Methods of Filtering in Instant Ambiguity Resolution and Their Application to RTK-OTF Positioning

Alexander Fridman

Abstract:	It is known that redundant phase measurements obtained from both GPS and GLONASS systems make it possible to implement instant, or single-epoch, phase ambiguity resolution, and thus to achieve centimeter-level accuracy in RTK-OTF positioning, even if cycle slips exist in phase measurements. However, very high accuracy of phase measurements is necessary, and this is not always provided in real environment because of multipath, ionospheric errors, etc. In this paper properties of phase measurements will be analyzed, mathematical models will be introduced, and corresponding algorithms will be derived for incorporation of several epoch data into the RTK-OTF solution. The algorithms are experimentally investigated and compared with the known ambiguity resolution algorithms. Comparison results indicate significant improvement in reliability of instant RTK ambiguity resolution. For example, 98% success rate has been achieved with L1 raw measurements of only 11 visible satellites of GPS+GLONASS system. Extensive experiments were conducted illustrating a possibility to gain reliable instant ambiguity resolution with the use of appropriate filtering with only 10 or more visible satellites. The proposed algorithms will be useful not only for single-frequency GPS+GLONASS receivers, but for (L1+L2) GPS or (L1+L2) GLONASS receivers as well, especially in bad muhipath environment.
Published in:	Proceedings of the 11th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1998) September 15 - 18, 1998 Nashville, TN
Pages:	381 - 388
Cite this article:	Fridman, Alexander, "Methods of Filtering in Instant Ambiguity Resolution and Their Application to RTK-OTF Positioning," Proceedings of the 11th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1998), Nashville, TN, September 1998, pp. 381-388.
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