NTIA Report 97-336

Broadband Spectrum Survey at

 Los Angeles, California

Frank H. Sanders

Bradley J. Ramsey

Vincent S. Lawrence

U.S. DEPARTMENT OF COMMERCE

William M. Daley, Secretary

Larry Irving, Assistant Secretary

for Communications and Information

May 1997
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PREFACE

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

the measurements. We wish to thank the following people and organizations who made the

spectrum survey at Los Angeles, California a success: W. Zehnder, M. Fukumoto, P. Keister,

and T. King of the ITT-Gilfillan Corporation, who provided access to the ITT-Gilfillan Angeles

Forest antenna range for our measurement location; and H. Grigsby of the Federal Communications Commission for providing valuable background information on spectrum activities in the

Los Angeles 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 (NTIA), nor does it imply

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

This report is available on the World Wide Web through the Institute for Telecommunication

Sciences home page. The ITS home page address is: http://www.its.bldrdoc.gov. Descriptions

and availability of other NTIA reports are found on the ITS publications page. The publications

page address is: http://www.its.bldrdoc.gov/pub/.

iii
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CONTENTS

Page

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

FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi

ABSTRACT .................................................... 1

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

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

1.2 Authority ............................................... 2

1.3 Purpose ................................................ 2

1.4 Extrapolation of Spectrum Occupancy Data ....................... 2

2. LOS ANGELES SPECTRUM SURVEY ............................. 3

2.1 Introduction ............................................. 3

2.2 Measurement Site Description ................................ 3

2.3 Data Considerations ....................................... 5

2.4 Measured Data ........................................... 8

2.5 Observations on Measured Data and Spectrum Use . . . . . . . . . . . . . . . . . 49

3. REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

APPENDIX A: OVERVIEW OF BROADBAND SPECTRUM SURVEYS . . . . . . . . 59

APPENDIX B: INTERPRETATION OF SPECTRUM SURVEY DATA . . . . . . . . . . 69

APPENDIX C: RADIO SPECTRUM MEASUREMENT SYSTEM . . . . . . . . . . . . . 83

APPENDIX D: DATA ACQUISITION SOFTWARE . . . . . . . . . . . . . . . . . . . . . . . 93

APPENDIX E: RSMS GAIN AND NOISE FIGURE CALIBRATION . . . . . . . . . . . 99

v
FIGURES

Page

Figure 1. Area map of Los Angeles showing the RSMS measurement site location . 4

Figure 2. ITS Radio Spectrum Measurement System at the measurement site ..... 6

Figure 3. Area map of Los Angeles showing line-of-sight areas from the RSMS . . 7

Figure 4. Spectrum survey graph summarizing swept/m3 measurements in the

108-138 MHz frequency range .............................. 9

Figure 5. Spectrum survey graph summarizing swept/m3 measurements in the

138-162 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Figure 6. Spectrum survey graph summarizing swept/m3 measurements in the

162-174 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Figure 7. Spectrum survey graph summarizing swept/m3 measurements in the

174-216 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Figure 8. Spectrum survey graph summarizing swept/m3 measurements in the

216-225 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Figure 9. Spectrum survey graph summarizing swept/m3 measurements in the

225-400 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Figure 10. Spectrum survey graph summarizing swept/m3 measurements in the

400-406 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Figure 11. Spectrum survey graph summarizing swept/m3 measurements in the

406-420 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Figure 12. Spectrum survey graph summarizing stepped measurements in the

420-450 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Figure 13. Spectrum survey graph summarizing swept/m3 measurements in the

450-470 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Figure 14. Spectrum survey graph summarizing swept/m3 measurements in the

470-512 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

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

512-806 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

vi
FIGURES (Continued)

Page

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

806-902 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Figure 17. Spectrum survey graph summarizing swept measurements in the

902-928 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Figure 18. Spectrum survey graph summarizing stepped measurements in the

902-928 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

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

928-960 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

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

960-1215 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Figure 21. Spectrum survey graph summarizing stepped measurements in the

1215-1400 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

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

1350-1400 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

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

1400-1530 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

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

1530-1710 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

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

1710-2300 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Figure 26. Spectrum survey graph summarizing swept measurements in the

2300-2500 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

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

2500-2700 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Figure 28. Spectrum survey graph summarizing stepped measurements in the

2700-2900 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Figure 29. Spectrum survey graph summarizing stepped measurements in the

2900-3100 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

vii
FIGURES (Continued)

Page

Figure 30. Spectrum survey graph summarizing stepped measurements in the

3100-3700 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Figure 31. Spectrum survey azimuth-scan graph of measurements in the

3700-4200 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Figure 32. Spectrum survey graph summarizing swept/m3 measurements in the

4200-4400 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Figure 33. Spectrum survey azimuth-scan graph of measurements in the

4400-5000 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Figure 34. Spectrum survey graph summarizing swept/m3 measurements in the

5000-5250 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Figure 35. Spectrum survey graph summarizing stepped measurements in the

5250-5925 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Figure 36. Spectrum survey azimuth-scan graph of measurements in the

5925-7125 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Figure 37. Spectrum survey azimuth-scan graph of measurements in the

7125-8500 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Figure 38. Spectrum survey graph summarizing stepped measurements in the

8500-10550 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Figure 39. Spectrum survey azimuth-scan graph of measurements in the

10550-13250 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Figure 40. Spectrum survey graph summarizing stepped measurements in the

13250-14200 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Figure 41. Spectrum survey azimuth-scan graph of measurements in the

14200-15700 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Figure 42. Spectrum survey graph summarizing stepped measurements in the

15700-17700 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

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

17700-19700 MHz frequency range . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

viii
FIGURES (Continued)

Page

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

cumulated data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

Figure C-1. Top and side view drawings of the RSMS . . . . . . . . . . . . . . . . . . . . . . 84

Figure C-2. Front panel of the RSMS instrument racks . . . . . . . . . . . . . . . . . . . . . . 85

Figure C-3. Block diagram of the RSMS receiver . . . . . . . . . . . . . . . . . . . . . . . . . . 86

Figure E-1. Example calibration graph of noise figure and correction factor curves . . 99

Figure E-2. Typical noise diode solid state noise source . . . . . . . . . . . . . . . . . . . . . 100

Figure E-3. Lumped-component noise diode calibration schematic . . . . . . . . . . . . . . 101

ix
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BROADBAND SPECTRUM SURVEY AT

LOS ANGELES, CALIFORNIA

Frank H. Sanders, Bradley J. Ramsey, and Vincent S. Lawrence1

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 funds the Institute for Telecommunication

Sciences 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 Los Angeles,

California during March, April, and May 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) conflicts, 4) interference resolution, and 5) systems review activity related

to new Federal Government systems.

1

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 needs 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 used solely 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 metropolitan areas

that do not have any maritime radionavigation or extensive military activity. A coastal city, such

2
as San Diego, California [3] with major naval installations, will show higher levels of usage in

bands that support such activities.

Choice of measurement site within an area also can 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 events such as natural disasters, olympic games, 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. LOS ANGELES SPECTRUM SURVEY

2.1 Introduction

This section 1) describes the measurement site selected for the Los Angeles, California spectrum

survey, 2) briefly describes the data processing used to characterize spectrum occupancy across

the 108-MHz to 19.7-GHz frequency range, 3) presents the measured data, and 4) provides bandby-band commentary on the survey results. Appendix A contains a thorough description of the

spectrum survey measurement procedure. Appendix B provides details for interpretation of data

presented in this report. Appendices C, D, and E provide descriptions of the RSMS hardware

and software used to make the measurements.

2.2 Measurement Site Description

The Los Angeles metropolitan area occupies a coastal basin that is open to the Pacific Ocean on

the south and west, partially bisected and surrounded by high rugged hills on the northwest and

east, and closed by the San Gabriel Mountains on the north. The RSMS was parked on the

summit of one of the San Gabriel Mountain peaks in the Angeles National Forest just north of

Los Angeles. The location was the deactivated site of a Nike Hercules radar and antiaircraft

battery, and is currently part of an (ITT-Gilfillan Corporation) antenna range. The site

coordinates were 118ß25’1.7" W, 34ß21’9.7" N and base altitude was 1260 m MSL. Figure 1

shows the location of the RSMS in the Los Angeles area.

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

vehicular traffic. Mobile communications originating locally were associated primarily with a

3
Figure 1. Area map of Los Angeles, California showing the location of the RSMS measurement

site. Map produced with MapExpertTM software from DeLorme Mapping.

4
Los Angeles County fire station below the summit. No ITT-Gilfillan antenna range transmissions

occurred during the RSMS measurements. Only one structure at the site was higher than the

RSMS antennas: a tower about 30 m high, on the north side of the measurement site, behind the

RSMS field of view over the Los Angeles basin. Figure 2 is a view of the RSMS and Los

Angeles basin from the tower.

Prominent physical features affecting radio propagation are the Santa Monica Mountains and

Beverly Hills that bisect the basin from the west. Although the RSMS site was inland, the

RSMS line-of-sight coverage extended to the Pacific Ocean and included most of the Channel

Islands. Urban development in the area is some of the most extensive in the United States.

Figure 3 shows areas that were line-of-sight (white areas in the Figure) to the RSMS from 2 m

above ground (typical mobile antenna height) and those areas that were obstructed (shaded with

plus (+) signs in the Figure) from the RSMS due to terrain. The RSMS survey location at Los

Angeles afforded extensive line-of-sight coverage of the Los Angeles metropolitan area.

2.3 Data Considerations

The Los Angeles spectrum survey, with the following few exceptions, was performed as

described in Appendix A. All System-12 frequency bands were measured with a 100-MHz to

1-GHz log periodic antenna (LPA) mounted at a 45ßangle for slant polarization and aimed

toward downtown Los Angeles. This improved RSMS detection for emissions from the Los

Angeles basin and maximized discrimination against signals originating in the mountains behind

the RSMS. System-2 frequencies were measured with a 500-MHz to 18-GHz slant polarized

biconical omni antenna, except for azimuth-scanned3 bands that were measured with a rotating

dish antenna (1-m Tecom parabolic reflector with dual horizontal and vertical feed).

Preliminary tests at the measurement site indicated that strong received signal levels from

FM radio broadcast stations operating below 108 MHz would generate intermodulation products

in the RSMS front-end at some frequencies above 108 MHz. To eliminate such responses, 40 dB

of attenuation was inserted ahead of the first RSMS receiver amplifier for measurements between

104-114 MHz. This desensitized the RSMS by 40 dB at these frequencies. Consequently, the

possibility of receiving measurable signals in this range (such as instrument-landing system

glideslope transmissions) was reduced. However, several signals were detected in this frequency

range. Similarly, commercial television broadcast signals forced the addition of attenuation

(20 dB) between 174-216 MHz.

2

For spectrum surveys, the RSMS is configured as two measurement systems operating

simultaneously. One, identified as "System-1," for frequency measurements below 1 GHz; and

the other, "System-2" for measurements above 1 GHz (see Appendix A).

3

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

rotating dish antenna with a swept measurement algorithm. See Section B.8 in Appendix B for

more about azimuth-scanning.

5
Figure 2. ITS Radio Spectrum Measurement System at the Los Angeles measurement site.

6
Figure 3. Area map of Los Angeles, California showing regions that are line-of-sight (white)

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

shadowing overlay provided by ITS Telecommunications Analysis Services.

7
All measured data, except the azimuth-scanning measurements, underwent a postmeasurement

cumulative processing (cuming) step before being displayed. Every frequency data point

recorded was cumulated (cumed) according to the measurement algorithm4 used to collect the

data. Swept and stepped measurements were cumed such that the graphed data points (received

signal levels; RSLs) show the maximum, mean, and minimum RSLs of all scans. Swept/m3 data

already contained this information, so cuming resulted in graphs showing maximum of maximum

RSLs, mean of mean RSLs, and minimum of minimum RSLs. On all survey band graphs of

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

drawn with dashed lines. Azimuth-scan data were not cumed, per se, but horizontally and

vertically polarized scans were combined in postmeasurement processing so the graphed data

show only one solid line curve.

