NTIA Report TR-10-465

Emission Measurement Results for a 

Cellular and PCS Signal-Jamming 

Transmitter 

Frank H. Sanders

Robert T. Johnk

Mark A. McFarland

J. Randall Hoffman

NTIA Report TR-10-465

Emission Measurement Results for 

a Cellular and PCS Signal-Jamming 

Transmitter 

Frank H. Sanders

Robert T. Johnk

Mark A. McFarland

J. Randall Hoffman

U.S. DEPARTMENT OF COMMERCE 

Lawrence E. Strickling

Assistant Secretary for Communications and Information

February 2010

iii

ACKNOWLEDGEMENT

The authors wish to thank the National Institute of Standards and Technology (NIST), 

and particularly Mr. Dennis Camell of NIST, for providing timely access to the anechoic 

chamber on the Boulder campus for the radiated emission measurements that are 

presented in this report. Iris Tobias of the NTIA/ITS laboratory built the mountings for 

the jammer antennas; one of the authors (Frank Sanders) took the photographic image of 

Figure 1; and Ms. Kristen Davis of the NTIA/ITS laboratory drafted the technical 

drawing of Figure 2.

DISCLAIMER

Some technical information regarding the cellular jammer that was measured may be 

considered intellectual property by the manufacturer of the device. The device 

descriptions that are given in this report, its operational parameters, and its emissions are 

provided solely for the purpose of evaluating what engineering impact, if any, the 

possible future operation of the device might have on other systems that use the radio 

spectrum. Please note that the device that is described herein is not FCC-certified, nor 

does there exist a certified standard design or operational configuration for it. 

Some test and measurement equipment are identified in this report for the purpose of 

comprehensively describing the methodology and results of the work that was performed. 

Such identification does not imply endorsement by the Department of Commerce of the 

equipment so identified, nor does such identification imply that the equipment was the 

only possible choice for adequate performance of such tests and measurements.

v

CONTENTS

Page

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

TABLES ............................................................................................................................ ix

ABBREVIATIONS/ACRONYMS......................................................................................x

EXECUTIVE SUMMARY ............................................................................................... xi

EMISSION MEASUREMENT RESULTS FOR A CELLULAR AND PCS SIGNALJAMMING TRANSMITTER .................................................................................1

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

1.1 Objective .................................................................................................................1

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

2 MEASUREMENT SETUP ..............................................................................................3

3 MEASUREMENT SYSTEM CALIBRATION, TECHNIQUES AND BANDWIDTH 4

4 DESCRIPTION OF THE JAMMER ...............................................................................6

4.1 Power Output ..........................................................................................................6

4.2 Antennas .................................................................................................................6

4.3 Frequency-Sweeping, or Chirp Range ....................................................................6

4.4 RF Output Filtering ................................................................................................6

4.5 Ancillary Equipment ...............................................................................................7

5 COMBINATIONS OF JAMMER PARAMETERS USED FOR EMISSION 

MEASUREMENTS ................................................................................................8

6 MEASUREMENT DATA .............................................................................................11

6.1 Time Domain Behavior ........................................................................................11

6.2 Effect of Measurement Bandwidth on Measured Emission Spectra ....................13

6.3 Diplexer Frequency Response Measurement Result ............................................14

6.4 Emission Spectrum Measurement Results ...........................................................14

7 ANALYSIS ....................................................................................................................40

8 SUMMARY ...................................................................................................................42

9 ISSUES NOT ADDRESSED BY THIS STUDY ..........................................................44

10 REFERENCES ............................................................................................................45
vi

FIGURES

Page

Figure 1. A jammer transmitter antenna and two measurement antennas inside the 

NIST anechoic chamber in Boulder, CO............................................................ 2

Figure 2. Block diagram schematic of the jammer transmitter measurement 

system. ................................................................................................................ 3

Figure 3. A measurement of the jammer’s tuned frequency vs. time in the targeted 

869-894 MHz and 1930-1990 MHz bands. The transmitter repetitively 

sweeps a carrier wave frequency (called FM or chirp modulation) 

across the frequency ranges that are jammed. .................................................. 11

Figure 4. Time-domain behavior of the jammer signal inside a targeted band at 

880 MHz, chirping across 861-894 MHz. The jammer signal tunes 

through the measurement frequency every 5.1 microsecond (μs), for a 

chirp rate of 4.9 MHz/μs. The short spikes are a frequency fly-back 

behavior of the transmitter between each chirp cycle. ..................................... 12

Figure 5. Time domain behavior of the jammer signal inside a targeted band at 

1962 MHz, chirping across 1930-1990 MHz. The jammer signal tunes 

through 60 MHz every 20.4 μs in this band, for a chirp rate of 2.9 

MHz/μs. The short spikes are a frequency fly-back behavior of the 

transmitter between each chirp cycle. .............................................................. 12

Figure 6. Example in-band emission spectra of the jammer in measurement 

bandwidths of 8 MHz, 2 MHz, and 300 kHz. .................................................. 13

Figure 7. Power-rejection (filtering) characteristic of the diplexer as a function of 

frequency up to 6000 MHz. .............................................................................. 14

Figure 8. Baseline (jammer turned off) environmental measurement in the 

anechoic chamber, 100 MHz-2000 MHz. Only measurement system 

internal noise is seen. The gradual change in the baseline power is due 

to change in the measurement system noise figure. ......................................... 15

Figure 9. Baseline (jammer turned off) environmental measurement in the 

anechoic chamber, 2000 MHz-6000 MHz. The gradual change in the 

baseline power is due to change in the measurement system’s noise 

figure. The spikes at 2450-2500 MHz are emissions from microwave 

ovens, and the spike at 5800 MHz is a cordless phone emission that 

penetrated the anechoic chamber shielding. ..................................................... 16

Figure 10. Measurement 1 (see Table 1). 100 MHz to 2000 MHz. Full power, 

both bands, no output filter............................................................................... 16

Figure 11. Measurement 1 (see Table 1). 2000 MHz to 6000 MHz. Full power, 

both bands, no output filter............................................................................... 17

Figure 12. Measurement 1 (see Table 1). 825 MHz to 945 MHz. Full power, both 

bands, no output filter. ...................................................................................... 17
vii

Figure 13.Measurement 1 (see Table 1). 1600 MHz to 2000 MHz. Full power, 

both bands, no output filter. Data curves from two different segments of 

the measurement overlap near 1900 MHz. ....................................................... 18

Figure 14. Measurement 2 (see Table 1). 20 MHz to 2000 MHz. Full power, 800 

MHz band jamming only, no output filter. ....................................................... 18

Figure 15. Measurement 2 (see Table 1). 2000 MHz to 6000 MHz. Full power, 

800 MHz band jamming only, no output filter. ................................................ 19

Figure 16. Measurement 2 (see Table 1). 825 MHz to 945 MHz. Full power, 800 

MHz band jamming only, no output filter. ....................................................... 19

Figure 17. Measurement 2 (see Table 1). 1600 MHz to 2000 MHz. Full power, 

800 MHz band jamming only, no output filter. Data curves from two 

different segments of the measurement overlap near 1900 MHz. .................... 20

Figure 18. Measurement 3 (see Table 1). 100 MHz to 2000 MHz. Full power, 

1900 MHz band jamming only, no output filter. .............................................. 20

Figure 19. Measurement 3 (see Table 1). 2000 MHz to 6000 MHz. Full power, 

1900 MHz band jamming only, no output filter. .............................................. 21

Figure 20. Measurement 3 (see Table 1). 825 MHz to 945 MHz. Full power, 1900 

MHz band jamming only, no output filter. ....................................................... 21

Figure 21. Measurement 3 (see Table 1). 1600 MHz to 2000 MHz. Full power, 

1900 MHz band jamming only, no output filter. Data curves from two 

different segments of the measurement overlap near 1900 MHz. .................... 22

Figure 22. Measurement 4 (see Table 1). 100 MHz to 2000 MHz. Low power, 

both bands jammed, no output filter. ................................................................ 22

