Trimble RTX, an Innovative New Approach for Network RTK

Xiaoming Chen, Timo Allison, Wei Cao, Kendall Ferguson, Simon Grunig, Victor Gomez, Adrian Kipka, Jan Kohler, Herbert Landau, Rodrigo Leandro, Gang Lu, Ralf Stolz, Nick Talbot

Abstract:	The concept of the Virtual Reference Station (VRS) for network RTK was introduced for real-time positioning in the late 90s. In this particular concept the atmospheric error sources and orbit errors are mitigated via the use of appropriate error models based on multiple base stations. The VRS technology requires bidirectional communication to allow the VRS server to generate data streams for specific rovers in a standardized data format such as RTCM or CMR. As an option for VRS, the RTCM SC104 committee has standardized a broadcast network RTK data format which is often referred to as Master-Auxiliary Concept (MAC). This data format consists of the transmission of observational data from multiple stations to the rover, where the carrier phase ambiguities have been leveled between the different stations of the network. One of the limitations of the RTCM MAC format is that the number of stations that can be included in the data stream is limited. Thus, while this type of correction does not require a bidirectional communication link, it still suffers the effect of potential connectivity limitations. Similarly to the VRS concept, the MAC concept is not readily suitable for applications in areas with limited connectivity. The paper introduces a new technology called RTX, which overcomes the limitations of the existing solutions and is now available as part of the Trimble CenterPoint RTX service. Trimble RTX is capable of providing cm-accurate positioning solutions in real-time with initialization times of less than a minute for unprecedented coverage areas. The solution utilizes a broadcast transmission with extremely optimized bandwidth, supporting GPS and GLONASS, and supports large networks with 100 and more stations. The authors describe in detail the overall concept of the server software, the communication via L-band satellite link from a geostationary satellite or via NTRIP (RTCM, 2011b) and the RTX rover implementation. Performance results from static and dynamic field testing demonstrate the overall Trimble CenterPoint RTX system performance.
Published in:	Proceedings of the 24th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2011) September 20 - 23, 2011 Oregon Convention Center, Portland, Oregon Portland, OR
Pages:	2214 - 2219
Cite this article:	Chen, Xiaoming, Allison, Timo, Cao, Wei, Ferguson, Kendall, Grunig, Simon, Gomez, Victor, Kipka, Adrian, Kohler, Jan, Landau, Herbert, Leandro, Rodrigo, Lu, Gang, Stolz, Ralf, Talbot, Nick, "Trimble RTX, an Innovative New Approach for Network RTK," Proceedings of the 24th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2011), Portland, OR, September 2011, pp. 2214-2219.
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