2.4 Measured Data

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

corresponding frequency allocations and assignment information (Figures 4-43). Each survey

band figure has an identical format. The survey band graph in the middle of the page shows

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

"min sample noise" on Figure 4) show measurement system noise limits. Measurement system

response to different types of signals and system noise limits are described in Appendix B. The

figure caption includes the survey location and principle measurement parameters.

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

Government and non-Government 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 upper

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

allocation is limited to the function shown.

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

frequencies (in megahertz) are written at the lower end of the vertical lines. 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-Government allocation, it is indicated by a number

referencing a note below the graph. General utilization (i.e., a description of how the frequency

allotment is typically used) also will show a reference number if insufficient space is available

4

Appendix B contains operational descriptions of the RSMS measurement algorithms, including

swept, stepped, and swept/m3.

8
9

40 dB added attenuation

(see note below)

GOVERNMENT AERONAUTICAL RADIONAVIGATION. AERONAUTICAL AERONAUTICAL MOBILE. AERALLOCATIONS: MOBILE. MONON-GOVERNMENT AERONAUTICAL RADIONAVIGATION. AERONAUTICAL 1. AERONAUTICAL MOBILE. 3. AERALLOCATIONS: MOBILE. MOGENERAL VHF Omnidirectional Range (VOR). Differential-Global- Air Traffic Control. 1. Air Traffic Control (ATC). 2. Air UTILIZATION: Positioning-System (DGPS), government only.

108 117.975 121.9375-123.0875 128.8125 132.0125 

avg sample noise

min sample noise

Note: Concerning 108-114 MHz attenuated data, see comments in Table 1 (Section 2.5.1).1. AERONAUTICAL MOBILE. Private aircraft.2. 123.1 MHz: SAR (search and rescue) operations.3. AERONAUTICAL MOBILE.

4. SPACE OPERATION (space-to-Earth), METEOROLOGICAL-S

RESEARCH (space-to-Earth), 137-137.025 MHz and 137.175-13137.025-137.175 MHz and 137.825-138: Mobile-Satellite.

5. Government use includes TIROS downlinks; non-Government inclu

satellite systems (Little LEOS).

Figure 4. NTIA spectrum survey graph summarizing 8,900 sweeps across the 108-138 MHz range (Syst

swept/m3 algorithm, sample detector, 10-kHz bandwidth) at Los Angeles, CA, 1995.
10

GOVERNMENT FIXED, MOBILE. FIXED, 5,6. 8.ALLOCATIONS: MOBILE, 3.NON-GOVERNMENT AMATEUR, AMATEUR. 3. 5. LAND MOBILE. 9. LAALLOCATIONS: 2.GENERAL Non-tactical military land mobile 4. 7. Land transportation, public safety, LanUTILIZATION: communications. 1. industrial, Earth telecommand, etc. safe

138 144 146 148 149.9 150.8 156.2475-157.1875 

avg sample noise

min sample noise

1. 143.75 MHz and 143.9 MHz: Civil Air Patrol.2. AMATEUR-SATELLITE.3. MOBILE-SATELLITE (Earth-to-space).4. Nontactical military land mobile communications. 148.15 MHz: Civil Air Patrol. Government use

includes TIROS command links and NASA satellite operations. Non-Government use includesnongeostationary nonvoice mobile satellite systems (Little LEOS).

5. 149.9-150.05 MHz: RADIONAVIGATION-SATELLITE, MOBILE-SATELLITE (Earth-to-space).

6. 150.05-150.8 MHz: FIXED, MOBILE.7. Government use includes military nontactical mobile and fixed 

downlinks. Non-Government use includes "Little LEOS."

8. 157.0375-157.1875 MHz: MARITIME MOBILE, VHF distress s9. 156.2475-157.0375 MHz: MARITIME MOBILE.10. 157.1875-157.45 MHz, 161.575-161.625 MHz, and 161.775-162.0

Figure 5. NTIA spectrum survey graph summarizing 8,300 sweeps across the 138-162 MHz range (Syst

swept/m3 algorithm, sample detector, 10-kHz bandwidth) at Los Angeles, CA, 1995.
11

GOVERNMENT FIXED, MOBILE ALLOCATIONS:NON-GOVERNMENT ALLOCATIONS:GENERAL Land Mobile Radio (LMR) including weather radio, public safety, and law enforcement. UTILIZATION:

162.0125 

avg sample noise

min sample noise

1. FIXED, Land Mobile.2. Industrial, public safety.

3. FIXED, MOBILE.

Figure 6. NTIA spectrum survey graph summarizing 73,500 sweeps across the 162-174 MHz range (Syste

swept/m3 algorithm, sample detector, 10-kHz bandwidth) at Los Angeles, CA, 1995.
12

20 dB added attenuation (see note below)

GOVERNMENTALLOCATIONS:NON-GOVERNMENT BROADCASTING (television broadcasting), 1, 2.ALLOCATIONS:GENERAL Channel 7 Channel 8 Channel 9 Channel 10 Channel 11 Channel 12 UTILIZATION: (Los Angeles) (San Diego) (Los Angeles) (San Diego) (Los Angeles) (San Diego) 

174 180 186 192 198 204 

avg sample noise

min sample noise

Note: Concerning 174-216 MHz attenuated data, see comments in Table 1 (Section 2.5.1).1. Subscription television services and limited wireless microphone operations also are permitted in this band.

2. TV broadcast licencees are permitted to use subcarriers on a secon

broadcast purposes.

Figure 7. NTIA spectrum survey graph summarizing 28,000 sweeps across the 174-216 MHz range (Syst

swept/m3 algorithm, sample detector, 100-kHz bandwidth) at Los Angeles, CA, 1995.
13

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 

avg sample noise

min sample noise

1. Radiolocation is limited to the military services. 2. Secondary services, other than radiolocation, generally are lim

telecommand operations.

Figure 8. NTIA spectrum survey graph summarizing 4,620 sweeps across the 216-225 MHz range (Syst

swept/m3 algorithm, sample detector, 3-kHz bandwidth) at Los Angeles, CA, 1995.
14

GOVERNMENT FIXED, MOBILE, 1. 2. FIXED, MOBILE, 3.ALLOCATIONS:NON-GOVERNMENT 2. 3.ALLOCATIONS:GENERAL Military tactical and training communications including air traffic control (ATC).UTILIZATION: 2.

225 328.6-335.4 

avg sample noise

min sample noise

1. Government usage is limited to military services; additionally, 235-322 MHz is allocated on a primary

basis to the mobile-satellite service. 242.95-243.05 MHz is used for search and rescue operationsincluding position-indicating radiobeacons.

2. AERONAUTICAL RADIONAVIGATION, instrument landing sy3. 399.9-400.05 MHz: RADIONAVIGATION-SATELLITE, MOBI

Figure 9. NTIA spectrum survey graph summarizing 4,300 sweeps across the 225-400 MHz range (Syst

swept/m3 algorithm, sample detector, 30-kHz bandwidth) at Los Angeles, CA, 1995.
15

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).

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

3. 400.15-401 MHz: SPACE RESEARCH (space-to-Earth), MOBILE-SATELLITE (space-to-Earth), Space

Operation (space-to-Earth).

4. 401-402 MHz: SPACE OPERATION (space-to-Earth), Earth Exploration-Satellite (Earth-to-space),

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

5. 402-403 MHz: Earth Exploration-Satellite (Earth-to-space), Meteorological-Satellite (Earth-to-space).

Figure 10. NTIA spectrum survey graph summarizing 3,000 sweeps across the 400-406 MHz range (System-1, band event 16,

swept/m3 algorithm, sample detector, 3-kHz bandwidth) at Los Angeles, CA, 1995.
16

GOVERNMENT FIXED, MOBILE, RADIO ASTRONOMY, 1. FIXED, MOBILE, Space Research (space-to-space).ALLOCATIONS:NON-GOVERNMENT RADIO ASTRONOMY, 1.ALLOCATIONS:GENERALUTILIZATION: LMR, 2. LMR, 2.

406 410 

avg sample noise

min sample noise

1. 406-406.1 MHz: MOBILE-SATELLITE (Earth-to-space). Satellite emergency position-indicating

radiobeacons (EPIRB) only. Supported by the joint U.S. SARSAT/Russian COSPAS satellite network.

2. Fixed and mobile services are allocated for Government nonmi

authorized on a local-coordinated, secondary, noninterfering basi

Figure 11. NTIA spectrum survey graph summarizing 22,200 sweeps across the 406-420 MHz range (Syst

swept/m3 algorithm, sample detector, 10-kHz bandwidth) at Los Angeles, CA, 1995.
17

GOVERNMENT RADIOLOCATION.ALLOCATIONS:NON-GOVERNMENT Amateur.ALLOCATIONS:GENERAL Long-range surveillance radars, 1, 2.UTILIZATION:

420 

min +peak noise

1. Radiolocation is limited to military services. Primarily, long-range radar systems essential to the nations

early warning capability, law enforcement, and tracking objects in space. These systems use very highpower and wide bandwidths. Low power radio control operations are permitted in the band. NASA andmilitary use of telemetry and telecommand is also extensive.

2. There is some non-Government use of spread spectrum modes; a

433 MHz), television (420-432 & 438-444 MHz), repeaters (435 MHz), and amateur satellite (435-438 MHz).

Figure 12. NTIA spectrum survey graph summarizing 103 scans across the 420-450 MHz range (System-1, b

algorithm, +peak detector, 1000-kHz bandwidth) at Los Angeles, CA, 1995.
18

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) 

450 455 460 465 

avg sample noise

min sample noise

1. 450-451 MHz and 455-456 MHz: Remote pickup broadcast.2. 451-454 MHz, 456-459 MHz, 460-462.5375 MHz, 462.7375-467.5375 MHz, and

467.7375-470 MHz: Public Safety, Industrial, Land Transportation.

3. 454-455 MHz and 459-460 MHz: Domestic Public.4. 462.5375-462.7375 MHz and 467.5375-467.7375 MHz: Personal5. 460-470 MHz: GOES and TIROS satellite downlinks.

Figure 13. NTIA spectrum survey graph summarizing 26,000 sweeps across the 450-470 MHz range (Syst

swept/m3 algorithm, sample detector, 10-kHz bandwidth) at Los Angeles, CA, 1995.
19

GOVERNMENTALLOCATIONS:NON-GOVERNMENT BROADCASTING, LAND MOBILE, 1, 2.ALLOCATIONS:GENERAL Channel 14 Channel 15 Channel 16 Channel 17 Channel 18 Channel 19 UTILIZATION: (Los Angeles T-band) (San Diego) (Los Angeles T-band) (Los Angeles) 

470 476 482 488 494 500 

max sample noise

avg sample noisemin sample noise

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

assignments in specific urban areas.

2. The band also is allocated to the fixed service to permit subscript

Figure 14. NTIA spectrum survey graph summarizing 14,500 sweeps across the 470-512 MHz range (Syst

swept/m3 algorithm, sample detector, 10-kHz bandwidth) at Los Angeles, CA, 1995.
20

GOVERNMENT 1.ALLOCATIONS:NON-GOVERNMENT BROADCASTING. 1. BROADCASTING.ALLOCATIONS:GENERAL Television broadcasting (channels 21-36). Television broadcasting (channels 38-69).UTILIZATION:

512 608-614 

max sample noise

avg sample noisemin sample noise

1. RADIO ASTRONOMY. No stations are authorized to transmit in this band.Figure 15. NTIA spectrum survey graph summarizing 10,200 sweeps across the 512-806 MHz range (Syst

swept/m3 algorithm, sample detector, 100-kHz bandwidth) at Los Angeles, CA, 1995.
21

GOVERNMENTALLOCATIONS:NON-GOVERNMENT LAND MOBILE, 1.ALLOCATIONS:GENERAL Conventional and 2. Cellular Systems (Public Mobile). 4. Conventional and 3. Cellular Systems (Public Base). UTILIZATION: Trunked (mobile). Trunked (base).

806 821 824 849-851 866 869 

avg sample noise

min sample noise

1. 806-890 MHz: Limited allocation is available for television Channels 70-83.2. Public Safety (mobile).3. Public Safety (base).4. Aeronautical Mobile (ground-to-air).

5. Aeronautical Mobile (air-to-ground).6. 896-901 MHz: Private Land Mobile (paired with 935-940 MHz)7. 901-902 MHz: General Mobile.

