GALILEO/Modernized GPS: A New Challenge to Network RTK

Ulrich Vollath, Richard Patra, Xiaoming Chen, Herbert Landau, Timo Allison

Abstract:	Network RTK in local or regional reference networks has been proven as an efficient technology for high accuracy GPS positioning over the last few years. Comparing with single base RTK, the advantage of network RTK is that large portions of ionospheric and geometric errors are removed through network corrections. Hence network solutions increase the reliability and productivity of ambiguity resolution and the positioning accuracy of rovers working in the system. Several preliminary studies have demonstrated that with the third/fourth frequency available from GALILEO and modernized GPS, the reliability and productivity of single base OTF (on the fly) initializations at the rover increase dramatically when comparing with a dual frequency RTK system. So, the question arises: will network RTK become obsolete when GALILEO and modernized GPS are operational because of the high performance of single base RTK? What can network RTK benefit from GALILEO and modernized GPS? It is a well-known fact that the initialization performance of an RTK system decreases significantly with higher ionospheric activity. Furthermore, the geometric errors (including troposphere and orbit), which are not frequency-dependent, will not be removed by adding more frequencies. In other words, positioning accuracy will be improved only marginally by mitigating multipath due to the availability of more observables. This paper demonstrates two and three carrier RTK performance in various single-base and network scenarios. Simulation studies show that in the presence of a reference station network, RTK initialization and positioning accuracy are improved considerably.
Published in:	Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004) September 21 - 24, 2004 Long Beach Convention Center Long Beach, CA
Pages:	2855 - 2863
Cite this article:	Vollath, Ulrich, Patra, Richard, Chen, Xiaoming, Landau, Herbert, Allison, Timo, "GALILEO/Modernized GPS: A New Challenge to Network RTK," Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004), Long Beach, CA, September 2004, pp. 2855-2863.
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