Long-Range RTK Positioning Using Virtual Reference Stations

Ulrich Vollath, Alois Buecherl, Herbert Landau, Christian Pagels and Bernhard Wagner

Abstract:	Long-Range RTK positioning is limited due to the growth of the influence of systematic errors with the baseline length. Especially during periods of high ionospheric influences the maximum distance from the reference station for RTK positioning might become as low as 10 km or less. The concept of virtual reference stations allows performing RTK positioning in reference station networks with distances of up to 40 km or more from the next reference station. The paper presents results from practical tests with a RTK system using standard reference stations and virtual reference stations. A special setup was used to allow the comparison of the two different RTK techniques using the identical GPS raw data stream by two different rovers. While the rover data was identical the RTCM data stream is different for the two RTK rovers, one is using the standard RTCM coming directly from the next reference station and the other is using the virtual reference station (VRS) data created from the GPS-Network. In that way we are able to compare the positioning results nicely with respect to accuracy, reliability and initialization time performance. It is shown that the use of VRS data results in a significant performance gain of the RTK rover system. While the rover with the standard RTCM data stream experiences a lot of problems with ambiguity initialization, the VRS rover has a far higher success rate a significantly less time for ambiguity initialization. The VRS rover reaches accuracies of 2 cm in horizontal coordinates with a high reliability on distances of up to 40 km.
Published in:	Proceedings of the 13th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2000) September 19 - 22, 2000 Salt Palace Convention Center Salt Lake City, UT
Pages:	1143 - 1147
Cite this article:	Vollath, Ulrich, Buecherl, Alois, Landau, Herbert, Pagels, Christian, Wagner, Bernhard, "Long-Range RTK Positioning Using Virtual Reference Stations," Proceedings of the 13th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2000), Salt Lake City, UT, September 2000, pp. 1143-1147.
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