ION Technical Content
Selective GPS Jamming
| Abstract: | As the use of GPS becomes more widespread, GPS jamming tests are increasingly more difficult to coordinate. Because GPS receivers are susceptible to jamming, a great number of users can be unintentionally jammed. GPS is a critical system for water navigation (which relies upon GPS augmented by the Coast Guard's differential system), cellular telephone networks (some of which rely upon GPS timing), air traffic (both private and commercial aircraft), and other civilian users (from hunters to hikers to rental cars). GPS jamming tests can also cause problems for the ranges on which tests are to be performed - if these ranges rely upon GPS for range instrumentation. With all these potential issues in mind, there remains a community wide need to test and train under the effects of GPS jamming. For the past three years, the Threat Systems Management Office at Redstone Arsenal, Alabama has been developing a threat simulator which will allow the military to test and train in a GPS jamming environment without interfering with civilian GPS users or range instrumentation GPS receivers. This program is known as Selective GPS Jamming. Selective GPS Jamming consists of two pieces of hardware. The first is a Control Signal Transmitter (CST). This transmitter radiates an open air RF signal that is close to the GPS center frequency (so that real world effects such as path loss, multipath, antenna masking, and body masking are represented) but is a benign (or non- jamming) signal. The CST is mounted on the same platform as the threat (ground based or airborne) and uses the same type of antenna to match polarization and pattern coverage. The second piece is a Remote Jammer Unit (RJU) which is installed between the antenna and the GPS receiver under test. The RJU measures the power level of the control signal and injects an appropriate amount of jamming power directly into the front end of the GPS receiver under test. The RJU can also be configured to scale the injected jamming power levels allowing threats from milliwatts to hundreds of kilowatts to be represented with the same RJU/CST combination. Since the center frequency jamming signals are generated and controlled within the RJU, only receivers which have been fitted with an RJU are jammed. No other GPS receivers are affected. This paper consists of a detailed description of the XMGPS system and a comparison of actual jamming and selective jamming test results. Also discussed are the control signal characteristics, dynamic range power levels, operational distances, and FAA issues/involvement. The paper concludes with future devices and requirements as well as results of a training specific device. |
| Published in: |
Proceedings of the 13th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2000) September 19 - 22, 2000 Salt Palace Convention Center Salt Lake City, UT |
| Pages: | 2096 - 2104 |
| Cite this article: | Price, Barry, Jetton, Jeremy, "Selective GPS Jamming," Proceedings of the 13th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2000), Salt Lake City, UT, September 2000, pp. 2096-2104. |
| Full Paper: |
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