-band graphs is substantially affected by the

measurement parameters and the analysis techniques employed. For example, data in Figures 5

and 6 were measured with similar techniques; but, Figure 5 appears to show a denser signal

population than Figure 6. Closer examination shows that Figure 5 covers twice the frequency

range of Figure 6 and this may be a primary reason for the apparently denser signal environment

of Figure 5. Similarly, various band events may be plotted with different amplitude scales or

18
19

40 dB added attenuation

(see note below)

GOVERNMENT AERONAUTICAL RADIONAVIGATION. AERONAUTICAL AERONAUTICAL MOBILE. AERONAUTICAL 4.

ALLOCATIONS: MOBILE. MOBILE.

NON-GOVERNMENT AERONAUTICAL RADIONAVIGATION. AERONAUTICAL 1. AERONAUTICAL MOBILE. 3. AERONAUTICAL 3. 4.

ALLOCATIONS: MOBILE. MOBILE.

GENERAL VHF Omnidirectional Range (VOR). Air Traffic Control. 1. Air Traffic Control (ATC). 2. Air Traffic Control. 5.

UTILIZATION:

108 117.975 121.9375-123.0875 128.8125 132.0125 136 137 138

avg sample noise

min sample noise

Note: Concerning 108-114 MHz attenuated data, see comments in Table 7 (Section 3.5.1). 4. SPACE OPERATION (space-to-Earth), METEOROLOGICAL-SATELLITE (space-to-Earth), SPACE

1. AERONAUTICAL MOBILE. Private aircraft. 137.025-137.175 MHz and 137.825-138: Mobile-Satellite.

2. 123.1 MHz: SAR (search and rescue) operations. 5. Government use includes TIROS downlinks; non-Government includes nongeostationary nonvoice mobile

3. AERONAUTICAL MOBILE. satellite systems (Little LEOS).

RESEARCH (space-to-Earth), 137-137.025 MHz and 137.175-137.825 MHz: MOBILE-SATELLITE,

Figure 4. NTIA spectrum survey graph summarizing 7,000 sweeps across the 108-138 MHz range (System-1, band event 11, swept/m3

algorithm, sample detector, 10-kHz bandwidth) at San Diego, CA, 1995.
2

0

GOVERNMENT FIXED, MOBILE. FIXED, 5,6. 8.

ALLOCATIONS: MOBILE, 3.

NON-GOVERNMENT AMATEUR, AMATEUR. 3. 5. LAND MOBILE. 8. LAND MOBILE. 9.

ALLOCATIONS: 2.

GENERAL Non-tactical military land mobile 4. 7. Land transportation, public safety, Land transportation, public

UTILIZATION: communications. 1. industrial, Earth telecommand, etc. safety, industrial, etc.

138 144 146 148 149.9 150.8 156.2475 157.45 161.575-162.0125

avg sample noise

min sample noise

1. 143.75 MHz and 143.9 MHz: Civil Air Patrol. 5. 149.9-150.05 MHz: RADIONAVIGATION-SATELLITE, MOBILE-SATELLITE (Earth-to-space).

2. AMATEUR-SATELLITE. 6. 150.05-150.8 MHz: FIXED, MOBILE.

3. MOBILE-SATELLITE (Earth-to-space). 7. Government use includes military non-tactical mobile and fixed communications and TRANSIT-SAT

4. Non-tactical military land mobile communications. 148.15 MHz: Civil Air Patrol. Government use includes downlinks. Non-Government use includes "Little LEOS."

TIROS command links and NASA satellite operations. Non-Government use includes nongeostationary 8. MARITIME MOBILE. 157.0375-157.1875 MHz: Govt only, VHF distress systems communications.

nonvoice mobile satellite systems (Little LEOS). 9. MARITIME MOBILE. 161.625-161.775 MHz: LAND MOBILE.

Figure 5. NTIA spectrum survey graph summarizing 7,000 sweeps across the 138-162 MHz range (System-1, band event 11, swept/m3

algorithm, sample detector, 10-kHz bandwidth) at San Diego, CA, 1995.
21

GOVERNMENT FIXED, MOBILE 3.

ALLOCATIONS:

NON-GOVERNMENT 1.

ALLOCATIONS:

GENERAL Land Mobile Radio (LMR) including weather radio, public safety, and law enforcement. 2.

UTILIZATION:

162.0125 173.2-173.4 174

avg sample noise

min sample noise

1. FIXED, Land Mobile. 3. FIXED, MOBILE.

2. Industrial, public safety.

Figure 6. NTIA spectrum survey graph summarizing 52,500 sweeps across the 162-174 MHz range (System-1, Band Event 12,

swept/m3 algorithm, sample detector, 10-kHz bandwidth) at San Diego, CA, 1995.
2

2

20 dB added attenuation (see note below)

GOVERNMENT

ALLOCATIONS:

NON-GOVERNMENT BROADCASTING (television broadcasting), 1, 2.

ALLOCATIONS:

GENERAL Channel 7 Channel 8 Channel 9 Channel 10 Channel 11 Channel 12 Channel 13

UTILIZATION:

174 180 186 192 198 204 210 216

avg sample noise

min sample noise

Note: Concerning 174-216 MHz attenuated data, see comments in Table 7 (Section 3.5.1). 2. TV broadcast licencees are permitted to use subcarriers on a secondary basis for both broadcast and non1. Subscription television services and limited wireless microphone operations are also permitted in this band.

broadcast purposes.

Figure 7. NTIA spectrum survey graph summarizing 18,500 sweeps across the 174-216 MHz range (System-1, band event 13,

swept/m3 algorithm, sample detector, 100-kHz bandwidth) at San Diego, CA, 1995.
2

3

GOVERNMENT MARITIME MOBILE, Radiolocation, Fixed, Aeronautical Mobile, 1, 2. LAND MOBILE, Radiolocation, 1. Radiolocation, 1.

ALLOCATIONS:

NON-GOVERNMENT MARITIME MOBILE, Fixed, Radiolocation, Aeronautical Mobile, 2. LAND MOBILE. AMATEUR.

ALLOCATIONS:

GENERAL Automated maritime telecommunications systems. Trunked and conventional systems. Amateur (1.25 meters).

UTILIZATION:

216 220 222 225

avg sample noise

min sample noise

1. Radiolocation is limited to the military services. 2. Secondary services, other than radiolocation, are generally limited to telemetering and associated telecommand

operations.

Figure 8. NTIA spectrum survey graph summarizing 4,020 sweeps across the 216-225 MHz range (System-1, band event 14, swept/m3

algorithm, sample detector, 3-kHz bandwidth) at San Diego, CA, 1995.

2

5

RSMS not configured to receive space-to-Earth transmissions

GOVERNMENT 1. METEOROLOGICAL AIDS (Radiosonde), 2, 3, 4, 5.

ALLOCATIONS:

NON-GOVERNMENT 1. METEOROLOGICAL AIDS (Radiosonde), 3, 4, 5.

ALLOCATIONS:

GENERAL 1. Meteorological radiosondes and satellite communication including GOES and TIROS-N.

UTILIZATION:

400.05-400.15 406

 avg sample noise

 min sample noise

1. STANDARD FREQUENCY AND TIME SIGNAL-SATELLITE (400.1 MHz ±25 kHz). 4. 401-402 MHz: SPACE OPERATION (space-to-Earth), Earth Exploration-Satellite (Earth-to-space),

2. 400.15-401 MHz: METEOROLOGICAL-SATELLITE (space-to-Earth). Meteorological-Satellite. (Earth-to-space).

3. 400.15-401 MHz: SPACE RESEARCH (space-to-Earth), MOBILE-SATELLITE (space-to-Earth), Space 5. 402-403 MHz: Earth Exploration-Satellite (Earth-to-space), Meteorological-Satellite (Earth-to-space).

Operation (space-to-Earth).

Figure 10. NTIA spectrum survey graph summarizing 2,040 sweeps across the 400-406 MHz range (System-1, band event 16, swept/m3

algorithm, sample detector, 3-kHz bandwidth) at San Diego, CA, 1995.
2

6

GOVERNMENT 1 FIXED, MOBILE, RADIO ASTRONOMY, FIXED, MOBILE, Space Research (space-to-space), 2.

ALLOCATIONS: 2.

NON-GOVERNMENT 1 RADIO ASTRONOMY.

ALLOCATIONS:

GENERAL

UTILIZATION: 1 LMR, 2. LMR, 2.

406-406.1 410 420

avg sample noise

min sample noise

1. MOBILE-SATELLITE (Earth-to-space). Low power satellite emergency position-indicating radiobeacons 2. Fixed and mobile services are allocated for Government nonmilitary agencies. Military use may be authorized

(EPIRB) only. Supported by the joint U.S. SARSAT/Russian COSPAS satellite network. on a local-coordinated, secondary, noninterfering basis.

Figure 11. NTIA spectrum survey graph summarizing 20,600 sweeps across the 406-420 MHz range (System-1, band event 17,

swept/m3 algorithm, sample detector, 10-kHz bandwidth) at San Diego, CA, 1995.
2

7

GOVERNMENT RADIOLOCATION.

ALLOCATIONS:

NON-GOVERNMENT Amateur.

ALLOCATIONS:

GENERAL Long-range surveillance radars, 1, 2.

UTILIZATION:

420 450

 avg +peak noise

 min +peak noise

1. Radiolocation is limited to military services. Primarily, long-range radar systems essential to the nations early 2. There is some non-Government use of spread spectrum modes; also, amateur weak signal modes (432-

warning capability, law enforcement, and tracking objects in space. These systems use very high power and 433 MHz), television (420-432 & 438-444 MHz), repeaters (442-450 MHz), auxiliary links (433-435 MHz),

wide bandwidths. Low power radio control operations are permitted in the band. NASA and military use of and amateur satellite (435-438 MHz).

telemetry and telecommand is also extensive.

Figure 12. NTIA spectrum survey graph summarizing 68 scans across the 420-450 MHz range (System-1, band event 18, stepped

algorithm, +peak detector, 1000-kHz bandwidth) at San Diego, CA, 1995.
2

8

GOVERNMENT Meteorological-Satellite (space-to-Earth).

ALLOCATIONS:

NON-GOVERNMENT LAND MOBILE. LAND MOBILE.

ALLOCATIONS:

GENERAL LMR, 1, 2, 3. LMR, 1, 2, 3. LMR, 2, 4, 5. LMR, 2, 4, 5.

UTILIZATION: (base or mobile) (mobile only) (base or mobile) (mobile only)

450 455 460 465 470

avg sample noise

min sample noise

1. 450-451 MHz and 455-456 MHz: Remote pickup broadcast. 3. 454-455 MHz and 459-460 MHz: Domestic Public.

2. 451-454 MHz, 456-459 MHz, 460-462.5375 MHz, 462.7375-467.5375 MHz, and 4. 462.5375-462.7375 MHz and 467.5375-467.7375 MHz: Personal.

467.7375-470 MHz: Public Safety, Industrial, Land Transportation. 5. 460-470 MHz: GOES and TIROS satellite downlinks.

Figure 13. NTIA spectrum survey graph summarizing 20,400 sweeps across the 450-470 MHz range (System-1, band event 19,

swept/m3 algorithm, sample detector, 10-kHz bandwidth) at San Diego, CA, 1995.
2

9

30 dB added attenuation (see note below)

GOVERNMENT

ALLOCATIONS:

NON-GOVERNMENT BROADCASTING, LAND MOBILE, 1, 2.

ALLOCATIONS:

GENERAL Channel 14 Channel 15 Channel 16 Channel 17 Channel 18 Channel 19 Channel 20

UTILIZATION:

470 476 482 488 494 500 506 512

max sample noise

avg sample noise

min sample noise

Note: Concerning 470-490 MHz attenuated data, see comments in Table 7 (Section 3.5.1). 2. The band is also allocated to the fixed service to permit subscription television operations.

1. Land Mobile Radio Services include Public Safety, Domestic Public, Industrial, and Land Transportation

assignments in specific urban areas.

Figure 14. NTIA spectrum survey graph summarizing 9,600 sweeps across the 470-512 MHz range (System-1, band event 20, swept/m3

algorithm, sample detector, 10-kHz bandwidth) at San Diego, CA, 1995.
3

0

GOVERNMENT 1.

ALLOCATIONS:

NON-GOVERNMENT BROADCASTING. 1. BROADCASTING.

ALLOCATIONS:

GENERAL Television broadcasting (channels 21-36). Television broadcasting (channels 38-69).

UTILIZATION:

512 608-614 806

avg sample noise

min sample noise

1. RADIO ASTRONOMY. No stations are authorized to transmit in this band.

Figure 15. NTIA spectrum survey graph summarizing 5,800 sweeps across the 512-806 MHz range (System-1, band event 21, swept/m3

algorithm, sample detector, 100-kHz bandwidth) at San Diego, CA, 1995.
31

GOVERNMENT

ALLOCATIONS:

NON-GOVERNMENT LAND MOBILE, 1.

ALLOCATIONS:

GENERAL Conventional and 2. Cellular Systems (Public Mobile). 4. Conventional and 3. Cellular Systems (Public Base). 5. 6, 7.

UTILIZATION: Trunked (mobile). Trunked (base).

806 821 824 849-851 866 869 894 896 902

avg sample noise

min sample noise

1. 806-890 MHz: Limited allocation is available for TV Channels 70-83. 5. Aeronautical Mobile (air-to-ground).

2. Public Safety (mobile). 6. 896-901 MHz: Private Land Mobile (paired with 935-940 MHz).

3. Public Safety (base). 7. 901-902 MHz: General Mobile.

4. Aeronautical Mobile (ground-to-air).

Figure 16. NTIA spectrum survey graph summarizing 4,020 sweeps across the 806-902 MHz range (System-1, band event 22, swept/m3

algorithm, sample detector, 10-kHz bandwidth) at San Diego, CA, 1995.
3

2

GOVERNMENT RADIOLOCATION.

ALLOCATIONS:

NON-GOVERNMENT

ALLOCATIONS:

GENERAL Military radiolocation systems, Industrial scientific and medical (ISM), Automatic Vehicle Monitoring (AVM), spread spectrum devices, microwave ovens, digital communications,

UTILIZATION: repeaters, 1.

902 928

min maxhold noise

1. Fixed and mobile radio services are permitted on a secondary basis; however, band utilization is increasing for non-Government ISM, spread spectrum and other modes, amateur, etc., as permitted in Region 2.

Figure 17. NTIA spectrum survey graph summarizing 16,800 sweeps across the 902-928 MHz range (System-1, band event 23, swept

algorithm, maximum-hold detector, 10-kHz bandwidth) at San Diego, CA, 1995.
3

3

GOVERNMENT RADIOLOCATION.

ALLOCATIONS:

NON-GOVERNMENT

ALLOCATIONS:

GENERAL Military radiolocation systems, Industrial scientific and medical (ISM), Automatic Vehicle Monitoring (AVM), spread spectrum devices, microwave ovens, digital communications,

UTILIZATION: repeaters, 1.

902 928

min +peak noise

1. Fixed and mobile radio services are permitted on a secondary basis; however, band utilization is increasing for non-Government ISM, spread spectrum and other modes, amateur, etc., as permitted in Region 2.

Figure 18. NTIA spectrum survey graph summarizing 63 scans across the 902-928 MHz range (System-1, band event 24, stepped

algorithm, +peak detector, 1000-kHz bandwidth) at San Diego, CA, 1995.
3

4

GOVERNMENT FIXED. FIXED.

ALLOCATIONS:

NON-GOVERNMENT 1. LAND FIXED. LAND MOBILE. 5. FIXED. FIXED.

ALLOCATIONS: MOBILE

GENERAL 1. 2. 3. Private land mobile (base), 3. Auxiliary broadcasting, private fixed microwave, studio-to-transmitter links (STL's), 6.

