Real-time PPP Ambiguity Resolution with Satellite FCBs Estimated Considering Obit Errors

Yihe Li, Yang Gao, Junbo Shi

Abstract:	Precise point positioning (PPP) integer ambiguity resolution is able to significantly shorten the time-to-first-fix (TTFF) and improve the positioning accuracy when fractional cycle biases (FCBs) are available to recover the integer feature of the ambiguities. When real-time orbit and clock products are used to estimate the satellite FCB corrections, the narrow-lane (NL) FCB corrections would be biased by the Line-Of-Sight (LOS) errors in the real-time orbits and clocks. The slightly biased NL FCB estimate, even it does not affect the identification of the correct integer ambiguities, may deteriorate the positioning accuracy. We propose a method for satellite FCB generation, which assimilates the orbit and clock errors to further improve the performance of PPP ambiguity resolution (AR). The satellite NL FCB corrections are modeled by one direction-independent component and three directional-dependent components for each satellite, instead of only one direction-independent component. The direction-independent component assimilates actual FCBs and clock errors whereas the directional-dependent components are used to assimilate the orbit errors. GPS measurements from an experimental network with 28 stations in North America are processed with the IGS-RT products on doy 103. The improvements by the proposed FCB generation method are validated in terms of the mean and RMS values of the estimated FCBs, the ambiguity fix-rate as well as the obtainable positioning accuracy. The numerical results confirm that the obtained FCBs using the proposed method outperform the original FCBs which improve not only the ambiguity fix rate but also the position solution.
Published in:	Proceedings of the 27th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2014) September 8 - 12, 2014 Tampa Convention Center Tampa, Florida
Pages:	1008 - 1019
Cite this article:	Li, Yihe, Gao, Yang, Shi, Junbo, "Real-time PPP Ambiguity Resolution with Satellite FCBs Estimated Considering Obit Errors," Proceedings of the 27th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2014), Tampa, Florida, September 2014, pp. 1008-1019.
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