A Robust RAIM Scheme Using GPS/GLONASS Systems

Wai L. Tsang, Barry A. Stein

Abstract:	The current Soviet GLASNOST policy has resulted in an initiative by the United States Department of Transportation's Federal Aviation Administration (FAA) and its Soviet counterpart to explore the use of the U. S. Global Positioning System (GPS) and the Soviet Global Orbiting Navigation Satellite System (GLONASS) for civil navigation. If successful, commercial aviators could use the GPS/GLONASS signals to safely navigate in peacetime around the world in all weather conditions, thus reducing the cost of future navigation systems. Due to FAA's concern about the integrity of GPS with its selective availability (SA) turned on, researchers and investigators have been studying self-contained receiver autonomous integrity monitoring (RAIM) methodologies. These range from the intuitively simple least squares method, which can be mechanized in a single microprocessor, to a highly complex bank of Kalman filters, which could only be mechanized with super/parallel signal processors. These are being evaluated by the GPS Integrity Working Group of the Radio Technical Commission for Aeronautics (RTCA) Special Committe-159 for inclusion in the recommendation to the RTCA executive committee on GPS for civil navigation. This paper proposes a combined methodology which draws on the desirable features associated with these RAIM methods. It is robust in mitigating against poor satellite geometry and is relatively simple to implement. The feasibility of this RAIM scheme using both satellite systems in a cooperative fashion for navigation is assessed against the combined GPS/GLONASS systems in their various phases of satellite constellation built up over the conterminous United States (CONUS). Issues concerning a hybrid GPS/GLONASS receiver arc also addressed.
Published in:	Proceedings of the 2nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1989) September 27 - 29, 1989 The Broadmoor Hotel Colorado Spring, CO
Pages:	373 - 378
Cite this article:	Tsang, Wai L., Stein, Barry A., "A Robust RAIM Scheme Using GPS/GLONASS Systems," Proceedings of the 2nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1989), Colorado Spring, CO, September 1989, pp. 373-378.
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