UTILIZATION: 4.

928 929 932 935 940 941 944 960

max sample noise

avg sample noise

min sample noise

1. FIXED. Private fixed microwave, public and private land mobile, telemetry applications. Two-way services 4. Trunked and conventional systems in 12.5 kHz channels (paired with 896-901 MHz).

paired with 952-953 MHz. 5. MOBILE.

2. Public and private land mobile. 6. 944-952 MHz: Primarily STL's. 952-953 MHz paired with 928-929 MHz. 953-960 MHz: Primarily, fixed

3. Paired band for point-to-point and point-to-multipoint communications. point-to-point communications.

Figure 19. NTIA spectrum survey graph summarizing 27,600 sweeps across the 928-960 MHz range (System-1, band event 25,

swept/m3 algorithm, sample detector, 10-kHz bandwidth) at San Diego, CA, 1995.
3

5

GOVERNMENT

AERONAUTICAL RADIONAVIGATION, 1.

ALLOCATIONS:

NON-GOVERNMENT AERONAUTICAL RADIONAVIGATION, 1.

ALLOCATIONS:

GENERAL TACAN, DME, MLS, ATCRBS, MODE-S, T-CAS, JTIDS, 2.

UTILIZATION:

960 1215

 

avg +peak noise

min +peak noise

1. The 960-1215 MHz band is reserved on a worldwide basis for the use and development of electronic aids to air 2. Tactical Air Navigation (TACAN). Distance Metering Equipment (DME). Microwave Landing System (MLS).

navigation. On a case by case basis, Government systems utilizing spread spectrum techniques for terrestrial Air Traffic Control Radar Beacon system (ATCRBS, MODE-S, and IFF). Collision Avoidance System

communication, navigation and identification may be authorized on condition that aeronautical radionavigation (T-CAS). Joint Tactical Information Distribution System (JTIDS).

services not experience harmful interference.

Figure 20. NTIA spectrum survey graph summarizing 36,500 sweeps across the 960-1215 MHz range (System-2, band event 05,

swept/m3 algorithm, +peak detector, 300-kHz bandwidth) at San Diego, CA, 1995.
3

6

GOVERNMENT RADIOLOCATION, RADIOLOCATION. AERONAUTICAL RADIONAVIGATION, FIXED, MOBILE, RADIOLOCATION.

ALLOCATIONS: 1. Radiolocation.

NON-GOVERNMENT Amateur. AERONAUTICAL RADIONAVIGATION.

ALLOCATIONS:

GENERAL 2, 3, 4. 3, 4, 5. 3, 4. 3, 6, Fixed and Mobile links.

UTILIZATION:

1215 1240 1300 1350 1400

1. RADIONAVIGATION-SATELLITE (space-to-Earth). 4. Tethered balloon mounted radar for drug interdiction.

2. 1227.6 MHz: Global Positioning System (GPS). 5. Amateur television. Amateur weak signal modes and other modes. Amateur satellite (Earth-to-space).

3. High-power long-range surveillance radars including FAA Air-Route Surveillance Radar (ARSR). 6. 1381.05 MHz: GPS data relay.

Figure 21. NTIA spectrum survey graph summarizing 28 scans across the 1215-1400 MHz range (System-2, band event 06, stepped

algorithm, +peak detector, 1000-kHz bandwidth) at San Diego, CA, 1995.
3

7

GOVERNMENT FIXED, MOBILE, RADIOLOCATION, 1.

ALLOCATIONS:

NON-GOVERNMENT 1.

ALLOCATIONS:

GENERAL Military radiolocation, fixed and mobile links, GPS, aeronautical radionavigation, 2, 3.

UTILIZATION:

1350 1400

 avg sample noise

 min sample noise

1. 1350-1370 MHz: AERONAUTICAL RADIONAVIGATION (allocation for U.S. and Canada only). 3. 1369.05-1393.05 MHz: Fixed and mobile satellite services (space-to-Earth) for the relay of nuclear burst data.

2. Military radiolocation applications are primarily high-power long-range surveillance radars. GPS operates at 1381.05 MHz to relay data detected by orbiting satellites.

Figure 22. NTIA spectrum survey graph summarizing 4,900 sweeps across the 1350-1400 MHz range (System-2, band event 07,

swept/m3 algorithm, sample detector, 10-kHz bandwidth) at San Diego, CA, 1995.
3

8

GOVERNMENT RADIO ASTRONOMY, 1. 2. 3. MOBILE (Aeronautical telemetering).

ALLOCATIONS:

NON-GOVERNMENT RADIO ASTRONOMY, 1. 4. 5. MOBILE (Aeronautical telemetering).

ALLOCATIONS:

GENERAL Passive. Aeronautical telemetry and telecommand.

UTILIZATION:

1400 1427-1429 1435 1530

max sample noise

avg sample noise

min sample noise

1. EARTH EXPLORATION-SATELLITE (Passive), SPACE RESEARCH (Passive). 4. SPACE OPERATION (Earth-to-space), Land Mobile (Telemetering and telecommand), Fixed (Telemetering).

2. FIXED, MOBILE except aeronautical mobile, SPACE OPERATION (Earth-to-space). 5 Land Mobile (Telemetering and telecommand), Fixed (telemetering).

3. FIXED, MOBILE.

Figure 23. NTIA spectrum survey graph summarizing 9,600 sweeps across the 1400-1530 MHz range (System-2, band event 08,

swept/m3 algorithm, sample detector, 30-kHz bandwidth) at San Diego, CA, 1995.

4

0

RSMS not configured to receive space-to-Earth transmissions

GOVERNMENT FIXED, MOBILE. FIXED (LOS only), 5.

ALLOCATIONS: MOBILE (LOS only), 3.

NON-GOVERNMENT FIXED. MOBILE, Fixed. 6.

ALLOCATIONS:

GENERAL LOS fixed links, telemetry, Private fixed microwave. Auxiliary broadcasting, domestic public fixed, cable TV, control TDRSS, SGLS, 4. 7.

UTILIZATION: telecommand, 1. Future PCS. and repeater links, point to multipoint video, cellular, 2.

1710 1850 1990 2200 2290-2300

min maxhold noise

1. Predominantly federal medium-capacity line of sight (LOS) fixed service band. 3. SPACE RESEARCH (space-to-Earth) (space-to-space), SPACE OPERATION (space-to-Earth) (Earth-to2. 1990-2110 MHz: Electronic news gathering (ENG). GOES uplink, NASA's global ground network and space), EARTH EXPLORATION-SATELLITE space-to-Earth)(space-to-space).

TDRSS (2025-2110 MHz). 2110-2200 MHz: NASA space and Earth to space command links support 4. Space telemetry, telecommand and control systems. Fixed microwave.

Pioneers, Voyagers, MAGELLAN, GALILEO, and ULYSSES (2110-2120 MHz). Paired fixed links (2110- 5. FIXED, MOBILE except aeronautical mobile, SPACE RESEARCH (space-to-Earth) (Deep Space only).

2130 MHz with 2160-2180 MHz; 2130-2150 MHz with 2180-2200 MHz). Point-to-point and point to 6. SPACE RESEARCH (space-to-Earth) (Deep Space only).

multipoint links (2150-2160 MHz). 7. NASA deep space network space-to-Earth telemetry. Radio astronomy observations.

Figure 25. NTIA spectrum survey azimuth-scan graph of the 1710-2300 MHz range (System-2, band event 10, swept algorithm,

maximum-hold detector, 100-kHz bandwidth) at San Diego, CA, 1995.
41

GOVERNMENT 1. RADIOLOCATION, MOBILE, Fixed. RADIOLOCATION, 5.

ALLOCATIONS:

NON-GOVERNMENT 2. MOBILE. 6. Amateur. FIXED, MOBILE,

ALLOCATIONS: Radiolocation. 8.

GENERAL 3. Telemetry, telemetry communications, aeronautical telemetry, 4. Amateur Satellite (space-to-Earth). 7. 7, 9.

UTILIZATION: Amateur mixed modes, 7.

2300 2310 2390 2400 2450 2483.5 2500

min maxhold noise

1. RADIOLOCATION, Fixed, Mobile. 6. AMATEUR.

2. Amateur. 7. 2400-2500 MHz: Is also used for industrial scientific and medical (ISM) applications including microwave

3. Amateur weak signal modes and other modes. ovens.

4. AF High-power long-range surveillance radar and air traffic control radar. Venus Radar Mapper (VRM) 8. RADIODETERMINATION-SATELLITE (space-to-Earth).

synthetic aperture radar. 9. Satellite downlinks and multichannel fixed and portable video transmission by TV broadcasters.

5. No Government allocations in this band after August 1995.

Figure 26. NTIA spectrum survey graph summarizing 28,800 sweeps across the 2300-2500 MHz range (System-2, band event 11, swept

algorithm, maximum-hold detector, 100-kHz bandwidth) at San Diego, CA, 1995.
4

2

RSMS not configured to receive space-to-Earth transmissions

GOVERNMENT 3. 4.

ALLOCATIONS:

NON-GOVERNMENT BROADCASTING-SATELLITE, FIXED, 1. FIXED, BROADCASTING- 4.

ALLOCATIONS: SATELLITE, 1, 3.

GENERAL Auxiliary broadcasting, pay television distribution, private video teleconferences, educational television (ITSF), 2. Private fixed microwave, 2.

UTILIZATION:

2500 2655 2690 2700

min maxhold noise

1. Broadcasting-satellite service is limited to community reception of educational and public service television 3. Earth Exploration-Satellite (Passive), Radio Astronomy, Space Research (Passive).

programming. 4. EARTH EXPLORATION-SATELLITE (Passive), RADIO ASTRONOMY, SPACE RESEARCH (Passive).

2. 2500-2686 MHz: Omnidirectional transmission of multipoint MDS that can be contained within 6 MHz

channel bandwidths.

Figure 27. NTIA spectrum survey azimuth-scan graph of the 2500-2700 MHz range (System-2, band event 12, swept algorithm,

maximum-hold detector, 10-kHz bandwidth) at San Diego, CA, 1995.
4

3

GOVERNMENT AERONAUTICAL RADIONAVIGATION, METEOROLOGICAL AIDS, Radiolocation, 1, 2.

ALLOCATIONS:

NON-GOVERNMENT

ALLOCATIONS:

GENERAL Airport surveillance radars (ASRs), military ground control approach radars (GCAs), NWS weather radars (NEXRAD, etc.), long-range surveillance radars and air traffic control radars.

UTILIZATION:

2700 2900

min +peak noise

1. The aeronautical radionavigation service is restricted to ground-based radars and associated airborne 2. The secondary radiolocation service is limited to the military and must be fully coordinated with the primary

transponders that transmit only in this band when actuated by these radars. services.

Figure 28. NTIA spectrum survey graph summarizing 28 scans across the 2700-2900 MHz range (System-2, band event 13, stepped

algorithm, +peak detector, 1000-kHz bandwidth) at San Diego, CA, 1995.
4

4

GOVERNMENT MARITIME RADIONAVIGATION, Radiolocation, 1, 2.

ALLOCATIONS:

NON-GOVERNMENT MARITIME RADIONAVIGATION, Radiolocation, 1, 2.

ALLOCATIONS:

GENERAL Maritime radars and radar beacons (racons), military high-power 3-D long-range surveillance radars and air traffic control radars.

UTILIZATION:

2900 3100

min +peak noise

1. Radiolocation assignments are primarily for the military; however, other agency use is permitted for 2. 2900-3000 MHz: Also, allocated for next generation weather radar (NEXRAD) systems.

experimentation, research, and survey operations, if no harmful interference occurs.

Figure 29. NTIA spectrum survey graph summarizing 48 scans across the 2900-3100 MHz range (System-2, band event 14, stepped

algorithm, +peak detector, 1000-kHz bandwidth) at San Diego, CA, 1995.
4

5

GOVERNMENT RADIOLOCATION. RADIOLOCATION. RADIOLOCATION, 1. RADIOLOCATION, 1.

ALLOCATIONS:

NON-GOVERNMENT Radiolocation. Amateur, Radiolocation. Radiolocation. FIXED-SATELLITE

ALLOCATIONS: (space-to-Earth), 2.

GENERAL 3. 3. 3. INMARSAT, INTELSAT.

UTILIZATION:

3100 3300 3500 3600 3700

min +peak noise

1. AERONAUTICAL RADIONAVIGATION (Ground-based). 3. Primarily, military airborne, land-based, and shipborne defense radars.

2. Radiolocation.

Figure 30. NTIA spectrum survey graph summarizing 46 scans across the 3100-3700 MHz range (System-2, band event 15, stepped

algorithm, +peak detector, 3000-kHz bandwidth) at San Diego, CA, 1995.
4

6

RSMS not configured to receive space-to-Earth transmissions

GOVERNMENT

ALLOCATIONS:

NON-GOVERNMENT FIXED, FIXED-SATELLITE (space-to-Earth).

ALLOCATIONS:

GENERAL Domestic public fixed, satellite communications.

UTILIZATION:

3700 4200

min maxhold noise

Figure 31. NTIA spectrum survey azimuth-scan graph of the 3700-4200 MHz range (System-2, band event 16, swept algorithm,

maximum-hold detector, 100-kHz bandwidth) at San Diego, CA, 1995.
4

7

GOVERNMENT AERONAUTICAL RADIONAVIGATION, 1.

ALLOCATIONS:

NON-GOVERNMENT AERONAUTICAL RADIONAVIGATION, 1.

ALLOCATIONS:

GENERAL Airborne radio altimeters.

UTILIZATION:

4200 4400

max +peak noise

avg +peak noise

min +peak noise

1. 4202 ±12 MHz: Standard frequency and time satellite service (space-to-Earth), permitted.

Figure 32. NTIA spectrum survey graph summarizing 32,500 sweeps across the 4200-4400 MHz range (System-2, band event 17,

swept/m3 algorithm, +peak detector, 300-kHz bandwidth) at San Diego, CA, 1995.
4

8

RSMS not configured to receive space-to-Earth transmissions

GOVERNMENT FIXED, MOBILE, 1. 2.

ALLOCATIONS:

NON-GOVERNMENT FIXED-SATELLITE (space-to-Earth). 2.

ALLOCATIONS:

GENERAL Narrowband and wideband uplinks and downlinks.

UTILIZATION:

4400 4500 4800 4990-5000

min maxhold noise

1. 4660-4685 MHz: No Government allocation after August 1994. 2. RADIO ASTRONOMY, Space Research (Passive).

Figure 33. NTIA spectrum survey azimuth-scan graph of the 4400-5000 MHz range (System-2, band event 18, swept algorithm,

maximum-hold detector, 100-kHz bandwidth) at San Diego, CA, 1995.
4

9

GOVERNMENT AERONAUTICAL RADIONAVIGATION.

ALLOCATIONS:

NON-GOVERNMENT AERONAUTICAL RADIONAVIGATION.

ALLOCATIONS:

GENERAL Microwave landing systems.

UTILIZATION:

5000 5250

 max +peak noise

avg +peak noise

min +peak noise

Figure 34. NTIA spectrum survey graph summarizing 32,000 sweeps across the 5000-5250 MHz range (System-2, band event 19,

swept/m3 algorithm, +peak detector, 300-kHz bandwidth) at San Diego, CA, 1995.
5

0

GOVERNMENT RADIOLOCATION. AERONAUTICAL 3. MARITIME RADIONAVIGA- 4. RADIOLOCATION.

ALLOCATIONS: RADIONAVIGATION, 1. TION, Radiolocation.

NON-GOVERNMENT Radiolocation. AERONAUTICAL 3. MARITIME RADIONAVIGA- 4. Amateur. 6.

