Precise Estimation of Absolute Ionospheric Delay Based on GPS Active Network

Wu Chen, Congwei Hu, Shan Gao,Yongqi Chen, Xiaoli Ding, Simon and Chi-wo Kowk

Abstract:	A new algorithm for absolute GPS ionospheric delay estimation is proposed in this paper. This algorithm is mainly based on GPS carrier phase observation. Instead of using geometry-free code or carrier phase observation directly, we first determine single difference (SD) ambiguity N1 and N2 by using ionosphere-free ambiguity obtained at one station with the precise point positioning (PPP) techniques and wide lane (WL) ambiguity. Thus only one geometry-free ambiguity bias is remained in all observations for one station. If a GPS network is used, the double difference (DD) ambiguity can be taken as an additional constraint. In our method, the information between different satellites and between stations are considered thus not only the number of constant parameters are reduced but also the stability of absolute ionosphere modeling and the accuracy of the estimation are improved. 24-hours GPS data from a GPS network are used to evaluate the models presented in the paper.
Published in:	Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004) September 21 - 24, 2004 Long Beach Convention Center Long Beach, CA
Pages:	420 - 427
Cite this article:	Chen, Wu, Hu, Congwei, Gao, Shan, Chen, Yongqi, Ding, Xiaoli, Simon,, Kowk, Chi-wo, "Precise Estimation of Absolute Ionospheric Delay Based on GPS Active Network," Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004), Long Beach, CA, September 2004, pp. 420-427.
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