Figure 23. Measurement 4 (see Table 1). 2000 MHz to 6000 MHz. Low power, 

both bands jammed, no output filter. ................................................................ 23

Figure 24. Measurement 4 (see Table 1). 820-960 MHz. Low power, both bands 

jammed, no output filter. .................................................................................. 23

Figure 25. Measurement 4 (see Table 1). 1600 MHz to 2000 MHz. Low power, 

both bands jammed, no output filter. ................................................................ 24

Figure 26. Measurement 5 (see Table 1). 100 MHz to 2000 MHz. Low power, 

both bands jammed, diplexer used as output filter. .......................................... 24

Figure 27. Measurement 5 (see Table 1). 2000 MHz to 6000 MHz. Low power, 

both bands jammed, diplexer used as output filter. .......................................... 25

Figure 28. Measurement 5 (see Table 1). 820-960 MHz. Low power, both bands 

jammed, diplexer used as output filter. ............................................................ 25

Figure 29. Measurement 5 (see Table 1). 1600 MHz to 2000 MHz. Low power, 

both bands jammed, diplexer used as output filter. .......................................... 26

Figure 30. Measurement 6 (see Table 1). 100 MHz to 2000 MHz. Low power, 

both bands jammed, diplexer, omni antenna. ................................................... 26
viii

Figure 31. Measurement 6 (see Table 1). 2000 MHz to 6000 MHz. Low power, 

both bands jammed, diplexer, omni antenna. The feature between 2600-

2700 MHz was a measurement anomaly of unknown origin. .......................... 27

Figure 32. Measurement 6 (see Table 1). 820-960 MHz. Low power, both bands 

jammed, diplexer, omni antenna. ..................................................................... 27

Figure 33. Measurement 6 (see Table 1). 1600 MHz to 2000 MHz. Low power, 

both bands jammed, diplexer, omni antenna. ................................................... 28

Figure 34. Measurement 7 (see Table 1). 100 MHz to 2000 MHz. Low power, 

both bands jammed, diplexer, 2 MHz chirp. .................................................... 28

Figure 35. Measurement 7 (see Table 1). 2000 MHz to 6000 MHz. Low power, 

both bands jammed, diplexer, 2 MHz chirp. .................................................... 29

Figure 36. Measurement 7 (see Table 1). 820-960 MHz. Low power, both bands 

jammed, diplexer, 2 MHz chirp........................................................................ 29

Figure 37. Measurement 7 (see Table 1). 1600 MHz to 2000 MHz. Low power, 

both bands jammed, diplexer, 2 MHz chirp. .................................................... 30

Figure 38. Measurement 8 (see Table 1). 162-174 MHz, high power, diplexer 

used as filter, hardline connection. ................................................................... 30

Figure 39. Measurement 8 (see Table 1). 406-420 MHz, high power, diplexer 

used as filter, hardline connection. ................................................................... 31

Figure 40. Measurement 8 (see Table 1). 450-460 MHz detail, high power, 

diplexer used as filter, hardline connection. ..................................................... 31

Figure 41. Measurement 8 (see Table 1). 851-869 MHz, high power, diplexer 

used as filter, hardline connection. ................................................................... 32

Figure 42. Measurement 8 (see Table 1). 1710-1755 MHz, high power, diplexer 

used as filter, hardline connection. ................................................................... 32

Figure 43. Measurement 8 (see Table 1). 2110-2155 MHz, high power, diplexer 

used as filter, hardline connection. ................................................................... 33

Figure 44. Measurement 8 (see Table 1). 1171-1181 MHz detail, high power, 

diplexer used as filter, hardline connection. ..................................................... 33

Figure 45. Measurement 8 (see Table 1). 1224-1232 MHz detail, high power, 

diplexer used as filter, hardline connection. ..................................................... 34

Figure 46. Measurement 8 (see Table 1). 1550-1600 MHz detail, high power, 

diplexer used as filter, hardline connection. ..................................................... 34

Figure 47. Measurement 9 (Table 1). 100 MHz to 2000 MHz. Full power, both 

bands, diplexer installed as filter. ..................................................................... 35

Figure 48. Measurement 9 (Table 1). 2000 MHz to 6000 MHz. Full power, both 

bands, diplexer installed as filter. ..................................................................... 35

Figure 49. Measurement 9 (Table 1). 820-960 MHz. Full power, both bands, 

diplexer installed as filter. ................................................................................ 36
ix

Figure 50. Measurement 9 (Table 1). 1600 MHz to 2000 MHz. Full power, both 

bands, diplexer installed as filter. ..................................................................... 36

Figure 51. Measurement 10 (Table 1). 100 MHz to 2000 MHz. Full power, both 

bands, diplexer installed, both antennas used................................................... 37

Figure 52. Measurement 10 (Table 1). 2000 MHz to 6000 MHz. Full power, both 

bands, diplexer installed, both antennas used................................................... 37

Figure 53. Measurement 10 (Table 1). 820-960 MHz. Full power, both bands, 

diplexer installed, both antennas used. ............................................................. 38

Figure 54. Measurement 10 (Table 1). 100 MHz to 2000 MHz. Full power, both 

bands, diplexer installed, both antennas used................................................... 38

Figure 55. Measurement 11 (Table 1). 100 MHz to 2000 MHz. Full power, both 

bands, diplexer installed, 10 dB output attenuation. ........................................ 39

TABLES

Page

Table 1. Jammer Configuration Parameters Used for Emission Measurements. ............... 8
x

ABBREVIATIONS/ACRONYMS

APD amplitude probability distribution

AWS Advanced Wireless Service

CMRS Commercial Mobile Radio Service

CW carrier wave

EMC electromagnetic compatibility

EIRP effective isotropic radiated power 

GPS Global Positioning System 

ITS Institute for Telecommunication Sciences, NTIA, U.S. Department of 

Commerce

LMR land mobile radio 

NIST National Institute of Standards and Technology (of the U.S. Department of 

Commerce)

NTIA National Telecommunications and Information Administration (of the U.S. 

Department of Commerce)

OOB out-of-band spectrum emission, as defined in the NTIA Manual of 

Regulations and Procedures for Federal Radio Frequency Management 

OSM Office of Spectrum Management, NTIA, U.S. Department of Commerce 

PCS Personal Communication Service 

RF radiofrequency 

RMS root mean square (average power detection)

YIG yttrium iron garnet (filter)
xi

EXECUTIVE SUMMARY

This report describes the results of radiated emission measurements on a radio-service 

denial device (called a jammer). The manufacturer temporarily provided the device to the 

National Telecommunications and Information Administration (NTIA) Institute for 

Telecommunication Sciences (ITS) Boulder laboratory for the purpose of such 

measurements. The device is designed to jam communication services in the 869-

894 MHz (cellular) and 1930-1990 MHz (PCS) radio bands. Please note that the device 

does not carry any Federal Communications Commission (FCC) certification and its 

design and parts are idiosyncratic to the manufacturer. 

NTIA performed the measurements mostly via radiated emissions in a National Institute 

of Standards and Technology (NIST) radio-anechoic chamber. NTIA measured the 

device’s emissions in both the frequency and time domains. NTIA performed spectrum 

measurements from 100 MHz to 6 GHz. This allowed the device’s emissions to be 

measured up to the sixth harmonic of its lower-band (cellular band) emissions and up to 

the third harmonic of its upper-band (PCS band) emissions. NTIA also performed 

especially detailed measurements in selected Federal and non-Federal frequency bands. 

The jammer transmitter operates by repetitively frequency-sweeping (called chirping) a 

carrier wave (CW) signal across the bands that are to be jammed. The transmitter 

essentially consists of a parallel pair of power supplies, amplifier controllers, high-power 

amplifiers, and outputs; the construction is parallel for the two jammer bands. 

An external radiofrequency (RF) signal combiner is normally installed at the output so 

that a single RF cable may be used to distribute signals in both bands via a single RF 

cable to the radiating jammer antenna or antennas. The amplifiers are rated at 100 W 

(+20 dBW) of output power in each band. A step attenuator inside the jammer box can 

adjust the output power to as little as about 30 W (+15 dBW) in each of the bands. 

