New Theories and GPS Experiments About Effects of Multipath and RF Jammers

Rene Landry and Shahrzad Mahooti

Abstract:	The CNES will provide a GPS receiver developped by SEXTANT Avionique to the MIT for the HETE spacecraft. HETE is funded by NASA and managed as a Rclass DS program by a small team at Center for Space Research at the MIT. HETE involves major contributions from several international teams, including CNES and CESR in France, STA and RIKEN in Japan, and ASI in Italy. Multipath and Radio-Frequency Jammers can be considered as two important examples of possible perturbation of the GPS signal. The objectives of the studies are related with advances on new concept analysis of these jammers on the build-m Code and Phase Loop GPS receivers to bring better knowledge and the possibility of further improvement on futur design. The measurements errors due to multipath are analysed theoretically in the case of a programmable chip spacing in the Delay Locked Loop of the GPS receiver. As the same point of view, narrow and wide band jammers are analysed in term of their effects on the CM,, pseudoranges and pseudospeeds. Error measurements results are presented in static and dynamic conditions, for static and dynamic specular multipath. The dynamic conditions generated with a programmable GPS Constellation Simulator correspond to the case of a space rendezvous. All experiments have been conducted using the NT GPS Constellation Simulator connected to a SEXTANT Avionique GPS Receiver Flight Model identical to the one mounted on the HETE spacecraft, presently located in the integration site at AeroAstro ( USA ). The RF Jammers analysed have various forms as: * Non-coherent GPS-like signal in L 1 band. * Coherent GPS-like signal in Ll band (multipath or orthogonal code). * Narrow band signal in Ll band * Narrow band signal in L band. Theoretical developments, and error measurement results associated to these jammers are presented.
Published in:	Proceedings of the 7th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1994) September 20 - 23, 1994 Salt Palace Convention Center Salt Lake City, UT
Pages:	883 - 897
Cite this article:	Landry, Rene, Mahooti, Shahrzad, "New Theories and GPS Experiments About Effects of Multipath and RF Jammers," Proceedings of the 7th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1994), Salt Lake City, UT, September 1994, pp. 883-897.
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