GPS Network RTK Performance Under Very Active Ionospheric Conditions

Ning Luo, Thihong Diep Dao, Gérard Lachapelle and Elizabeth Cannon

Abstract:	The traditional RTK method only needs one reference station, and is capable of providing cm accuracy for static positioning and dm accuracy for kinematic positioning under normal atmospheric conditions when the interantenna distance is less than approximately ten kilometres. However, under localized high atmospheric activity, the increase in the residual differential errors can degrade position accuracy substantially. An effective method to improve position accuracy under such circumstance is to use network RTK. This method uses a network of GPS reference stations to model the atmospheric conditions over the geographic region covered by the network, and then to provide users with corrections of spatially correlated errors. Applying these corrections can reduce the residual double differenced carrier phase errors, thus improving the ambiguity resolution and the accuracy of the rover’s position. The differential ionospheric errors have a major impact on the improvement provided by the network RTK method. Previous research has shown that the network method can yield significant improvement under normal ionospheric conditions. To have a thorough understanding of the capabilities and limitations of the network RTK method, this paper focuses on evaluating its performance under very active ionospheric conditions. Results of this method and the traditional RTK method are compared to assess the quality of the network corrections. After comparison, it is found that in a medium scale network, the network RTK method fails to provide more accurate solutions under such harsh ionospheric conditions. Some data processing strategies are recommended to improve rover receiver positioning.
Published in:	Proceedings of the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2005) September 13 - 16, 2005 Long Beach Convention Center Long Beach, CA
Pages:	2531 - 2539
Cite this article:	Luo, Ning, Dao, Thihong Diep, Lachapelle, Gérard, Cannon, Elizabeth, "GPS Network RTK Performance Under Very Active Ionospheric Conditions," Proceedings of the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2005), Long Beach, CA, September 2005, pp. 2531-2539.
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