The PoSAT Microsatellite GPS Experiment

Martin J. Unwin

Abstract:	Satellite engineers have long recognised the many potential advantages that the Global Positioning System has to offer for low Earth orbit satellite tracking. This is especially true for low-cost small- scale spacecraft, such as the UoSAT-class microsatellites. With the GPS constellation nearing completion, and the increasing availability of advanced low-power GPS receivers, microsatellite tracking through GPS is now practical. The PoSAT-A microsatellite is being launched this September (1993) by Arianespace into an 800 km polar orbit, along with two other UoSAT-class microsatellites. One of the payloads on PoSAT will be the GPS Navigation Unit, an experiment consisting of GPS receiver, antenna and processing hardware and software. Using the Navigation Unit, the satellite will be able to track itself directly to a high degree of accuracy. The supporting software will enable the logging of experimental data, the synchronisation of the satellite and ground station clocks, payload switching and on-board orbit determination through data filtering. The Classical Keplerian Elements of the microsatellite will be derived in space and broadcast to all ground-based users. There will be an automatic management of the GPS receiver to conserve power while retaining position accuracy through on-board orbit filtering. The autonomous operation of the Navigation Unit will simplify the satellite operations, and promote new technological capabilities within the small scale of the microsatellite. The Navigation Unit is designed in such a way as to be expandable to integrate new sensors and modules to be of use for future microsatellites and larger satellites.
Published in:	Proceedings of the 6th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1993) September 22 - 24, 1993 Salt Palace Convention Center Salt Lake City, UT
Pages:	811 - 817
Cite this article:	Unwin, Martin J., "The PoSAT Microsatellite GPS Experiment," Proceedings of the 6th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1993), Salt Lake City, UT, September 1993, pp. 811-817.
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