External attenuation may be installed to further reduce the jammer output power. 

The manufacturer provided a standard cellular-PCS diplexer that was used as an RF 

filter; it was not part of the jammer transmitter. Being an external, non-integral 

component, such a filter may or may not be included in the design and final configuration 

of any given jammer installation. Alternatively, a filter with characteristics that are 

different than the diplexer could be used in any given field installation. The exact choice 

of RF filtering could depend on various factors, including the frequency range over which 

the signal might be chirped. If jamming were to be performed across the full width of the 

targeted bands, improved RF output filtering might be needed to reduce the device's outof-band (OOB) emission levels in the adjacent bands. An alternative approach to 

reducing OOB emissions in the adjacent bands would be to reduce the device's in-band 

chirp width while using less-effective RF output filtering. All of these degrees of freedom 

(use of no RF output filter, use of a diplexer as a filter, use of filtering with faster OOB 

roll-off characteristics, and use of either a diplexer or some alternative filtering with a 

reduced in-band chirp width) are technically available options for the device that was 

evaluated in this study. 
xii

The jammer system provides four degrees of freedom to the user: output power, chirping 

range, RF filtering, and transmitter antenna design and spatial configuration. There is no 

standard design or installation configuration. Because these parameters would vary from 

one installation to the next, there is no standard jammer configuration that NTIA can 

measure. Therefore, the approach for the measurements in this report has been to 

demonstrate the ways in which the device’s emissions change in response to its output 

power level (100 W vs. 30 W); chirp range (full-band vs. 2 MHz chirping); RF filter 

installation (diplexer vs. no diplexer); and antenna choice (flat-panel directional antenna 

vs. omnidirectional antenna). NTIA did not consider possible use of special-purpose 

output filtering in these measurements, since such filtering would be one-of-a-kind, to be 

designed and used on an ad hoc basis for any given installation. 

The spectrum measurements achieved a dynamic range of 100 dB. That is, the 

measurement data show characteristics of the jammer’s emissions to 100 dB below the 

jammer’s fundamental-frequency power level. The emission spectrum, relative to the 

power at the fundamental frequencies, does not change when output power is changed, 

because the power is controlled with an attenuator at the output of the high-power 

amplification stage. The choice of transmitter antenna did not affect the spectrum. The 

device’s unwanted emissions are better contained within the cellular and PCS bands 

when the chirp range is limited to a 2 MHz band segment vs. a full band. The diplexer did 

improve the OOB roll-off in the spectrum immediately adjacent to the jammed bands, 

although measurable emissions did occur in those bands even with the diplexer installed. 

Beyond the OOB region of the adjacent bands, and with the exception of one emission 

near 3000 MHz, installation of the diplexer reduced unwanted spectrum emissions to 

levels that were below the 100 dB dynamic range of the measurement system across the 

range of 100 MHz to 6 GHz. 

Technical issues that the measurements in this report could not address include: 

1) Jammer product effectiveness;

2) Jammer OOB and unwanted emission levels for alternative jammer designs and 

modulations; and 

3) The aggregate radiation level from a jammer installation, resulting from 

production of high-power emissions from one or more jammer transmitters, that is 

then split between a set of transmitter antennas, which radiate individually 

reduced power densities.
EMISSION MEASUREMENT RESULTS FOR A CELLULAR AND PCS 

SIGNAL-JAMMING TRANSMITTER

Frank H. Sanders, Robert T. Johnk, Mark A. McFarland, and J. Randall Hoffman1

This report describes emission measurements on a denial-of-service (jammer) 

transmitter operating in the 800 MHz and 1900 MHz cellular and PCS bands. 

The jammer operates at a power level of up to 100 watts in each band, 

repetitively sweeping a carrier-wave signal across the range of frequencies in 

which service is to be denied. Frequency domain emissions were measured 

from 100 MHz to 6 GHz with 100 dB of dynamic range. With the installation 

of a diplexer that is used as an RF filter, some measurable out-of-band (OOB) 

emissions occur in spectrum adjacent to the fundamental-frequency bands. 

Across the rest of the 100 MHz to 6 GHz spectrum range, unwanted emission 

levels are suppressed by 100 dB or more when the diplexer is installed. OOB 

emissions in adjacent bands may be reduced by sweeping across less than the 

full width of the targeted bands, or by installing custom-designed RF output 

filtering.

Key words: cellular communications jamming; denial-of-service jamming; 

emission bandwidth; out-of-band (OOB) emissions; personal communication 

service (PCS) communications jamming; radio jamming; unwanted emissions 

1 INTRODUCTION

For correctional facilities in the United States, parties have proposed to operate radio 

transmitters that produce intentional denial-of-service (jammer) emissions in the base 

station transmitter frequency bands of 869-894 MHz (cellular band) and 1930-1990 MHz 

(PCS band).2 This report describes the results of measurements that the National 

Telecommunications and Information Administration (NTIA) Institute for 

Telecommunication Sciences (ITS) laboratory performed in Boulder on radio spectrum 

emissions produced by one such jammer transmitter. 

1.1 Objective 

The objective of this work has been to perform laboratory measurements to obtain a set 

of peak-detected and root mean square (RMS, or average) emission spectrum data, in the 

form of effective isotropic radiated power (EIRP), of a jammer transmitter that can be 

used to characterize the jammer’s radiated emissions.

 

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

Telecommunications and Information Administration (NTIA), U.S. Department of Commerce, 

Boulder, CO.

2 For brevity, this report refers to the 869-894 MHz and 1930-1990 MHz frequency bands as 

the 800 MHz and 1900 MHz bands, respectively.
2

1.2 Approach 

NTIA performed the measurements inside a National Institute of Standards and 

Technology (NIST) anechoic chamber (Figure 1) at the Department of Commerce facility 

in Boulder. NTIA performed the following tasks: 

1) NTIA initially checked the spectrum and time-domain emissions of the jammer 

transmitter via conducted-line (non-radiated) measurements. This initial check 

allowed measurement personnel to assess the design of the jammer, the degrees of 

freedom available for adjustments of operational parameters, and the best set of 

measurement parameters and techniques to use for assessment of its emissions as 

a function of variations in its operational parameters. 

2) NTIA collected emission spectrum and time-domain data, via radiated emissions, 

in the anechoic chamber between 100 MHz and 6 GHz. This frequency range 

included the transmitter’s emissions through the third harmonics of the two 

jammer bands.

3) NTIA analyzed measurement data, which are provided in this report. These data 

show the detail of the spectral and time domain characteristics of the jammer 

emissions. These data may be used to perform future electromagnetic 

compatibility (EMC) analyses3

 of the potential impacts, if any, on other spectrum 

users.

Figure 1. A jammer transmitter antenna and two measurement antennas inside the NIST 

anechoic chamber in Boulder, CO. 

 

3 EMC analyses may be performed separately from the work described in this document.
3

2 MEASUREMENT SETUP

NTIA configured the measurement hardware as shown in the block-diagram schematic of 

Figure 2. The jammer transmitter antenna was attached to a non-conductive mount within 

the anechoic chamber. Two calibrated, broadband antennas (a 0.1-2 GHz discone and a 2-

6 GHz horn) were placed on non-conductive tripods three meters from the jammer 

antenna. Each antenna was connected to the measurement system via radio frequency 

(RF) cabling passing through a bulkhead in the chamber wall. 

The measurement system consisted of a pair of RF front-ends (0.1-2 GHz and 2-6 GHz) 

connected to a spectrum analyzer. Each RF front-end contained the following elements: a 

step attenuator (0-50 dB for the low-frequency front-end; 0-70 dB for the high-frequency 

front-end); tunable bandpass preselection using yttrium-iron-garnet (YIG) filter 

technology for automatic tracking of the spectrum analyzer frequency; and low-noise 

preamplification [1]. Computer software controlled the RF front-ends and the spectrum 

analyzer, and recorded the measurement data. At some frequencies, NTIA used 

supplemental fixed-tuned bandpass filters to augment the power-rejection characteristics 

of the YIG filter and thus ensure that no mixing products or harmonic products were 

generated within the RF front ends. 