Figure 16. NTIA spectrum survey graph summarizing 6,420 sweeps across the 806-902 MHz range (Syst

swept/m3 algorithm, sample detector, 10-kHz bandwidth) at Los Angeles, CA, 1995.
22

GOVERNMENT RADIOLOCATION.ALLOCATIONS:NON-GOVERNMENTALLOCATIONS:GENERAL Military radiolocation systems; Industrial scientific and medical (ISM); Automatic Vehicle Monitoring (AVM); spread spectrum devices; microwave ovens; digital UTILIZATION: Fixed and mobile radio services are permitted on a secondary basis. Band utilization is increasing for non-Government ISM, spread spectrum and other modes, 1, 

902 

min maxhold noise

1. Location and Monitoring Service (LMS) systems are authorized subject to not causing harmful interference

to Government stations and must tolerate interference from ISM devices and all authorized stations.

2. Emissions from microwave ovens manufactured after December 31

be confined within the band 902-928 MHz.

Figure 17. NTIA spectrum survey graph summarizing 66,000 sweeps across the 902-928 MHz range (System-1

algorithm, maximum-hold detector, 10-kHz bandwidth) at Los Angeles, CA, 1995.
23

GOVERNMENT RADIOLOCATION.ALLOCATIONS:NON-GOVERNMENTALLOCATIONS:GENERAL Military radiolocation systems; Industrial scientific and medical (ISM); Automatic Vehicle Monitoring (AVM); spread spectrum devices; microwave ovens; digital UTILIZATION: Fixed and mobile radio services are permitted on a secondary basis. Band utilization is increasing for non-Government ISM, spread spectrum and other modes, 1, 

902 

1. Location and Monitoring Service (LMS) systems are authorized subject to not causing harmful interference

to Government stations and must tolerate interference from ISM devices and all authorized stations.

2. Emissions from microwave ovens manufactured after December 31

be confined within the band 902-928 MHz.

Figure 18. NTIA spectrum survey graph summarizing 104 scans across the 902-928 MHz range (System-1, b

algorithm, +peak detector, 1000-kHz bandwidth) at Los Angeles, CA, 1995.
24

GOVERNMENT FIXED. FIXED.ALLOCATIONS:NON-GOVERNMENT 1. LAND FIXED. LAND MOBILE. 5. FIXED. FIXED.ALLOCATIONS: MOBILEGENERAL 1. 2. 3. Private land mobile (base), 3. Auxiliary broadcasting, private fixed microwave, studio-to-transUTILIZATION: 4.

928 929 932 935 940 941 944 

max s. n.

avg sample noisemin sample noise

1. FIXED. Private fixed microwave, public and private land mobile, telemetry applications. Two-way

services paired with 952-953 MHz.

2. Public and private land mobile.3. Paired band for point-to-point and point-to-multipoint communications.

4. Trunked and conventional systems in 12.5 kHz channels (paired w5. MOBILE.6. 944-952 MHz: Primarily, studio-to-transmitter links. 952-953 M

960 MHz: Primarily, fixed point-to-point communications.

Figure 19. NTIA spectrum survey graph summarizing 46,500 sweeps across the 928-960 MHz range (Syst

swept/m3 algorithm, sample detector, 10-kHz bandwidth) at Los Angeles, CA, 1995.
25

GOVERNMENT AERONAUTICAL RADIONAVIGATION, 1.ALLOCATIONS:NON-GOVERNMENT AERONAUTICAL RADIONAVIGATION, 1.ALLOCATIONS:GENERAL TACAN, DME, MLS, ATCRBS, MODE-S, T-CAS, JTIDS, 2.UTILIZATION:

960 

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 navigation. On a case-by-case basis, Government systems utilizing spread spectrum techniques forterrestrial communication, navigation, and identification may be authorized on condition that aeronauticalradionavigation services not experience harmful interference.

2. Tactical Air Navigation (TACAN). Distance Metering Equipmen

(MLS). Air Traffic Control Radar Beacon system (ATCRBS, MOSystem (T-CAS). Joint Tactical Information Distribution System 

Figure 20. NTIA spectrum survey graph summarizing 53,000 sweeps across the 960-1215 MHz range (Syst

swept/m3 algorithm, +peak detector, 300-kHz bandwidth) at Los Angeles, CA, 1995.
26

GOVERNMENT RADIOLOCATION, RADIOLOCATION. AERONAUTICAL RADIONAVIGATION, FIXED, MOBALLOCATIONS: 1. Radiolocation.NON-GOVERNMENT Amateur. AERONAUTICAL RADIONAVIGATION.ALLOCATIONS:GENERAL 2, 3, 4. 3, 4, 5. 3, 4. 3, 6, Fixed anUTILIZATION:

1215 1240 1300 1350 

min +peak noise

1. RADIONAVIGATION-SATELLITE (space-to-Earth).2. 1227.6 MHz: Global Positioning System (GPS).3. High-power long-range surveillance radars including FAA Air-Route Surveillance Radar (ARSR).

4. Tethered balloon-mounted radar for drug interdiction.5. Amateur television. Amateur weak signal modes and other mode6. 1381.05 MHz: GPS data relay.

Figure 21. NTIA spectrum survey graph summarizing 42 scans across the 1215-1400 MHz range (System-2, b

algorithm, +peak detector, 1000-kHz bandwidth) at Los Angeles, CA, 1995.
27

GOVERNMENT FIXED, MOBILE, RADIOLOCATION, 1.ALLOCATIONS:NON-GOVERNMENT 1.ALLOCATIONS:GENERAL Military radiolocation, fixed and mobile links, GPS, aeronautical radionavigation, 2, 3.UTILIZATION:

1350 

avg sample noise

min sample noise

1. 1350-1370 MHz: AERONAUTICAL RADIONAVIGATION (allocation is for the United States and

Canada only).

2. Military radiolocation applications are primarily high-power long-range surveillance radars.

3. 1369.05-1393.05 MHz: Fixed and mobile satellite services (space

data. GPS operates at 1381.05 MHz to relay data detected by orb

Figure 22. NTIA spectrum survey graph summarizing 7,100 sweeps across the 1350-1400 MHz range (Syst

swept/m3 algorithm, sample detector, 10-kHz bandwidth) at Los Angeles, CA, 1995.
28

GOVERNMENT EARTH EXPLORATION- FIXED, MOBILE (Aeronautical telemetering). ALLOCATIONS: SATELLITE (Passive), 1. 2.NON-GOVERNMENT EARTH EXPLORATION- 3, 4. MOBILE (Aeronautical telemetering). ALLOCATIONS: SATELLITE (Passive), 1.GENERAL Passive. Aeronautical telemetry and telecommand.UTILIZATION:

1400 1427 1435 

max s. n.

avg sample noisemin sample noise

1. RADIO ASTRONOMY, SPACE RESEARCH (Passive).2. MOBILE. 1427-1429 MHz: MOBILE except aeronautical mobile, SPACE OPERATION

(Earth-to-space).

3. Land Mobile (Telemetering and telecommand), Fixed (Telemeteri4. 1427-1429 MHz: SPACE OPERATION (Earth-to-space).5. MOBILE-SATELLITE (space-to-Earth), Mobile (Aeronautical tel

Figure 23. NTIA spectrum survey graph summarizing 14,200 sweeps across the 1400-1530 MHz range (Sys

swept/m3 algorithm, sample detector, 30-kHz bandwidth) at Los Angeles, CA, 1995.
29

RSMS not configured to receive sp

GOVERNMENT 1. 2. RADIONAVIGATION-SATELLITE (space-to- 3. 4. 5. 6. METEORALLOCATIONS: Earth), AERONAUTICAL RADIONAVIGATION. (RadiosonNON-GOVERNMENT 1. 2. RADIONAVIGATION-SATELLITE (space-to- 3. 4. 5. 6. METEORALLOCATIONS: Earth), AERONAUTICAL RADIONAVIGATION. (RadiosonGENERAL INMARSAT, AMS(R)S. GPS, GLONASS. Aids to air INMARSAT. AMS(R)S. RadiosondUTILIZATION: SARSAT. navigation imagery.

1530 1545 1559 1610 1626.5 1646.5 1660 1668.4 

max s. n.

avg sample noisemin sample noise

1. MOBILE-SATELLITE (space-to-Earth). 1530-1544 MHz: MARITIME MOBILE-SATELLITE (space-toEarth). 1530-1535 MHz: Mobile (Aeronautical telemetering).2. AERONAUTICAL MOBILE-SATELLITE (space-to-Earth). 1545-1549.5 MHz: Mobile-Satellite (spaceto-Earth). 1549.5-1558.5 MHz: MOBILE-SATELLITE (space-to-Earth).3. AERONAUTICAL RADIONAVIGATION, RADIODETERMINATION-SATELLITE (Earth-to-space),

MOBILE-SATELLITE (Earth-to-space). 1610.6-1613.8 MHz: RADIO ASTRONOMY. 1613.8-1626.5:Mobile-Satellite (space-to-Earth).

4. 1626.5-1645.5 MHz: MARITIME MOBILE-SATELLITE (Earth-to-space). 1645.5-1646.5 MHz:

MOBILE-SATELLITE (Earth-to-space, distress and safety only).

5. AERONAUTICAL MOBILE-SATELLITE (Earth-to-space). 1646

to-space). 1651-1660 MHz: MOBILE-SATELLITE (Earth-to-sp

6. RADIO ASTRONOMY. 1660-1660.5 MHz: AERONAUTICAL M

1660.5-1668.4 MHz: SPACE RESEARCH (Passive).

7. 1668.4-1670 MHz: RADIO ASTRONOMY. 1670-1700 MHz: 

(space-to-Earth).

8. METEOROLOGICAL-SATELLITE (space-to-Earth).9. GOES, TIROS-N.

Figure 24. NTIA spectrum survey graph summarizing 50,500 sweeps across the 1530-1710 MHz range (Sys

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

RSMS not configured to receive sp

GOVERNMENT FIXED, MOBILE. ALLOCATIONS: NON-GOVERNMENT FIXED. MOBILE, Fixed. ALLOCATIONS:GENERAL Federal fixed microwave, telemetry, Private fixed microwave. Auxiliary broadcasting, domestic public fixed, cable TV, control UTILIZATION: telecommand, 1. Future PCS. and repeater links, point to multipoint video, cellular, 2.

1710 1850 1990 22

minimum maxhold noise

1. Predominantly federal medium-capacity line of sight (LOS) fixed service band.2. 1990-2110 MHz: Electronic news gathering (ENG). GOES uplink, NASA’s global ground network and

TDRSS (2025-2110 MHz). 2110-2200 MHz: NASA space and Earth to space command links supportPioneers, Voyagers, MAGELLAN, GALILEO, and ULYSSES (2110-2120 MHz). Paired fixed links(2110-2130 MHz with 2160-2180 MHz; 2130-2150 MHz with 2180-2200 MHz). Point-to-point and pointto multipoint links (2150-2160 MHz).

3. SPACE RESEARCH (space-to-Earth)(space-to-space), SPACE O

space), EARTH EXPLORATION-SATELLITE space-to-Earth)(sp

4. Space telemetry, telecommand and control systems. Fixed micro5. FIXED, MOBILE except aeronautical mobile, SPACE RESEARC6. SPACE RESEARCH (space-to-Earth)(Deep Space only).7. NASA deep space network space-to-Earth telemetry. Radio astro

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

maximum-hold detector, 100-kHz bandwidth) at Los Angeles, CA, 1995.
31

ISM band

GOVERNMENT 1. RADIOLOCATION, MOBILE, Fixed. RADIOLOCATION, 5.ALLOCATIONS:NON-GOVERNMENT 2. MOBILE. 6. Amateur. FIXED, MOALLOCATIONS: RadiolocatioGENERAL 3. Telemetry, telemetry communications, aeronautical telemetry, 4. Amateur Satellite (space-to-Earth). 7. UTILIZATION: Amateur mixed modes, 7.

2300 2310 2390 2400 2450 

minimum maxhold noise

1. RADIOLOCATION, Fixed, Mobile.2. Amateur.3. Amateur weak signal modes and other modes.4. AF high-power long-range surveillance radar and air traffic control radar. Venus Radar Mapper (VRM)

synthetic aperture radar.

