A New Positioning Filter: Phase Smoothing in the Position Domain

Thomas J. Ford and Jason Hamilton

Peer Reviewed

Abstract: Motivated by a requirement to provide real-time meter-level positioning of a NASCAR racing car, a modification of the standard Kalman filter was devised. This paper describes an approach that incorporates previous as well as current position states in a Kalman filter to take advantage of phase measurements differenced over time. In this formulation, the phase measurement difference is a measure of the difference in position in the line-of-sight direction to the satellite, so it can act as a relative position constraint of the current position with respect to the previous one. The formulation of the delta-phase observation equation is described, as well as the modifications made to the Kalman filter to incorporate it. An example used to illustrate the effectiveness of the delta-phase measurements in controlling position error growth is included. Test results in various urban environments are presented.
Published in: NAVIGATION: Journal of the Institute of Navigation, Volume 50, Number 2
Pages: 65 - 78
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