NTIA used a high-speed oscilloscope to obtain additional data on the swept-frequency 

(chirped) behavior of the jammer. Those data were taken during the initial conducted-line 

measurements.

Figure 2. Block diagram schematic of the jammer transmitter measurement system.
4

3 MEASUREMENT SYSTEM CALIBRATION, TECHNIQUES AND 

BANDWIDTH

Measurement system calibrations were performed with a noise diode and a standard Yfactor method [2]. Measurement system antenna gain factors were taken from custom 

calibrations performed at an earlier date on an antenna range.

The measurement technique used for all spectrum measurements consisted of a 

computer-controlled, stepped-frequency approach [1]. Using this approach, the tuned 

frequencies of the measurement system are not swept, but rather are stepped in discretely 

spaced increments. The increment, or step, size is the same as the IF (or resolution) 

bandwidth of the measurement system (effectively the measurement bandwidth). The 

advantage of the stepped-frequency approach is that the dynamic range of the 

measurement is extended by discretely adjusting attenuation at the RF front-end on a 

frequency-by-frequency basis as the measurement progresses. More attenuation is used at 

the fundamental frequency of the transmitter, and less attenuation, ranging eventually to 

zero, is used at other frequencies. This measurement approach also allows the timedomain characteristics of the measured signal to be observed and collected on a 

frequency-by-frequency basis.

For the jammer measurements, the standard stepped-frequency measurement routine was 

augmented by the collection of 100,000 time-domain samples at each frequency. From 

these the amplitude-probability distribution (APD) of the signal was obtained at each 

measured frequency [3]. This data set, which shows the time statistics of the signal at 

each measured frequency, allowed for the maximum (peak-detected), mean (root-mean 

square, or RMS), median, and minimum signal levels to be displayed as separate data 

traces across the entire spectrum.

Because the stepped-APD measurement technique is much slower than the steppedfrequency technique (which only collects the peak-detected data trace), not all spectrum 

measurements were performed with the stepped-APD technique. Instead, the entire 

emission spectrum was initially measured across 0.1-6 GHz with the stepped-APD 

technique, so that the offsets in amplitude between the peak, mean, median, and 

minimum data traces could be assessed for every measured feature in the spectrum. Using 

the observed offsets between these data traces as an anchor, the subsequent spectrum 

measurements were performed with the peak-detector only, since the relative levels of the 

mean, median, and minimum curves to the peak-detected curve were known from the 

APD measurements.

The four types of spectrum data that were acquired (peak-detected; mean; median; and 

minimum) are briefly described as follows. Peak data show the highest power level that 

the transmitter produces in the measurement bandwidth during the sampling interval at 

each measured frequency. Mean data show the average power level for each measured 

frequency; median data show the power level that is exceeded half of the time; and 

minimum data show the lowest power levels recorded by the measurement system in any 

given time interval.
5

All four data types were recorded for the jammer transmitter signals at the beginning of 

the measurements. The resulting data curves show the offsets, at each measured 

frequency in the spectrum, between the peak, mean, median, and minimum power levels. 

However, these four statistical data sets are time-consuming to acquire; there was not 

enough time to acquire all four data curves for every spectrum measurement that needed 

to be performed. Therefore, subsequent measurements were mostly performed using peak 

detection only. The offsets between peak values and the other statistics having already 

been established by the initial data, the mean, median, and minimum levels of the jammer 

emissions may be inferred from the peak data for all data sets in this report.

The measurement bandwidth was tailored to achieve optimal signal-to-noise ratio in the 

measurement results.4

 

4 For the FM-CW modulation of the jamming signal, the optimum measurement bandwidth, Bmeas, is Bmeas = 

(Bc/τ)

1/2, where Bc = the FM (chirp) bandwidth, and τ = the time interval required to sweep across Bc [1].

 For this jammer, the combination of its chirp bandwidth and its 

chirp rate gave an optimum measurement bandwidth of 2 MHz. This was also the stepsize increment for the spectrum measurements.
6

4 DESCRIPTION OF THE JAMMER

The jammer unit NTIA used for these measurements was constructed for this purpose. 

Please note that the device that was provided to NTIA did not carry any FCC 

identification or certification. It is not known to what extent this device may or may not 

resemble or not resemble any other models or types of radio-jamming devices or systems.

The jammer design provides four degrees of freedom in its operational parameters: 

transmitter output power; antenna configuration; modulation frequency-sweeping range; 

and RF output filtering. The jammer design and construction do not constrain either the 

installer or the user to any fixed, standard configuration for these parameters. Because 

every installation could use a unique combination of these parameters, there is no 

standard jammer configuration that can be tested or measured. For this study, the degrees 

of freedom for these parameters were controlled as follows. 

4.1 Power Output 

The jammer included a programmable option for output power levels between 100 W 

(+20 dBW) to 30 W (+15 dBW). The power was controlled by adjusting the value of an 

attenuator that was installed at the output of the high-power amplifiers inside the jammer 

unit, and that was controlled via a hardware cable connection to an external laptop 

computer. 

4.2 Antennas 

Two external dual-band antennas were provided, one being a directional flat-panel unit 

and the other being an omnidirectional, dual-band unit. The directional gain of the flatpanel unit is estimated to have been approximately 6 dBi; a measurement of its pattern 

was beyond the scope of this effort. The omni-antenna gain is estimated to have been 

approximately 2 dBi. 

4.3 Frequency-Sweeping, or Chirp Range 

The frequency-sweeping range for each band could be programmed to be as narrow as 

2 MHz to as much as the full width of the cellular and PCS bands. Intermediate amounts 

of frequency sweeping could be used, but for this study only the full-band and 2 MHz 

sweeping options were used during the measurements. In the 2 MHz mode, the signal 

was chirped across the central portion of each band. The chirp frequency range may be 

controlled independently in the two bands. The chirp rate (averaging approximately 5 

MHz of frequency change per microsecond) stays roughly constant as chirp range is 

adjusted. 

4.4 RF Output Filtering

The jammer unit itself contained no RF output filter. Rather, the manufacturer provided a 

standard cellular-PCS band diplexer to be used as a filter. This diplexer was not integral 
7

to the jammer; instead, it was connected manually to the output of the jammer 

transmitter. Because of this, it is not known to what extent such filtering would or would 

not be provided for any given jammer installation. Alternative technical options would 

be: use no filter; use an alternative filter with faster OOB roll-off characteristics; or, in 

concert with a reduced operational in-band chirp width, either use no filter, use a 

diplexer, or use an alternative filter. During the measurements, the jammer spectra were 

assessed both with and without the diplexer at the output. 

4.5 Ancillary Equipment 

In addition to the equipment discussed above, it is NTIA's understanding that this type of 

jammer would normally be used with a combination of RF combiners, splitters, cables, 

and sometimes external attenuation to adjust the radiation power levels of individual 

radiating elements throughout a jamming zone. Typical installations could involve the 

installation of many antennas, and sometimes so-called lossy (radiating) cables, along 

with the required ancillary RF hardware for combining and splitting the jammer signals 

between cables and antennas.

Within a facility, it is possible to distribute the jammer amplifiers’ total power spatially 

across an array of antennas (or, in some cases, lossy cables) in order to better-control and 

provide lower power-density around individual antennas than could be produced if a 

single antenna were used to radiate a high-power signal. Although such antenna arrays 

were not studied during these measurements, the effect on spectrum emission levels of 

using two antennas (the omni antenna and flat-panel antenna that were supplied with the 

jammer) simultaneously, rather than individually, was explored and measured. 
8

5 COMBINATIONS OF JAMMER PARAMETERS USED FOR EMISSION 

MEASUREMENTS

Because there is no standard jammer configuration, the measurement parameters needed 

to span a range of likely selections for output power levels, antennas, frequency sweeping 

ranges, and RF output filters. Table 1 lists the measurements that were performed to 

assess the extent of the effects each parameter caused on the jammer’s emission 

spectrum.

