Real-time, Autonomous, Precise Orbit Determination Using GPS

David B. Goldstein, George H. Born and Penina Axelrad

Abstract:	The desire for autonomously generated, rapidly available, and highly accurate satellite ephemeris is growing with the proliferation of constellations of satellites and the cost and overhead of ground tracking resources. Autonomous Orbit Determination (OD) based upon observations from spaceborne GPS receivers is done on the ground in a postprocessing mode or in real-time on board satellites. In an effort to estimate precise satellite ephemerides in realtime on board a satellite, the Goddard Space Flight Center (GSFC) created the GPS Enhanced OD Experiment (GEODE) flight navigation software. This paper presents a characterization of GEODE performance and illustrates enhancements to GEODE to increase on board, real-time total position accuracy and precision without increasing computational burden. Specifically we investigated an alternative gravity field representation, a relative ionospheric error correction based on code-carrier divergence, and a dynamic model adjustment for filter tuning. Processing of flight data from TOPEX/Poseidon (T/P) indicates that total position accuracy at the meter level is possible in real time with the proposed enhancements to GEODE.
Published in:	Proceedings of the 57th Annual Meeting of The Institute of Navigation (2001) June 11 - 13, 2001 Albuquerque, NM
Pages:	149 - 158
Cite this article:	Updated citation: Published in NAVIGATION: Journal of the Institute of Navigation
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