Ambiguity Resolution in Precise Point Positioning: Preliminary Results

M. Abdel-Salam, Y. Gao

Abstract:	Carrier phase based Precise Point Positioning (PPP) is a method that has received increased attention in the last few years within the GPS community. It has the potential to provide centimeter to decimeter position accuracy in stand-alone mode. In contrast to traditional methods like double difference GPS positioning, PPP does not need a base station. It uses un-differenced code and carrier phase observations from a high precision dual-frequency receiver in addition to precise satellite orbit and clock data. Several challenges exist for precise point positioning to be feasible to real-time applications. Ambiguity resolution and position convergence are among the major ones to be discussed in this paper. Ambiguity resolution is the key for quick position convergence. Due to the non-differential nature of the observations in PPP data processing, a number of errors must be eliminated through data corrections, observation combination, modeling or estimation. Ambiguity resolution in PPP is also different from the conventional double difference ambiguity resolution. This paper will present some preliminary research results on ambiguity resolution in precise point positioning. The investigation has been based on an observation model developed at The University of Calgary, which is capable of simultaneously estimating the ambiguities in both L1 and L2 carrier phase observations. The role of receiver clock and error residuals as well as their effects on ambiguity resolution will also be discussed. The research work would help the understanding of PPP data processing and the future development of ambiguity resolution algorithms for PPP.
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:	1222 - 1228
Cite this article:	Abdel-Salam, M., Gao, Y., "Ambiguity Resolution in Precise Point Positioning: Preliminary Results," 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. 1222-1228.
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