ALLOCATIONS: RADIONAVIGATION, 2. TION, Radiolocation.

GENERAL Weather radars. 5. Military radars, 7. 7.

UTILIZATION:

5250 5350 5460-5470 5600 5650 5850 5925

min +peak noise

1. RADIOLOCATION. 5. Government weather radars, e.g., Terminal Doppler Weather Radar (TDWR).

2. Radiolocation. 6. FIXED-SATELLITE (Earth-to-space), Amateur.

3. RADIONAVIGATION, Radiolocation. 7. 5725-5875 MHz: Industrial, scientific, and medical (ISM).

4. MARITIME RADIONAVIGATION, METEOROLOGICAL AIDS, Radiolocation.

Figure 35. NTIA spectrum survey graph summarizing 22 scans across the 5250-5925 MHz range (System-2, band event 20, stepped

algorithm, +peak detector, 3000-kHz bandwidth) at San Diego, CA, 1995.
51

GOVERNMENT

ALLOCATIONS:

NON-GOVERNMENT FIXED, FIXED-SATELLITE (Earth-to-space). 1. FIXED, FIXED-SATELLITE (Earth-to-space). FIXED-SATELLITE 2.

ALLOCATIONS: (Earth-to-space), 2.

GENERAL Common carrier fixed links. Common carrier fixed links. Common carrier fixed links.

UTILIZATION:

5925 6425 6525 6875 7075 7125

min maxhold noise

1. FIXED-SATELLITE (Earth-to-space), MOBILE. 2. FIXED, MOBILE.

Figure 36. NTIA spectrum survey azimuth-scan graph of the 5925-7125 MHz range (System-2, band event 21, swept algorithm,

maximum-hold detector, 300-kHz bandwidth) at San Diego, CA, 1995.
5

2

RSMS not configured to receive space-to-Earth transmissions

GOVERNMENT FIXED, 1. 3. FIXED, FIXED-SATELLITE (space-to-Earth), FIXED. FIXED-SATELLITE (Earth-to-space), 5, 6, 7. FIXED, 8,

ALLOCATIONS: Mobile-Satellite (space-to-Earth), 4. 9.

NON-GOVERNMENT 8.

ALLOCATIONS:

GENERAL 2. 2. 2. 2. 2. 2. 2.

UTILIZATION:

7125 7250 7300 7750 7900 8400 8450 8500

min maxhold noise

1. 7190-7235 MHz: SPACE RESEARCH (Earth-to-space). 6. 8025-8400 MHz: EARTH EXPLORATION-SATELLITE (space-to-Earth), FIXED, Mobile-Satellite (Earth2. Point-to-point microwave voice/data links, defense satellite communications systems (DSCS). to-space) (no airborne transmissions).

3. FIXED-SATELLITE (space-to-Earth), MOBILE-SATELLITE (space-to-Earth), Fixed. 7. 8175-8215 MHz: METEOROLOGICAL-SATELLITE (Earth-to-space).

4. 7450-7550 MHz: METEOROLOGICAL-SATELLITE (space-to-Earth). 8. SPACE RESEARCH (space-to-Earth) (Government: 8400-8450 MHz deep space only).

5. 7900-8025 MHz: MOBILE-SATELLITE (Earth-to-space), fixed. 9. 8400-8450 MHz: Deep space only.

Figure 37. NTIA spectrum survey azimuth-scan graph of the 7125-8500 MHz range (System-2, band event 22, swept algorithm,

maximum-hold detector, 300-kHz bandwidth) at San Diego, CA, 1995.
5

3

GOVERNMENT RADIOLOCATION. 1. 2. 3. RADIOLOCATION.

ALLOCATIONS:

NON-GOVERNMENT Radiolocation. 1. 2. 3. Radiolocation. Amateur, Radiolocation. 6.

ALLOCATIONS:

GENERAL Military use is primary. 4. 5.

UTILIZATION:

8500 9000 9200 9300 9500 10000 10450 10550

minimum +peak noise

1. AERONAUTICAL RADIONAVIGATION, Radiolocation. 4. Maritime radionavigation radar, airborne weather radar, radar transponder beacons (RACONS).

2. MARITIME RADIONAVIGATION, Radiolocation. 5. Military airborne radar.

3. RADIONAVIGATION, Meteorological Aids, Radiolocation. 6. RADIOLOCATION. 10450-10500 MHz: Amateur, Amateur-Satellite.

Figure 38. NTIA spectrum survey graph summarizing 23 scans across the 8500-10550 MHz range (System-2, band event 23, stepped

algorithm, +peak detector, 3000-kHz bandwidth) at San Diego, CA, 1995.
5

4

RSMS not configured to receive space-to-Earth transmissions

GOVERNMENT 1.

ALLOCATIONS:

NON-GOVERNMENT 2. FIXED, FIXED-SATELLITE (space-to-Earth). FIXED-SATELLITE FIXED, BROADCASTING- FIXED, FIXED-SATELLITE

ALLOCATIONS: (space-to-Earth), 3. SATELLITE. (Earth-to-space), MOBILE.

GENERAL Common carrier point-to-point microwave links, television Direct broadcast Cable Relay Systems (CARS), 4.

UTILIZATION: studio-to-transmitter links. satellite services (DBS).

10550 10700 11700 12200 12700 13250

min maxhold noise

1. 10600-10700 MHz: EARTH EXPLORATION-SATELLITE (Passive), SPACE RESEARCH (Passive). 10680- 3. Mobile except aeronautical mobile.

10700 MHz: RADIO ASTRONOMY. 4. Television auxiliary broadcasting (includes: SHL, STL, ENG, and ICR's).

2. 10550-10680 MHz: FIXED. 10600-10700 MHz: EARTH EXPLORATION-SATELLITE (Passive), SPACE

RESEARCH (Passive). 10680-10700 MHz: RADIO ASTRONOMY.

Figure 39. NTIA spectrum survey azimuth-scan graph of the 10550-13250 MHz range (System-2, band event 24, swept algorithm,

maximum-hold detector, 3000-kHz bandwidth) at San Diego, CA, 1995.
5

5

GOVERNMENT AERONAUTICAL RADIOLOCATION, Space Research, Standard Frequency and Time Signal-Satellite (Earth-to-space). RADIONAVIGATION,

ALLOCATIONS: RADIONAVIGATION, 1. Space Research.

NON-GOVERNMENT AERONAUTICAL Radiolocation, Space Research, Standard Frequency and Time Signal-Satellite (Earth-to-space). RADIONAVIGATION,

ALLOCATIONS: RADIONAVIGATION, 1. Space Research, 2.

GENERAL Military airborne radars.

UTILIZATION:

13250 13400 14000 14200

min +peak noise

1. Space Research (Earth-to-space). 2. FIXED-SATELLITE (Earth-to-space).

Figure 40. NTIA spectrum survey graph summarizing 40 scans across the 13250-14200 MHz range (System-2, band event 25, stepped

algorithm, +peak detector, 3000-kHz bandwidth) at San Diego, CA, 1995.
5

6

GOVERNMENT Fixed, FIXED, Mobile, MOBILE, Fixed, Space Research. FIXED, Mobile, 3. AERONAUTICAL

ALLOCATIONS: Mobile. Space Research. Space Research. RADIONAVIGATION.

NON-GOVERNMENT FIXED-SATELLITE 1. 3. AERONAUTICAL

ALLOCATIONS: (Earth-to-space). RADIONAVIGATION.

GENERAL 2. 2.

UTILIZATION:

14200 14400 14500 14714.5 15136.5 15350-15400 15700

min maxhold noise

1. FIXED-SATELLITE (Earth-to-space). 3. EARTH EXPLORATION-SATELLITE (Passive), RADIO ASTRONOMY, SPACE RESEARCH (Passive).

2. Military communication links and microwave links. Air traffic control links, including video data.

Figure 41. NTIA spectrum survey azimuth-scan graph of the 14200-15700 MHz range (System-2, band event 26, swept algorithm,

maximum-hold detector, 3000-kHz bandwidth) at San Diego, CA, 1995.
5

7

GOVERNMENT RADIOLOCATION. RADIOLOCATION, Space Research 1. 3. Radiolocation.

ALLOCATIONS: (Deep Space) (Earth-to-space).

NON-GOVERNMENT Radiolocation. Radiolocation. 2. 4. FIXED-SATELLITE

ALLOCATIONS: (Earth-to-space).

GENERAL Military airborne radars. Military airborne radars.

UTILIZATION:

15700 16600 17100 17200 17300 17700

max +peak noise

min +peak noise

1. RADIOLOCATION. 3. RADIOLOCATION, Earth Exploration-Satellite (Active), Space Research (Active).

2. Radiolocation. 4. Earth Exploration-Satellite (Active), Radiolocation, Space Research (Active).

Figure 42. NTIA spectrum survey graph summarizing 39 scans across the 15700-17700 MHz range (System-2, band event 27, stepped

algorithm, +peak detector, 3000-kHz bandwidth) at San Diego, CA, 1995.
5

8

RSMS not configured to receive space-to-Earth transmissions

GOVERNMENT 2.

ALLOCATIONS:

NON-GOVERNMENT FIXED, MOBILE, FIXED-SATELLITE (space-to-Earth), 1. 3. FIXED, FIXED-SATELLITE (space-to-Earth), MOBILE.

ALLOCATIONS:

GENERAL General purpose point-to-point microwave band including private, common carrier, cable television relay systems (CARS), studio-to-transmitter (STL) television links,

UTILIZATION: Digital Electronic Message Services (DEMS), etc.

17700 18600 18800 19700

min maxhold noise

1. 17700-17800 MHz: FIXED-SATELLITE (Earth-to-space). 3. FIXED, FIXED-SATELLITE (space-to-Earth), EARTH EXPLORATION-SATELLITE (Passive), MOBILE

2. EARTH EXPLORATION-SATELLITE (Passive), SPACE RESEARCH (Passive). (exc. aeronaut. mobile), SPACE RESEARCH (Passive).

Figure 43. NTIA spectrum survey aximuth-scan graph of the 17700-19700 MHz range (System-2, band event 28, swept algorithm,

maximum-hold detector, 3000-kHz bandwidth) at San Diego, CA, 1995.
measured with different bandwidths and algorithms. This is the case for Figures 21 and 22.

Figure 22 covers the same frequency range as the upper 25% of Figure 21, but the appearance

of the two graphs is completely different. The signals in Figure 22 appear (at first glance) to be

much stronger and denser than those in the common part of Figure 21.

The previous two examples are given as a caution to the reader that each survey band is intended

to best describe the signal environment within its frequency range and is not, generally

comparable to other survey bands. The summary observations of Section 3.5 should be of help

with interpretation of the data graphs.

3.5 Observations on Measured Data and Spectrum Use

It is important to understand what aspects of spectrum use can be extrapolated from the RSMS

data presented in this report, and also what aspects of spectrum use cannot be inferred from these

data. First, the data acquisition was performed at a single location in the San Diego metropolitan

area during a two-week period spanning the end of February and the beginning of March 1995.

In most measured bands, the RSMS data presented in this report show maximum, minimum, and

average measured power levels of received signals. In these bands, the cumulative measurement

time during the survey was typically several hours, spread uniformly over the diurnal cycle. For

some bands that were nondynamic and measured with the azimuth-scanning technique, only a

single occupancy curve is shown.

Based on the measurement and sampling techniques used, we believe that these data represent

an extremely good statistical sampling of the activity in the radio spectrum in the San Diego

metropolitan area. Maximum and minimum activity levels measured in the spectrum are

probably very good representations of actual activity levels. The average curves provide a good

qualitative estimate of the typical received power as a function of frequency. The maximum,

minimum, and average curves can also be used to qualitatively assess the relative density of

channel occupancy on a band-by-band basis. In the azimuth-scan bands, the single curve which

is shown likewise provides a good estimate of the density of spectrum occupancy in the survey

area.

However, while the data presented here can be used to infer the density of frequency occupancy,

these data cannot be used to infer the statistical percentage of time that channels are occupied.

A good analogy is to imagine counting houses while driving along a street: one can easily count

the number of houses that have been built on each block (analogous to counting the number of

frequencies that show activity in each band in the RSMS survey), but one cannot tell, on the

basis of that count, what percentage of time the houses are occupied. Signals that are observed

in 100% of the scans can be determined, because the minimum curve will show such activity.

Other than 100% signals, the average curves provide a qualitative, not quantitative, measure of

occupancy for the measured frequencies.

There is an RSMS measurement technique for obtaining absolute channel occupancy statistics.

Measurements of this type were performed (in mobile radio bands) in conjunction with the RSMS

occupancy survey in San Diego. Results of those measurements will be published separately.

59
3.5.1 Band-by-bad Observations on Spectrum Use in the San Diego Area

Table 7 contains band-by-band observations on spectrum occupancy in the San Diego area. The

comments are based on examination of the RSMS data collected during the spectrum survey and

frequency allocation information in the NTIA Manual [l, Chapter 4]. -

Table 7. Comments on San Diego Spectrum Occupancy Measurement Results

Spectral Range Figure Comments

108-138 MHz 4 Across the 108-114 MHz range, 40 dB of RF attenuation were used in the

RSMS front-end to prevent overload by signals in the adjacent 88-108 MHz

commercial FM radio broadcast band. This raised the RSMS noise floor in

this range by 40 dB relative to the rest of the band, and reduced RSMS

sensitivity to signals in the 108-114 MHz range by the same amount.

Instrument landing system (ILS) localizes transmit in the 108-112 MHz

range, but detection was not expected due to the high RSMS noise figure in

this range. However, an ILS glideslope signal is observed at 333 MHz.

Across 108-118 MHz, very-high frequency omnidirectional range (VOR)

aeronautical navigation beacons are observed as 100% emitters. These are

seen as vertical lines coming up from the minimum curve. Also, in the air

traffic control (ATC) band across 118-136 MHz, automated terminal information service transmissions appear as high-average or 100% signals. Frequently used ATC frequencies also appear as high points on the average curve.

Air mobile frequencies that were used at least once during the survey are

observed on the maximum curve. A large number of the available channels

in the ATC band were used during the survey period.

In the 137-138 MHz band, television infrared observation satellite signals are

not receivable by the RSMS. NOAA weather satellites operate at

137.62 MHz. Signal occupancy observed at 137.6 MHz (at about -60 dBm)

is stronger than expected for a NOAA weather satellite.

138-162 MHz 5 A large number of mobile and amateur signals are observed in the 138-

148 MHz portion of the spectrum. The average curve is significantly raised

across 144-148 MHz, used by amateurs. Between 148-162 MHz, a large

percentage of available channels also show use. Transmitters between 152-

153 MHz were in operation continuously during the survey period.

Maritime mobile signals occur between 156.2475-162.025 MHz. All of these

channels show some occupancy, consistent with expectations for the San

Diego area.

During the survey, routine station identification monitoring indicated unauthorized use of frequencies at and near 150 MHz in the San Diego area. This

information was sent to the FCC Field Enforcement Bureau, which later

located several unauthorized sources in southern California, including fishing

boats offshore.

60
Table 7. Comments on San Diego Spectrum Occupancy Measurement Results (Continued)

Spectral Range Figure Comments

162-174 MHz 6 A variety of fixed and mobile signals are observed. The signal near

162.5 MHz is a public broadcast weather information channel. Essentially all

of the channels in this band show some occupancy during the survey period,

and many channels raise the average curve.

174-216 MHz 7 Television broadcast channels 8, 10, and 12 are occupied. Adjacent broadcast

channels are unoccupied, in accordance with FCC regulations. Twenty dB

attenuation was used to prevent front-end overload in RSMS.

216-225 MHz 8 Some channels are used in the 216-220 MHz maritime mobile allocation.

