GPS Signal Selective Availability - Modeling And Simulation For FAA WAAS IV&V

Yi Bian

Abstract:	FAA is currently developing a Wide Area Augmentation System (WAAS) to improve the accuracy, availability, continuity, and integrity of the Global Positioning Sys- tem (GPS) for civil aviation applications. The initial WAAS (IWAAS) is planned to provide operational ca- pability over the entire continental US airspace, from en-route down to Cat I Precision Approach, by the end of 1998. Illgen Simulation Technologies, Inc. (ISTI) is currently tasked with Independent Verification and Val- idation (IV&V) of the system software. To verify alter- native WAAS designs, an I-WAAS simulator (iWAASs) has been developed at ISTI. This iWAASs is designed to evaluate with high confidence the performance of the IWAAS throughout its development life cycle. A key element of the iWAASs is a set of “golden scenar- ios” which simulate the operational conditions of the IWAAS. The basic building blocks of the iWAASs are a set of validated models which take into account various effects and sources of error for GPS and WAAS. Among these, Selective Availability (SA) is a large error source of critical importance. This paper presents a design study of SA modeling and simulation suitable for implementation in iWAASs. It gives a detailed description of the mathematical procedures of SA modeling. Auto-Regressive Moving- Average (ARMA) modeling techniques are used. Data collected from FAA flight tests is used to derive the SA models; these models are then used to generate simu- lated SA in iWAASs. A number of techniques, which can be used to analyze and verify the derived SA mod- els, are described. Limitations of the approach and the resulting SA models are discussed, and future directions of work are identified.
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:	761 - 769
Cite this article:	Bian, Yi, "GPS Signal Selective Availability - Modeling And Simulation For FAA WAAS IV&V," 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. 761-769.
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