Reconfigurable GPS-Galileo Receiver for Satellite Based Applications

Arnaud Dion, Vincent Calmettes, Emmanuel Boutillon

Abstract:	The trajectory of Space Vehicles (SVs) derives due to external perturbations, such as the variation in the gravitation fields (earth, moon and sun) or the solar pressure effect. The station keeping of SVs is the operation that keeps the satellites in a predefined window. This operation implies that the SV position is known. Actual positioning systems for SVs are mainly based on ground equipment, that means heavy infrastructures. Autonomous positioning and navigation systems using Global Navigation Satellite System (GNSS) can then represent a great reduction in platform design and operating costs. This paper presents the configurations for Low Earth Orbit (LEO) and Geosynchronous Earth Orbit (GEO) missions. These configurations have been modeled from real mission parameters with the help of a dedicated software. Due to high dynamics of LEO SVs, the Doppler spans and Doppler rates are much larger than for a ground application. However, there is always a sufficient number of GNSS satellites in visibility to compute the point position solution. For missions such as GEO or Highly Elliptical Orbit (HEO), the Doppler effect is less critical than LEO but the major problems are the GPS signal availability and the received power. A receiver that could process Galileo and GPS signals would have more satellites in the visibility domain than a GPS-only receiver. The greater availability of GNSS signals allows significant increase of the number of point solutions. However, the signals availability would vary during a mission, the receiver will have then to be flexible. Using the two constellations allows a great improvement in term of visibility, thus simplifying the design of a receiver. This paper shows the determination of the link budget and detailed the various parameters taken into account. Then the expected performances of GEO and LEO applications are presented. They have been simulated under various conditions in order to specify the system constraints. And, finally, the performances of a receiver model are presented. This model is purely functional and allows the comparison between various algorithms.
Published in:	Proceedings of the 2008 National Technical Meeting of The Institute of Navigation January 28 - 30, 2008 The Catamaran Resort Hotel San Diego, CA
Pages:	277 - 287
Cite this article:	Dion, Arnaud, Calmettes, Vincent, Boutillon, Emmanuel, "Reconfigurable GPS-Galileo Receiver for Satellite Based Applications," Proceedings of the 2008 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 2008, pp. 277-287.
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