Signals that are possibly from a trunked system occur between 220-

220.75 MHz. Identical received amplitudes of five signals between 220-

220.7 MHz implies the possibility of a single, fixed location of origin. These

signals may be from an LMR base station. Amateur signals are observed

above 221 MHz, and the relative density of channel occupancy increases

above 223.5 MHz. No military radiolocation occurs in this spectral range in

the San Diego area.

225-400 MHz 9 Military ATC communications are observed. Many of these signals are 100%

transmissions from fixed locations. Even signals that are less than 100%

often are used enough of the time to significantly affect the average curve.

ILS glideslope signal is observed “at about 333 MHz.

400-406 MHz 10 Fifteen to twenty signals are observed in this meteorological aids band for

brief intervals during the survey period. The relative paucity of observed

signals is consistent with typically low EIRP and typically intermittent

operation of most systems that use this band (e.g., radiosonde).

406-420 MHz 11 A number of fixed and mobile signals (about 30) affecting the minimum and

average curves, are observed. Four of the signals are observed in 100% of

RSMS data scans.

420-450 MHz 12 High-power radar signals produce essentially all of the occupancy observed in

this band. Some of these signals saturated the RSMS at amplitudes in excess

of -25 dBm in 50 ohms, with the omnidirectional receiving antenna. The

radars are on ships and naval aircraft. Compare the high level of activity in

this band in the San Diego area with practically nonexistent activity in the

same band in the Denver, Colorado area [2].

450-470 MHz 13 A large number of land mobile signals are observed, and many of them affect

the average curve. The band edges of the 460-465 MHz base station

allocation are very distinct.

61
. .

,

Table 7. Comments on San Diego Spectrum Occupancy Measurement Results (Continued)

Spectral Range Figure Comments

470-512 MHz 14 Between 470-490 MHz, the RSMS front-end was operated with 30 dB

RF attenuation to prevent front-end overload by the TV broadcast channel 15

signal. The rest of this band was measured without RF attenuation. The

result is a noise floor that is 30 dB higher across 470-490 MHz than across

the rest of the band.

Television broadcast channels 15 and 19 are occupied by local San Diego

stations. Channel 18 is occupied by station KSCI in Los Angeles. The rest

of the occupancy observed in this band is generated by nontelevision

transmitters.

Spectrum nominally allocated for television broadcast channels 14, 16 and 20

shows use by the Los Angeles T-band land mobile radio allocation, as defined

in the CFR [3, Part 90.311], for ten major urban areas in the United States.

Base stations operate in the lower half of each channel, and mobile stations

operate in the upper half of each channel. In particular, the lower half of

channel 16 shows use by Los Angeles County public safety base stations for

land mobile radio. Note that, although the T-band allocations are for Los

Angeles, which is nominally well beyond line-of-sight from the RSMS

location at Point Loma, spectrum occupancy by these systems is still readily

observed in the San Diego area. This may be due to propagation from high

terrain in the southern Los Angeles area, and/or to ducting phenomena.

Channel 17 shows occupancy by low-power television in the San Diego area,

and also by local area networks in Mexico.

512-806 MHz 15 All of the signals observed in this band appear to be UHF television broadcast. At least nine of them were observed in 100% of RSMS scans, the

remainder having been turned off at least once during the survey.

806-902 MHz 16 Cellular, trunked, and public safety portions of this part of the spectrum are

clearly delineated. Mobile and base parts of the band are also clearly

identifiable,

Within the 806-821 MHz (mobile conventional and trunked) band segment,

most occupancy occurs between 811-821 MHz. The 821-824 MHz mobile

public safety band shows occupancy by four signals, but the probability of

intercept (POI) for such signals by the RSMS is low (compare to the 866-

869 MHz base public safety band, below). The 824-849 MHz cellular mobile

band shows enough use by mobile units to raise the average curve slightly.

The 849-851 MHz ground-to-air allocation shows no measured occupancy,

although the POI for such signals by the RSMS is low. The 851-866 MHz

base conventional and trunked band shows occupancy that significantly raises

the average curve. The 866-869 MHz base public safety shows occupancy on

about twenty channels, and the average curve is affected. The 869-894 MHz

band, occupied by cellular base stations, is distinctly observed. The 100% use

channels between 879.3 -880.5 MHz are probably system control channels.

Air-to-ground signals between 894-896 MHz are observed, confirming that

low POI probably prevents the RSMS from measuring corresponding groundto-air signals. A few signals are observed in the 896-901 private land mobile

band, and a single signal was recorded in the 901-902 MHz general mobile

allocation.

62
Table 7. Comments on San Diego Spectrum Occupancy Measurement Results (Continued)

63
Table 7. Comments on San Diego Spectrum Occupancy Measurement Results (Continued)

Spectral Range Figure Comments

960-1215 MHz 20 Activity in this band is produced entirely by aeronautical navigation aids.

These include tactical air navigation beacons (TACAN), distance-measuring

equipment (DME), and air traffic control radar beacon system (ATCRBS)

interrogators and transponders. Probable TACAN signals appear as bumps in

the average curve at (approximately) 978, 995, 1007, 1012, 1174, 1187, 1204,

and 1212 MHz. DME airborne interrogations occur from 1025-1150 MHz;

DME ground beacons reply between 962-1025 MHz and 1150-1213 MHz,

Note the delineation that is visible at 1150 MHz. ATCRBS ground-based

interrogations occur at 1030 MHz, and airborne replies occur at 1090 MHz.

Both of these peaks are clearly visible in the data. Because the emissions in

this band are primarily pulsed, the average curve is essentially unaffected by

all signals except TACAN.

1215-1400 MHz 21 This band shows occupancy by high-power, long-range air search radars.

Frequencies occupied by distinctly identifiable radar signals are 1255, 1270,

(with other peaks noted at 1274-1282, 1314-1318, and 1359-1371 MHz),

1295, 1305, 1342, 1349, and 1392 MHz. The radar at 1255 MHz also

operated briefly at 1250 MHz, and this occurred during a scan in which

attenuation was not invoked in the RSMS; hence, this peak occurs as a shelf

to the left of the peak at 1255 MHz. It is not known which of these radars, if

any, generated the peak at 1265 MHz. All of the measured signals between

these peaks are spurious emissions from these radars. Emission parameters

vary, but values measured by the RSMS crew are typically as follows:

mechanical beam rotation, 9-12 s rotation time, 1-6 us pulse widths, and 300-

600 pulses per second transmitted. These radars usually are observed to emit

staggered pulse trains, probably to enhance doppler processing of target

returns.

1350-1400 MHz 22 Unlike the measurements made in the 1215-1400 MHz band, measurements in

this band are optimized to observe nonradar emissions. Nevertheless, most of

the activity observed in this band is from radars. The prominent features at

1350-1355, 1360-1372, and 1392 MHz are generated by the air search radars

shown in Figure 21. No nonradar signals are noted in this band. Because

they are pulsed signals received approximately every 9-12 s, the average and

minimum curves are unaffected.

1400-1530 MHz 23 Six distinct signals are observed in this band by the RSMS. The frequencies

are 1449, 1459, 1464, 1482, 1502, and 1512 MHz. Four of these signals are

present in 100% of RSMS data scans.

1530-1710 MHz 24 Some signals are observed at 1610.5, 1625-1645, 1655-1665, and 1670-

1690 MHz. We infer that the other signals are probably earth-to-space for

maritime mobile satellite (allocated 1626.5 -1646.5 MHz), earth-to-space for

aeronautical mobile satellite (allocated 1646.5 -1668.4 MHz), and radiosondes

(allocated 1668.4-1700 MHz).

64
Table 7. Comments on San Diego Spectrum Occupancy Measurement Results (Continued)

Spectral Range Figure Comments

1710-2300 MHz 25 All signals observed in this band are terrestrial point-to-point communications,

as measured with the RSMS azimuth-scanning technique (see Section C.8 in

Appendix C). As in the Denver, Colorado survey [2], two parts of this

spectral range show a comparatively small number of transmitters: 1990-

2110 MHz (terrestrial allocations being auxiliary broadcasting, cable TV, and

GOES uplink), where four signals are observed, and 2200-2300 MHz

, (terrestrial allocation being fixed microwave links), where one digital and one

analog signal occur. Note that all signals observed in this band in San Diego

are analog, except for the digital signal at approximately 2262 MHz.

2300-2500 MHz 26 Four communications signals, probably analog, are observed at 2315, 2333,

2367, and 2383 MHz. Their significant effect on the average curve suggests

that they likely are fixed links. Above 2388 MHz, all of the observed activity

is background radiation generated by ISM devices, and especially by aggregate emissions from microwave ovens in the San Diego area. This background is observed at levels 10 dB higher than in the Denver, Colorado

measurements [2]. See also Gawthrop, et al. [4], for further information on

emission characteristics of microwave ovens.

2500-2700 MHz 27 At least 27 fixed transmitters are observed in this band. Some of the carriers

are low-amplitude, and difficult to discern at the graphic resolution presented

in Figure 27, but are clearly distinguishable in the RSMS raw data scans.

The individual signal spectra are standard NTSC television broadcast, so these

are multipoint distribution system (MDS, also called wireless cable television)

transmitters.

2700-2900 MHz 28 All signals in this band are generated by high-power air-search radars. Four

frequencies are easily discernable (2755, 2795, 2825, and 2880 MHz).

Additional frequencies that are occupied by radars, as identified by the RSMS

crew, are 2705, 2715, and 2855 MHz. Because automatic attenuation is not

yet implemented in the RSMS, these radars saturate the RSMS front-end at

their center frequencies during most of the measurements. However, a few

manually attenuated scans were performed to document the peak received

power, and are shown as the maximum curve. So, the average curve reflects

the maximum, positive-peak detected amplitudes of the majority of scans

(which were unattenuated), while the maximum curve shows the true envelope

of radar emissions in this band. Note that the radar at ,2795 MHZ was tuned

to about 2785 MHz on at least one (unattenuated) scan, resulting in the flat

area on the maximum curve at that frequency. Radars in this band as

measured by RSMS crew, typically have the following characteristics:

mechanical rotation, no elevation scanning, 4.7-5.0 s rotation time, about 1-us

pulse width, and about 1000 pulses/s emitted at a high-order stagger,

presumably for Doppler processing of target returns.

2900-3100 MHz 29 High-power air-search radars are observed in this band. Compare the high

levels of activity observed in San Diego to the nonexistent activity in Denver,

Colorado [2].

The high peak and average values recorded at 3050 MHz are generated by

numerous surface-search radars used for maritime navigation. Most large

vessels carry a surface-search radar that operates at or near 3050 MHz.

65
Table 7. Comments on San Diego Spectrum Occupancy Measurement Results (Continued)

Spectral Range Figure Comments

3100-3700 MHz 30 Numerous high-power radars are observed in this band. Compare the high

levels of activity observed in San Diego to the nonexistent activity in Denver,

Colorado [2].

3700-4200 MHz 31 RSMS azimuth scans observe two fixed, point-to-point microwave links in

this band. The spectra show that both of the links are digitally modulated.

4200-4400 MHz 32 Airborne radio altimeter signals, transmitted by aircraft on approach and

departure from nearby airfields, are clearly observed between 4230-

4370 MHz. Two modulations predominate: pulsed and FM/CW. Because

the signals occur very intermittently, and some are pulsed, the average and

minimum curves are not affected.

4400-5000 MHz 33 At least thirteen fixed, point-to-point microwave links are observed in this

band, as measured with the RSMS azimuth-scanning technique. Narrow

emission spectra are analog signals, and wide emission spectra are digital

signals, Five of the thirteen identifiable signals are digital.

5000-5250 MHz 34 The signals observed in this band are spurious emissions from radars

operating in the 5250-5925 MHz radiolocation band. Because they are pulsed

emissions that occur sporadically, depending upon such factors as beam

scanning, proximity of the observed radars to the RSMS, and operational

times of the radars, the occupancy by the radar spurious emissions in this

band looks “spiky” on the graph. (The optimal algorithm for observation of

these signals would have been stepped, but the RSMS only uses that algorithm in radiolocation bands during spectrum surveys. This band was

measured with the swept/m3 algorithm.)

None of the signals in this band are microwave landing system (MLS) signals;

there are no MLS deployed in the San Diego area.

5250-5925 MHz 35 All emissions in this band are produced by radars. Radars using this band

include maritime surface-search and weather surveillance units. The flat

plateaus in the maximum curve are caused by radar emissions that were

measured when no personnel were present at the RSMS to invoke attenuation;

automatic attenuation is being added to RSMS capabilities.

5925-7125 MHz 36 At least seven fixed links, all of them analog, are observed between 5925-

6425 MHz, in a fixed and fixed-satellite band, in the RSMS azimuth-scan

measurement. Another sixteen links, most of them analog, are observed

between 6550-6875 MHz, in another fixed and fixed-satellite band. Four

links, two of them digital, occur between 6875-7100 MHz in the fixed-satellite/auxiliary broadcasting band. Overall, less occupancy is observed from

Point Loma by the RSMS than was recorded in Denver, Colorado [2].

7125-8500 MHz 37 Approximately seven fixed links, six of them analog, are observed in the

RSMS azimuth-scan measurement. Substantially less occupancy is observed

in this band in the RSMS San Diego survey than in the Denver survey [2].

66
Table 7. Comments on San Diego Spectrum Occupancy Measurement Results (Continued)

Spectral Range Figure Comments

8500-10550 MHz 38 All signals observed in this band are generated by radars. The majority of

radars observed in this band in San Diego are maritime surface-search units.

Some airborne units are also observed. A shore-based navigation radar tuned

to 9400 MHz was present in 100% of RSMS scans. Essentially all surfacesearch radars carried by small vessels operate in this band; larger vessels also

frequently carry radars that operate in this band. Typical operational

parameters of the surface search radars, as measured by RSMS crew, are:

mechanical rotation, 2-4 s rotation, less than 300-ns pulse width, pulse

repetition rates of several thousand pulses per second, no pulse staggering

present.

Compare occupancy in this band in San Diego to much lower occupancy in

land-locked Denver, Colorado [2].

10550-13250 39 One digital signal is observed in this band. Observed occupancy is lower

MHz than was observed in Denver, Colorado [2].

13250-14200 40 A radar is observed at 13730 MHz.

MHz

14200-15700 41 One or two signals are observed in the RSMS azimuth scan. In general, the

MHz probability of intercept by the RSMS for signals in this band is low. See

Appendix C.

15700-17700 42 A few signals are observed in the RSMS azimuth scan. In general, the

MHz probability of intercept by the RSMS for signals in this band is low. See

Appendix C.

17700-19700 43 No signals are observed; the change in the RSMS noise floor is due to a band

MHz edge in the spectrum analyzer. In general, the probability of intercept by the

RSMS for signals in this band is low. See Appendix C.

67
4. REFERENCES

[1] Manual of Regulations and Procedures for Federal Radio Frequency Management, revised

Sep. 1993 and Jan. 1994, NTIA Office of Spectrum Management, U.S. Government Printing

Office, Stock No. 903-008-00000-8.

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

Report 95-321, Sep. 1995.

[3] Title 47 Code of Federal Regulations, Telecommunications, Part 80 to End, revised Oct.

1994, (U, S. Government Printing Office, Superintendent of Documents, Mailstop: SSOP,

Washington, DC 20402-9328).

[4] P.E. Gawthrop, F.H. Sanders, K.B. Nebbia, and J.J. Sell, '' Radio spectrum measurements of

individual microwave ovens,” NTIA Report 94-303-1,2, Mar. 1994.