Table 1. Jammer Configuration Parameters Used for Emission Measurements.

Meas. 

Name

Figure 

Numbers

Transmit 

Bands

Chirp 

Range

Output 

Power

Transmit

Antenna 

Diplex 

Output 

Filter

Measurement 

Data Type

Baseline 8-9 None n/a 0 None None Stepped APD

Meas 1 10-13 Both Full Full

(100 W)

Flat

Panel No Stepped APD

Meas 2 14-17 800 only Full Full

(100 W)

Flat

Panel No

Stepped APD 

below 2 GHz; 

stepped +peak 

above 2 GHz

Meas 3 18-21 1900 only Full Full

(100 W)

Flat

Panel No

Stepped APD 

below 2 GHz; 

stepped +peak 

above 2 GHz

Meas 4 22-25 Both Full Min.

(30 W)

Flat

Panel No Stepped +peak

Meas 5 26-29 Both Full Min.

(30 W) Flat Panel Yes Stepped +peak

Meas 6 30-33 Both Full Min.

(30 W) Omni Yes Stepped +peak

Meas 7 34-37 Both 2 MHz Min.

(30 W) Flat Panel Yes Stepped +peak

Meas 8

(LMR, 

CMRS, 

AWS, 

GPS)

38-46 Both 2 MHz Min

(30 W)

Flat Panel Yes

Stepped +peak 

Conducted-line 

measurement

Meas 9 47-50 Both Full Full

(100 W)

Flat Panel Yes Stepped +peak

Meas 10 51-54 Both Full Full

(100 W) Both Yes Stepped +peak

Meas 11 55 Both Full

100 W w. 

10 dB 

external 

atten.

Both Yes

Stepped +peak 

100-2000 MHz 

only
9

The methodology underlying the measurement matrix is as follows: 

Baseline: This measurement was performed across 0.1-6 GHz inside the anechoic 

chamber with the jammer turned off. If any background signals had been observed, they 

would have been subtracted from subsequent jammer emission spectra. Except for 

weakly received energy from microwave ovens near 2450 MHz, no background signals 

were observed with the jammer turned off. See Figures 8-9. 

Measurement 1: This measurement was performed with full jammer power, full-band 

chirping, and no external diplexer. The purpose was to observe the worst-case emission 

spectrum that could occur. This measurement was performed with the stepped-APD 

routine, so that the relative levels of the peak, mean, median, and minimum power levels 

generated by the jammer inside every observed spectral feature could be observed. This 

measurement served as an anchor for later measurements that used peak detection only. 

See Figures 10-13. 

Measurement 2: This measurement was performed with the 800 MHz jammer amplifier 

running and the 1900 MHz amplifier output terminated. This allowed the spectrum 

features produced by the 800 MHz amplifier to be isolated. See Figures 14-17. 

Measurement 3: This measurement was performed with the 1900 MHz jammer 

amplifier running and the 800 MHz amplifier output terminated. This allowed the 

spectrum features produced by the 1900 MHz amplifier to be isolated. See Figures 18-21. 

Measurement 4: This measurement was performed to demonstrate the effect of running 

the jammer transmitter at its minimum programmable power output level of 30 W (as 

compared to the full power level of 100 W). Jammer power was about +15 dBW in each 

band, as compared to the full power level of +20 dBW in each band. See Figures 22-25. 

Measurement 5: This was the first measurement in which the external diplexer, used as 

an RF output filter, was installed, thus demonstrating its effect on out-of-band (OOB) and 

unwanted jammer emissions. See Figures 26-29. 

Measurement 6: This measurement was performed with the omni transmitter antenna 

used in place of the flat-panel antenna, to show what effect (if any) the omni antenna had 

on the spectrum relative to the flat-panel antenna. See Figures 30-33. 

Measurement 7: This measurement was performed with the chirp range of the jammer 

adjusted to 2 MHz, to show the effect of a narrow frequency sweep compared to fullband frequency sweeping. See Figures 34-37. 

Measurement 8: This was a set of conducted-line, rather than radiated, measurements of 

two key Federal land mobile radio (LMR) bands (162-174 MHz and 406-420 MHz), two 

non-Federal Commercial Mobile Radio Service (CMRS) bands (450-460 MHz and 851-

869 MHz), Advanced Wireless Service (AWS) bands (1710-1755 MHz and 2110-

2155 MHz), and three of the Global Positioning System (GPS) bands (near 1176 MHz, 
10

1227 MHz, and 1575 MHz). The LMR, CMRS, and AWS bands were measured using 

10 kHz and 1 MHz measurement bandwidths, while the GPS bands were measured in 

1 MHz only. The jammer was operated with the diplexer installed as a filter. See Figures 

38-46. 

Measurement 9. This measurement was performed with the jammer at high power and 

the flat-panel, to establish the measurement system was still performing nominally. See 

Figures 47-50. 

Measurement 10: This measurement was performed with both the flat-panel antenna and 

the omni antenna radiating simultaneously via a two-way splitter supplied with the 

jammer. See Figures 51-54. 

Measurement 11: This measurement was performed with 10 dB of external attenuation 

to demonstrate that such attenuation reduces the amplitude of every feature in the 

emission spectrum by a uniform amount equal to the attenuation parameter. See 

Figure 55.
11

6 MEASUREMENT DATA

6.1 Time Domain Behavior 

Figure 3 shows the jammer frequency as a function of time (the modulation domain) in 

each of the service bands. The time-domain behavior of the jammer is shown in Figures 4 

and 5. These figures show that the jammer signal looks like a pulsed transmitter, when 

observed on a single frequency in each of the service bands (cellular and PCS), as it 

sweeps the carrier through each band. For the measurements in Figures 3-5, the widest 

available bandwidth was used to achieve the highest possible resolution in the time 

domain. The bandwidth of the measurement in Figure 3 (conducted-line) was 2 GHz; the 

bandwidth of the measurements in Figures 4 and 5 (radiated) was 8 MHz. The data in 

Figures 4 and 5 were taken with a spectrum analyzer in a 0-Hz span mode with positivepeak detection. 

Figure 3. A measurement of the jammer’s tuned frequency vs. time in the targeted 869-

894 MHz and 1930-1990 MHz bands. The transmitter repetitively sweeps a carrier wave 

frequency (called FM or chirp modulation) across the frequency ranges that are jammed.
12

Figure 4. Time-domain behavior of the jammer signal inside a targeted band at 880 MHz, 

chirping across 861-894 MHz. The jammer signal tunes through the measurement 

frequency every 5.1 microsecond (μs), for a chirp rate of 4.9 MHz/μs. The short spikes 

are a frequency fly-back behavior of the transmitter between each chirp cycle.

Figure 5. Time domain behavior of the jammer signal inside a targeted band at 

1962 MHz, chirping across 1930-1990 MHz. The jammer signal tunes through 60 MHz 

every 20.4 μs in this band, for a chirp rate of 2.9 MHz/μs. The short spikes are a 

frequency fly-back behavior of the transmitter between each chirp cycle.
13

6.2 Effect of Measurement Bandwidth on Measured Emission Spectra

Figure 6 shows the effect of measurement bandwidth on the peak-detected spectrum. 

Specifically, this figure demonstrates that the full power of the transmitter is measured in 

a bandwidth of / Bc τ (which for this system is 2 MHz), in accordance with 

measurement theory, by comparing the measured power in 2 MHz to the same power 

level that is measured in 8 MHz. This figure also demonstrates how the same shape of the 

emission is preserved for bandwidths less than / Bc τ , such as, in this case, 300 kHz. 

This figure further demonstrates that the preferred bandwidth for the measurement is 2 

MHz, because that choice provides maximum frequency-step increment size and thus 

yields the minimum required amount of total measurement time.

Figure 6. Example in-band emission spectra of the jammer in measurement bandwidths 

of 8 MHz, 2 MHz, and 300 kHz. 

