Auulication of SCORE Techniques to Improve Ionospheric Observations

Gregory Bishop, Andrew Mazzella and Elizabeth Holland

Abstract:	Self-Calibration Of pseudoRange Error (SCORE) techniques [l] can improve accuracy of ionospheric total electron content (TEC) covering 10 degrees of latitude from one station. SCORE uses self-consistency constraints on the TEC data to calibrate a two-frequency GPS receiver system for the sum of system contributions to pseudorange error. These errors come from components such as receiver, pre-amp, antenna and satellite transmitters. Frequent application of SCORE can thus reduce system component drift contributions to TEC measurement error and improve long-term measurement accuracy. SCORE was first developed out of data presentation techniques that permitted a single GPS station to simulate zenith TEC monitoring from stations spaced over 10 degrees of latitude, along the same longitude [2]. Applying these presentation techniques in conjunction with SCORE allows accurate parallel monitoring of the diurnal TEC behavior over this wide latitude region from a single station. Typically, in well-calibrated data, latitudinal TEC gradients of less than 1 TEC unit per degree may be identified. We will present results of SCORE application studies showing variation in TEC accuracy with the time interval and the number of satellites used in the process, and the effects of improved calibration on the observable TEC morphology in widely-spaced latitude regions. We will also examine how these results differ in high-latitude and equatorial regions, where the diurnal behavior of the ionosphere can be radically different from over CONUS. We will also present results from an initial application of the SCORE process to single-frequency measurements, compared with simultaneous two-frequency TEC data. These initial tests show potential for useful single- frequency ionospheric TEC observation.
Published in:	Proceedings of the 8th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1995) September 12 - 15, 1995 Palm Springs, CA
Pages:	1209 - 1218
Cite this article:	Bishop, Gregory, Mazzella, Andrew, Holland, Elizabeth, "Auulication of SCORE Techniques to Improve Ionospheric Observations," Proceedings of the 8th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1995), Palm Springs, CA, September 1995, pp. 1209-1218.
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