A Proposal for Standardized Network RTK Messages

Bryan Townsend, Keith Van Dierendonck, Janet Neumann, I. Petrovski, S. Kawaguchi and H. Torimoto

Abstract:	Over the last few years, large advances have been made in RTK positioning using a network of reference stations (RS’s). Initially the concept involved having the rover receiver select the nearest RS and use it for differential positioning. More advanced techniques use the network of RS’s to compute the trend in atmospheric and orbital errors over the area covered by the RS’s [1][2][3]. The computed errors are then used to correct the RS data broadcast to the rover receiver. This technique allows the RS’s to be spaced further apart without degrading the positioning performance of the rover receiver. Virtual reference stations (VRS’s) are often used to reduce the baseline distance to the rover receiver. The VRS data is also corrected for the users location. The use of VRS’s is necessary since most RTK algorithms used in today’s receivers make decisions based on baseline distance. The drawback to VRS approach is the user receiver does not know it is on a network. This means the receiver may be making sub-optimal decisions in the RTK processing. In recent RTCM SC-104 committee meetings it was agreed that a standard should exist for Network RTK corrections messages. A “Network RTK Correction Working Group” was formed to develop such messages. This paper makes a proposal for some messages and shows results from implementing these messages in a real- time network. The Network RTK messages proposed here are should meet the specifications of most Network RTK software. The messages are compact and will economize the use of broadcast bandwidth. These messages are implemented in the MultiRef software and are being used for broadcast. These messages are a proposal. Feedback and discussion on these is expected and encouraged. It is hoped that the result of this effort is set of standardized Network RTK messages that are independent of the Network RTK software and GPS receivers alike.
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:	1871 - 1878
Cite this article:	Townsend, Bryan, Van Dierendonck, Keith, Neumann, Janet, Petrovski, I., Kawaguchi, S., Torimoto, H., "A Proposal for Standardized Network RTK Messages," 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. 1871-1878.
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