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URTK: undifferenced network RTK positioning

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Abstract

Standard network RTK has been widely used since it was proposed in the mid-1990s. Rovers can obtain high-precision estimates of position by resolving double-differenced (DD) ambiguities. The focus of this study is a new undifferenced network RTK method, abbreviated as URTK hereafter, based on undifferenced (UD) observation corrections whose single-differenced (SD) ambiguities between satellites can be resolved in several seconds. The tools for studying the real-time realization of the new method are our developments of logical schemes that have the capability for the real-time modeling of a reference network and the instantaneous resolution of SD ionosphere-free (IF) ambiguities at a single station. This research demonstrates the validity of modeling regional UD-unmodeled errors on the ground and examines the maximum differences when compared to modeling the errors using ionospheric pierce points (IPP). With data collected at 48 stations from a CORS network in Shanxi Province (SXCORS) in China through May 21, 2010, the efficiency of the presented real-time strategies is validated using IGS final products in a postprocessing mode. The results verify that more than 83 % of SD wide-lane (WL) ambiguity can be fixed with 5 s of observation data, and the average resolution time of all the WL tests is 4.96 s. More than 80 % of SD L1 ambiguity can be fixed within 5 s, and the average resolution time is only 6.66 s. Rovers could gain rapidly centimeter-level absolute positioning service, comparable to standard network RTK. In addition, the URTK method transforms the fixed DD-ambiguities of the reference network into UD-ambiguities, and it does not need to set the base station and base satellite. Since the UD-corrections are modeled for each common visible satellite, it breaks down the connections between stations and satellites of the DD-corrections in the current network RTK. The UD-corrections can be broadcast by the base station and automatically selected and optimized by a rover during the real-time kinematic processing, thus avoiding ambiguity in reinitialization due to the change of reference, so it should be very flexible and useful for a wide range of applications.

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Acknowledgments

This work is supported by the National Natural Science Foundation of China (Grant No. 41004014), the Open Foundation of State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University (Grant No. 11P01), the China Postdoctoral Science Foundation (Grant No. 20110491191) and the 111 project (Grant No. B07037).

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Authors and Affiliations

  1. GNSS Research Center, Wuhan University, 129 Luoyu Road, Wuhan, 430079, China

    Xuan Zou, Weiming Tang, Chuang Shi & Jingnan Liu

  2. Helmholz Centre Potsdam, German Research Centre for Geosciences (GFZ), Telegrafenberg, 14473, Potsdam, Germany

    Maorong Ge

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  1. Xuan Zou
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  2. Maorong Ge
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  3. Weiming Tang
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  4. Chuang Shi
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  5. Jingnan Liu
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Correspondence to Weiming Tang.

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Zou, X., Ge, M., Tang, W. et al. URTK: undifferenced network RTK positioning. GPS Solut 17, 283–293 (2013). https://doi.org/10.1007/s10291-012-0277-5

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  • DOI: https://doi.org/10.1007/s10291-012-0277-5

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