Spacecraft Full Attitude Determination from a Single Antenna: Experimentation with the PoSAT-1 GPS Receiver

P.J. Buist, Y.Hashida, M.Unwin, M. Schroeder

Abstract:	A Global Positioning System (GPS) receiver can provide the Carrier to Noise for the GPS signal currently being tracked, which may give the user additional attitude information. This paper describes the first results for full attitude determination from real orbital data. This method can especially be useful for small satellites, which normally do not have too high accuracy requirements for attitude and have already a single GPS antenna for positioning. For this project data was collected from the microsatellite PoSAT-1. This data is analysed to find a possible relationship between CNR and attitude. The modelling of the relationship was achieved through two methods; a look-up-table and a continuous function based on spherical harmonics. The attitude of the satellite is determinated with the use of this relationship and an Extended Kalman filter. The conclusion is that attitude determination using a single GPS antenna is feasible, and the potential accuracy can be expected to be 3 degrees for roll and pitch and 10 degrees for yaw for a gravity gradient stabilised satellite and can be improved if the proper mathematical modelling of the antenna gain pattern is applied.
Published in:	Proceedings of the 11th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1998) September 15 - 18, 1998 Nashville, TN
Pages:	1811 - 1817
Cite this article:	Buist, P.J., Y.Hashida,, M.Unwin,, Schroeder, M., "Spacecraft Full Attitude Determination from a Single Antenna: Experimentation with the PoSAT-1 GPS Receiver," Proceedings of the 11th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1998), Nashville, TN, September 1998, pp. 1811-1817.
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