Derivation of Acceptable Error LimitsFor Satellite Signal Faults in LAAS

Curtis A. Shively

Abstract:	Satellite signal faults are of concern in LAAS because they may not be detected by ground monitoring and the errors they produce may not be fully removed by application of broadcast differential corrections. This paper derives tolerable limits on the ranging error due to undetected signal faults affecting all satellites at once and faults affecting only one satellite at a time. Contributions from fault-free error sources are also considered in the derivation. The limits are derived so that the error is safely bounded for the worst satellite geometry allowed assuming the satellites are fault-free. The resulting limits are proportional to the satellite ranging error standard deviation as a function of elevation angle. For faults affecting only one satellite, the limit is also minimized as a function of the geometric relationship between the faulty satellite and the other fault-free satellites. Performance is analyzed as a function of the relationship between the assumed standard deviation of the integrity test and the required limit. Tradeoffs between probability of missed detection (integrity) and probability of fault-free detection (continuity) are illustrated. Values of the error limits are recommended for inclusion in the LAAS Ground Facility Specification.
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:	761 - 770
Cite this article:	Shively, Curtis A., "Derivation of Acceptable Error LimitsFor Satellite Signal Faults in LAAS," Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999), Nashville, TN, September 1999, pp. 761-770.
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