Improving Real-time PPP Ambiguity Resolution with Ionospheric Characteristic Consideration

Xingxing Li

Abstract:	Real-time precise point positioning (PPP) service can achieve accurate positioning on a global scale based on a global reference network of 50 to 100 stations and has been a research focus of the international GNSS community since years. The weakness of this traditional real-time PPP is its longer initialization time and lower positioning accuracy, comparing to the Real-Time Kinematic positioning with a local dense reference network. For improving PPP performance, this paper presents a new data processing scheme to shorten the convergence time and the observation time required for a reliable ambiguity-fixing. In the new scheme, L1 and L2 raw observations are used and the slant ionospheric delays are treated as unknown parameters. The empirical spatial and temporal constraints and the ionospheric delays derived from a real-time available ionospheric model are all considered as pseudo-observations into the estimation for strengthening the solution. In order to validate the efficiency of the new method, the real-time products including orbits, clocks, UPDs and GIMs generated by the real-time PPP service system operationally running at GFZ is utilized to run PPP with the traditional and the new schema. The experimental results indicate that. The new scheme considering ionospheric characteristics can reduce the convergence time by 30%, i.e., from more than 30 minutes to less than 20 minutes for float solutions. Furthermore, the observation time for a reliable ambiguity-fixing is also shortened by 25% compared to that of the traditional fixed solution, i.e., from 20 minutes to 15 minutes. Moreover, in the new method the re-convergence problem caused by data gaps or cycle slips disappears if the gap length is of a few minutes because of the special handling of the ionospheric delays.
Published in:	Proceedings of the 25th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2012) September 17 - 21, 2012 Nashville Convention Center, Nashville, Tennessee Nashville, TN
Pages:	3027 - 3037
Cite this article:	Li, Xingxing, "Improving Real-time PPP Ambiguity Resolution with Ionospheric Characteristic Consideration," Proceedings of the 25th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2012), Nashville, TN, September 2012, pp. 3027-3037.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In