Ionospheric Effect Modelling for Single Frequency GPS Users

Weigen Qiu, Gérard Lachapelle, and M. Elizabeth Cannon

Abstract:	The code-carrier phase divergence property of the ionosphere at GPS frequencies is used to derive the group delay or, alternatively, the carrier phase advance, using single frequency observations. The model used to separate the carrier phase ambiguity from the initial ionospheric delay is reviewed. The results of tests conducted with P code Ll and narrow correlator spacing C/A code Li receivers are presented and analysed. The latter receiver type delivers pseudorange observations at the same level of accuracy as that of P code Ll observations. These results show that 90% of the relative effect of the ionosphere is removed using the divergence method. The initial delay can be estimated with an accuracy of a few metres. The method is also tested to estimate the effect of the ionosphere on baseline determination. Double difference carrier phase observations are used and only the relative effect of the ionosphere is required in this case. The results show that most of the ionospheric effect is removed. The conditions which have to be met to apply the divergence method successfully are summarized in the conclusions.
Published in:	Proceedings of the 1994 National Technical Meeting of The Institute of Navigation January 24 - 26, 1994 Catamaran Resort Hotel San Diego, CA
Pages:	911 - 919
Cite this article:	Qiu, Weigen, Lachapelle, Gérard, Cannon, M. Elizabeth, "Ionospheric Effect Modelling for Single Frequency GPS Users," Proceedings of the 1994 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 1994, pp. 911-919.
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