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

6. AMATEUR.7. 2400-2500 MHz: This spectrum is used increasingly for ind

applications including microwave ovens, spread spectrum cordles

8. RADIODETERMINATION-SATELLITE (space-to-Earth).9. Satellite downlinks and multichannel fixed and portable video tra

Figure 26. NTIA spectrum survey graph summarizing 41,400 sweeps across the 2300-2500 MHz range (Sys

swept algorithm, maximum-hold detector, 100-kHz bandwidth) at Los Angeles, CA, 1995.
32

RSMS not configured to receive sp

GOVERNMENT 3. ALLOCATIONS:NON-GOVERNMENT BROADCASTING-SATELLITE, FIXED, 1. FIXED, ALLOCATIONS: SATELLGENERAL Auxiliary broadcasting, pay television distribution, private video teleconferences, educational television (ITSF), 2. Private fUTILIZATION:

2500 2655 

minimum maxhold noise

1. Broadcasting-satellite service is limited to community reception of educational and public service

television programming.

2. 2500-2686 MHz: Omnidirectional multichannel multipoint distribution service (MMDS) transmissions

that can be contained within 6-MHz channel bandwidths.

3. Earth Exploration-Satellite (Passive), Radio Astronomy, Space Re4. EARTH EXPLORATION-SATELLITE (Passive), RADIO ASTRON

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

maximum-hold detector, 10-kHz bandwidth) at Los Angeles, CA, 1995.
33

GOVERNMENT AERONAUTICAL RADIONAVIGATION, METEOROLOGICAL AIDS, Radiolocation, 1, 2.ALLOCATIONS:NON-GOVERNMENTALLOCATIONS:GENERAL Airport surveillance radars (ASRs), military ground control approach radars (GCAs), NWS weather radars (NEXRAD, etc.), long-range surveillance radars and air UTILIZATION:

2700 

min +peak noise

1. The aeronautical radionavigation service is restricted to ground-based radars and associated airborne

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

2. The secondary radiolocation service is limited to the military an

primary services.

Figure 28. NTIA spectrum survey graph summarizing 39 scans across the 2700-2900 MHz range (System-2, b

algorithm, +peak detector, 1000-kHz bandwidth) at Los Angeles, CA, 1995.
34

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 three-dimensional long-range surveillance radars and air traffic control radars.UTILIZATION:

2900 

min +peak noise

1. Radiolocation assignments are primarily for the military; however, other agency use is permitted for

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

2. 2900-3000 MHz: Also, allocated for next generation weather rad

Figure 29. NTIA spectrum survey graph summarizing 69 scans across the 2900-3100 MHz range (System-2, b

algorithm, +peak detector, 1000-kHz bandwidth) at Los Angeles, CA, 1995.
35

GOVERNMENT RADIOLOCATION. RADIOLOCATION. RADIOLOCATION, 1. ALLOCATIONS:NON-GOVERNMENT Radiolocation. Amateur, Radiolocation. Radiolocation. ALLOCATIONS: GENERAL 3. 3. 3. UTILIZATION:

3100 3300 3500 36

min +peak noise

1. AERONAUTICAL RADIONAVIGATION (Ground-based).2. Radiolocation.

3. Primarily, military airborne, land-based, and shipborne defense ra

Figure 30. NTIA spectrum survey graph summarizing 70 scans across the 3100-3700 MHz range (System-2, b

algorithm, +peak detector, 3000-kHz bandwidth) at Los Angeles, CA, 1995.
36

RSMS not configured to receive sp

Noise floor rise caused by front-endamplifier variation

GOVERNMENTALLOCATIONS:NON-GOVERNMENT FIXED, FIXED-SATELLITE (space-to-Earth).ALLOCATIONS:GENERAL Domestic public fixed, satellite communications.UTILIZATION:

3700 

minimum maxhold noise

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

maximum-hold detector, 100-kHz bandwidth) at Los Angeles, CA, 1995.
37

GOVERNMENT AERONAUTICAL RADIONAVIGATION, 1.ALLOCATIONS:NON-GOVERNMENT AERONAUTICAL RADIONAVIGATION, 1.ALLOCATIONS:GENERAL Airborne radio altimeters.UTILIZATION:

4200 

max +peak noise

avg +peak noisemin +peak noise

1. 4202 ±12 MHz: Standard frequency and time satellite service (space-to-Earth), permitted.Figure 32. NTIA spectrum survey graph summarizing 47,500 sweeps across the 4200-4400 MHz range (Sys

swept/m3 algorithm, +peak detector, 300-kHz bandwidth) at Los Angeles, CA, 1995.
38

RSMS not configured to receive sp

GOVERNMENT FIXED, MOBILE. FIXED, MOBILE. FIXED, MOBILE. FIXED, MOBILE. ALLOCATIONS:NON-GOVERNMENT FIXED-SATELLITE (space-to-Earth). 1. 1, 2. FIXED-SATELLITE ALLOCATIONS: (space-to-Earth).GENERAL Military tactical Military tactical communications. Military tactical communications. Military tactical communicationUTILIZATION: communications. spread spectrum.

4400 4500 4635 4660 4685 4800 

minimum maxhold noise

1. FIXED-SATELLITE (space-to-Earth). 3. RADIO ASTRONOMY, Space Research (Passive).2. FIXED, MOBILE.Figure 33. NTIA spectrum survey azimuth-scan graph of the 4400-5000 MHz range (System-2, band event 

maximum-hold detector, 100-kHz bandwidth) at Los Angeles, CA, 1995.
39

GOVERNMENT AERONAUTICAL RADIONAVIGATION.ALLOCATIONS:NON-GOVERNMENT AERONAUTICAL RADIONAVIGATION.ALLOCATIONS:GENERAL Microwave landing systems. Differential Global-Positioning System (DGPS) for aircraft navigation (5000-5150 MHz).UTILIZATION:

5000 

max +peak noise

avg +peak noisemin +peak noise

Figure 34. NTIA spectrum survey graph summarizing 47,500 sweeps across the 5000-5250 MHz range (Sys

swept/m3 algorithm, +peak detector, 300-kHz bandwidth) at Los Angeles, CA, 1995.
40

GOVERNMENT RADIOLOCATION. AERONAUTICAL 3. MARITIME RADIONAVIGA- 4. RADIOLOCATION.ALLOCATIONS: RADIONAVIGATION, 1. TION, Radiolocation.NON-GOVERNMENT Radiolocation. AERONAUTICAL 3. MARITIME RADIONAVIGA- 4. Amateur. ALLOCATIONS: RADIONAVIGATION, 2. TION, Radiolocation.GENERAL Weather radars. 5. Military radars, 7. UTILIZATION:

5250 5350 5460-5470 5600 5650 

min +peak noise

1. RADIOLOCATION.2. Radiolocation.3. RADIONAVIGATION, Radiolocation.4. MARITIME RADIONAVIGATION, METEOROLOGICAL AIDS, Radiolocation.

5. Government weather radars, e.g., Terminal Doppler Weather Rad6. FIXED-SATELLITE (Earth-to-space), Amateur.7. 5725-5875 MHz: Industrial, scientific, and medical (ISM).

Figure 35. NTIA spectrum survey graph summarizing 35 scans across the 5250-5925 MHz range (System-2, b

algorithm, +peak detector, 3000-kHz bandwidth) at Los Angeles, CA, 1995.
41

GOVERNMENTALLOCATIONS:NON-GOVERNMENT FIXED, FIXED-SATELLITE (Earth-to-space). 1. FIXED, FIXED-SATELLITE (Earth-to-space). FIXEDALLOCATIONS: (EarthGENERAL Common carrier fixed links. Common carrier fixed links. CommUTILIZATION:

5925 6425 6525 6875 

minimum 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 

maximum-hold detector, 300-kHz bandwidth) at Los Angeles, CA, 1995.
42

RSMS not configured to receive sp

Noise floor fall caused by front-endamplifier variation

GOVERNMENT FIXED, 1. 3. FIXED, FIXED-SATELLITE (space-to-Earth), FIXED. FIXED-SATELLITE (Earth-to-space), 5, 6, 7. ALLOCATIONS: Mobile-Satellite (space-to-Earth), 4.NON-GOVERNMENT ALLOCATIONS:GENERAL 2. 2. 2. 2. 2. UTILIZATION:

7125 7250 7300 7750 7900 

minimum maxhold noise

1. 7190-7235 MHz: SPACE RESEARCH (Earth-to-space).2. Point-to-point microwave voice/data links, defense satellite communications systems (DSCS).3. FIXED-SATELLITE (space-to-Earth), MOBILE-SATELLITE (space-to-Earth), Fixed.4. 7450-7550 MHz: METEOROLOGICAL-SATELLITE (space-to-Earth).5. 7900-8025 MHz: MOBILE-SATELLITE (Earth-to-space), fixed.

6. 8025-8400 MHz: EARTH EXPLORATION-SATELLITE (spa

(Earth-to-space) (no airborne transmissions).

7. 8175-8215 MHz: METEOROLOGICAL-SATELLITE (Earth-to-8. SPACE RESEARCH (space-to-Earth) (Government: 8400-8450 

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

maximum-hold detector, 300-kHz bandwidth) at Los Angeles, CA, 1995.
43

GOVERNMENT RADIOLOCATION. 1. 2. 3. RADIOLOCATION.ALLOCATIONS:NON-GOVERNMENT Radiolocation. 1. 2. 3. Radiolocation. Amateur, RadiolocatioALLOCATIONS:GENERAL Military use is primary. 4. 5.UTILIZATION:

8500 9000 9200 9300 9500 10000 

minimum +peak noise

1. AERONAUTICAL RADIONAVIGATION, Radiolocation.2. MARITIME RADIONAVIGATION, Radiolocation.3. RADIONAVIGATION, Meteorological Aids, Radiolocation.

4. Maritime radionavigation radar, airborne weather radar, radar tran5. Military airborne radar.6. RADIOLOCATION. 10450-10500 MHz: Amateur, Amateur-Sa

Figure 38. NTIA spectrum survey graph summarizing 35 scans across the 8500-10550 MHz range (System-2, b

algorithm, +peak detector, 3000-kHz bandwidth) at Los Angeles, CA, 1995.
44

RSMS not configured to receive sp

GOVERNMENT 1.ALLOCATIONS:NON-GOVERNMENT 2. FIXED, FIXED-SATELLITE (space-to-Earth). FIXED-SATELLITE FIXED, BROADCASTING- FIXEDALLOCATIONS: (space-to-Earth), 3. SATELLITE. (EarthGENERAL Common carrier point-to-point microwave links, television Direct broadcast Cable UTILIZATION: studio-to-transmitter links. satellite services (DBS).

10550 10700 11700 12200 12700 

minimum maxhold noise

1. 10600-10700 MHz: EARTH EXPLORATION-SATELLITE (Passive), SPACE RESEARCH (Passive).

10680-10700 MHz: RADIO ASTRONOMY.

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

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

3. Mobile except aeronautical mobile.4. Television auxiliary broadcasting (includes: SHL, STL, ENG, an

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

maximum-hold detector, 3000-kHz bandwidth) at Los Angeles, CA, 1995.
45

GOVERNMENT AERONAUTICAL RADIOLOCATION, Space Research, Standard Frequency and Time Signal-Satellite (Earth-to-space). RADIONAVIGALLOCATIONS: RADIONAVIGATION, 1. Space ResearchNON-GOVERNMENT AERONAUTICAL Radiolocation, Space Research, Standard Frequency and Time Signal-Satellite (Earth-to-space). RADIONAVIGALLOCATIONS: RADIONAVIGATION, 1. Space ResearchGENERAL Military airborne radars.UTILIZATION:

13250 13400 14000 

+peak noise

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

Figure 40. NTIA spectrum survey graph summarizing 67 scans across the 13250-14200 MHz range (Syst

stepped algorithm, +peak detector, 3000-kHz bandwidth) at Los Angeles, CA, 1995.
46

GOVERNMENT Fixed, FIXED, Mobile, MOBILE, Fixed, Space Research. FIXED, Mobile, 3. AERALLOCATIONS: Mobile. Space Research. Space Research. RADNON-GOVERNMENT FIXED-SATELLITE 1. 3. AERALLOCATIONS: (Earth-to-space). RADGENERAL 2. 2.UTILIZATION:

14200 14400 14500 14714.5 15136.5 15350-15400 

minimum maxhold noise

1. FIXED-SATELLITE (Earth-to-space).2. Military communication links and microwave links. Air traffic control links, including video data.

