An experimental assessment of observation cross-correlation in dual frequency GPS receivers

Peter Bona and Christian Tiberius

Abstract:	In processing GPS data for precise differential positioning, modelling considerations underlying the observations' variance-covariance matrix generally concern only the variances of the individual pseudorange and carrier phase observations, and usually disregard any possible correlation between different observation types. One of the causes of this correlation is that civilian dual frequency GPS receivers employ particular techniques under Anti-Spoofing to reconstruct the pseudorange and carrier phase observables on the L2 frequency. These so- called codeless and semi-codeless techniques may result in correlations between the observation types. Accounting for the correlations is crucial in high precision GPS applications to obtain optimal positioning estimators. An experiment was carried out recently with seven dual- frequency GPS receivers of different type and makes in order to examine the cross-correlation on pseudorange and carrier phase observations between the L 1 and L2 frequency. With a method for statistical variance component estimation cross-correlation coefficients were computed. The coefficients between L1 and L2 pseudorange observations may reach up to 0.75. Between L1 and L2 carrier phase this figure turns out to be even more significant for some of the receivers. The results also underline that carrier phase cross-correlation is a true issue as it turns out to be present on all receivers considered. With these results the currently used stochastic models can be refined and, they may contribute to our knowledge about the receivers' internal processes.
Published in:	Proceedings of the 13th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2000) September 19 - 22, 2000 Salt Palace Convention Center Salt Lake City, UT
Pages:	792 - 798
Cite this article:	Bona, Peter, Tiberius, Christian, "An experimental assessment of observation cross-correlation in dual frequency GPS receivers," Proceedings of the 13th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2000), Salt Lake City, UT, September 2000, pp. 792-798.
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