Improving a Multi-Reference GPS Station Network Method for OTF Positioning in the St. Lawrence Seaway

L. P. Fortes, M. E. Cannon, S. Skone and G. Lachapelle

Abstract:	Real time kinematic GPS positioning is able to provide cm-level positioning accuracies, as long as the carrierphase ambiguities are resolved on-the-fly (OTF) to integer values. Classical methods are based on differential positioning using a single fixed reference station located in the vicinity of the rover. The maximum distance allowed between the reference station and user is generally limited by the effects of the atmosphere and orbit. A novel and unique method was developed at the University of Calgary, which uses all available reference stations to optimally generate regional code and carrier phase corrections, which can be transmitted to the user in order to resolve integer ambiguities OTF over the region. One of the major advantages of this method is to increase the coverage under which successful OTF ambiguity resolution is possible. This method has been tested using several data sets collected under various atmospheric conditions in the world. The improvement brought by the method was very good in practically all cases. Further research has been developed at the University of Calgary towards optimizing the method in order to maximize the improvement obtained by it. This new approach, also using least square collocation, separately models the errors into ionospheric, tropospheric and satellite orbital components. An additional effort has been carried out in terms of modeling the ionosphere into directional components, which has shown to be relevant under high ionospheric conditions. Results of the enhanced method are presented using data collected in the St. Lawrence Seaway region, Canada, and compared with the ones obtained modeling the total error in L1 and Wide Lane carrier phases.
Published in:	Proceedings of the 14th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2001) September 11 - 14, 2001 Salt Palace Convention Center Salt Lake City, UT
Pages:	404 - 414
Cite this article:	Fortes, L. P., Cannon, M. E., Skone, S., Lachapelle, G., "Improving a Multi-Reference GPS Station Network Method for OTF Positioning in the St. Lawrence Seaway," Proceedings of the 14th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2001), Salt Lake City, UT, September 2001, pp. 404-414.
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