A New Data Processing Strategy for Combined GPS/GLONASS Carrier Phase-Based Positioning

Shaowei Han, Liwen Dai and Chris Rizos

Abstract:	Due to the different signal frequencies for the GLONASS satellites, the commonly used double-differencing proce-dure for carrier phase data processing cannot be imple-mented in its straightforward form, as in the case of GPS. In this paper a new data processing strategy for combined GPS/GLONASS positioning is proposed, involving a three-step procedure. The first step is pseudo-range-based positioning, using double-differenced GPS pseudo-range and single-differenced GLONASS pseudo-range meas-urements, to derive the initial position and receiver clock bias. The second step is to form double-differenced ob-servables (expressed in cycles) in order to estimate the ambiguities, using the receiver clock bias as estimated in the previous step. The third step is to form double-differenced observables (expressed in metric units) with the unknown single-differenced integer ambiguity for the GLONASS reference satellite as the only parameter (which is constant until a cycle slip occurs for this satel-lite). A real-time stochastic model estimated by residual series over previous epochs is proposed for combined GPS/GLONASS carrier phase and pseudo-range data processing. Other associated issues, such as cycle slip detection, validation criteria and adaptive procedure(s) for ambiguity resolution, will also be discussed. The per-formance of this data processing strategy will be demon-strated through case study examples of rapid static posi-tioning and kinematic positioning. Based on four experiments carried out to date, the results indicate that rapid static positioning requires 1 minute of data for 100% positioning success rate. The single epoch posi-tioning solution for kinematic positioning can achieve 94.6% success rate over short baselines (<6km).
Published in:	Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999) September 14 - 17, 1999 Nashville, TN
Pages:	1619 - 1628
Cite this article:	Han, Shaowei, Dai, Liwen, Rizos, Chris, "A New Data Processing Strategy for Combined GPS/GLONASS Carrier Phase-Based Positioning," Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999), Nashville, TN, September 1999, pp. 1619-1628.
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