Multipath Effects on GPS Measurements During an Orbital Rendez-vous

Jean-Luc Issler, Bruno Cugny and Patrick Agnieray

Abstract:	The HERMES spaceplane project nominal mission includes an orbital rendez-vous. The navigation will be performed with a GPS receiver during this flight phase. The GPS signal could be deteriorated by a specular multipath during the rendez-vous phase. A theoretical study performed at CNBS in 1990 identifies the possible multipath effects on the chaser GPS raw measurements, during a dynamic rendez-vous. The multipath is modeled as one direct GPS signal and one signal reflected on the target. The reflected signal originates from the same GPS satellite than the direct one. The reflected signal parameters are its relative amplitude and delay. The GPS receiver considered for this preliminary study is based on a classical design. A detailed analysis of the Costas and code loops transfer function modifications due to multipath has been performed. The pseudorange and pseudospeed errors due to multipath have been calculated for several space rendez-vous dynamic configuration cases. The study enables to define a precise experimentation plan dedicated to the measurements of multipath effects with real GPS receivers. A solution adapted to multipath effects reduction during a space rendez-vous is proposed.
Published in:	Proceedings of the 5th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1992) September 16 - 18, 1992 Albuquerque, NM
Pages:	841 - 851
Cite this article:	Issler, Jean-Luc, Cugny, Bruno, Agnieray, Patrick, "Multipath Effects on GPS Measurements During an Orbital Rendez-vous," Proceedings of the 5th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1992), Albuquerque, NM, September 1992, pp. 841-851.
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