GPS - GIOVE Mixed PVT Experimentation

B. Bonhoure, C. Boulanger, J. Legenne

Abstract:	The future is GNSS, i.e. the major part of navigation satellite receivers are likely to receive and combine signals from several systems. This will permit improvement of performances, in particular in constrained environments, and also will offer operational back-up or independence in case of failure or unavailability of one system. According to the USA/EUROPE agreement for the compatibility and interoperability of Galileo and GPS, a key GNSS receiver should be the one merging GPS signals with Galileo ones to calculate a common PVT. Actually, with current GALILEO prototype satellites, i.e. GIOVE-A and GIOVE-B, combination with GPS can already be achieved for some periods. This article discusses about theoretical approach and practical results when mixing real measurements from GPS and GIOVE. As the satellite navigation systems are based on a synchronization of the satellites clocks, combination of GPS and GIOVE (or GALILEO) signals require a common time scale for merging the measurements. So the difference of GPS time scale and GIOVE time scale, also known as GGTO (GALILEO/GPS Time Offset) shall be taken into account in the PVT process. Two different approaches have been implemented for the experimentation : equations with the 4 usual unknowns (3D position and delta receiver time from GPS time) using the transmitted GGTO by the GIOVE system, or with 5 unknowns including an additional GGTO parameter. First results are that when mixing the pseudo-range measurements from GPS and GIOVE, GPS or GIOVE pseudo-range residuals or position errors of a few meters can be achieved in a PVT. Those are quite pretty good results at a receiver level, but also for the whole GIOVE system. GPS/GIOVE PVT is a first step before the GPS/GALILEO one.
Published in:	Proceedings of the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2009) September 22 - 25, 2009 Savannah International Convention Center Savannah, GA
Pages:	2996 - 3007
Cite this article:	Bonhoure, B., Boulanger, C., Legenne, J., "GPS - GIOVE Mixed PVT Experimentation," Proceedings of the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2009), Savannah, GA, September 2009, pp. 2996-3007.
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