Removal of SA: Benefits to GPS Integrity

Karen L. Van Dyke

Abstract:	The recent Presidential Decision Directive (PDD) on the Global Positioning System (GPS) recommends that Selective Availability (SA) be turned off within a decade. This paper examines the benefits of removing SA as it relates to airborne GPS integrity and demonstrates that there are substantial improvements in the availability of GPS integrity. The paper evaluates the current TSO C- 129 RAIM algorithm, which provides fault detection for supplemental use of GPS, as well as the fault detection and exclusion (FDE) algorithm for primary means navigation. The availability of integrity is examined globally and the results are compared to RAIM and FDE availability with SA on the system. The results of this analysis demonstrate significant improvement in the availability of the fault detection and exclusion functions if SA is turned off. This capability may provide significant benefits to countries who either do not plan to implement a WAAS-type system, or may not have one until well into the next century. Although these results hinge on the removal of SA, it is important nonetheless to quantify the magnitude of improvement in the availability of GPS integrity.
Published in:	Proceedings of the 9th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1996) September 17 - 20, 1996 Kansas City, MO
Pages:	1657 - 1670
Cite this article:	Van Dyke, Karen L., "Removal of SA: Benefits to GPS Integrity," Proceedings of the 9th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1996), Kansas City, MO, September 1996, pp. 1657-1670.
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