Orbit Determination with NASA's High Accuracy Real-Time Global Differential GPS System

Ronald J. Muellerschoen, Angie Reichert, Da Kuang, Michael Heflin, Willy Bertiger and Yoaz Bar-Sever

Abstract:	GPS orbits and clocks are computed in real-time with data from NASA’s global GPS network. The accuracy of the GPS orbits and reference frame alignment to ITRF’97 is discussed. The dissemination of the global correction message is over the Internet, and a signal-in-space (SIS) is provided by America’s Inmarsat satellite. The SIS will soon expand for global coverage with Inmarsat’s ASPAC (Asia/Pacific) and EMEA (Europe/Africa) satellites yielding coverage over the entire globe between +/-75 degrees in latitude. The inherent latency in providing the corrections to the user through the geosynchronous satellites is shown to have little impact on true real-time positioning. Orbit determination, post-processed but filtered as if in real-time, of a low-Earth orbiter's GPS data using the real-time orbit and clock products will be presented. Anticipated plans call for uploading the code to a space-qualified receiver and performing orbit determination with the GPS differential global corrections as transmitted by the Inmarsat beams.
Published in:	Proceedings of the 14th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2001) September 11 - 14, 2001 Salt Palace Convention Center Salt Lake City, UT
Pages:	2294 - 2303
Cite this article:	Muellerschoen, Ronald J., Reichert, Angie, Kuang, Da, Heflin, Michael, Bertiger, Willy, Bar-Sever, Yoaz, "Orbit Determination with NASA's High Accuracy Real-Time Global Differential GPS System," Proceedings of the 14th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2001), Salt Lake City, UT, September 2001, pp. 2294-2303.
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