68
APPENDIX A: RADIO SPECTRUM MEASUREMENT SYSTEM (RSMS)

A.1 Introduction

The NTIA RSMS is a mobile, self-contained computer-controlled radio-receiving system capable

of many measurement scenarios over a frequency range of 30 MHz to 22 GHz. This appendix

contains specifications on the vehicle, instrumentation, and operation of the RSMS when it is

deployed for broadband spectrum survey measurements.

A.2 Vehicle

For maximum effectiveness, the spectrum measurement system must be readily transported to

near or distant locations that may not be easily accessible, e.g., open fields or hilltops without

an access road. To meet this need, the measurement system, including antennas and support

hardware, is carried in a shielded, insulated, climate-controlled shell mounted on a Chevrolet

truck cab and chassis. The assembled measurement system and vehicle unit is called “the

RSMS.” The vehicle has a high power-to-weight ratio, four-wheel drive, and a low-geared

transmission for use on rough terrain and steep grades. The RSMS is still sufficiently small and

light to fit on C-130 or larger aircraft for rapid transport over long distances. The chief

disadvantage of a smaller unit is the loss of operating room inside the shell.

Figure A-1 shows the internal layout of the RSMS. Four full-height equipment racks are located

transversely above the rear axle. These racks divide the box-like equipment compartment into

two parts: one in front and one behind the racks. The forward area comprises the operator’s

compartment with access to the equipment front panels, the main power panel and breaker box,

work counters, two chairs, telephone, fax machine, and a cellular fax/modem, A built-in safe

below the equipment racks provides storage for classified materials. A full-height cabinet in the

forward driver’s side comer provides for storage of small, frequently used items. A compartment

for the smaller of two telescoping masts is located behind this cabinet, and is accessed from

outside the van.

Additional storage cabinets are available to the rear of the racks for larger and less-used items.

Compartments for the large mast and the external-tap power cable and its electrically driven reel

are located behind these cabinets, with outside access. The weight of the mast-rotator, power

cable and reel is counterbalanced on the driver’s side by the 10-kW generator and two air

conditioners. The rear area provides access to the back of the equipment racks. The generator

compartment is accessed via an outside lift-up panel. The air conditioners are not readily

accessible.

The tightly-shielded, windowless measurement compartment (shell) provides good radio

frequency (RF) isolation between the measurement system and the outside environment. The

small working compartment also reduces requirements for air conditioning and heating. Both of

the telescoping masts are installed on rotators (at their bases) and will raise the antennas to a

little over 8 m above ground.

69
Figure A-1. Top and side view drawings of the RSMS.

70
A.3 Instrumentation

The RSMS is normally configured as two independent spectrum measurement systems, one

optimized to measure lower frequency portions of the spectrum (System-1), and the other to

measure higher frequencies (System-2) with some frequency overlap between the two systems.

Figure A-2 is a fish-eye front panel view of the rack mounted instrumentation, Measurement and

control instruments for System- 1 are in the two racks on the right of center, and for System-2,

the two racks left of center. Both systems use RF front-ends that incorporate dynamic RF

attenuation, low noise preamplification and tunable frequency preelection. These features allow

the RSMS to achieve the best possible combination of dynamic range, sensitivity, and off-tuned

signal rejection in its measurements.

Figure A-2. Front panel of the RSMS instrument racks,

For spectrum surveys, the low-frequency system is usually operated between 100 MHz and

1 GHz, with its antenna(s) mounted on the smaller forward mast and its RF front-end located

inside the operator’s compartment. The high-frequency system is used for the remaining survey

frequencies from 1-19.7 GHz, with its antenna(s) mounted on the larger mast and its RF frontend located at the top of that mast to overdrive the higher line losses that occur above 1 GHz.

The RSMS receiver is depicted as a block diagram in Figure A-3. As the diagram shows, both

the high and low frequency systems are designed around a 0-22 GHz range Hewlett-Packard

8566B spectrum analyzer, although the RSMS software will control other spectrum analyzers,

such as the HP-70000 series. The selection of 1 GHz as the break point between the two systems

in a site survey mode is determined primarily by the availability of antennas, which often begin

or end their frequency response at 1 GHz.

71

Each of the measurement systems can be controlled in fully automatic, semiautomatic, and fully

manual modes. In fully automatic operation, each system is controlled by ITS-written software

(named DA, for Data Acquisition) that runs under Microsoft-DOS on 80486-based computers.

Spectrum surveys are normally conducted in the fully automatic mode. RSMS operators are able

to interrupt automatic measurements to perform work in semiautomatic and manual modes.

These modes allow special measurements with varying degrees of automated assistance.

The two measurement systems utilize independent antennas, RF front-ends, masts, spectrum

analyzers and computers, but share the use of auxiliary equipments for special measurements,

analysis, and troubleshooting. Support equipments include a digital oscilloscope, pulse train

analyzer, demodulator, modulation domain analyzer, rotator controllers, signal generators

(frequencies range from a few kilohertz to 18 GHz), power supplies, low noise amplifiers, cables,

connectors, and hand tools. Data from the oscilloscope can be downloaded to the controller

computers. Data from the auxiliary devices are often used to determine specific characteristics

of selected emitters during the course of a spectrum survey or other measurement.

The RF operational characteristics of the two measurement systems are shown as a function of

frequency in Table A-1. The lower-frequency system can be operated across a frequency range

of 100 Hz to 2 GHz, with fixed bandpass and varactor preelection at frequencies below

500 MHz and tracking yttrium-iron-garnet (YIG) preelection from 0.5-2 GHz. This system

includes 0-50 dB of dynamically selectable RF attenuation in the front-end, and achieves a typical

overall noise figure of 10 dB across its entire frequency range. The higher-frequency system can

be operated across the 0.5-22 GHz range, with YIG preelection from 2-20 GHz. This system

incorporates 0-70 dB of dynamically selectable RF attenuation in the front-end, and uses low

noise preamplifiers to achieve a typical noise figure of 10-15 dB up to about 10 GHz, and a noise

figure that increases from 15-25 dB at frequencies from 10-20 GHz. Better noise figures can be

obtained by using the fixed bandpass filters for preelection instead of the YIG, but that

arrangement is tenable only if there are no in-band signals strong enough to overload the

preamplifiers.

A.4 Antennas

The RSMS normally carries a complement of broadband antennas that cover a 0.1-20 GHz

frequency range. Other antennas necessary for measurements at higher or lower frequencies are

stored at the ITS laboratory. Omnidirectional, slant-polarized biconical antennas are most

frequently used for site surveys. These antennas provide a good response to circular, vertical,

and horizontal signal polarizations. At frequencies from 0.1-1 GHz, a slant-polarized log periodic

antenna (LPA) may be used if (as in the San Diego survey) most of the radio activity in the area

is confined to an area subtending 180° or less relative to the RSMS and a satisfactory omni

antenna is not available. Besides the 0.1-1 GHz LPA, the following omnidirectional slantpolarized biconical antennas are also carried: 0.5-20 GHz, 1-12 GHz, 2-8 GHz, and 8-20 GHz.

In addition to the LPA and omnidirectional antennas, a variety of broadband cavity-backed spiral

(CBS) antennas are carried. These have antenna patterns that are most useful for directionfinding using differential methods at relative observation angles of 60° or 90°. They are also

73
Table A-1. Available RSMS RF Signal-processing Paths

useful as auxiliary antennas for manual monitoring of emitters or spectrum of special interest and

for use on side excursions to measure specific emitters of interest in the area of a site survey.

The frequency ranges of these CBS antennas are 1-12 GHz, 8-18 GHz, and 400 MHz-2 GHz.

The latter is not normally carried due to its size.

A l-m parabolic dish antenna with a linear cross-polarized feed of 2-18 GHz is normally carried.

This antenna may be used to perform azimuth-scanning measurements in the common carrier

(point-to-point microwave) bands, but is primarily used for measurements on specific emitters

(e.g., selected radars).

74
The receiving antennas are the only components of the RSMS that are not calibrated in the field.

Because most RSMS measurements are performed to acquire relative emission levels, rather than

absolute incident field strength values, the main requirement for RSMS antennas is that they have

a fairly flat gain response as a function of measured frequency. If absolute incident field

strengths must be known for received signals, then the gain factors (or, equivalently, the antenna

correction factors) for the applicable antennas are determined from manufacturer-generated tables

and curves, and the RSMS measurements are corrected in a post-acquisition analysis phase.

A.5 Attenuators, Preselectors, and Preamplifers

All RSMS measurements are made using the RF front-ends depicted in Figure A-3. These frontends incorporate dynamically switched RF attenuation, preelection, and preamplification. The

Hewlett-Packard 85685A is used for frequencies below 2 GHz, and a unit designed and fabricated

by ITS is used at frequencies between 2 and 20 GHz. The two boxes (HP 85685A and ITS

designed unit) are functionally similar, but differ in significant details. For example, the 85685A

provides 0-50 dB of RF attenuation, and the ITS box provides 0-70 dB of RF attenuation. This

active attenuation allows the total dynamic range of the RSMS to be extended to as much as

130 dB.

Effective bandpass preelection is required if low noise preamplifiers (LNAs) are used; this is

the case for essentially all RSMS measurements. Preelection prevents strong off-tuned signals

from overloading the front-end LNAs. At frequencies below 500 MHz, preelection in the HP85685A is provided by fixed filtering, up to 2 MHz, and by 5% tracking varactors from

2-500 MHz. Tracking YIG filters are used in the frequency ranges of 500 MHz to 2 GHz and

2 GHz to 20 GHz. YIG filters provide the narrowest preelection (15 MHz wide at 500 MHz

to about 25 MHz wide at 20 GHz), but at a cost of about 6 dB of insertion loss. Using fixed

bandpass filters can reduce the preelection insertion loss to about 1 dB; fixed bandpass filters

in an approximately octave progression are available in the ITS front-end (see Figure A-3).

These can only be used if no signals are present in the band which are strong enough to overload

the LNAs.

LNAs are used to achieve the best possible sensitivity, coupled with (ideally) just enough gain

to overdrive the noise figure of the rest of the measurement system, Operationally, at frequencies

below 1 GHz, line losses are sufficiently low to allow placement of the RF front-end inside the

operator’s compartment with an RF line to the antenna mounted on the mast. At frequencies

above 1 GHz, however, the line loss is 10 dB or more, and thus the LNAs (and the rest of the

RF front-end) must be positioned at the top of the mast. (Consequently, the mast must be

sturdier than the lower-frequency system mast.) If a single LNA at the top of the mast were

used, it would have to overdrive at least 41 dB of signal loss (6 dB of insertion loss, 10 dB of

RF line loss, and at least 25 dB of spectrum analyzer noise figure). Thus, to achieve an overall

noise figure of 10 dB, a single LNA would have to have a noise figure of about 8 dB, and a gain

of at least 33 dB. Because LNAs to accomplish this are not available, low noise preamplification

is provided by cascaded preamplifiers located at two points in the high-frequency system: one

at the top of the mast (overdriving YIG insertion loss, mast line loss, and the 4-dB noise figure

75
of the second LNA) and one at the input to the spectrum analyzer (to overdrive the analyzer

noise figure).

A.6 Calibration

RSMS calibrations are performed with noise diodes and a Y-factor excess noise ratio (ENR)

technique described in detail in Appendix D. Typically, a noise diode ENR source is used to

calibrate an entire signal path for measurements about to be performed. Resultant frequencydependent noise figure and gain calibration curves are used to automatically correct the measured

amplitudes of all received signals. This calibration technique has proven very successful for

field-deployed systems. It is a fast way to determine sensitivity and gain-correction values for

a measurement system, and it is also very useful for isolating the gain and loss factors of

individual system components.

A.7 Additional Measurement Capabilities

When deployed for general spectrum occupancy measurements (broadband spectrum surveys),

the RSMS is also equipped to perform other measurements. Following are brief descriptions of

other measurement capabilities currently available.

Extended Emission Spectra: Measurements of radiated and in-guide emission spectra of

individual radio transmitters, particularly radars, are a major strength of the RSMS program. A

combination of high sensitivity and interactive front-end RF attenuation make it possible to

routinely measure the emission spectra of radio emitters across several gigahertz of spectrum.

Specialized RSMS measurement techniques and algorithms support spectrum measurements of

intermittently received emitters, such as scanning radars, without the need to interrupt or interfere

with their operations. The RSMS uses a stepped measurement routine that allows for measurements that are faster, have more dynamic range, and are more repeatable than swept measurements. Accurately tracked YIG and varactor-tuned preelection make stepped measurements

highly resistant to problems of overload from strong center-frequency signals while measuring

low-amplitude emissions in adjacent parts of the spectrum.

Azimuth Scan: This special measurement routine is used to determine the receivability of

selected signals at particular locations, even if those signals propagate via unconventional

(nonline-of-sight) routes. The RSMS parabolic dish antenna is rotated through 360° on the

horizon while recording received signal strength. This results in data showing the receivability

of signals at all azimuths, and reveals nonline-of-sight propagation routes, if any exist. Azimuth

scanning may be used to support spectrum surveys.

Transmitter Equipment Characteristics: The RSMS is capable of measuring and recording

signal characteristics of multiple transmitter types. As part of any measurement scenario, certain

received signals may be singled out for monitoring and detailed analysis. These special

measurements may be used to determine radiated emission characteristics of known transmitters

or identify the source of unknown transmissions. Measured transmitter (signal) characteristics

76
include: tuned frequency or frequencies, beam-scanning method (regular rotation, sector scan,

etc.), beam scan interval, radiated antenna pattern, modulation type (AM, chirped, etc.), pulse

width, pulse repetition rate, pulse jitter, pulse stagger, and intrapulse modulation. Although the

RSMS can observe the presence of phase coding in pulsed signals, no phase measurement

capability is explicitly included in RSMS capabilities.

77

APPENDIX B: DATA ACQUISITION SOFTWARE

B.1 Introduction

The RSMS is designed to identify and characterize spectrum usage at certain frequencies or in

selected bands, and to perform in-depth analysis of factors such as system compatibilities with

each other or with spectrum assignments. Because of the diverse signal types encountered when

measuring an extended spectrum, the measurement system must be able to detect all or at least

most of the signals and to display or record as much information about them as possible.

Obviously, a general-purpose measurement system cannot receive every signal type; however,

the RSMS receiver detects almost every signal type encountered. As shown in Appendix A, the

RSMS hardware can be configured as a receiver for practically all signal types occurring within

an extended frequency range spanning 100 Hz to 19.7 GHz.

The key to efficient use of this extended measurement capability is rapid reconfiguration. The

RSMS uses software developed by ITS to control all measurement system functions via

computer. This control program, called “DA” (for Data Acquisition), runs on any DOS-based

computer with sufficient memory. It interfaces via general-purpose interface bus (GPIB) with

the measurement system at rates limited only by the computer’s operating speed and functional

speed of the managed hardware (interfaces, switches, components, etc.). DA will support many

combinations of RF front-ends, spectrum analyzers, and auxiliary analysis equipment. DA also

controls noise diode calibration of the RSMS and characterizes the noise figure and gain for

individual components and entire measurement signal paths.

The DA program is basically four control subroutines that direct operation of multiple subroutine

kernels that in turn control every function of the measurement system. This appendix includes

descriptions of the four control subroutines (receiver algorithm, spectrum analyzer, RF front-end,

and calibration) and the resultant system functions. As DA program development continues to

meet new measurement demands, these functional descriptions may change with time.

B.2 Receiver Algorithm Subroutine

The DA receiver algorithm subroutine provides software management for up to 32 measurement

algorithms (called band events for RSMS operations; see Section 2.3.1). Any one of these

algorithms, when coupled with spectrum analyzer and front-end selections (described later in this

appendix), becomes a customized measurement system for receiving certain signals or signal

types. Because the characteristics of emitters and the requirements for data on those emitters

vary considerably, many different algorithms have been developed. However, all of the

algorithms are based upon either a frequency sweep across the spectrum of interest, or a series

of discrete steps across that spectrum.

