Performance Analysis of Precise Point Positioning Based on Combined GPS and GLONASS

Changsheng Cai and Yang Gao

Abstract:	Current PPP (Precise Point Positioning) model is implemented using GPS observations. The accuracy, availability and reliability of the positioning results are very dependent on the number of visible satellites, which is often insufficient in the environments such as urban canyons and open-pit mines. Further, even in the open area where sufficient GPS satellites are available, the PPP accuracy and reliability could still be affected by poor satellite geometry. One possible way to increase the availability of satellites and improve the reliability of positioning results is to integrate GPS and GLONASS. Since the International GLONASS Experiment (IGEX-98) and the follow-on GLONASS Service Pilot Project (IGLOS), the GLONASS precise orbit and clock data have become available gradually. A combined GPS and GLONASS PPP could therefore be implemented using GPS and GLONASS precise orbits and clock data. In this research, the PPP model based on combined GPS and GLONASS is described. The performance of the combined GPS and GLONASS PPP is assessed using the IGS tracking network observation data and the currently available precise GLONASS orbit and clock data. The corresponding positioning accuracy and convergence time are compared for GPS-only and GPS/GLONASS precise point positioning. The results have indicated a significant improvement on the position convergence time although the improvement is quite dependent on the geometry improvement of the visible satellite configurations. The results also indicate a slight improvement on the positioning accuracy due to limited availability of GLONASS satellites.
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:	858 - 865
Cite this article:	Cai, Changsheng, Gao, Yang, "Performance Analysis of Precise Point Positioning Based on Combined GPS and GLONASS," 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. 858-865.
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