An Integrity Monitoring Scheme for Precision Approach Applications

Mats Brenner

Abstract:	A scheme for integrity monitoring in a GPS based SCAT I satellite landing system is presented. This scheme is based on the redundancy provided by several ground station receivers. A set of 3 integrity related parameters (reflecting the ground station receiver redundancy and threshold setting) are broadcast for each satellite. In the airborne system the 3 parameters are used in combination with the geometry information for each satellite to form a lateral protection limit LPL and a vertical protection limit VPL. These two limits reflect upper bounds of the possible sensor related errors ( exceeded with a probability smaller than 1 O-*/approach) that may be present if an undetected failure occurs in the ground station. These protection limits can be combined with the measured or estimated flight technical error (FTE) to provide an upper bound of the total system error. The ideas behind the scheme are related to receiverautonomous integrity monitoring @AIM) in currently used GPS equipment but ratherthan relying on the redundancy in the satellite set used for positioning (as in RAIM), which for the vertical integrity has a low availability, it relies on the redundancy provided by several receivers. To enhance continuity of function in the ground station an exclusion mechanism has been developed for ground stations with 3 receivers or more. The accuracy and integrity performance, including multipath effects, of the SCAT I system is demonstrated based on data collected at Minneapolis airport.
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:	1635 - 1644
Cite this article:	Brenner, Mats, "An Integrity Monitoring Scheme for Precision Approach Applications," 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. 1635-1644.
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