The 2 MHz bandwidth curve of Figure 6 is thus demonstrated both theoretically (via the 

expression for optimum measurement bandwidth, Bmeas = / Bc τ ) and empirically (this 

figure) to be the optimum bandwidth for spectrum measurements because it maximizes 

measured power, maximizes dynamic range, and yields the fastest possible measurement 

speed due to a maximal step size between spectrum data points. The offsets between the 

curves in Figure 6 demonstrate that, for receivers with bandwidths, Brx, that are narrower 
14

than 2 MHz, the peak measured EIRP data (Pmeas, decibels) presented in this report need 

to be scaled as follows:

Pcoupled = Pmeas + 20 log10

Brx

2MHz





 



 , 

where Pcoupled is the decibel power coupled into the receiver’s bandwidth. For example, a 

receiver with a 10 kHz bandwidth will couple 20log10((0.01)/2) = -46 dB (that is, 46 dB 

less) peak power than the levels shown in this report in a measurement bandwidth of 

2 MHz.

6.3 Diplexer Frequency Response Measurement Result

The frequency response of the diplexer was measured with a vector network analyzer. 

The result is shown in Figure 7. 

Figure 7. Power-rejection (filtering) characteristic of the diplexer as a function of 

frequency up to 6000 MHz. 

6.4 Emission Spectrum Measurement Results

The results of the measurements that are outlined in Table 1 are shown in Figures 8-55. 

EIRP power levels were computed using a free-space relationship between the transmitter 

antennas and the measurement antennas [4]. The EIRP calculation took into account the 
15

measurement antenna gain, the free-space loss between the transmitter antenna and the 

measurement antenna, and the internal gains and losses in the measurement system, as 

established initially with a noise diode calibration.

After Figure 21, with a few exceptions (and unless otherwise noted), only peak data were 

measured. The relative levels of mean, median, and minimum power are related to the 

peak for all measurements in this report, however, by the offset amounts that are 

established in Figures 8-21. Mostly peak data were acquired after Figure 21 due to 

scheduling and time constraints on the completion of these measurements. 

Between 100-2000 MHz the measurement system noise figure ranged between 11 dB to 

16 dB. Between 2000-6000 MHz the measurement system noise figure ranged between 

8 dB to 18 dB. Although all of the spectrum graphs show EIRP as a function of 

frequency, it is important to understand that, strictly speaking, the EIRP label applies only

to frequencies where jammer power is observed. Thus, in graphs that show only 

measurement system noise (such as, for example Figure 46 for the 1575 MHz GPS band), 

and where no jammer emissions are observed, the measurement system’s noise-power 

levels that are shown are effectively the upper possible limits on the jammer’s unwanted 

EIRP levels across these frequency ranges.

Figure 8. Baseline (jammer turned off) environmental measurement in the anechoic 

chamber, 100 MHz-2000 MHz. Only measurement system internal noise is seen. The 

gradual change in the baseline power is due to change in the measurement system noise 

figure.
16

Figure 9. Baseline (jammer turned off) environmental measurement in the anechoic 

chamber, 2000 MHz-6000 MHz. The gradual change in the baseline power is due to 

change in the measurement system’s noise figure. The spikes at 2450-2500 MHz are 

emissions from microwave ovens, and the spike at 5800 MHz is a cordless phone 

emission that penetrated the anechoic chamber shielding. 

Figure 10. Measurement 1 (see Table 1). 100 MHz to 2000 MHz. Full power, both bands, 

no output filter.
17

Figure 11. Measurement 1 (see Table 1). 2000 MHz to 6000 MHz. Full power, both 

bands, no output filter. 

Figure 12. Measurement 1 (see Table 1). 825 MHz to 945 MHz. Full power, both bands, 

no output filter. 
18

Figure 13.Measurement 1 (see Table 1). 1600 MHz to 2000 MHz. Full power, both 

bands, no output filter. Data curves from two different segments of the measurement 

overlap near 1900 MHz.

Figure 14. Measurement 2 (see Table 1). 20 MHz to 2000 MHz. Full power, 800 MHz 

band jamming only, no output filter. 
19

Figure 15. Measurement 2 (see Table 1). 2000 MHz to 6000 MHz. Full power, 800 MHz 

band jamming only, no output filter. 

Figure 16. Measurement 2 (see Table 1). 825 MHz to 945 MHz. Full power, 800 MHz 

band jamming only, no output filter. 
20

Figure 17. Measurement 2 (see Table 1). 1600 MHz to 2000 MHz. Full power, 800 MHz 

band jamming only, no output filter. Data curves from two different segments of the 

measurement overlap near 1900 MHz. 

Figure 18. Measurement 3 (see Table 1). 100 MHz to 2000 MHz. Full power, 1900 MHz 

band jamming only, no output filter. 
21

Figure 19. Measurement 3 (see Table 1). 2000 MHz to 6000 MHz. Full power, 1900 

MHz band jamming only, no output filter. 

Figure 20. Measurement 3 (see Table 1). 825 MHz to 945 MHz. Full power, 1900 MHz 

band jamming only, no output filter. 
22

Figure 21. Measurement 3 (see Table 1). 1600 MHz to 2000 MHz. Full power, 1900 

MHz band jamming only, no output filter. Data curves from two different segments of the 

measurement overlap near 1900 MHz. 

Figure 22. Measurement 4 (see Table 1). 100 MHz to 2000 MHz. Low power, both bands 

jammed, no output filter. 
23

Figure 23. Measurement 4 (see Table 1). 2000 MHz to 6000 MHz. Low power, both 

bands jammed, no output filter. 

Figure 24. Measurement 4 (see Table 1). 820-960 MHz. Low power, both bands jammed, 

no output filter. 
24

Figure 25. Measurement 4 (see Table 1). 1600 MHz to 2000 MHz. Low power, both 

bands jammed, no output filter. 

Figure 26. Measurement 5 (see Table 1). 100 MHz to 2000 MHz. Low power, both bands 

jammed, diplexer used as output filter. 
25

Figure 27. Measurement 5 (see Table 1). 2000 MHz to 6000 MHz. Low power, both 

bands jammed, diplexer used as output filter. 

Figure 28. Measurement 5 (see Table 1). 820-960 MHz. Low power, both bands jammed, 

diplexer used as output filter. 
26

Figure 29. Measurement 5 (see Table 1). 1600 MHz to 2000 MHz. Low power, both 

bands jammed, diplexer used as output filter. 

Figure 30. Measurement 6 (see Table 1). 100 MHz to 2000 MHz. Low power, both bands 

jammed, diplexer, omni antenna. 
27

Figure 31. Measurement 6 (see Table 1). 2000 MHz to 6000 MHz. Low power, both 

bands jammed, diplexer, omni antenna. The feature between 2600-2700 MHz was a 

measurement anomaly of unknown origin. 

Figure 32. Measurement 6 (see Table 1). 820-960 MHz. Low power, both bands jammed, 

diplexer, omni antenna. 
28

Figure 33. Measurement 6 (see Table 1). 1600 MHz to 2000 MHz. Low power, both 

bands jammed, diplexer, omni antenna. 

Figure 34. Measurement 7 (see Table 1). 100 MHz to 2000 MHz. Low power, both bands 

jammed, diplexer, 2 MHz chirp. 
29

Figure 35. Measurement 7 (see Table 1). 2000 MHz to 6000 MHz. Low power, both 

bands jammed, diplexer, 2 MHz chirp. 

Figure 36. Measurement 7 (see Table 1). 820-960 MHz. Low power, both bands jammed, 

diplexer, 2 MHz chirp. 
30

Figure 37. Measurement 7 (see Table 1). 1600 MHz to 2000 MHz. Low power, both 

bands jammed, diplexer, 2 MHz chirp. 

Figure 38. Measurement 8 (see Table 1). 162-174 MHz, high power, diplexer used as 

filter, hardline connection. 
31

Figure 39. Measurement 8 (see Table 1). 406-420 MHz, high power, diplexer used as 

filter, hardline connection. 

