Complementary Kalman Filter for Smoothing GPS Position with GPS Velocity

H. Leppäkoski, J. Syrjärinne, J. Takala

Abstract:	In this study, a fusion filter was implemented to combine carrier phase and code phase information of a standalone, mobile GPS receiver. The filter was designed for personal positioning in urban and especially in suburban environments, where usually the continuous carrier phase is not available for long times, but varying combinations of at least four satellite signals are often available. The basic idea of the filter is to use the velocity estimate that is computed from delta pseudorange measurements, to smooth the position estimate computed from pseudorange measurements. The usage of adaptive noise covariances is another key feature of the filter. The filter is implemented without motion models of the user, i.e. the position output is based solely on measured information, not on any assumptions of what the motion state of the user might be. Test results from pedestrian navigation and vehicle tests show that this kind of filter can be used to smooth the estimated position trajectory. In suburban navigation tests, the performance of the proposed filter is shown to be better than the alternative filter that consists of carrier smoothing for each satellite channel and WLS position estimation from the smoothed pseudoranges. Reports of this kind of fusion filter for GPS carrier and code phase information, where the filter operates in position coordinates, do not exist in the open literature.
Published in:	Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003) September 9 - 12, 2003 Oregon Convention Center Portland, OR
Pages:	1201 - 1210
Cite this article:	Leppäkoski, H., Syrjärinne, J., Takala, J., "Complementary Kalman Filter for Smoothing GPS Position with GPS Velocity," Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003), Portland, OR, September 2003, pp. 1201-1210.
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