For spectrum surveys, sweeping algorithms are generally used to examine spectral bands occupied

by high duty cycle emitters such as mobile radios and television transmitters, and stepping

algorithms are used to monitor spectral bands occupied by low duty cycle emitters such as

79
radiolocation equipments (radars). Following are brief descriptions of the algorithms used during

a spectrum survey.

Swept: This algorithm controls a conventional spectrum analyzerl sweep across a

selected portion of spectrum. Any type of detection available in the analyzer (i.e.,

positive peak, sample, etc.) can be used. Repeated sweeps may be programmed, and

multiple sweeps incorporating the maximum-hold spectrum analyzer mode may also

be performed. This algorithm also allows for sweeping a spectral band in several subbands (scans). This feature is important if a narrow bandwidth (e.g., 10 kHz) must be

used to measure a spectral band that is more than 1000 times the width of the

measurement bandwidth, e.g., measuring 900-930 MHz with a 10-kHz bandwidth

requires at least three scans to ensure no loss of data.

Swept/m3: This is a swept measurement (as described above) that produces three data

traces across a measurement range. At each of the 1000 frequencies measured on each

individual spectrum analyzer sweep, the maximum, minimum, and (log) mean received

signal levels are measured. Repeated sweeps are made across the spectrum of interest,

and for each of the measurement points returned from each sweep, the three registers

for current maximum, minimum and mean are updated. This process continues until

it is halted programmatically. The total amount of time for each sweep, and the total

number of sweeps to be performed, are specified in advance by the operator. The

duration of each individual sweep maybe a few milliseconds, with a typical Swept/m3

measurement (hundreds of sweeps) lasting a total of several minutes. These

cumulative three-trace Swept/m3 measurements are saved on magnetic media, and may

themselves be cumed (see Section 3.3) in the analysis phase of a site survey to yield

long-term Swept/m3 curves. Typical RSMS site surveys use Swept/m3 measurements

for mobile radio bands.

Stepped: Stepping measurements consist of a series of individual amplitude measurements made at predetermined (fixed-tuned) frequencies across a spectrum band of

interest. The measurement system remains tuned to each frequency for a specified

measurement interval, This interval is called step-time, or dwell. The frequency

interval for each step is specified by an operator, and is usually about equal to the IF

bandwidth of the measurement system. For example, measurements across 200 MHz

might use 200 steps at a 1-MHz step interval and a 1-MHz IF bandwidth. Computer

control of the measurement system is needed for this (step, tune, and measure) process

to be performed at maximum speed.

Stepped measurements are usually performed to capture peak signals occurring on an

intermittent basis. A prime example is a periodically scanning radar. If the step-time

(dwell) is set slightly longer than the rotation or scanning interval of the radar beam,

then the maximum receivable level from the beam will illuminate the RSMS at some

‘For most RSMS operations with DA software control, any GPIB-interfaced spectrum analyzer

that processes at least 1000 points (frequencies) per display sweep may be used.

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time during that interval. The RSMS, which is fixed-tuned for the entire dwell period,

records each peak-detected point during that interval and the maximum amplitude

recorded is saved for that frequency. The RSMS then tunes to the next frequency (one

step), and repeats the process until the entire specified spectrum has been measured.

For intermittently received signals, such as scanned-beam radars, the stepped algorithm

has advantages over swept measurements. Stepping is faster, allows more dynamic

range (attenuation can be added and subtracted as a function of measured frequency

to extend the total available dynamic range of the measurement system), and has better

repeatability than swept measurements.

The RSMS uses stepped measurements to gather data in radiolocation bands where

measurements can be tailored to transmitter characteristics; i.e., dwell times, IF bandwidths, step widths, etc. are determined as a function of the parameters of the

radiolocation equipments which normally operate in the band.

Swept/az-scan: This is not currently a selectable algorithm in DA, but is a hybrid

routine using the Swept algorithm (above) with a rotating dish antenna. The dish is

targeted on the horizon then rotated 360° while the Swept algorithm is running with

positive peak detection and Maximum-Hold screen mode on the spectrum analyzer.

The result is an analyzer display that shows the maximum activity across a band in an

omnidirectional receiver sense, but with the effective gain of a dish antenna. This

routine is most useful for nondynamic bands where received signal levels tend to be

weak. Good examples are the common carrier (point-to-point) microwave bands; their

transmitters are fixed-tuned, operate continuously, and do not move. The transmitters

are also low-powered, and use high-gain antennas which further reduce their

probability of intercept.

B.2.1 Receiver Parameters

Following are brief descriptions of the DA program input parameters needed to run the above

subroutines (algorithms). Brackets identify the corresponding column headings as they appear

in the band event tables of Section 2.3.1. For example, [algorithm] in the tables shows which

of the above described subroutines is controlling the band event.

Start and Stop Frequencies [start (MHz)] [end (MHz)]: The value in megahertz of

the first and last frequency point to be measured. These numbers must be equal to or

fall outside the event frequency band range.

Passes: The number of times the algorithm iterates for each run command. This

value is always one for spectrum surveys.

Scans [scans (# of)]: The number of measurement sub-bands to occur between the

start and stop frequencies. This value is usually determined by comparing measurement bandwidth and frequency range. For example, a 30-MHz frequency range

81
measured with a 100-kHz IF bandwidth would ensure sampling of all frequencies

(1001 points) in one scan. However, if a 10-kHz IF bandwidth were used in the above

example, three scans would be required to ensure sampling of all frequencies.

Sweeps [sweeps (# of)]: The number of sweeps in each scan. DA processes each

sweep so increasing this number can add greatly to measurement time; however,

increasing this value also increases the probability of intercept for intermittent signals.

Steps [steps (# of)]: The number of frequency steps to occur between the start and

stop frequencies. This parameter is only used with stepped algorithms.

Graph Min and Graph Max: The minimum and maximum values in dBm for the

graphical display of measured amplitude data.

B.3 Spectrum Analyzer Subroutine

The DA spectrum analyzer subroutine manages configuration control strings (via GPIB) for the

spectrum analyzer. The operator selects spectrum analyzer parameters (listed in the following

subsection) from menus in the DA program. Generally, parameters are selected that will

configure the analyzer to run with a receiver algorithm for a desired measurement scenario. The

software protects against out-of-range and nonlinear configurations but the operator can control

the analyzer manually for unusual situations.

B.3.1 Spectrum Analyzer Parameters

When the DA program sends command strings to the analyzer, all signal path parameters are

reset according to the operator selections for the measurement scenario. Following are brief

descriptions of the analyzer parameter choices controlled by DA. Brackets identify the

corresponding column headings as they appear in the band event tables in Section 2.3.1.

Attenuation: May be adjusted from 0-70 dB in 10-dB increments. The spectrum

analyzer subroutine determines whether or not RSMS front-end attenuators are

available and if so will set them to the selected value. Spectrum analyzer attenuation

is set to zero when RSMS attenuation is active; if however, RSMS attenuators are not

available, the spectrum analyzer attenuation will be set to the selected value,

IF Bandwidth [IFBW (kHz)]: May be selected from 0.01-3000 kHz in a 1, 3, 10

progression.

Detector [detector type]:+,- peak, positive peak, negative peak, sample, maximum hold,

and video average modes are available. See Appendix C for discussions on detector

selection for receiver algorithms.

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Video Bandwidth [VBW (kHz)]: Maybe selected from 0.01-3000 kHz in a 1, 3, 10

progression.

Display: Amplitude graticule choices in dB/division are: 1, 2, 5, and 10. This

parameter selection applies to both the analyzer and the system console displays.

Reference Level [RL (dBm)]: May be adjusted from -10 to -70 dBm in 10-dB

increments.

Sweeps [MH/VA (#swps)]: Number of analyzer-processed sweeps per scan. This

parameter is only used with maximum hold or video-averaged detection.

Sweep Time [swp/stp (see)]: This parameter (entered in seconds) specifies sweep

(trace) time if used with swept algorithms, or specifies step time (dwell) if used with

a stepped algorithm.

B.4 RF Front-end Subroutine

The DA software handles the RF front-end path selection differently than other routines. Most

of the RF-path parameters are predetermined by the measurement algorithm so operators need

only select an antenna and choose whether preamplifiers are turned on or off. Preelection is also

controlled by the antenna selection.

The antenna selection is made from a list of antenna choices that is stored in a separately

maintained library file called by the RF Front-end Subroutine. Antenna information stored in the

file includes:

antenna type (omni, cavity-backed, etc.);

manufacturer (may include identification or model number);

port (tells the computer where signals enter the RSMS and includes particulars on

any external signal conditioning such as special mounting, additional amplifiers,

or extra path gain or loss);

frequency range;

vertical and horizontal beam widths;

gain relative to an isotropic antenna;

front to back gain ratio; and

side lobe gain levels.

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B.5 Calibration Subroutine

The calibration subroutine may be run at any time the operator chooses, but measurements must

be interrupted. The software is interactive and flexible, allowing the operator to choose any

calibration path desired. RSMS calibrations are performed with noise diodes and Y-factor excess

noise ratio (ENR) techniques, as described in Appendix D.

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APPENDIX C: INTERPRETATION OF SPECTRUM SURVEY DATA

C.1 Introduction

RSMS spectrum survey measurements are performed with a variety of receiver algorithms (see

Section B.2 of Appendix B). These algorithms provide various combinations of frequencysweeping or frequency-stepping, positive-peak or sample detection, and data-processing

capabilities during the data acquisition phase of the spectrum survey. Additional processing is

performed on the data after the acquisition phase. Measurement algorithms are assigned on an

individual basis to optimally measure spectrum use in each band.

Each algorithm has a particular response to noise and signal activity. It is critical to understand

the noise and signal response of each algorithm if the RSMS data are to be used accurately. This

appendix describes the algorithms currently used for RSMS site surveys. The noise and signal

response of each algorithm is described, along with the types of spectrum occupancy it is best

suited to measure. Some of the data-processing techniques are also discussed to fully explain

the measurement algorithms.

C.2 Signal Probability of Intercept Factors

RSMS measurements are intended to achieve a high probability of intercept for the types of

signal activity occurring in each spectral band. Factors that are considered include:

 the types of emitters allocated to the band (e.g., land mobile radio, radiolocation,

or broadcasting);

 the percentage of time individual transmitters in the band typically operate (e.g.,

100% on-air time by broadcasters vs. intermittent radio dispatch messages);

 the dependence (or nondependence) of band activity on diurnal and other cyclic

occurrences (e.g., radionavigation beacons with no time dependence vs. marine

mobile activity which varies as a function of time-of-day and day-of-week);

 the time interval that individual transmissions usually occupy (e.g., air traffic

control communications vs. cellular telephone communications);

 the periodicity, if any, of individual transmissions (e.g., a highly periodic search

radar beam that completes a rotation every 4 s vs. mobile communications that

occur in a random distribution over time);

 the directional gain, if any, of antennas used by the transmitters (e.g., an omnidirectional navigation beacon vs. a point-to-point microwave link);

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 the typical peak and average power outputs of transmitters in the band (e.g, 4 MW

peak power from a radar vs. perhaps a fraction of a watt from a typical land

mobile radio);

 the signal duty cycle (e.g., a 30-dB duty cycle for a typical radar vs. a near 0-dB

duty cycle for a two-way radio transmission);

 the relative abundance or paucity of systems using the band (e.g., a band used

largely by airborne fire-control radars vs. a band used by thousands of local voicecommunication radios); and

 the polarization of typical transmitted signals in the band.

These factors are used to optimize the receiver parameters for the selected band, select the

measurement algorithm, and determine how measurement time should be allocated. The relative

amount of time devoted to measure each band is roughly proportional to the dynamics of band

usage. For example, point-to-point microwave bands are not very dynamic, because the

transmitters in these bands normally operate 24 hours/day, 365 days/year, at uniform power

levels, and fixed beam directions. Their operations are not normally affected by external factors,

such as weather or local emergencies, Consequently, these bands are measured only once during

a spectrum survey. In contrast, activity in land mobile radio bands is highly dynamic, varying

significantly with time-of-day, day-of-week, and other factors such as local emergency conditions.

Consequently, these bands are measured frequently throughout a site survey, so that a maximal

number of time-dependent signals will be intercepted. Slightly less dynamic bands, such as those

used by tactical radars, are measured less frequently than the mobile bands, but more frequently

than the point-to-point microwave bands. Bands whose use varies with local weather, such as

those used by weather radars, are measured on different clear-weather and foul-weather

schedules.

Swept-spectrum measurement techniques are used in highly dynamic bands. Stepped-spectrum

techniques are used in bands occupied by periodic emitters, such as radars. A slow dish antenna

sweep of the horizon coupled with simultaneous swept-spectrum measurements is used in pointto-point microwave bands. These measurement techniques are detailed in the following

subsections.

A parabolic antenna is used to measure signals from fixed-beam, highly directional transmitters

in the point-to-point microwave bands (see the description of azimuth scanning in Section C.8).

For bands in which signals are expected to originate primarily from a single quadrant as seen

from the RSMS location, a moderately directional antenna (such as a cavity-backed spiral or a

log-periodic antenna) is used. For bands in which signals are expected to originate from any

direction with an approximately constant probability, such as bands used by airborne beacon

transponders and air-search radars, the RSMS uses omnidirectional antennas.

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Slant (antenna) polarization is used for all RSMS measurements except those in the point-to-point

microwave bands. Slant-polarized biconical omnidirectional antennas are usually used above

1 GHz, and slant-oriented log-periodic or conical omnidirectional antennas are usually used below
1 GHz. Slant polarization provides adequate response to all signals except those having a slant

direction orthogonal to the RSMS antennas. Orthogonally oriented slant-polarized signals are

rare, In the point-to-point microwave bands, the transmitted signals are always vertically or

horizontally polarized, and thus RSMS receive polarization in those bands is alternately vertical

and horizontal, with the results being combined into a composite scan.

The end result of these selections (number of measurements made in each band, selection of

antenna type and polarization, and selection of measurement algorithm) is to optimize the

probability of intercept for signals present during the course of the RSMS site survey. Inevitably,

some signals will be missed; however, the standard RSMS spectrum survey data set should

provide a good measure of the relative number, levels, and types of signals in each of the bands

between 100 MHz and 19.7 GHz.

C.3 Overview of Swept Measurement Techniques

To fully understand the measurement algorithms described in this appendix, it is necessary to

describe how the spectrum analyzers perform swept-frequency measurements.

The HP-8566B spectrum analyzers used in the RSMS sweep across the spectrum in individual

segments called spans. The frequency range of each span is in turn broken into 1001 individual

frequency bins. When the spectrum analyzers perform sweeps across a selected span, they spend

a finite amount of time measuring received power in each of the 1001 bins. For example, a

20-ms sweep time divided by 1001 measurement bins per sweep yields a 20-us measurement time

in each frequency bin. Within each bin measurement interval (in this example, 20 us), the power

measured in the waveform may take on multiple values. However, the spectrum analyzer can

only provide a single power measurement per bin.

The single value derived from the multiple values occurring within each bin-sampling interval

depends upon which spectrum analyzer detector mode has been selected. The detector modes

available in the RSMS spectrum analyzers are positive peak, negative peak, sample, and

“normal.” (Note: positive peak detection is different from the maximum-hold display mode

discussed in Section C.6.) Positive peak detector mode will latch to the highest power value

attained by the measured waveform during the sampling interval (continuing the example above,

this would be 20 us) for each bin. Similarly, the negative peak detector mode latches to and

displays the lowest power level measured during each bin interval. In sample detector mode, the

value displayed is the power level that the input waveform has assumed at the end of the bin

measurement interval. If the bin sampling interval is uncorrelated. with respect to the input

waveform, then this value can be considered to be randomly selected from the input waveform,

Finally, in “normal” detection mode, alternate bins use positive peak and negative peak detection,

If the analyzer’s video bandwidth is substantially narrower than the IF bandwidth, and if a white

noise source (such as thermal electron noise in a circuit or a noise diode) is being measured, then

an average value of the noise will be displayed, irrespective of the detector mode which has been

selected.