Figure 40. Measurement 8 (see Table 1). 450-460 MHz detail, high power, diplexer used 

as filter, hardline connection. 
32

Figure 41. Measurement 8 (see Table 1). 851-869 MHz, high power, diplexer used as 

filter, hardline connection. 

Figure 42. Measurement 8 (see Table 1). 1710-1755 MHz, high power, diplexer used as 

filter, hardline connection. 
33

Figure 43. Measurement 8 (see Table 1). 2110-2155 MHz, high power, diplexer used as 

filter, hardline connection. 

Figure 44. Measurement 8 (see Table 1). 1171-1181 MHz detail, high power, diplexer 

used as filter, hardline connection. 
34

Figure 45. Measurement 8 (see Table 1). 1224-1232 MHz detail, high power, diplexer 

used as filter, hardline connection. 

Figure 46. Measurement 8 (see Table 1). 1550-1600 MHz detail, high power, diplexer 

used as filter, hardline connection. 
35

Figure 47. Measurement 9 (Table 1). 100 MHz to 2000 MHz. Full power, both bands, 

diplexer installed as filter.

Figure 48. Measurement 9 (Table 1). 2000 MHz to 6000 MHz. Full power, both bands, 

diplexer installed as filter.
36

Figure 49. Measurement 9 (Table 1). 820-960 MHz. Full power, both bands, diplexer 

installed as filter.

Figure 50. Measurement 9 (Table 1). 1600 MHz to 2000 MHz. Full power, both bands, 

diplexer installed as filter.
37

Figure 51. Measurement 10 (Table 1). 100 MHz to 2000 MHz. Full power, both bands, 

diplexer installed, both antennas used. 

Figure 52. Measurement 10 (Table 1). 2000 MHz to 6000 MHz. Full power, both bands, 

diplexer installed, both antennas used. 
38

Figure 53. Measurement 10 (Table 1). 820-960 MHz. Full power, both bands, diplexer 

installed, both antennas used. 

Figure 54. Measurement 10 (Table 1). 100 MHz to 2000 MHz. Full power, both bands, 

diplexer installed, both antennas used.
39

Figure 55. Measurement 11 (Table 1). 100 MHz to 2000 MHz. Full power, both bands, 

diplexer installed, 10 dB output attenuation. 
40

7 ANALYSIS

The jammer performs frequency-sweeping (chirping) across the bands in which service is 

to be denied. The chirp rate is approximately 4.9MHz/μs and 2.9 MHz/μs, for 25 MHz 

and 60 MHz chirping across the cellular and PCS bands, respectively. The jammer’s 

chirped-frequency behavior makes its emissions look like a series of pulses to receivers 

in its jamming bands. Its effective emission bandwidth of / Bc τ is approximately 

2 MHz, where Bc is the chirp range and τ is the time to chirp across Bc. 

When a diplexer is installed as an output filter, and when the transmitter chirps across the 

full widths of both targeted bands (800 MHz cellular and 1900 MHz PCS), some OOB 

emissions are observed in the adjacent bands, rolling off from the fundamental-frequency 

emissions in the targeted bands. These OOB emissions are reduced but not necessarily 

eliminated in the adjacent bands when the jammer only chirps across 2 MHz in the 

centers of the targeted bands. Another technical option to reduce OOB emissions would 

be to use specialized RF output filtering. 

Beyond the OOB region of the adjacent bands, unwanted emissions between 100 MHz to 

6 GHz with the diplexer installed were below the measurement system’s noise-sensitivity 

limit at all frequencies.5,6 These levels were typically 100 dB lower than the 

fundamental-frequency power in the targeted bands.7 That is, the jammer’s unwanted 

emissions were typically suppressed by 100 dB or more, relative to its fundamental--

frequency power across the 100 MHz to 6 GHz frequency range. This suppression level 

corresponded to an upper limit of -65 to -90 dBW (peak-detected) and -75 to -100 dBW 

(RMS average) for the EIRP emission level of the jammer transmitter when it was 

operated at its maximum transmission EIRP level of +20 dBW.

The jammer emission spectrum does not change, relative to the power at its fundamental 

frequencies, when its output power is varied. This is because the transmitter power is 

varied by adjusting RF attenuation levels at the output of the high-power transmitter 

amplifiers, rather than by adjusting the input power to its high-power amplifiers.

Using two transmitter antennas instead of a single transmitter antenna did not change the 

EIRP level measured from the transmitter. This observation supports the concept that 

 

5 Variations that occur in the measurement system’s noise level in Figures 8-55 are due to 

variations in the measurement system’s noise figure between 100 MHz to 6 GHz, and are not due 

to any unwanted jammer emissions in that frequency range.

6 During Measurement 6, an anomaly occurred in one scan between 2500-2600 MHz. The 

anomaly consisted of a recording of energy at about -61 dBW EIRP across that range. The feature 

was not observed in any other jammer emission data, and is not believed to have been an 

emission from the jammer. The cause of the anomaly is unknown.

7 A very low-amplitude emission was observed at 3 GHz, 95 dB below the fundamentalfrequency power level.
41

total radiated transmitter power will be conserved, regardless of whether the power is 

radiated from a single antenna versus being divided between multiple antennas.8

The power that the jammer emissions can couple into a receiver, Pcoupled (decibel units) 

varies as a function of the receiver bandwidth, Brx. If a receiver has a bandwidth of 

2 MHz or wider, then the data that are presented in the graphs in this report (all taken in 

2 MHz bandwidth unless otherwise noted) may be used directly to indicate the peak EIRP 

levels that may be coupled into a victim receiver. However, for receivers with 

bandwidths that are narrower than 2 MHz, the measured peak EIRP data (Pmeas) presented 

in this report need to be scaled as follows:

Pcoupled = Pmeas + 20 log10

Brx

2MHz





 



 , 

under the condition that Brx is less than 2 MHz. For example, a receiver with a 10 kHz 

bandwidth will couple 20log10((0.01)/2) = -46 dB (that is, 46 dB less) power relative to 

the levels shown in this report in a measurement bandwidth of 2 MHz. 

 

8 This allows for inevitable splitter and combiner losses that would occur concomitantly with an 

array of multiple transmission antennas.
42

8 SUMMARY

1) The system in this report carried no FCC identification or certification and was 

supplied specially to NTIA by the manufacturer for the purpose of performing 

measurements of its emissions.

2) The jammer that has been measured for its emission characteristics in this study has 

no standard operational configuration. Its emission characteristics are adjustable for 

the following parameters: power output level, swept-frequency (FM or chirp) range, 

radiating antenna designs and configurations, and RF output filtering. The jammer's 

design allows these parameters to be varied from one installation to the next. 

3) The jammer works by repetitively sweeping a carrier wave across the bands in which 

communication services are to be denied. The chirp rate was 4.9 MHz/μs and 

2.9 MHz/μs, respectively, for 25-MHz chirping in the cellular band and 60-MHz 

chirping in the PCS band. The jammer’s effective emission bandwidth of / Bc τ is 

approximately 2 MHz. The jammer’s swept-frequency emissions effectively look 

pulsed on individual frequencies within the bands that are jammed. 

4) The maximum EIRP of the jammer is approximately +22 dBW in the 800 MHz 

cellular band and +24 dBW in the 1900 MHz PCS band when low-gain transmitting 

antennas are used. The EIRP will vary, of course, depending upon the choice of 

transmitter antenna.9

5) The emission power level is controlled by using variable RF attenuators at the output 

of the power amplifiers, inside the jammer unit. Additional attenuation may be added 

externally to further reduce the jammer’s EIRP level. This method of controlling the 

transmitter output power causes the unwanted emission-spectrum levels relative to 

the power at the jammer fundamental frequencies not to be affected by the jammer’s 

transmitter output power level.

6) The choice of radiating antenna (omni versus low-gain, flat-panel antenna) made no 

measurable difference in the relative levels of OOB and unwanted emissions to 

fundamental-frequency emissions. 

7) While the use of multiple antennas reduces the power radiated per antenna, the total

power radiated from a combination of multiple antennas remains equal to the power 

output of the jammer transmitter, less unavoidable dissipative losses in ancillary 

equipment such as RF combiners, splitters, and cables. 

