GPS RAIM: SCREENING OUT BAD GEOMETRIES WORST-CASE BIAS CONDITIONS

Gerald Y. Chin, John H. Kraemer, and R. Grover Brown

Peer Reviewed

Abstract:	A RAIM algorithm should provide (1) a procedure for detection of a navigation failure, and (2) a procedure for screening out geometries that may be satisfactory for navigation purposes, but cannot provide failure detection within the required specifications. Declaring such “bad” geometries as inadmissible diminishes the RAIM availability, so the algorithm must not do the screening indiscriminately. This paper concentrates on the screening function of RAIM. It compares the effectiveness of the older HDOPmax criterion and a newer criterion called approximate radial-error protection (ARP). ARP is shown to be a much more reliable measure. The results of extensive Monte Carlo simulations are presented. In establishing reliable ARP ceilings for various phases of flight, it was found necessary to determine empirically the worst-case satellite bias that was applicable in each case. The main contribution is a reliable and straightforward screening criterion that can be readily implemented on line in a GPS receiver.
Published in:	NAVIGATION: Journal of the Institute of Navigation, Volume 39, Number 4
Pages:	407 - 428
Cite this article:	Chin, Gerald Y., Kraemer, John H., Brown, R. Grover, "GPS RAIM: SCREENING OUT BAD GEOMETRIES WORST-CASE BIAS CONDITIONS", NAVIGATION: Journal of The Institute of Navigation, Vol. 39, No. 4, Winter 1992-1993, pp. 407-428.
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