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If the analyzer’s video bandwidth is equal to or greater than the IF bandwidth, and if a white

noise source is being measured, then the displayed power level will vary as a function of the

detector mode. Positive peak detection will display noise values approximately 10-12 dB higher

than the RMS noise level, and negative peak will display values about 10-20 dB below the RMS

noise level. “Normal” detection used on such a noise source will display an illuminated band

about 20-30 dB wide, with an average value equal to the RMS level of the noise. Normal

detection mode is useful for estimating the duty cycle of a signal (the wider the illuminated band

underneath a signal peak, the lower the duty cycle of the signal).

C.3.1 Description of the Swept/m3 Measurement Algorithm

The Swept/m3 algorithm, developed by ITS, is an extension to the swept measurements just

described. In Swept/m3 mode, frequency-domain data traces are measured repeatedly across a

band on the spectrum analyzer. Each sweep is returned individually to the PC controller, but the

data traces are not individually recorded. Instead, for each of the 1001 frequency bins that the

analyzer returns in each sweep, the PC sorts the returned values as follows: the value in each

bin is compared to the highest and lowest values so far observed in that bin, and if the new value

represents a new maximum or minimum in that bin, then it is saved as such. (This is, in effect,

a software-implemented version of maximum-hold and minimum-hold trace mode.) Also, the

current value of each bin is included in a running average of all the values returned for that bin

in previous sweeps. This is an average of measured power in the selected detector mode (i.e.,

the decibel values are averaged). Thus, the maximum, minimum, and mean (m3) signal levels

in a band are simultaneously obtained over the time interval (typically several minutes) that the

spectrum analyzer continues sweeping. This real-time turning process compresses data volume

by several orders of magnitude, but the compression causes loss of the original data sweeps, and

thus precludes the possibility of processing the original data sweeps with different algorithms

during postmeasurement analysis. Figure C-1 shows how the Swept/m3 cumulative processing

is integrated with the normal RSMS processing path. All other cumulative processing is

accomplished during postmeasurement analysis.1In the diagram, all measured data identified

as “RSMS data output for lab analysis” is considered to be postmeasurement data.

C.4 Description of Swept/m3/Sample Data Collection

If the Swept/m3 algorithm (described in Subsection C.3. 1 ) is performed using the sample detector

(see Section C.3 for a description of the sample detector in the RSMS analyzers), then the data

are referred to as “Swept/m3/sample,”

1All band events measured more than once during the same survey are cumed as explained in this

appendix. Stepped and swept data records are processed for maximum, mean, and minimum

received signal levels. Swept/m3 data already contains this information so a maximum of

maximums, mean of means, and minimum of minimums is extracted for survey graphs.

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Figure C-l. Functional diagram of the RSMS signal-processing path for cumulated data.

C.4.1 Interpretation of Noise Responses in Swept/m3/SampIeData

The noise level displayed by a measurement system using the sample detector will be equal to

[kTB+(measurement system noise figure) -2.5dB].2 With a 1-MHz IF bandwidth and a l0-dB

measurement system noise figure, for example, the average noise level would occur at-104 dBm.

2

kTB is derived from the Nyquist Theorem for electron thermal noise, where: k is Boltzmann’s

constant (1.38.10-20 mW*s/K), T is system temperature (290K for these measurements), and

B is measurement IF bandwidth in Hz. For B = 1 Hz, at room temperature: kTB = -174 dBm.

In a l-MHz IF bandwidth, kTB = -174+ 10log(106

) = -114 dBm.

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If the video bandwidth (that is, the postenvelope detector, low-pass filtering bandwidth) is

significantly narrower than the IF bandwidth, then the variance in the measured average noise

will be very small (approximately 1 dB). This mode is normally used only for calibrations in

the RSMS.

However, if the video bandwidth is set to a value equal to or greater than the IF bandwidth

(which is the case for RSMS spectrum survey measurements), then the maximum level sampled

on thermal noise will be about 10-12 dB above the average, and the minimum level sampled on

thermal noise will be about 10-20 dB below the average.

C.4.2 Interpretation of Signal Responses in Swept/m3/Sample Data

Because the sample detector value displayed for each bin is the value of the waveform at the end

of each bin interval, the value displayed for a signal with a duty cycle of 100% will be equal to

the peak power of the signal (if the signal was present for the entire bin interval). However, if

a signal has less than a 100% duty cycle (and is not present during the entire bin interval), then

the probability that the signal will be sampled is less than one. For example, if the signal is only

present for half of the bin interval, there is only a 50% chance that the sample detector will

capture the value of the signal (and a 50% chance that the measurement system’s thermal noise

will be displayed). For typical radar signals, which operate with a duty cycle of about 1:1000,

the probability that a bin will display the radar signal value is only about 1/1000 (O. 1 %). The

same rationale holds for impulsive noise; sample detection mode tends to display high-duty cycle

signals, but not low-duty cycle signals such as radars and impulsive noise. This makes sample

detection a desirable option for measurements in bands handling mobile communications, where

the signals of interest have high duty cycles, and where measurement of impulsive noise is not

desirable for the purposes of the RSMS project.

For Swept/m3/sample data, the highest curve shows the maximum signal ever captured by the

sample detector on any trace at each measured frequency. This represents the highest value ever

attained by high-duty cycle signals at each measured frequency; impulsive energy could have

been present at even higher values, but would have been discriminated against by the sample

detector. At frequencies where no signal was ever measured, the maximum curve will have a

value of kTB + measurement system noise figure + (nearly) 10 dB. This value will be 10 dB

higher than the average noise (middle) curve. Since a signal displayed on the maximum curve

can occur with different amplitudes at different times, there is no way to determine, solely from

examination of the maximum curve, how frequently the displayed signals were measured.

The middle curve of Swept/m3/sample data shows the power average (average of the measured

decibel values) of all of the raw data traces gathered in the band. Qualitatively, the closer this

curve comes to the maximum curve at any given frequency, the higher the percentage of scans

in which the signal was observed. Quantitatively, it is not possible to derive an actual percentage

of scans in which the signal was present. This is because the signal may not have always been

received at the same level, and the level received on raw scans is not recorded. If, however, the

average curve comes close to touching the maximum curve, then the signal must have been

present in nearly 100% of the raw data traces, Conversely, if the maximum and mean curves are

90
far apart, then the signal was probably observed in a lower percentage of raw data scans. If no

signals were ever measured at any given frequency, then the middle curve will show

measurement system noise at a value of kTB + measurement system noise figure, about 10 dB

below the maximum noise curve.

Finally, the lowest curve shows the minimum power level measured in any raw data trace, at

each measured frequency bin. If no signal is measured in a bin during any sweep, then this

curve will have a value of kTB + measurement system noise figure - (10-20 dB). This is

10-20 dB lower than the average curve. If a signal is present in 100% of the measurement

sweeps, then a bump will occur in the minimum curve at that frequency. The amplitude of the

bump will be equal to the minimum power measured for the signal. Thus, this curve serves the

purpose of showing signals that are continuously present during the spectrum survey.

In this report, the nominal levels of the measurement system noise for the maximum, minimum

and mean curves are indicated by tick marks on the lower left side of each swept/m3/sample

graph. The tick marks, labelled “max sample noise,” “avg sample noise,” and “min sample

noise,” are intended to assist report users in determining which graphed features are signal and

which graphed features are measurement system noise.

C.5 Description of Swept/m3/+Peak Data Collection

If the Swept/m3 algorithm is performed using the positive peak (+peak) detector (see Section C.3

for a description of the +peak detector in the RSMS spectrum analyzers), then the data are called

“Swept/m3/+peak.”

C.5.1 Interpretation of Noise Responses in Swept/m3/+Peak Data

The average noise level displayed by a measurement system using a +peak detector will be equal

to kTB + measurement system noise figure + approximately 10-12 dB. With a l-MHz IF

bandwidth and a 10-dB measurement system noise figure, for example, the average +peak noise

level would occur at -174 dBm/Hz + 10log( 106 Hz) + 10-dB noise figure + 10-dB peak detector

offset = -94 dBm.

If the video bandwidth (the postenvelope detector, low-pass filtering bandwidth) is equal to or

greater than the IF bandwidth (which is the case for RSMS site survey measurements), and if the

sweep time is short (a few tens of microseconds per bin), then the maximum level sampled on

thermal noise will be about 10 dB above the average; the minimum level of thermal noise will

be about 10 dB below the average. Note that this +,- 10-dB value for maximum and minimum

levels of +peak noise is the same as the +,-10-dB offset levels for sample detection, but that the

maximum, mean, and minimum peak-detected levels are 10 dB higher than the corresponding

sample-detected levels.

Positive peak detection shows less than a +,-10-dB difference between the maximum, mean, and

minimum as sample times increase (i.e., as sweep times become longer). This is because the

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positive peak detector will have a higher probability of latching to a high noise level if it samples

the noise for a relatively long interval. In this case, the minimum and average noise levels will

approach the maximum noise level to within a few decibels. The maximum will be 2-3 dB

higher than the short sweep-time values.

C.5.2 Interpretation of Signal Responses in Swept/m3/+Peak Data

Because the +peak detector latches to the highest value that the waveform assumes during each

bin interval, the value displayed for a signal will be equal to the peak power of the signal

(assuming that the measurement system is not bandwidth-limited in its response) regardless of

the signal’s duty cycle. This makes +peak detection mode useful for measuring impulsive

activity such as radar signals. (This also means that +peak detection will also record impulsive

noise in the spectrum.) Thus, the +peak detector is used in RSMS spectrum surveys to measure

radiolocation bands and other bands where activity is dominated by impulsive (low-duty cycle)

transmissions.

For Swept/m3/+peak data, the highest curve shows the maximum signal ever captured by the

+peak detector on any trace in each measured frequency bin. At frequencies at which no signal

was ever measured, the maximum curve will have a value of kTB + measurement system noise

figure + about 10-dB peak detector offset + 10 dB. If the sweep time is short (a few tens of

microseconds per bin), this will be about 10 dB higher than the average peak detector response.

If the sweep time is much longer, the average will be higher, coming to within a few dB of the

maximum. There is no way to determine, solely from examination of the maximum curve, how

frequently the displayed signals were observed.

The middle curve of Swept/m3/+peak data shows the power average (average of the antilogs of

the measured decibel values) of all the data traces that were gathered in the band. Qualitatively,

the closer this curve comes to the maximum curve at any frequency, the higher the percentage

of scans in which the signal was observed. Quantitatively, it is not possible to derive a

percentage of time the signal was present, because the signal may not always be received at the

same level. If, however, the average curve nearly touches the maximum curve, then the signal

must have been present in nearly all of the raw data traces. Conversely, if the maximum and

mean curves are far apart, then the signal was probably observed in a low percentage of scans.

If no signals were measured at a frequency, and if sweep time is a few tens of milliseconds, the

middle curve will show measurement system noise at a value of kTB + measurement system

noise figure + about 10-dB peak detector offset. This value will be nearly 10 dB higher if the

sweep time is appreciably longer.

Finally, the lowest curve shows the minimum power level measured with the +peak detector in

any sweep, in each frequency bin. If no signal is measured at a frequency, and if the sweep time

is a few tens of milliseconds, this curve will have a value of kTB + measurement system noise

figure + about 10 dB peak detector offset - 10 dB, which is 10 dB lower than the mean peak

detector curve. If the sweep time is longer, the minimum curve will approach the maximum and

mean curves. If a signal is observed at a frequency in every data sweep, then a bump will occur ‘

92
in the minimum curve at that frequency. Thus, this curve shows signals that are continuously

present during the spectrum survey.

In this report, the nominal levels of the measurement system noise for the maximum, minimum

and mean curves are indicated by tick marks on the lower left side of each swept/m3/+peak

graph. The tick marks, labelled “max +peak noise,” “avg +peak noise,” and “min +peak noise,”

are intended to assist report users in determining which graphed features are signal and which

graphed features are measurement system noise.

C.6 Description of Swept/Max-Hold Data Collection

If a frequency-sweeping algorithm is performed using the +peak detector (see Section C.3 for a

description of the +peak detector in the RSMS spectrum analyzers) while the spectrum analyzer

display is being operated in the Maximum-Hold mode,

3 then the data are referred to as

“Swept/max-hold”

The measured data are peak-detected, maximum-hold scans. Each scan represents an interval of

a few minutes of maximum-hold running on the measurement system. The scans do not contain

mean or minimum information. They are intended only to show the presence of intermittent,

low-duty cycle signals, and therefore no additional information is obtained,

The individual scans are cumed for the site survey report, and as a result, the final graphs show

maximum, minimum, and mean curves. However, the distribution of maximum-hold data is

narrow when noise is being measured, and so the difference between these curves is only about

+,-3 dB on noise, instead of the +,-10 dB difference which usually characterizes swept/m3 data.

C.6.1 Interpretation of Noise Responses in Swept/Max-Hold Data

The maximum, mean, and minimum curves displayed by a measurement system will be nearly

identical if the hold time is more than a few tens of microseconds per bin. If white noise is

measured, the three curves will all have a value of about kTB (at room temperature) +

measurement system noise figure + about 10-dB peak detector offset + 10 dB. With a 1-MHz

IF bandwidth and a 10-dB measurement system noise figure, for example, the noise level is about

-174 dBm/Hz + 10log( 106 Hz) + 10-dB noise figure + 10-dB peak detector offset + 10 dB =

-84 dBm.

3

In Maximum-Hold mode, the spectrum analyzer repeatedly sweeps a portion of spectrum, and

saves the highest value measured in any sweep in each screen display bin. Thus, Maximum-Hold

mode generates a maximum-level trace which is analogous to the maximum-level trace generated

by RSMS software in the Swept/m3/+peak mode.

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If the video bandwidth is equal to or greater than the IF bandwidth, then the maximum level

sampled on thermal noise in maximum-hold mode is about 2 dB above the mean, and the

minimum level sampled on thermal noise is about 2 dB below the mean.

C.6.2 Interpretation of Signal Responses in Swept/Max-Hold Data

Swept/max-hold measurement mode is ideal for capturing low-duty cycle signals from

intermittently operating systems. It can be used in bands occupied by impulsive emitters that

operate intermittently (e.g., airborne radars). A Swept/max-hold measurement displays the

maximum activity observed in a band for an interval of a few minutes. No information is

collected to indicate mean or minimum activity during that interval.

For cumed Swept/max-hold data, the highest curve shows the maximum signal ever captured by

the +peak detector on any maximum-hold trace at each measured frequency. Since a signal

displayed on the maximum curve could have occurred with different amplitudes at different

times, there is no way to determine, solely from examination of the maximum curve, how

frequently the displayed signals were actually observed.

The middle curve of cumed Swept/max-hold data shows the power-average (average of the

antilogs of the measured decibel values) of all individual maximum-hold data traces that were

measured in the band. Qualitative y, the closer this curve comes to the maximum curve at a

frequency, the higher the percentage of scans in which the signal was observed. Quantitatively,

it is not possible to derive an actual percentage of time that the signal was present, because the

signal may not have always been received at the same level. If the mean curve nearly touches

the maximum curve, then the signal must have been present in most of the raw data traces. If

no signals were ever measured at any given frequency, then the middle curve will be about 3 dB

lower than the maximum curve.