3. EARTH EXPLORATION-SATELLITE (Passive), RADIO ASTRON

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

maximum-hold detector, 3000-kHz bandwidth) at Los Angeles, CA, 1995.
47

GOVERNMENT RADIOLOCATION. RADIOLOCATION, Space Research 1. 3. RadiALLOCATIONS: (Deep Space) (Earth-to-space).NON-GOVERNMENT Radiolocation. Radiolocation. 2. 4. FIXEALLOCATIONS: (EarGENERAL Military airborne radars. Military airborne radars.UTILIZATION:

15700 16600 17100 17200 17300 

+peak noise

1. RADIOLOCATION.2. Radiolocation.

3. RADIOLOCATION, Earth Exploration-Satellite (Active), Space R4. Earth Exploration-Satellite (Active), Radiolocation, Space Researc

Figure 42. NTIA spectrum survey graph summarizing 65 scans across the 15700-17700 MHz range (Syst

stepped algorithm, +peak detector, 3000-kHz bandwidth) at Los Angeles, CA, 1995.
48

RSMS not configured to receive sp

GOVERNMENT 2.ALLOCATIONS:NON-GOVERNMENT FIXED, MOBILE, FIXED-SATELLITE (space-to-Earth), 1. 3. FIXED, FIXED-SATELLITE (space-to-Earth), MOBILALLOCATIONS:GENERAL General purpose point-to-point microwave band including private, common carrier, cable television relay systems (CARS), studio-to-transmitter (STL) television linUTILIZATION: Digital Electronic Message Services (DEMS), etc.

17700 18600 18800 

minimum maxhold noise

1. 17700-17800 MHz: FIXED-SATELLITE (Earth-to-space).2. EARTH EXPLORATION-SATELLITE (Passive), SPACE RESEARCH (Passive).

3. FIXED, FIXED-SATELLITE (space-to-Earth), EARTH EXPLORA

(except aeronautical mobile), SPACE RESEARCH (Passive).

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

maximum-hold detector, 3000-kHz bandwidth) at Los Angeles, CA, 1995.
within the vertical line delimiters. All notes are written in simple text format distinguishable

from the allocated service entries that are entered according to convention, as previously

explained.

It should be noted that the appearance of survey band graphed data is affected substantially by

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

Figures 5 and 6 were measured with similar techniques; however, 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 survey bands may be plotted with different graph

scales or measured with different bandwidths and algorithms. This is the case for Figures 17

and 18. Both figures cover the same frequency range, but the bandwidths and measurement

algorithms are completely different.

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 band-by-band summary observations of Section 2.5

should help in interpreting the data graphs.

2.5 Observations on Measured Data and Spectrum Use

It is important to understand those aspects of spectrum use that can be extrapolated from the

RSMS data presented in this report, and also those aspects of spectrum use that cannot be

inferred from these data. First, the data acquisition was performed at a single location in the Los

Angeles metropolitan area during a two-week period spanning the end of March through mid

April of 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

accumulative measurement time during the survey typically was several hours, spread uniformly

over the diurnal cycle. For some bands that were nondynamic and measured with the azimuthscanning 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 Los Angeles

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

are 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 also can be used to qualitatively assess the relative density of

channel occupancy on a band-by-band basis. Likewise in the azimuth-scan bands, the single

plotted curve provides a density estimate 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

49
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 Los Angeles. Results of those measurements will be published separately.

2.5.1 Band-by-band Observations on Spectrum Use in the Los Angeles Area

The Table contains band-by-band observations on spectrum occupancy in the Los Angeles area.

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

and frequency allocation information in the NTIA Manual [1, Chapter 4].

Comments on Los Angeles 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) localizers transmit in the 108-112 MHz

range, so detection of ILS localizers was degraded by the high RSMS noise

figure in this range. Some ILS localizers, including Burbank airport, were

nevertheless observed. Across 108-118 MHz, very high frequency omnidirectional range (VOR) aeronautical navigation beacons were observed as 100%

emitters. These are seen as vertical lines on 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

usually are not receivable by the RSMS. However, the National Oceanic and

Atmospheric Administration (NOAA) weather satellite signal at 137.62 MHz

showed a received signal level as high as -70 dBm.

50
Comments on Los Angeles Spectrum Occupancy Measurement Results (Continued)

Spectral Range Figure Comments

138-162 MHz 5 A large number of mobile signals were observed in the 138-144 MHz portion

of the spectrum. The average curve is raised significantly across the 144-

148 MHz band, used by amateurs. Between 148-162 MHz, a large percentage

of available channels also showed use. Transmitters between 152-153 MHz

were in operation continuously during the survey period.

Maritime mobile signals occurred between 156.2475-162.0125 MHz. All of

these channels showed some occupancy; this is consistent with expectations

for the RSMS coverage of the Pacific coastal area near Los Angeles.

During the Los Angeles survey, routine station identification monitoring

indicated unauthorized use of frequencies at and near the 150 MHz Transit

satellite allocation. This information was sent to the FCC Field Enforcement

Bureau, where further investigation revealed several unauthorized signal

sources in southern California, including fishing boats offshore.

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

162.5 MHz is a public broadcast weather information channel. Most channels

in this band showed some usage during the survey period, and many channels

were occupied enough to raise the average curve. The minimum curve shows

that several channels were active during every measurement sweep, indicating

that some of the channels might be used all the time.

174-216 MHz 7 Television broadcast channels 7, 9, 11, and 13 are occupied by Los Angeles

stations. Channels 8, 10, and 12 are occupied by San Diego stations.

Attenuation of 20 dB was used to prevent front-end overload in the RSMS.

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

Signals, possibly from a trunked system, occurred between 220-220.75 MHz.

Identical received amplitudes of signals between 220.0-220.7 MHz may

indicate a single fixed location of origin. These signals might have been from

a mobile radio base station. Amateur signals were observed above 222 MHz,

and the relative density of channel occupancy increased above 223.3 MHz.

No military radiolocation occurred in this band in the Los Angeles area.

225-400 MHz 9 Military ATC and other communications were observed. Many of these

signals are 100% transmissions from fixed locations. Many signals that were

observed less often than 100% were seen enough of the time to significantly

affect the average curve. An ILS glideslope signal was observed at about

332 MHz.

400-406 MHz 10 A few dozen signal frequencies showed occupancy in this meteorological aids

band for brief intervals during the survey period. The relatively low amplitude and number of observed signals is consistent with low effective isotropic

radiated power and intermittent operation of most systems that use this band

(e.g., radiosondes).

406-420 MHz 11 A number of fixed and mobile signals, about 40 of them affecting the minimum and average curves, were observed. Eight of the signals were observed

in 100% of the RSMS data scans.

51
Comments on Los Angeles Spectrum Occupancy Measurement Results (Continued)

Spectral Range Figure Comments

420-450 MHz 12 High-power air search radar signals produce essentially all usage observed in

this band. Most 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 Los Angeles area with similarly high usage in San Diego [3]

and practically nonexistent activity in the Denver, Colorado area [2].

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

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

allocation are very distinct. The 454-455 MHz domestic public base stations

also were distinctly observed.

470-512 MHz 14 Television broadcast channel 18 is a Los Angeles area station. Television

channel 15 is occupied by a San Diego station. 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

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

defined in the CFR [4, 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 showed use by Los Angeles County public safety base

stations for land mobile radio. Although the T-band allocations are for Los

Angeles, which is well beyond line-of-sight from an earlier RSMS measurement location at Point Loma, San Diego, spectrum occupancy by these

systems was readily observed in the San Diego area [3].

512-806 MHz 15 All of the signals observed in this band are UHF television broadcast. At

least nine of them were observed in 100% of RSMS scans. Both Los Angeles

and San Diego area stations were observed.

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

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

clearly identifiable.

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

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

public safety band showed relatively low usage, 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 showed enough use by mobile units to raise the average curve slightly.

The 849-851 MHz ground-to-air allocation showed lower usage, but the POI

for such signals by the RSMS is low. The 851-866 MHz base conventional

and trunked band showed usage that significantly raises the average curve.

The 866-869 MHz base public safety showed usage on most channels, and the

average curve was affected. The 869-894 MHz band, occupied by cellular

base stations, was 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 was observed, confirming that low POI

probably prevents the RSMS from measuring corresponding ground-to-air

signals. A few signals was observed in the 896-901 MHz private land mobile

band, and in the 901-902 MHz general mobile allocation.

52
Comments on Los Angeles Spectrum Occupancy Measurement Results (Continued)

Spectral Range Figure Comments

902-928 MHz 17 & 18 This band was measured two different ways: with the positive peak detector

in maximum hold mode and 10-kHz IF bandwidth, as shown in Figure 17,

and with the positive peak detector in stepped mode and 1-MHz bandwidth, as

shown in Figure 18. The narrow-IF bandwidth, maximum-hold measurement

was intended to show industrial, scientific, and medical (ISM) and Part 15

device operations, while the wide-IF bandwidth, stepped algorithm was

intended to optimize the RSMS for measurement of radar signals in the band.

For the Los Angeles area, both algorithms produced measured occupancy data

that showed a higher level of usage than was indicated in the Denver,

Colorado survey measurements [2]. The data showed also that usage density

was similar to San Diego [3], but the measured spectra of the transmitters

differs from San Diego.

A wide variety of systems operate in this band. These include, but are not

limited to, high-power naval radars (primary allocation in the band), ISM

devices, Part 15 devices, wireless local area networks (required to use either

spread spectrum or frequency-hopping transmitters), automatic vehicle

monitoring, digital communication systems, repeaters, and amateurs. The

measurements shown in Figure 17 were designed to discriminate against radar

signals and show the cumulative effect of nonradar devices on spectrum usage

in this band. Radar emissions tend to be discriminated out of these data by

the narrowband (10-kHz) IF. Maximum observed signal amplitude in this

bandwidth was about -60 dBm on an omni antenna. Note that many of the

signals were observed in 100% of RSMS data scans.

Figure 18, made with positive peak detection in a 1-MHz IF bandwidth,

primarily showed activity of high-power naval radars. Note that with the

wider measurement bandwidth, which more closely matches the emission

bandwidth of the radar signals, the maximum measured amplitude of the

signals in the band exceeded a value of -15 dBm in 50 ohms, as received on

the RSMS omnidirectional antenna.

928-960 MHz 19 Paging systems were observed between 928-932 MHz.

The 932-935 MHz point-to-point and point-to-multipoint band clearly is

delineated, as is the 935-940 MHz land mobile band. Two signals were

present constantly in the 941-944 MHz band for fixed, point-to-point, and

point-to-multipoint communications. Most signals in the 944-960 MHz fixed

band (auxiliary broadcasting, fixed private microwave, and studio-to-transmitter links) were present in 100% of RSMS data scans.

53
Comments on Los Angeles 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 appeared as bumps

in the average curve at (approximately) 982, 986, 1113, 1159, 1165, 1170,

1191, 1195, 1206, and 1211 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 Figure. Because

emissions in this band primarily are pulsed, the average curve essentially was

unaffected by all signals except TACAN.

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

Frequencies occupied by distinctly identifiable radar signals are 1255 MHz

and 1346 MHz. The radar at 1255 MHz also was measured from the earlier

San Diego RSMS location [3]. All of the measured signals between these

peaks are spurious emissions from these radars, and they primarily are

generated by the 1346 MHz radar. The emissions are generated by a crossedfield amplifier used by that radar. Emission parameters vary, but values

measured by the RSMS crew typically were as follows: mechanical beam

rotation time, 9-12 s; pulse width, 1-6μs; and transmitted pulse repetition

rate, 300-600 pps. These radars usually were observed to emit staggered

pulse trains, to enhance moving target indicator processing of target returns.

The emissions roll-off below 1230 MHz and above 1375 MHz in the Figure is

due to the presence of a bandpass filter in the output of the 1346 MHz radar.

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

this band were optimized to observe nonradar emissions. Nevertheless, most

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

1350-1383 MHz and 1392 MHz are generated by the air search radars.

