New Techniques Relating Fault Detection and Exclusion Performance to GPS Primary Means Integrity Requirements

Young Lee

Abstract:	In the use of GPS, receiver autonomous fault detection and exclusion (FDE) often plays a major role in assuring integrity of the user navigation solution For use of GPS as a supplemental means of navigation, simple detection of the presence of a fault was considered sufficient since the aircraft can immediately revert to an alternate means of navigation. In the case for the use of GPS as a primary means of navigation, however, detection would not be sufficient; upon detection of a fault, the avionics should try to exclude the bad satellite and continue navigation whenever possible since no other normal means of navigation is available. Such use of FDE for primary means of navigation is currently being proposed to provide integrity for -oceanic airspace and even in conjunction with the Wide-Area Augmentation System (WAAS), namely outside WAAS signal coverage area or as a backup in the unlikely event of a WAAS outage. While the basic FDE techniques have been well established, the relation between the FDE algorithm performance and the primary means integrity requirements has not bedn well established. This paper proposes and analyzes new methods of correctly calculating two quantities that must be properly calculated to ensure meeting the primary means integrity requirements. The first one is a proposed method of calculating the horizontal protection level (HPL), based on which the probability of missed detection (Pmd) is determined. It will be shown that this new method consistently meets the integrity requirements while the existing method does not, and yet it has minimal impact on FDE availability. The second is a method of calculating probability of incorrect identification/exclusion, which has not been investigated before.
Published in:	Proceedings of the 8th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1995) September 12 - 15, 1995 Palm Springs, CA
Pages:	1929 - 1939
Cite this article:	Lee, Young, "New Techniques Relating Fault Detection and Exclusion Performance to GPS Primary Means Integrity Requirements," Proceedings of the 8th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1995), Palm Springs, CA, September 1995, pp. 1929-1939.
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