Real-time Combination of GNSS Orbit and Clock Correction Streams Using a Kalman Filter Approach

Leos Mervart and Georg Weber

Abstract:	Within the framework of the Real-Time IGS Working Group, a number of Analysis Centers (ACs) estimate GNSS satellite orbit and clock corrections to broadcast ephemeris. Corrector streams are encoded in RTCM ‘State Space Representation’ (SSR) messages and disseminated over the Open Internet using the NTRIP transport protocol. The major application is real-time ‘Precise Point Positioning’ (PPP) which is possible nowadays with accuracy of one decimeter after about 15 minutes or less convergence time. As availability and reliability are of enormous significance in the real-time positioning area, an effort has been made to develop a combination technique for ephemeris correctors based on the application of a Kalman filter. This new combination procedure is supposed to be beneficial especially with regards to handling outages and offsets in individual AC solutions. The final goal is the provision of a reliable real-time GNSS combination product free from outages and outliers. The implementation in an Open Source tool combines, encodes, uploads and saves correctors coming from any number of service providers. This paper describes the new Kalman filter combination technique and presents some real-time test results.
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:	707 - 711
Cite this article:	Mervart, Leos, Weber, Georg, "Real-time Combination of GNSS Orbit and Clock Correction Streams Using a Kalman Filter Approach," Proceedings of the 24th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2011), Portland, OR, September 2011, pp. 707-711.
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