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

average and minimum curves were unaffected.

1400-1530 MHz 23 Telemetry signals, probably from flight activity associated with a test range

north of the RSMS, were observed.

1530-1710 MHz 24 Numerous signals were observed above 1559 MHz. Although the RSMS was

not configured explicitly to receive space-to-earth signals, some apparently

were received in the 1559-1610 MHz band. We infer that the other signals

are from earth-to-space allocations for maritime mobile satellite (1626.5-

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

radiosondes (1668.4-1700 MHz).

1710-2300 MHz 25 All signals observed in this band were terrestrial point-to-point communications, as measured with the RSMS azimuth-scanning technique (see Section

B.8 in Appendix B). The measurement system noise floor varied across this

frequency range, as evidenced by the dip centered at 2090 MHz. Note that all

signals observed in this band in Los Angeles were analog, except for the

digital signal at approximately 1955 MHz.

54
Comments on Los Angeles Spectrum Occupancy Measurement Results (Continued)

Spectral Range Figure Comments

2300-2500 MHz 26 Two communications signals, one digital and one analog, were observed at

2369 and 2384 MHz. Their significant effect on the average curve suggests

that they likely are fixed links. Above 2387 MHz, all of the observed activity

is background radiation generated by ISM devices, and especially by aggregate emissions from microwave ovens in the Los Angeles area. This background has been observed at other RSMS spectrum survey locations [2,3].

See also Gawthrop, et al. [5], for further information on emission characteristics of microwave ovens.

2500-2700 MHz 27 At least 20 fixed transmitters were observed in this band. Some of the

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

presented in Figure 27, but were distinguishable in the RSMS raw data scans.

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

are multichannel multipoint distribution systems (MMDS, also called wireless

cable television) transmitters. Note variation in RSMS system noise floor

across this frequency range.

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

Eleven frequencies were easily discernable (2705, 2730, 2755, 2780, 2795,

2810, 2815, 2833, 2845, 2855, and 2885 MHz). Because automatic attenuation was not yet implemented in the RSMS, many of these radars saturated

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

(two radar frequencies, 2795 MHz and 2833 MHz were not used during the

manually attenuated scans, and they show saturation effects). 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. Radars in this band, as measured

by the RSMS crew, typically have the following characteristics: mechanical

rotation, no elevation scanning, about a 5 s rotation time, about a 1 μs pulse

width, and about 1000 pps emitted at a high-order stagger, presumably for

doppler processing of target returns.

2900-3100 MHz 29 High-power air-search radars were observed in this band. Compare the high

levels of activity observed in Los Angeles to similarly high levels in San

Diego [3] and to nonexistent levels of activity in Denver, Colorado [2].

The high peak and average values recorded at 3050 MHz were 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.

3100-3700 MHz 30 Numerous high-power radars were observed in this band. A single type of

radar was observed across the frequency range of 3100-3500 MHz. Compare

the high levels of activity observed in Los Angeles to similarly high activity

in San Diego [3] and to the nonexistent activity in Denver, Colorado [2].

3700-4200 MHz 31 RSMS azimuth scans indicate four fixed, point-to-point microwave links in

this band. The spectra showed that the links were using analog modulation.

The RSMS noise floor showed variation between 3860-4000 MHz.

55
Comments on Los Angeles Spectrum Occupancy Measurement Results (Continued)

Spectral Range Figure Comments

4200-4400 MHz 32 Airborne radio altimeter signals, transmitted by aircraft on approach and

departure from nearby airfields, were observed between 4245-4350 MHz.

Two modulations predominate: pulsed and FM-CW. Because the signals

occurred very intermittently, and some were pulsed, the average and minimum

curves were not affected. The source of the signal at 4292 MHz is not

known.

4400-5000 MHz 33 Only a single fixed, point-to-point microwave link was observed in this band,

as measured with the RSMS azimuth-scanning technique. The narrow

emission spectrum in the Figure indicates an analog signal.

5000-5250 MHz 34 No signals were observed in this band during the Los Angeles spectrum

survey. No microwave landing system (MLS) is currently deployed in the

Los Angeles area. This band was measured similarly with no detectable

signals in Denver [2] and San Diego [3], although some radar spurious

emissions did bleed over from an adjacent band in San Diego [3].

5250-5925 MHz 35 All emissions in this band are produced by radars (typically, maritime surfacesearch and weather surveillance units). Because automatic attenuation was

not yet implemented in the RSMS, a few of these radars saturated the RSMS

front-end at their center frequencies, as evidenced by clipped peaks in the

maximum curve.

5925-7125 MHz 36 Numerous fixed links (all analog) were observed between 5925-6425 MHz in

a fixed and fixed-satellite band in the RSMS azimuth-scan measurement.

Additional links (all but one of them analog) were observed between 6550-

6875 MHz in another fixed and fixed-satellite band. Three or four links (all

analog) occurred between 6875-7100 MHz in the fixed-satellite/auxiliary

broadcasting band. Overall, slightly more occupancy was observed in Los

Angeles than San Diego [3], and less occupancy was observed in Los Angeles

than in Denver [2].

7125-8500 MHz 37 Only two fixed links (both analog) were observed in the RSMS azimuth-scan

measurement. Substantially less occupancy was observed in this band in Los

Angeles than in either the Denver or San Diego surveys [2,3]. The dip

between 7850-8000 MHz in the Figure is due to a decrease in the RSMS

noise floor across that range.

8500-10550 MHz 38 All signals observed in this band are generated by radars. The radars

observed in this band in Los Angeles are maritime surface-search and

airborne search and navigation units. A land-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, were:

mechanical rotation time, 2-4 s; pulse width, less than 300-ns; pulse repetition

rate, several thousand pps (no pulse staggering present). Airborne radars have

similar pulse characteristics, but employ mechanical sector scans.

Measured occupancy of this band in Los Angeles is remarkably similar to that

observed in San Diego [3], and much higher than that observed in Denver [2].

56
Comments on Los Angeles Spectrum Occupancy Measurement Results (Continued)

Spectral Range Figure Comments

10550-13250

MHz

39 No signals were observed in this band in Los Angeles. Observed occupancy

was similar to San Diego [3], and lower than was observed in Denver [2].

13250-14200

MHz

40 A ship-based radar was observed at 13360 MHz. Radars in this band are

short-range, and are often used for weapons-control functions.

14200-15700

MHz

41 No signals were observed in the azimuth scan. In general, the probability of

intercept by the RSMS for signals in this band is low (see Appendix B).

15700-17700

MHz

42 No signals were observed in this band. In general, the probability of intercept

by the RSMS for signals in this band is low (see Appendix B).

17700-19700

MHz

43 No signals were observed; the change in the RSMS noise floor at 19300 MHz

was due to a band edge in the spectrum analyzer. In general, the probability

of intercept by the RSMS for signals in this band is low (see Appendix B).

4. REFERENCES

[1] Manual of Regulations and Procedures for Federal Radio Frequency Management, revised

Jan. and May 1996, 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] F.H. Sanders, B.J. Ramsey, and V.S. Lawrence, "Broadband spectrum survey at San Diego,

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

[4] 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).

[5] P.E. Gawthrop, F.H. Sanders, K.B. Nebbia, and J.J. Sell, "Radio Spectrum Measurements

of Individual Microwave Ovens," NTIA Report 94-303 Vol 1 & 2, Mar. 1994.

57
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APPENDIX A. OVERVIEW OF BROADBAND SPECTRUM SURVEYS

A.1 Introduction

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

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

software configurations developed for the surveys are described. Measurement system response

to various types of signals is described in Appendix B. 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 C and D. RSMS

calibration theory and application are described in Appendix E.

A.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 preselection and/or filtering is used for survey measurements; and 3) limited man-made

noise such as impulsive noise from automobile ignition systems, electrical machinery, and power

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

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 possibly could 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.

A.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 commonly are observed during RSMS spectrum surveys:

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

59
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.

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 B 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.

60
The data acquisition (DA) measurement software1 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 monitoring and

control of the RSMS is possible via a telephone modem linked to the computer. Standardized

measurement band event schedules are used for each spectrum survey, with the measured data

stored for postmeasurement processing.

A.3.1 Survey Band Events

The 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 with a

particular set of signal input ports, front-end configurations, spectrum analyzer modes and

settings, and data-recording options. Band event parameters and options are detailed in

Appendix D. The factors considered when selecting frequency sub-bands, receiver algorithms,

and other parameters for the band events are discussed in Appendix B. Spectrum survey

"standard" band events for System-1 and System-2 are shown in Tables A-1 and A-2,

respectively.

Each row in the survey band event tables, beginning with an event number, shows the

measurement parameters for a specific receiver configuration in the RSMS. Instruction to run

the event can be entered by an operator or come from a computer-loaded band event schedule,

as explained in Section A.3.2. The DA software, when instructed, sends the command

parameters for an event to the system hardware and initiates measurements for the event. Tables

A-1 and A-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 D contains operational descriptions for all of the

table parameters found under 2) and 3) above.

1

All automated measurements are accomplished through computer software control of the

measurement hardware. Appendix D contains a complete description of the RSMS data

acquisition software.

61
Table A-1. Standard Spectrum Survey Band Events for RSMS System-1

62

Standard Events DA Receiver Parameters DA Spectrum Analyzer Parameters* Antenna**

Event

Number

Freq. Band

(MHz)

AlgorithmStart

(MHz)

End

(MHz)

Scans

(# of)

Sweeps

(# of)

Steps

(# of)

IFBW

(kHz)

Detector

Type

VBW

(kHz)

RL

(dBm)

MH/VA

(#swps)

Swp/stp

(sec)

Type Gain

(dBi)

11 108-162 sw/m3 104 164 6 100 1 10 sample 10 -20 1 0.3 omni -5

12 162-174 sw/m3 160 180 2 500 1 10 sample 10 -20 1 0.3 omni -2

13 174-216 sw/m3 170 220 1 500 1 100 sample 100 -10 1 0.02 omni 0.7

14 216-225 sw/m3 216 225 3 60 1 3 sample 3 -30 1 0.9 omni 1.0

15 225-400 sw/m3 225 405 6 100 1 30 sample 30 -10 1 0.09 omni 1.5

16 400-406 sw/m3 400 406 2 60 1 3 sample 3 -10 1 0.9 omni 2.9

17 406-420 sw/m3 400 420 2 200 1 10 sample 10 -20 1 0.9 omni 2.8

18 420-450 stepped 420 450 1 1 30 1000 +peak 3000 -10 1 12 omni 2.5

19 450-470 sw/m3 450 470 2 200 1 10 sample 10 -20 1 0.9 omni 2.3

20 470-512 sw/m3 470 520 5 100 1 10 sample 10 -20 1 0.9 omni 2.0

21 512-806 sw/m3 512 812 3 200 1 100 sample 100 -10 1 0.02 omni 2.6

22 806-902 sw/m3 806 906 10 60 1 10 sample 10 -20 1 0.3 omni 1.4

23 902-928 swept 900 930 3 1 1 10 MXMH 10 -10 600 0.3 omni 0.9

24 902-928 stepped 900 930 1 1 30 1000 +peak 3000 -10 1 12 omni 0.9

25 928-960 sw/m3 920 960 4 300 1 10 sample 10 -20 1 0.3 omni 0.9

* For spectrum surveys, attenuation is set to 0 (default), display to 10 dB/div, and the spectrum analyzer in use must measure at least 1000 points per scan.

