Evaluation of Positioning Accuracy with Differential GPS/GLONASS

Hideki Yamada, Tomoji Takasu, Nobuaki Kubo, Akio Yasuda

Abstract:	Combined GPS and GLONASS is expected to enhance reliability, availability, and integrity of satellite navigation. In practice, however, the point positioning accuracy using both the GPS and GLONASS pseudorange measurements tends to be worse than that of GPS-only solutions mainly because of higher Signal-In-Space (SIS) User Range Error (URE) of GLONASS observations, which include broadcast ephemeris errors and satellite clock bias. Differential GPS (DGPS) is an effective way to correct SIS-URE from pseudorange measurements and improve the positioning accuracy. Combined DGPS and differential GLONASS, however, is not straight forward and requires estimating the system time difference between GPS and GLONASS. After successful range corrections and the system time difference estimation in DGPS/GLONASS, multipath is one of the dominant error sources in a pseudorange measurement. In this paper, we estimated multipath errors using a linear combination of dual-frequency code and carrier phase measurements and applied them to correct the remaining errors in DGPS/GLONASS measurements. The proposed method was tested in an urban canyon environment that provides very poor satellite geometry. The results showed that the multipath was the dominant error source in such situation, and the proposed method worked efficiently to improve the positioning accuracy.
Published in:	Proceedings of the 21st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2008) September 16 - 19, 2008 Savannah International Convention Center Savannah, GA
Pages:	2221 - 2226
Cite this article:	Yamada, Hideki, Takasu, Tomoji, Kubo, Nobuaki, Yasuda, Akio, "Evaluation of Positioning Accuracy with Differential GPS/GLONASS," Proceedings of the 21st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2008), Savannah, GA, September 2008, pp. 2221-2226.
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