GEO GPS Receiver Demonstration on a Galileo System Test Bed Satellite

T. Ebinuma, M. Unwin, R. Myatt, E. Rooney, Y. Hashida and A. Garutti

Abstract:	In collaboration with the European Space Agency (ESA), Surrey Satellite Technology Ltd (SSTL) has an opportunity to demonstrate an experimental GPS receiver on the Galileo System Test Bed V2/A (GSTB-V2/A) satellite. GPS receivers have been used successfully on low Earth orbit (LEO) satellite missions for several years. SSTL has developed its own spaceborne GPS receiver (SGR) series and has a long history of successful operations on both SSTL and customer satellite missions. In coordination with SSTL’s ongoing GEMINI development to design a small geostationary orbit (GEO) platform, the GPS team within SSTL is currently involved in the design and development of a new GPS receiver, SGR-GEO, which will operate at GEO. The design of a GPS receiver to operate at GEO is quite similar to that required for use at medium Earth orbit (MEO), and the SGR-GEO design can readily be adapted for inclusion on GSTB-V2/A. The use of a GPS receiver at altitudes higher than LEO is non-trivial as the receiver will be outside the main lobe of the GPS broadcast signals and it will have to track signals from GPS satellites transmitting from the other side of the Earth. Hardware adaptations include increased radiation shielding, a more precise reference oscillator to assist in coasting, and a specialised antenna. This paper will describe the status of the GPS experiment intended for demonstration on GSTB-V2/A, scheduled for launch in October 2005. The paper will also review the special adaptations required for MEO/GEO orbit including radiation assessment and mitigation, antenna design and oven controlled crystal oscillator (OCXO) accommodation. Some of the more advanced algorithm and experimentation for the future SGR-GEO product will be introduced, along with preliminary simulation test results.
Published in:	Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004) September 21 - 24, 2004 Long Beach Convention Center Long Beach, CA
Pages:	2721 - 2727
Cite this article:	Ebinuma, T., Unwin, M., Myatt, R., Rooney, E., Hashida, Y., Garutti, A., "GEO GPS Receiver Demonstration on a Galileo System Test Bed Satellite," Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004), Long Beach, CA, September 2004, pp. 2721-2727.
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