** A 100-MHz to 1-GHz omnidirectional antenna is used for spectrum surveys. For the Los Angeles survey, however, a 100-MHz to 1-GHz log periodic

antenna (LPA) with 5.5- to 6.1-dBi gain was used. The LPA was mounted at a 45ß angle to emulate slant polarization (see Section 2.3)
Table A-2. Standard Spectrum Survey Band Events for RSMS System-2

63

Standard Events DA Receiver Parameters DA Spectrum Analyzer Parameters* 

Event

Number

Freq. Band

(MHz)

Algorithm Start (MHz) End (MHz) Scans (# of) Sweeps (# of) Steps (# of) IFBW (kHz) Detector Type VBW (kHz) RL (dBm) MH/VA (#swps) 

05 960-1215 sw/m3 950 1250 1 500 1 300 +peak 3000 -10 1 06 1215-1400 stepped 1200 1400 1 1 200 1000 +peak 3000 -10 1 07 1350-1400 sw/m3 1350 1400 5 100 1 10 sample 10 -20 1 08 1400-1530 sw/m3 1400 1550 5 200 1 30 sample 30 -10 1 09 1530-1710 sw/m3 1530 1710 6 500 1 30 sample 30 -10 1 10 1710-2300 swept 1700 2300 6 1 1 100 MXMH 100 -10 600 11 2300-2500 swept 2300 2500 2 1 1 100 MXMH 100 -10 600 12 2500-2700 swept 2500 2700 2 1 1 100 MXMH 100 -10 600 13 2700-2900 stepped 2700 2900 1 1 200 1000 +peak 3000 -10 1 14 2900-3100 stepped 2900 3100 1 1 200 1000 +peak 3000 -10 1 15 3100-3700 stepped 3100 3700 1 1 200 3000 +peak 3000 -10 1 16 3700-4200 swept 3700 4200 5 1 1 100 MXMH 100 -10 600 17 4200-4400 sw/m3 4200 4400 1 500 1 300 +peak 3000 -10 1 18 4400-5000 swept 4400 5000 6 1 1 100 MXMH 100 -10 600 19 5000-5250 sw/m3 5000 5300 1 500 1 300 +peak 3000 -10 1 20 5250-5925 stepped 5250 5950 1 1 240 3000 +peak 3000 -10 1 
Table A-2. Standard Spectrum Survey Band Events for RSMS System-2 (Continued)

64

Standard Events DA Receiver Parameters DA Spectrum Analyzer Parameters* 

Event

Number

Freq. Band

(MHz)

Algorithm Start (MHz) End (MHz) Scans (# of) Sweeps (# of) Steps (# of) IFBW (kHz) Detector Type VBW (kHz) RL (dBm) MH/VA (#swps) 

21 5925-7125 swept 5925 7125 4 1 1 300 MXMH 1000 -10 600 22 7125-8500 swept 7100 8600 5 1 1 300 MXMH 1000 -10 600 23 8500-10550 stepped 8500 10600 1 1 720 3000 +peak 3000 -10 1 24 10550-13250 swept 10550 13250 1 1 1 3000 MXMH 3000 -10 600 25 13250-14200 stepped 13250 14250 1 1 340 3000 +peak 3000 -10 1 26 14200-15700 swept 14200 15700 1 1 1 3000 MXMH 3000 -10 600 27 15700-17700 stepped 15700 17700 1 1 700 3000 +peak 3000 -10 1 28 17700-19700 swept 17700 19700 1 1 1 3000 MXMH 3000 -10 600 

* For spectrum surveys, attenuation is set to 0 (default), display to 10 dB/div, and the spectrum analyzer in use must measure at l** A 500-MHz to 18-GHz slant polarized biconical omnidirectional antenna is used for spectrum survey measurements. A parabo

is used for azimuth-scanning. See Sections C.4 and D.2 of Appendices C and D, respectively, for descriptions of the antennas and thalgorithm used with the dish antenna.

+ If slow-rotation emitters (e.g., weather radars) contribute significantly to the measured occupancy in a survey band, an increased 

used to better characterize their peak power envelope (see Section B.7.2 in Appendix B).
A.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 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 band

event 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, the

case for Los Angeles). Any number of special schedules can be run during a survey.

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

respectively. Tables A-5 and A-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 execute in the sequence);

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 schedule 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.

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

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

are 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.

2

Schedule numbers are assigned sequentially from 1 to 64. The system software supports only

64 band events in a schedule; however, there is no limit on how many times the schedule

executes during a survey.

65
Table A-3. Standard Band Event Schedule for RSMS System-1

Schedule

Number

Band Event

Number

Priority

Number

Event Time

(minutes)

Accumulative

Time (hours)

1 12 1 16.3 0.27

2 11 2 10.3 0.44

3 17 1 10.8 0.62

4 14 2 5.1 0.71

5 13 3 5.8 0.81

6 19 1 10.8 0.99

7 22 2 10.8 1.17

8 20 1 13.8 1.40

9 23 2 5.3 1.48

10 25 1 20.0 1.82

11 18 2 6.7 1.93

12 12 1 16.3 2.20

13 16 3 3.4 2.26

14 17 1 10.8 2.44

15 24 2 6.7 2.55

16 19 1 10.8 2.73

17 11 2 10.3 2.90

18 20 1 13.8 3.13

19 14 2 5.1 3.22

20 25 1 20.0 3.55

21 21 3 7.3 3.67

22 12 1 16.3 3.94

23 22 2 10.8 4.12

24 17 1 10.8 4.30

25 23 2 5.3 4.39

26 15 3 8.3 4.53

27 19 1 10.8 4.71

28 18 2 6.7 4.82

29 20 1 13.8 5.05

30 24 2 6.7 5.16

31 25 1 20.0 5.50

66
Table A-4. Standard Band Event Schedule for RSMS System-2

Schedule

Number

Band Event

Number

Priority

Number

Event Time

(minutes)

Accumulative

Time (hours)

1 05 3 5.6 0.09

2 06 3 42.0 0.79

3 07 2 8.6 0.94

4 08 2 12.7 1.15

5 09 1 37.2 1.77

6 11 3 3.0 1.82

7 13 3 18.0 2.12

8 14 2 42.0 2.82

9 15 2 42.0 3.52

10 17 3 5.6 3.61

11 19 3 5.6 3.71

12 20 2 49.0 4.52

13 23 2 49.0 5.34

14 25 1 25.0 5.76

15 27 1 52.0 6.62

16 05 3 5.6 6.72

17 09 1 37.2 7.34

18 17 3 5.6 7.43

19 19 3 5.6 7.52

20 25 1 25.0 7.94

21 27 1 52.0 8.81

22 05 3 5.6 8.90

23 07 2 8.6 9.04

24 08 2 12.7 9.25

25 09 1 37.2 9.87

26 11 3 3.0 9.92

27 14 2 42.0 10.62

28 15 2 42.0 11.32

29 17 3 5.6 11.42

30 19 3 5.6 11.51

67
The standard band event schedules are usually arranged to execute priority 1 events three times

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

Schedule

Number

Band Event

Number

Priority

Number

Event Time

(minutes)

Accumulative

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

Schedule

Number

Band Event

Number

Priority

Number

Event Time

(minutes)

Accumulative

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

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 in Table A-4) might not be run three times as often as

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

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.

68
APPENDIX B: INTERPRETATION OF SPECTRUM SURVEY DATA

B.1 Introduction

RSMS spectrum survey measurements are performed with a variety of receiver algorithms (see

Section D.2 of Appendix D). 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 spectrum 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 also are discussed to fully

explain the measurement algorithms.

B.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);

69
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 personal

cellular telephone);

the signal amplitude 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

voice-communication 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 normally are not 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, may be 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-rotating dish

antenna sweep of the horizon coupled with simultaneous swept-spectrum measurements is used

in point-to-point microwave bands. These measurement techniques are detailed in the following

subsections.

A parabolic dish 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 B.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 cavitybacked 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.

Slant (antenna) polarization is used for all RSMS measurements except those in the point-to-point

microwave bands. Slant-polarized biconical omnidirectional antennas usually are used above

1 GHz, and slant-oriented log periodic or conical omnidirectional antennas usually are used below

70
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 always are 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 108 MHz and 19.7 GHz.

B.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 are used to perform swept-frequency measurements.

The HP-8566B spectrum analyzers used in the RSMS sweep across the spectrum in individual

segments that are 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-μs

measurement time in each frequency bin. Within each bin measurement interval (in this example,

20 μ s), 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 the particular spectrum analyzer detector mode selected. The 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

B.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 μs) 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, 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 that has been

selected.

71
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 approximately 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).

B.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 recorded individually. 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 cumulating (cuming) 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 B-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.1 In the diagram, all measured data identified

as "RSMS data output for lab analysis" is considered to be postmeasurement data.

B.4 Description of Swept/m3/Sample Data Collection

If the Swept/m3 algorithm (described in Subsection B.3.1) is performed using the sample detector

(see Section B.3 for a description of the sample detector in the RSMS analyzers), then the data

are referred to as "Swept/m3/sample."

1

All band events measured more than once during the same survey are cumulated (cumed) as

explained in this appendix. Stepped and swept data records are cumed 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.

72
B.4.1 Interpretation of Noise Responses in Swept/m3/Sample Data

Figure B-1. Functional diagram of the RSMS signal-processing path for cumulated data.

The noise level displayed by a measurement system using the sample detector will be equal to

[kTB + (measurement system noise figure) - 2.5 dB].2 With a 1-MHz IF bandwidth and a 10-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 x 10-20 mW x s/K), T is system temperature (290 K for these measurements), and

B is measurement IF bandwidth in Hz. For B = 1 Hz, at room temperature: kTB = -174 dBm.

In a 1-MHz IF bandwidth, kTB = -174 + 10log(106) = -114 dBm.

73
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 normally is 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.

B.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 (0.1%). 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 + (typically)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 present.

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 always have 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

74
far apart, then the signal probably was 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 labeled tick marks on the y-axis of each swept/m3/sample

graph. The tick marks, labeled "max sample noise," "avg sample noise," and "min sample noise,"

are intended to assist report users in determining which graphed features are signal responses and

which graphed features are measurement system noise.

B.5 Description of Swept/m3/+Peak Data Collection

If the Swept/m3 algorithm is performed using the positive peak (+peak) detector (see Section B.3

for a description of the +peak detector in the RSMS spectrum analyzers), then the data are called

"Swept/m3/+peak."

B.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 1-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-B offset levels for sample detection; however 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+/- ±1-dB difference between the maximum, mean, and

minimum as sample times increase (i.e., as sweep times become longer). This is because the

75
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.

B.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 means that +peak detection also will 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

1/10 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

76
in the minimum curve at that frequency. Thus, this curve shows signals that are present

continuously 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 y-axis of each swept/m3/+peak graph. The

tick marks, labeled "max +peak noise," "avg +peak noise," and "min +peak noise," are intended

to assist report users in determining which graphed features are detected signals and which

graphed features are measurement system noise.

B.6 Description of Swept/Max-Hold Data Collection

If a frequency-sweeping algorithm is performed using the +peak detector (see Section B.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.

B.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.

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 empirically observed to limit at about 2 dB

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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above the mean of the maximum, and the minimum level sampled on thermal noise is about 2 dB

below the mean of the maximum.

B.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 1/10 the measured decibel values) of all individual maximum-hold data traces that

were measured in the band. Qualitatively, 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 shows signals that were present in all of the scans.

B.7 Description of Stepped/+Peak Data Collection

Although most spectrum analyzers routinely are operated by sweeping in the frequency domain,

this is not the most efficient method for measuring 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

radars, this interval is selected on the basis of the typical recurrence of the radar beam at the

78
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 certainly would

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,

corrected for calibration factors, and stored. This process of waiting at a frequency in a 0-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. Attenuation can be added or subtracted at the

RSMS signal input at each measurement step. Thus, the instantaneous dynamic range of the

RSMS, (normally about 60 dB) can be increased by the maximum amount of input attenuation

that is available. Currently, maximum available attenuation is 50-70 dB (depending upon which

front-end is selected) and total RSMS dynamic range of measurement is about 110-130 dB.

The spectrum interval between adjacent measured frequencies is approximately equal to the IF

bandwidth of the measurement system. For example, if a 1-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 μs is the shortest pulse width

expected from emitters in a band, then a 1-MHz measurement (IF) bandwidth is used. In this

manner, the measurement system progressively tunes 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.

B.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 1-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.

B.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 fill the

emission envelope completely.

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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

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 1/10 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.

B.8 Description of Swept/Az-Scan Data Collection

In bands dominated by point-to-point fixed microwave communication systems, the transmitter

main beams are seldom pointed towards the RSMS. To enhance the probability of intercepting

low-level sidelobe and backlobe signals from these sources, a high-gain parabolic reflector with

a linear horizontal and vertical cross-polarized feed antenna is used. However, the site survey

data must include signals received from all points on the horizon; so, azimuth-scanning with the

parabolic reflector (dish) antenna is performed. The RSMS dish is pointed at the horizon and

slowly rotated through 360ß. 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 6ß/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 1ß, the dish

rotates through one beamwidth in 1/6 s (170 ms). 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 point-to-point linked signals of either

polarization. The two polarization scans are combined to show the maximum envelope of both

scans on a single data curve.

