A Sequential RAIM Based on the Civil Aviation Requirements

Bacem Bakhache

Abstract:	Integrity monitoring requires that a navigation system de-tects, isolates faulty measurement sources, and removes them from the navigation solution before they sufficiently contaminate the output. In this paper we consider the Re-ceiver Autonomous Integrity Monitoring (RAIM) of the GPS channels. RAIM is a method of GPS integrity mon-itoring that uses redundant GPS (or DGPS) measurements at the user’s receiver. Two types of algorithms can pro-vide RAIM functions : the widely known snapshot meth-ods which use a single set of GPS measurements collected simultaneously and the sequential methods which use all past and current sets of GPS measurements. The princi-pal limitation of snapshot RAIM is its availability. There are periods when the fault detection and/or exclusion func-tion of snapshot RAIM are not available. The sequential approach has a potential advantage over the snapshot one : its capacity to detect a positioning failure with a low magni-tude of fault to noise ratio in the residual of the least squares algorithm. Sometimes the impact of such a fault on the esti-mated horizontal or/and vertical position of the vehicle can seriously degrade its accuracy due to a poor satellite geom-etry. Hence, this (at first glance “minor”) fault should be detected within a given (usually short) time-to-alert and we expect to show an advantage of the sequential fault detec-tion algorithm over the snapshot one in this situation. The sequential RAIM used in the previous papers was based on the traditional quickest detection criterion. A new approach based on the requirements of civil aviation is described in this paper.
Published in:	Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999) September 14 - 17, 1999 Nashville, TN
Pages:	1201 - 1210
Cite this article:	Bakhache, Bacem, "A Sequential RAIM Based on the Civil Aviation Requirements," Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999), Nashville, TN, September 1999, pp. 1201-1210.
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