GEO Satellite Positioning Using GPS Collective Detection

P. Axelrad, B.K. Bradley, J. Tombasco, S. Mohiuddin, J. Donna

Abstract:	Unlike low Earth orbit satellites that routinely use onboard GPS receivers for positioning, satellites at high altitudes including the geostationary orbit (GEO) are typically tracked using ground-based radars or telescopes. GPS receivers designed for high altitude operations are being developed and used. They employ long integration times to improve acquisition and tracking sensitivity and dynamic filters to improve the orbit estimates based on sparse measurements. This paper describes the application of a collective detection and direct positioning approach to orbit determination in a GEO scenario. Collective detection requires a priori information on the GPS satellite orbits and clocks, and an initial estimate of the receiver motion. To combine correlations from multiple satellites, a position and clock uncertainty space is mapped to the delay/Doppler space for each satellite. The correlation values corresponding to the delay/Doppler point are accumulated non-coherently and a method for selecting the best position estimate from the position/clock domain correlogram is applied. A hardware simulator, sampling receiver, and software position solution have been used to explore the accuracy of this approach in GEO. Results using 20 ms of data, at approximately nominal signal levels, are on the order of 70 m in North and East directions and 100 m vertical. Using observations of this quality as input to a dynamic filter, navigation accuracy on the order of tens of meters, 1??, per axis is shown.
Published in:	Proceedings of the 23rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2010) September 21 - 24, 2010 Oregon Convention Center, Portland, Oregon Portland, OR
Pages:	2706 - 2716
Cite this article:	Axelrad, P., Bradley, B.K., Tombasco, J., Mohiuddin, S., Donna, J., "GEO Satellite Positioning Using GPS Collective Detection," Proceedings of the 23rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2010), Portland, OR, September 2010, pp. 2706-2716.
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