Single Frequency Ionosphere Determination Using GPS

Michael L. Trethewey, Ivan Catchpole, and Ashwini Hansla

Abstract:	There has been much interest in alternate and improved methods of identifying ionosphere delays for users of C/A code GPS. A Wide Area Differential GPS service is one way in which users can obtain better estimates than those provided by GPS in the navigation message. The development of single frequency determination ionospheric delay algorithms is another. In this paper it is shown how single frequency measurements may be used to provide a real-time estimate of ionospheric delays. The basis and theory have been developed elsewhere, and the authors have applied this using data collected from a number of sites widely distributed around the Atlantic Ocean; north and south. Two algorithms have been developed and the results presented. The first is a simplistic batch algorithm that has obvious limitations but nevertheless has served to prove the feasibility of the approach and identify difficulties. The second algorithm is a real- time Kalman filter based estimator. Results from both algorithms are compared with the broadcast GPS message. These demonstrate the feasibility of a real-time ionosphere delay estimator that also achieves real-time identification of carrier phase ambiguities.
Published in:	Proceedings of the 6th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1993) September 22 - 24, 1993 Salt Palace Convention Center Salt Lake City, UT
Pages:	1373 - 1381
Cite this article:	Trethewey, Michael L., Catchpole, Ivan, Hansla, Ashwini, "Single Frequency Ionosphere Determination Using GPS," Proceedings of the 6th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1993), Salt Lake City, UT, September 1993, pp. 1373-1381.
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