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The single data curve is corrected for noise diode calibration factors and recorded. Unlike other

RSMS site survey measurements, this measurement is performed only once at each survey

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.

B.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 normally are not detected by the RSMS.

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APPENDIX C: RADIO SPECTRUM MEASUREMENT SYSTEM

C.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.

C.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 sufficiently small and light

enough 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 C-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 corner 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 provides good radio frequency (RF)

isolation between the measurement system and the outside environment. This shields equipment

and personnel from high-level fields, as well as preventing internal computer noise from

contaminating the measurements. 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.

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

84
C.3 Instrumentation

The RSMS normally is 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 C-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,

they are in the two racks left of center. Both systems use RF front-ends that incorporate dynamic

RF attenuation, low noise preamplification and tunable frequency preselection. These features

allow the RSMS to achieve the best possible combination of dynamic range, sensitivity, and offtuned signal rejection in its measurements.

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

For spectrum surveys, the low-frequency system usually is 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 C-3. As the diagram shows, both

the high and low frequency systems are designed around a Hewlett-Packard 8566B spectrum

analyzer (0-22 GHz), 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 around 1 GHz.

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

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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 normally are 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.

Each of the two measurement systems have 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 often are 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 the Table. The lower-frequency system can be operated across a frequency range

of 100 Hz to 2 GHz, with fixed bandpass and varactor preselection at frequencies below

500 MHz and tracking yttrium-iron-garnet (YIG) preselection 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 preselection 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 preselection instead of the YIG, but that

arrangement is tenable only if there are no in-band signals strong enough to overload the

preamplifiers.

C.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 Los Angeles survey) most of the radio activity in the

area is confined to an area subtending 180ßor less relative to the RSMS. Besides the 0.1- to

1-GHz LPA, the following omnidirectional slant-polarized biconical antennas also are carried:

0.1-1 GHz, 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 60ßor 90ß. They also are

87
useful as auxiliary antennas for manual monitoring of emitters or spectrum of special interest and

Available RSMS RF Signal-processing Paths

Frequency Range RSMS

System

Dynamic

RF Atten.

(dB)

Type of Preselection and

Low-noise Preamplification

Noise

Fig.*

(dB)

100 Hz-2 MHz** 1 0-50 Fixed bandpass; HP-85685A preamps+ 10

2 MHz - 20 MHz** 1 0-50 5% varactor; HP-85685A preamps+ 10

20 MHz - 100 MHz** 1 0-50 5% varactor; HP-85685A preamps 10

100 MHz - 500 MHz 1 0-50 5% varactor; HP-85685A preamps 10

500 MHz-2 GHz 1 0-50 0.2% tracking YIG; HP-85685A preamps 10

500 MHz-2 GHz 2 0-70 Fixed bandpass; 0.5-2 GHz preamp± 10

2 GHz-4 GHz 2 0-70 Fixed bandpass; 2-4 GHz preamp± 10

4 GHz-8 GHz 2 0-70 Fixed bandpass; 4-8 GHz preamp± 10-15

8 GHz - 18 GHz 2 0-70 Fixed bandpass; 8-18 GHz preamp± 15-25

2 GHz - 20 GHz 2 0-70 0.2% tracking YIG; 1-20 GHz preamp≤ 15-25

* Noise figure is measured using a +25-dB ENR noise diode and variant Y-factor calibration performed at

the antenna terminals.

** Due to the shortage of storage space for large antennas, this frequency range is not normally measured as

part of an RSMS spectrum survey.

+ The low-frequency input on the HP-85685A preselector must be used.

+/- Generally, this path is only used to perform azimuth-scans or special measurements during an RSMS

spectrum survey, but may be used for normal survey bands if no high-amplitude signals are anticipated

in the measured frequency range.

≤ This path normally is used for all spectrum survey bands (except azimuth-scans, see note +/- above) in the

1- to 19.7-GHz frequency range. The YIG and preamplifier nominally operate in the 2- to 18-GHz

frequency range, but have demonstrated adequate performance across a 1- to 20-GHz range.

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 to 2 GHz.

The latter normally is not carried due to its size.

A 1-m parabolic reflector antenna with a choice of feeds (linear cross-polarized and circular)

normally is carried. This antenna may be used to perform the azimuth-scanning measurements

in the common carrier (point-to-point microwave) spectrum survey bands, but is used primarily

for measurements on specific emitters (e.g., selected radars).

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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.

C.5 Attenuators, Preselectors, and Preamplifiers

All RSMS measurements are made using the RF front-ends depicted in Figure C-3. These frontends incorporate dynamically switched RF attenuation, preselection, 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 preselection is required if low noise preamplifiers (LNAs) are used; this is

the case for essentially all RSMS measurements. Preselection prevents strong off-tuned signals

from overloading the front-end LNAs. At frequencies below 500 MHz, preselection 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 preselection (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 preselection insertion loss to about 1 dB; fixed bandpass filters

in an approximately octave progression are available in the ITS front-end (see Figure C-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 produce at least 41 dB of excess noise to overdrive system noise (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

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line loss, and the 4-dB noise figure of the second LNA) and one at the input to the spectrum

analyzer (to overdrive the analyzer noise figure).

C.6 Calibration

RSMS calibrations are performed with noise diodes and a Y-factor excess noise ratio (ENR)

technique described in detail in Appendix E. 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 also is very useful for isolating the gain and loss factors of

individual system components.

C.7 Additional Measurement Capabilities

When deployed for general spectrum occupancy measurements (broadband spectrum surveys),

the RSMS also is 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 capability of the RSMS program.

A combination of high sensitivity and interactive front-end RF attenuation make it possible to

measure routinely 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 preselection 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. A dynamic range of 110-130 dB is

achievable through the use of switched attenuation (invoked as a function of input signal level).

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 360ßon 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

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or identify the source of unknown transmissions. Measured transmitter (signal) characteristics

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 included explicitly in RSMS capabilities.

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APPENDIX D: DATA ACQUISITION SOFTWARE

D.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 C, 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.

D.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 A.3.1 in Appendix A). 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 generally are used to examine spectral bands occupied

by high duty cycle emitters such as mobile radios and television transmitters; stepping algorithms

are used to monitor spectral bands occupied by low duty cycle emitters such as radiolocation

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equipments (radars). Following are brief descriptions of the algorithms used during a spectrum

survey.

Swept: This algorithm controls a conventional spectrum analyzer1 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 also may

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 may be 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 2.3) 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 usually are 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

1

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, and step widths, 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 360ßwhile 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

also are low-powered, and use high-gain antennas which further reduce their

probability of intercept.

D.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 (Section A.3.1 of Appendix A). 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 usually is determined by comparing measurement bandwidth and frequency range. For example, a 30-MHz frequency range

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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. The DA program

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 used only with stepped algorithms.

Graph Min and Graph Max: The minimum and maximum values in dBm for the

graphical display of measured amplitude data.

D.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 nonfunctional configurations but the operator can

control the analyzer manually for unusual situations.

D.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 A.3.1 of

Appendix A.

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 B for discussions on detector

selection for receiver algorithms.

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Video Bandwidth [VBW (kHz)]: May be 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 used only with maximum hold or video-averaged detection.

Sweep Time [swp/stp (sec)]: 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.

D.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. Preselection also

is 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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D.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 techniques, as described in Appendix E.

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APPENDIX E: RSMS GAIN AND NOISE FIGURE CALIBRATION

Noise Figure

Gain Correction

E.1 Introduction

Measurement system calibration is performed prior to and during every RSMS site survey.

Calibration curves, as in Figure E-1, showing system noise figure and gain corrections as a

function of frequency across a selected range are generated. As measurements are performed,

gain corrections are added automatically to every sampled data point. Gain and noise figure

curves are used by RSMS operators to determine the relative health of the measurement system,

and to pinpoint locations in the measurement system RF path that are operating suboptimally.

Figure E-1. Example calibration graph for RSMS System-1 showing noise figure (upper, dashed

curve) and correction factors (lower, solid curve).

RSMS calibrations are performed automatically with noise diodes such as the one shown in

Figure E-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),

noise diodes are commonly used for calibration of measurement systems where minimal size,

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weight, and power consumption are crucial. Noise diodes provide these features while

maintaining adequate calibration accuracy and this is why they are used for RSMS calibrations.1

This appendix describes the theory and operation of RSMS noise diode calibrations.

Figure E-2. A typical noise diode solid state noise source. A +28-volt potential applied to the

type BNC connector on the right produces +24-dB excess noise ratio from the

type N connector on the left.

1

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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E.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 E-3. In this diagram, the symbol labeled ∑

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 labeled 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 E-3. Lumped-component noise diode calibration schematic diagram; reference equations

(E1) and (E2).

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

2

Many 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, (E1)

and for the noise diode = off condition:

poff = (nfs) x gkTB. (E2)

The quantity k is Boltzmann’s constant, equal to 1.38 x 10-20 mW x 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) (E3a)

Y = 10log(y) = 10log(pon/poff)=Pon - Poff. (E3b)

From equation (E3), the system noise factor can be solved as:

nfs = (enrd)/(y-1). (E4)

The measurement system noise figure is 10 log of the noise factor:

NFs = 10log(enrd/(y-1)) (E5)

= ENRd - 10log(y-1)

= ENRd - 10log(10Y/10 - 1).

Solving equations (E1) and (E2) for gain (g) yields:

g = (pon - poff)/(enrd x kTB) (E6a)

G = 10log(pon - poff) - 10log(enrd x kTB) (E6b)

= 10log(10Pon/10 - 10Poff/10) - ENRd - 10log(kTB). (E6c)

In RSMS calibrations, equation (E6c) is used to calculate gain from measured noise diode values.

Note that this calculation uses 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 (E5) could be used to calculate measurement system noise figure, the

implementation in RSMS software uses an equivalent equation. It is derived from (E1):

nfs = poff/gkTB (E7a)

NFs = 10log(poff) - 10log(gkTB) (E7b)

= Poff - G - 10log(kTB).

Substituting expression (E6b) for gain into (E7b) yields:

NFs = Poff + ENRd - (10Pon/10 - 10Poff/10). (E7c)

In RSMS calibrations, equation (E7c) is used to calculate noise figure. Whenever an RSMS

calibration is performed, Pon and Poff are measured at 128 frequencies across the frequency range

to be measured, and equations (E6c) and (E7c) are then used to calculate system gain and noise

figure for each of those 128 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.

Incident field strength is not calculated for RSMS spectrum surveys, because signal polarizations

are not routinely known. If incident field strength is required, and if appropriate signal

characteristics are known, then antenna factors can be included as part of measurement analysis.

The conversion from measured power to field strength in free space is:

FSfree space = (Pmeas) + (77.2 dB) + (20log(f)) - Giso (E8)

where

FSfree space = incident field strength, dBuV/m;

Pmeas = power measured in 50 ohms, dBm, corrected for RSMS path gain calibration;

f = measurement frequency, MHz; and

Giso = gain of the measurement antenna, dBi (dB relative to isotropic antenna).

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:

FSfree space = (Pmeas) + (107 dB) + ACF (E9)

where

ACF = antenna correction factor, dB.

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E.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 E-2, is connected at the point 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 128 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 128 calibration points to solve the

calibration equations (E6c) and (E7c) shown above. The gain values are inverted in sign to

become correction values. The resulting set of 128 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 E-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 also is 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 in long and less than 1 in diameter; weight

is a few ounces.

Power consumption is low, at about 50 mA of direct current at a +28 volt

potential.

Cost is about $1000 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 to diagnose where system losses are

occurring, 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.

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

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falls to about +/-2.5 dB due to a higher system noise figure. For noise diodes producing an excess

noise ratio of about +25 dB, as are used for RSMS measurements, gain and noise figure

calibrations cannot be performed in a practical sense if the 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.

E.4 Reference

[1] S. Adam, Microwave Theory and Applications, Englewood Cliffs, NJ: Prentice-Hall, Inc.,

1969, pp. 490-502.

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