Receiver Autonomous Integrity Monitoring for the 21 Primary and Optimal 21 GPS Satellite Constellations

Per K. Enge

Abstract:	A radionavigation system with integrity protects its users by notifying them if their position errors are likely to be greater than a pre-specified level. The Global Positioning System provides a great deal of such protection. The ground control segment continuously monitors the health of the satellite signals. If any faults are detected, then it uplinks data to all the satellites, which then broadcast warnings to the users. However, certain slowly increasing bias errors could still be troublesome. They could introduce relatively large position errors before detection and notification by the ground control segment. Consequently, additional integrity monitoring techniques have been analyzed and described in the literature. Among these, receiver autonomous integrity monitoring (RAIM) detects and isolates satellite faults without using information external to the GPS receiver. RAIM uses redundant information in the satellite signals to fault detect and isolate. This paper approximates the probability that RAIM is possible given the recently described 21 Primary and Optimal 21 satellite constellations [6]. The analysis also approximates RAIM availability given 1, 2 or 3 satellites failures in either of these constellations. The availability approximations are simple functions of the constellation values provided by [6]. The approximations are shown to be accurate by comparing them to results based on extensive computer analysis.
Published in:	Proceedings of the 45th Annual Meeting of The Institute of Navigation (1989) June 27 - 29, 1989 Alexandria, VA
Pages:	127 - 133
Cite this article:	Enge, Per K., "Receiver Autonomous Integrity Monitoring for the 21 Primary and Optimal 21 GPS Satellite Constellations," Proceedings of the 45th Annual Meeting of The Institute of Navigation (1989), Alexandria, VA, June 1989, pp. 127-133.
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