Dependence of GEO UDRE on Ground Station Geometries

Nitin Pandya, Jya-Syin Wu, and Mohinder Grewal

Abstract:	This paper will discuss the dependence of the User Differential Ranging Error (UDRE) for Geostationary Earth Orbiting (GEO) satellites on alternative Wide Area Differential GPS (WADGPS) system architectures with different station geometries. These different geometries will be characterized by the Geometric Dilution of Precision (GDOP) parameter. GDOP is obtained by treating the GEO as a ranging signal source with respect to a network of synchronized ground stations and performing a least squares estimate from the linearized pseudorange differential with respect to the GEO position and clock offset. An estimate of UDRE is obtained from the covariance matrix of an extended Kalman filter for the orbit determination of the satellite. The state transition matrix, the measurement sensitivity matrix, the process noise covariance matrix, and the measurement noise covariance matrix for the filter are presented. The dependence of the UDRE on GDOP is plotted for various station geometries. A simple, approximate analytic relation between UDRE and GDOP is proposed which allows a rough estimate of the UDRE for any station geometry.
Published in:	Proceedings of the 2000 National Technical Meeting of The Institute of Navigation January 26 - 28, 2000 Pacific Hotel Disneyland Anaheim, CA
Pages:	80 - 90
Cite this article:	Pandya, Nitin, Wu, Jya-Syin, Grewal, Mohinder, "Dependence of GEO UDRE on Ground Station Geometries," Proceedings of the 2000 National Technical Meeting of The Institute of Navigation, Anaheim, CA, January 2000, pp. 80-90.
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