Comparison of GEO and GPS Orbit Determination

Mohinder Grewal, Edward Carolipio and Michael Bailey

Abstract:	Geostationary Earth Orbit (GEO) satellites serve as relays to transmit messages for Space Based Augmentation Systems (SBASs), such as the Wide Area Augmentation System (WAAS), the European Geostationary Navigation Overlay Service (EGNOS), and the Multifunction Transport Satellite Based Augmentation System (MSAS). GEO satellites can act as ranging sources for SBAS users as well, adding to the availability and continuity of a number of SBAS services. Unfortunately, since the GEO is nearly stationary relative to the SBAS stations, separating the position and velocity errors from the clock errors is difficult and makes the GEO range errors much larger than GPS range errors. A technique has been proposed to decouple the clock errors in a bent-pipe GEO system and has been shown to drop the GEO range errors to levels comparable to those for GPS satellites [1]. This paper explores further the expected improvement in the GEO orbit determination using this clock error decoupling technique. WAAS field data are used in an extended Kalman filter based on the WAAS Corrections and Verifications (C&V) software to study the GEO range errors with a known clock. The GEO range errors with a known clock are found to be up to a factor of ~5 better than those for the fielded WAAS and to within 50% of the GPS range errors.
Published in:	Proceedings of the 15th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2002) September 24 - 27, 2002 Oregon Convention Center Portland, OR
Pages:	790 - 799
Cite this article:	Grewal, Mohinder, Carolipio, Edward, Bailey, Michael, "Comparison of GEO and GPS Orbit Determination," Proceedings of the 15th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2002), Portland, OR, September 2002, pp. 790-799.
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