8) When a diplexer is installed as an output filter, and when the transmitter chirps across 

the full widths of both targeted bands (800 MHz cellular and 1900 MHz PCS), some 

 

9 As antenna directionality (gain) increases, higher EIRP levels will occur in the main beams but 

concomitantly lower EIRP levels will occur in the sidelobes and backlobes; total transmitter 

power through 4π steradians of an antenna’s radiation pattern will always be conserved.
43

OOB emissions are observed in the adjacent bands, rolling off from the fundamentalfrequency emissions. These OOB emissions are reduced but not necessarily 

eliminated in the adjacent bands when the jammer only chirps across 2 MHz in the 

centers of the targeted bands. Specialized filtering could further reduce OOB 

emissions in spectrum adjacent to the targeted bands. 

9) Outside the OOB region of the adjacent bands, unwanted emissions between 

100 MHz to 6 GHz with the diplexer installed were below the measurement system’s 

noise-sensitivity limit at all frequencies.10, 11, 12 The jammer’s unwanted emissions 

were typically suppressed by 100 dB or more relative to its fundamental-frequency 

power across the 100 MHz to 6 GHz frequency range. This suppression level 

corresponded to an upper limit of -65 to -90 dBW (peak-detected) and -75 to -100 

dBW (RMS average) for the EIRP emission level of the jammer transmitter when it 

was operated at its maximum transmission level of +20 dBW.

10) With the diplexer installed, no measurable emissions were observed at levels on the 

order of 100 dB below the fundamental frequencies when especially detailed 

measurements were performed in the following bands: 162-174 MHz; 405-420 MHz; 

1176 MHz; 1227 MHz; 1575 MHz; 1710-1755 MHz; and 2110-2155 MHz. Some 

adjacent-band OOB emissions were observed in the 851-869 MHz band when the 

jammer was chirped across the full width of the 800 MHz cellular band. This may be 

mitigated by either chirping across a narrower frequency range or by installing 

specially designed RF output filtering.

11) The power that the jammer emissions can couple into a receiver, Pcoupled (decibel 

units) varies as a function of the receiver bandwidth, Brx. If a receiver has a 

bandwidth of 2 MHz or wider, then the data that are presented in the graphs in this 

report (all taken in 2 MHz bandwidth unless otherwise noted) may be used directly to 

indicate the EIRP levels that may be coupled into victim receivers. For receivers with 

bandwidths that are narrower than 2 MHz, the measured EIRP data (Pmeas) presented 

in this report need to be scaled as follows:

Pcoupled = Pmeas + 20⋅log10(Brx/2 MHz),

under the condition that Brx is less than 2 MHz. For example, a receiver with a 10 kHz 

bandwidth will couple 20log10((0.01)/2) = -46 dB (that is, 46 dB less) peak power 

relative to the levels shown in this report in a measurement bandwidth of 2 MHz.

 

10 Variations that occur in the measurement system’s noise level in Figures 8-55 are due to 

variations in the measurement system’s noise figure between 100 MHz to 6 GHz, and are not due 

to any unwanted jammer emissions in that frequency range.

11 A very low-amplitude emission was observed at 3 GHz, 95 dB below the fundamentalfrequency power level.

12 In one data scan, some power was measured about 80 dB below the fundamental, at -61 dBW 

peak EIRP, between 2500-2600 MHz. The feature was never observed in any other data, and is 

believed to have been a measurement anomaly. The cause of the anomaly is unknown.
44

9 ISSUES NOT ADDRESSED BY THIS STUDY

The following issues, questions, and areas for possible further study were not addressed 

as part of this study: 

1) Jammer product effectiveness;

2) Jammer OOB and unwanted emission levels for alternative jammer designs and 

modulations; and

3) The aggregate radiation level from a jammer installation, resulting from 

production of high-power emissions from one or more jammer transmitters, that is 

split between a set of transmitter antennas which radiate at individually reduced 

power densities. 
45

10 REFERENCES

[1] F. H. Sanders, R. L. Hinkle, and B. J. Ramsey, “Measurement procedures for the 

NTIA radar spectrum engineering criteria (RSEC),” NTIA Technical Report TR05-420, U.S. Department of Commerce, Mar. 2005. Available: 

http://www.its.bldrdoc.gov/pub/ntia-rpt/05-420/index.php. 

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

Los Angeles, California,” NTIA Report TR-97-336, U.S. Department of 

Commerce, May 1997. Available: http://www.its.bldrdoc.gov/pub/ntia-rpt/97-

336/index.php. 

[3] R. J. Achatz,, “Tutorial on using amplitude probability distributions to characterize 

interference of ultrawideband transmitters to narrowband receivers”, Appendix A, 

In: W. Kissick (ed.), The temporal and spectral characteristics of ultrawideband 

signals. NTIA Report 01-383: U.S. Dept. of Commerce. Jan. 2001. Available: 

http://www.its.bldrdoc.gov/pub/ntia-rpt/01-383/index.php. 

[4] F. H. Sanders, “Conversion of power measured in a circuit to incident field strength 

and incident power density, and corrections to measured emission spectra for nonconstant aperture measurement antennas”, Appendix C, In: W. Kissick (ed.), The 

temporal and spectral characteristics of ultrawideband signals. NTIA Report 01-

383, U.S. Dept. of Commerce. Jan. 2001. Available: 

http://www.its.bldrdoc.gov/pub/ntia-rpt/01-383/index.php. 

FORM NTIA-29 U.S. DEPARTMENT OF COMMERCE

(4-80) NATIONAL. TELECOMMUNICATIONS AND INFORMATION ADMINISTRATION

BIBLIOGRAPHIC DATA SHEET

1. PUBLICATION NO.

TR-10-465

2. Government Accession No. 3. Recipient’s Accession No.

4. TITLE AND SUBTITLE

Emission Measurement Results for a Cellular and PCS Signal-Jamming 

Transmitter

5. Publication Date

February 2010

6. Performing Organization 

Code

7. AUTHOR(S)

Frank H. Sanders, Robert T. Johnk, Mark A. McFarland, J. Randall

Hoffman

9. Project/Task/Work Unit 

No.

8. PERFORMING ORGANIZATION NAME AND ADDRESS 3102012-300

Institute for Telecommunication Sciences

National Telecommunications & Information Administration

U.S. Department of Commerce

325 Broadway

Boulder, CO 80305

10. Contract/Grant No.

11. Sponsoring Organization Name and Address

National Telecommunications & Information Administration

Herbert C. Hoover Building, 14th & Constitution Ave., NW

Washington, DC 20230

12. Type of Report and 

Period Covered

Tech Report, FY10

14. SUPPLEMENTARY NOTES

15. ABSTRACT

This report describes emission measurements on a denial-of-service (jammer) transmitter operating in the 

800 MHz and 1900 MHz cellular and PCS bands. The jammer operates at a power level of up to 100 watts 

in each band, repetitively sweeping a carrier-wave signal across the range of frequencies in which service is 

to be denied. Frequency domain emissions were measured from 100 MHz to 6 GHz with 100 dB of 

dynamic range. With the installation of a diplexer that is used as an RF filter, some measurable out-of-band 

(OOB) emissions occur in spectrum adjacent to the fundamental-frequency bands. Across the rest of the 

100 MHz to 6 GHz spectrum range, unwanted emission levels are suppressed by 100 dB or more when the 

diplexer is installed. OOB emissions in adjacent bands may be reduced by sweeping across less than the 

full width of the targeted bands, or by installing custom-designed RF output filtering.. 

16. Key Words (Alphabetical order, separated by semicolons)

cellular communications jamming; denial-of-service jamming; emission bandwidth; out-of-band (OOB) 

emissions; personal communication service (PCS) communications jamming; radio jamming; unwanted 

emissions

17. AVAILABILITY STATEMENT

  UNLIMITED.

18. Security Class. (This report)

Unclassified

20. Number of pages

 69

19. Security Class. (This page)

Unclassified

21. Price:

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