Finally, the lowest curve shows the minimum power level ever measured with the +peak detector

in any maximum-hold data trace, at each measured frequency. If a signal was present in every

scan, then the curve shows a bump at that frequency. Otherwise, the curve will show noise 3 dB

below the mean curve. Thus, this curve serves the purpose of showing signals that were present

in all of the scans.

C.7 Description of Stepped/+Peak Data Collection

Although most spectrum analyzers are routinely operated by sweeping in the frequency domain,

this is not the most efficient method for the measurement of spectral emissions from pulsed

emitters like radars. An alternative method, called stepping, is usually faster and can provide

measurement results with wider dynamic range than is possible with sweeping.

Stepping is performed by tuning the measurement system to a frequency in the radar spectrum,

and then performing a time-scan at that frequency over a span of zero hertz. Positive peak

detection is always used. For rotating radars, the interval (called dwell time) for a single timescan is set equal to or greater than the radar rotation time. (For electronically beam-scanning

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radars, this interval is selected on the basis of the typical recurrence of the radar beam at the

measurement site.) For example, if a radar has a 10-s rotation time, then the dwell time at each

measured frequency might be set to 12 s. Thus, the emitter’s rotating main beam would certainly

be aimed in the direction of the measurement system at some moment during the 12-s time-scan,

At the end of the dwell period, the highest-amplitude point that was measured is retrieved,

connected for calibration factors, and stored. This process of waiting at a frequency in a O-Hz

span and recording the highest point measured during a radar rotation (or beam-scanning) interval

is called a “step.” When each step is completed, the measurement system is tuned to another,

higher frequency, and the process is repeated.

The spectrum interval between adjacent measured frequencies is approximately equal to the IF

bandwidth of the measurement system. For example, if a l-MHz IF bandwidth is being used,

then the frequency interval between steps will be about 1 MHz. The IF bandwidth is determined

from the inverse of the emitter pulse width. For example, if 1 us is the shortest pulse width

expected from emitters in a band, then a 1-MHz measurement (IF) bandwidth is used. In this

manner, the entire spectrum is convolved with the measurement bandwidth across the band of

interest.

Stepped measurements are used for all dominantly radiolocation (radar) bands. IF bandwidth and

dwell times are optimized for typical radars in the band. The individual stepped measurement

scans are cumed for spectrum surveys and the final graphs show a maximum, minimum, and

mean value for each dwell time at each measured frequency during the entire survey.

C.7.1 Interpretation of Noise Responses in Stepped/+Peak Data

The mean noise level displayed by the measurement system in the +peak detector stepped mode

will be equal to kTB (at room temperature) + measurement system noise figure + 10-dB peak

detector offset. With a l-MHz IF bandwidth and a 10-dB measurement system noise figure, for

example, the mean +peak noise level is -174 dBm/Hz + 10log( 106 Hz) + 10-dB noise figure +

10-dB peak detector offset = -94 dBm.

The difference between the maximum and minimum levels measured for noise in the stepped

mode is small; the maximum and minimum curves will be about +,-2 dB relative to the mean

curve.

C.7.2 Interpretation of Signal Responses in Stepped/+Peak Data

Stepped/+peak measurement mode is ideal for capturing low-duty cycle signals from systems that

direct energy at the measurement site at regular intervals (e.g., rotating radars). If the dwell time

is greater than or equal to the rotation time of the radar, then the stepped algorithm will

completely fill the emission envelope.

The maximum curve on each site survey graph for stepped measurements depicts the maximum

envelope of the spectral emissions of the emitters observed in the band. The result is a

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representation of the spectrum occupancy when emissions (usually radar beams) are directed at

the measurement site.

The minimum curve represents the lowest signal ever measured at each frequency step during

the survey. If an emitter is turned off during a single scan, then this curve will be at the system

noise level for that emitter. At frequencies where this curve is above the noise level, but well

below the maximum curve, the difference represents either varying emitter power output levels,

varying emitter-scanning modes, varying propagation between the emitter and the measurement

site, or a combination of these factors.

The mean curve represents the linear mean (the average of the antilogs of the decibel values of

received signal level) for each frequency step in the band of interest during the site survey. This

is not necessarily the same as the mean signal level transmitted by a radar to the measurement

location. For example, a radar that was turned on during half the stepped scans, and turned off

during the other half would appear, after cuming, with a maximum curve that is its emission

envelope, a minimum curve that is the measurement system noise floor, and a mean curve

roughly midway between the radar envelope and the noise. However, the radar would never have

been measured at the amplitudes shown on the average curve.

C.8 Description of Swept/Az-scan Data Collection

In bands dominated by point-to-point fixed microwave communication systems, the main beams

of the transmitters are seldom pointed towards the RSMS. To enhance the probability of

intercepting signals from these sources, a dish antenna is used. However, the site survey data

must include signals received from all points on the horizon. These two apparently contradictory

requirements are reconciled by performing azimuth scanning with the dish antenna. The RSMS

dish antenna is pointed at the horizon and slowly rotated through 360°. Simultaneously, a

spectrum analyzer sweeps the band of interest with positive peak detection and maximum-hold

scan mode. Such measurements are called “Swept/az-scan.”

The dish antenna is rotated at approximately 60

/s (1 rpm), while the sweep time across the band

is set at 20 ms. At the highest frequencies, where the dish beamwidth is about 10, the dish

rotates through one beamwidth in 1/6 s (170 ins). This is long enough for 7 or 8 sweeps

(170 ms/20 ms) within the beam width. Thus, every point on the horizon is sampled at least 7 or

8 times across the entire band of interest. Maximum-hold mode and positive peak detection

ensure that any signal that arrives at the RSMS site is retained on the scan.

The dish is rotated twice around the horizon: once with horizontal polarization and once with

vertical polarization. The purpose is to observe signals from point-to-point links utilizing either

polarization. The two polarization scans are combined to show the maximum envelope of both

scans on a single data curve.

The single data curve is corrected for noise diode calibration factors and recorded. Unlike other

RSMS site survey measurements, this measurement is only performed once at each survey

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location and no cuming is performed on this data. Activity in these bands does not vary much

with time and little information is gained by measuring these bands repetitively.

C.8.1 Interpretation of Signal Responses in Swept/Az-scan Data

Swept/az-scan data show the presence of a signal at some point or points on the horizon. The

data curve does not reveal the direction of any signals, but does show the aggregate occupancy

of the spectrum by all point-to-point signals detected omnidirectionally on the horizon.

Generally, two types of signals will be noted in the az-scan graphs: those having narrow

emission spectra, and those having wider emissions. The narrow signals are analog links, and

the wider signals are digital links. Because a single transmitting tower (a single point on the

horizon) may have many channels in operation (often located next to each other in the spectrum),

clusters of signals with uniform amplitudes will be observed. Space-to-earth and earth-to-space

links in these bands are not normally detected by the RSMS.

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APPENDIX D: CALIBRATION OF THE MEASUREMENT SYSTEM

D.1 Introduction

Measurement system calibration is performed prior to and during every RSMS site survey.

Calibration curves, as in Figure D-1, showing system noise figure and gain corrections as a

function of frequency across the entire frequency range are generated. As measurements are

performed, gain corrections are automatically added to every raw data point that is collected.

Gain and noise figure curves are used by RSMS operators to determine the relative health of the

measurement system, and are also used to pinpoint locations in the measurement system RF path

that are operating suboptimally.

Frequency (MHz)

Figure D-1. Example calibration graph for RSMS System-1 showing noise figure (upper; dashed

curve) and correction factors (lower; solid curve).

RSMS calibrations are performed exclusively with noise diodes such as the one shown in

Figure D-2. Although the technique of noise diode calibration is not as well known in electrical

engineering activities as other techniques (e.g., signal generators or vector network analyzers),

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noise diodes are commonly used for calibration of measurement systems where minimal size,

weight, and power consumption are required. Noise diodes provide these features while

maintaining high calibration accuracy and this is why they are used for RSMS calibrations.’

This appendix describes the theory and operation of RSMS noise diode calibrations.

Figure D-2. A typical noise diode solid state noise source. A +28-volt potential applied to the

BNC connector on the right produces +24-dB excess noise ratio from the type N

connector on the left.

‘Another example of noise diode use for measurement system calibration is the Cosmic

Background Explorer (COBE) satellite, which recently produced a whole-sky map of 2.5-K

background radiation, The same features that make noise diodes attractive for critical satellite

calibrations also make them attractive for RSMS work at field locations.

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D.2 Theory

RSMS calibrations are implemented as a variant of the y-factor calibration method [1], The

y-factor method of amplitude calibration provides for a simple, yet accurate characterization of

the amplitude response and noise figure of an RF receiver system. Using noise diodes, amplitude

uncertainties of 1 dB in calibration may be achieved in field calibrations over a frequency range

of more than 18 GHz.

The noise diode calibration of a receiver tuned to a particular frequency may be represented in

simple, lumped-component terms as in Figure D-3. In this diagram, the symbol labelled 

represents a power-summing function that linearly adds any power at the measurement system

input to the inherent noise power of the system. The symbol labelled g represents the total gain

in the measurement system. The measurement system noise factor is denoted by nfs, and the

input is a noise diode with an excess noise ratio of enrd.

2

Figure D-3. Lumped-component noise diode calibration schematic diagram; reference equations

(Dl) and (D2).

Note that in this appendix all algebraic quantities denoted by lower-case letters, such as “g,”

represent linear units. All algebraic quantities denoted by upper-case letters, such as “G,”

represent decibel units. Lower-case and upper-case quantities are connected to each other by the

2Many references do not offer a clear explanation of the difference between noise factor and

excess noise ratio. Noise factor is the ratio of noise power from a device and thermal noise,

(ndevice/kTB). The excess noise ratio is equal to the noise factor minus one, making it the fraction

of power above (in excess of) kTB. The noise figure of a system is defined as 10 log of the

noise factor, forcing a solution for noise factor in the calculations. However, since many noise

sources are specified in terms of excess noise ratio, that quantity must sometimes be used.

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relation (UPPER CASE TERM) = 10log(lower case term); for example, G = 10log(g), or if

enrd = 100 mW, then ENRd = 20 dBm,

In noise diode calibration, the primary concern is the difference in output signal when the noise

diode is switched on and off. For the (noise diode = on) condition, the linear expression is:

pon = (nfs + enrd) x gkTB, (Dl)

and for the noise diode = off condition:

Poff 

= (nfs

) x gkTB. (D2)

The quantity k is Boltzmann’s constant, equal to 1.38 *10-20 mW*s/K (milliwatt seconds per

kelvin). T is the system temperature in kelvin, and B is the bandwidth in hertz. The ratio of

these two quantities is called the Y factor:

y = (pon/poff) = (nfs + enrd)/(nfs) (D3a)

Y = l0log(y) = loIog(pon/poff) = Pon - Poff. (D3b)

From equation (D3), we solve for the system noise factor:

nfs = (enrd)/(y-1).

The measurement system noise figure is 10 log of the noise factor:

NFs = 10log(enrd/(y- 1))

= ENRd - 10log(y- 1)

= ENRd - 10log(l0y/10 - 1).

Solving equations (Dl) and (D2) for gain, g, yields:

g = (pon - poff)/(enr d x kTB)

(D4)

(D5)

(D6a)

G = 10log(pon- poff) - 10log(enrd x kTB)

In RSMS calibrations, equation (D6c) is used to calculate gain from measured noise diode values.

Note that this calculation utilizes the difference between pon and poff, rather than the y-factor ratio

of these values. Thus, the RSMS noise diode calibration is a variant of the standard y-factor

calibration technique.

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Although equation (D5) could be used to calculate measurement system noise figure, the

implementation in RSMS software uses an equivalent equation. It is derived from (D1):

Substituting expression (D6b) for gain into (D7b) yields:

In RSMS calibrations, equation (D7c) is used to calculate noise figure. Whenever an RSMS

calibration is performed, Pon. and Poff are measured at 100 frequencies across the frequent y range

to be measured, and equations (D6c) and (D7c) are then used to calculate system gain and noise

figure for each of those 100 calibration points. The result is the gain response and noise figure

of the system as a function of frequency for the frequency range of the measurement. Negative

values of the system gain are stored in look-up tables, and are added to raw data values as a

correction factor. The gain-corrected power values are stored as spectrum survey data.

Antenna gain corrections are not routinely added to the raw data points as part of RSMS

spectrum survey measurements; if incident field strength is required, then antenna correction

factors are subtracted separately, after the measurement has been completed. The conversion

from power measured in the 50-ohm RSMS circuitry to incident field strength in free space is:

where

Alternatively, if the receiving antenna correction factor (ACF) is known, instead of the antenna

gain relative to isotropic, then the incident field strength conversion equation is:

where

ACF = antenna correction factor, dB.

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D.3 Application

Excluding the receiving antenna, the entire signal path within the RSMS is calibrated with a noise

diode source both before and during a spectrum survey; a noise diode, such as shown in

Figure D-2, is connected at thepoint where the RF line attaches to the receiving antenna. The

connection may be accomplished manually or via an automatic relay, depending upon the

measurement scenario. The noise level in the system is measured at 100 points across the desired

frequency range with the noise diode turned on (ON) and turned off (OFF). The RSMS control

computer stores all of the ON vs. OFF noise diode values. The control computer then uses the

measured difference between ON and OFF at each of the 100 calibration points to solve the

calibration equations (D6c) and (D7c) shown above. The gain values are inverted in sign to

become correction values. The resulting set of 100 noise figure and gain correction values are

stored as a function of system frequency in look-up tables on the computer disk. The frequencydependent gain-correction curve is used to automatically correct the measured amplitudes of all

received signals in subsequent measurements. Figure D-1 shows the gain-correction curve and

noise figure curve for a typical RSMS measurement.

This calibration technique has proven very successful for field-deployed radio spectrum

measurement systems. It is a fast way to determine sensitivity and gain-correction values for a

measurement system, and it is also very useful for isolating the gains and losses through

individual components of the measurement system, such as RF lines and amplifiers. Compared

to alternative calibration equipment, such as signal generators or vector network analyzers, noise

diodes have several advantages:

 The physical size and weight of a noise diode are comparatively small: dimensions

are typically less than 5” long and less than an inch diameter; weight is a few

ounces.

 Power consumption is low, at about 50 mA of direct current at a +28 volt

potential.

 Cost is low, at a few hundred dollars or less for a noise diode.

 Because noise diode sources are inherently broadband (typically 100 MHz to

18 GHz or more), there are no frequency-tracking problems in the calibration, as

are encountered with many other calibration techniques.

All of these features lend themselves to measurements in the field, where small size and weight,

low power consumption, and simplicity of operation are all at a premium. Moreover the low cost

and small requirements for size, weight, and power make it possible to locate several noise

diodes at various places in the measurement system, and to carry spares in the event that a noise

diode fails. Noise diodes can themselves be calibrated by such entities as the National Institute

of Standards and Technology.

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At frequencies below 12 GHz, accuracy of noise diode calibration with spectrum analyzers

installed in the RSMS is good to within a decibel. At frequencies from 12-18 GHz, accuracy

falls to about +,- 2.5 dB due to a higher system noise figure. For noise diodes producing an ENR

of about +25 dB, as are used for RSMS measurements, calibrations cannot be performed in a

practical sense if system noise figure is more than about 30 dB or is less than about 1 dB. This

is because the difference between Pon and Poff becomes too small to measure reliably in the first

case, and too close to the rated ENR of the noise diode to measure reliably in the second case.

Noise diode calibrations will not provide information on phase shift as a function of frequency;

if a measurement system must be calibrated for phase shift, then additional or alternative

calibration methods must be used.

D.4 Reference

[1] S. Adam, Microwave Theory and Applications, Englewood Cliffs, NJ: Prentice-Hall, Inc.,

1969, pp. 490-502.

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