Real-time GEO orbit determination using TOPSTAR 3000 GPS receiver

Christian Mehlen and Denis Laurichesse

Abstract:	Real-time spacecraft navigation based on spaceborne GPS receiver is nowadays becoming a common technique for low-Earth orbits (LEO). Extension of this technique to geostationary (GEO) mission has been restrained by the difficulty of the GPS receivers to cope with unfavorable conditions encountered in GEO, which are mainly : 1) poor GPS SV visibility and 2) weak signal power. New generation of GPS receiver, which integrates enhanced techniques to address these concerns, is now available and is going to be used in on-flight experiments of GEO autonomous navigation. The TOPSTAR 3000 spaceborne GPS receiver was developed by Alcatel Space Industries and incorporates an high-accuracy orbital filter which was developed in partnership with CNES. The receiver was designed to fulfill a wide set of missions, including high-altitude orbits. It integrates dedicated techniques for processing weak GPS signals. A flight model of the receiver has been delivered to the STENTOR GEO program, of which purpose is to experi- ment new techniques for next generation of GEO tele- communication spacecraft (STENTOR will be launched in beginning of 2001). One of these experiments is the autonomous orbit control, for which the on-board GPS receiver acts as the main equipment of localisation and time transfer. This paper discusses the particular aspects of GPS receiver in GEO, and introduces additional features required for autonomous orbit control. Results of tests performed with TOPSTAR 3000 receiver in GEO configuration are presented, including behavior during GEO station-keeping manoeuvres using electric propulsion.
Published in:	Proceedings of the 13th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2000) September 19 - 22, 2000 Salt Palace Convention Center Salt Lake City, UT
Pages:	1985 - 1994
Cite this article:	Updated citation: Published in NAVIGATION: Journal of the Institute of Navigation
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