Mutual Effects of Satellite Signal Quality and Satellite Geometry on Positioning Quality

A.T. Baelaei, B. Motella and A.G. Dempster

Abstract:	The accuracy of positioning, using the measured pseudoranges from the receiver to each of the satellites, depends on several different factors. The position evaluation in the GPS receiver estimates four quantities (x, y, z and time) using four or more pseudoranges. In GPS text books, it is easy to find the nonlinear relationship between the measured pseudoranges, the satellite position at transmit time, the receiver position at receive time, the bias in the receiver clock and the composite of errors that can be estimated from a budget [1]. It can be seen that in the linearized version of this equation about a nominal point, the position accuracy is decided by two factors, the measurement quality and the user-tosatellite geometry. These factors separately are extensively discussed in [1] in two separate chapters. In this work we will make a quantitative comparison of the effect of each one of these two factors and investigate their mutual effects on the positioning accuracy. The aim is to establish if the pseudorange error is large because of the poor satellite signal quality (low C/No), under which circumstances we can achieve better position accuracy by eliminating that satellite, noting the fact that eliminating the satellite will affect the geometry.
Published in:	Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007) September 25 - 28, 2007 Fort Worth Convention Center Fort Worth, TX
Pages:	1182 - 1190
Cite this article:	Baelaei, A.T., Motella, B., Dempster, A.G., "Mutual Effects of Satellite Signal Quality and Satellite Geometry on Positioning Quality," Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007), Fort Worth, TX, September 2007, pp. 1182-1190.
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