A New Model for Retrieving Slant TEC Corrections for Wide Area Differential GPS

L. Sparks, B.A. Iijima, A.J. Mannucci, X. Pi and B.D. Wilson

Abstract:	To provide delay corrections to single frequency users, wide area differential GPS systems depend upon accurate determination of ionospheric total electron content (TEC). This paper describes a new model for retrieving ionospheric calibrations from sets of GPS measurements. A distinctive feature of this approach is the simultaneous retrieval of multiple parameters from the GPS data, representing various integrated quantities in addition to vertical TEC. Instead of converting each slant TEC measurement to a single associated vertical TEC value, the simplest version of this model treats each slant TEC measurement as a linear combination of two-parameters, i.e., integrals of the electron density along raypaths at two or more fixed, fiducial elevation angles. A four-parameter version of the model includes linear terms that correct for horizontal gradients along the raypath of each measurement. Analysis and initial retrieval results indicate that even the two-parameter model produces slant TEC calibrations that are significantly more accurate than those generated using other current models, especially for measurements at low elevation angle, where errors from other approaches tend to be largest.
Published in:	Proceedings of the 2000 National Technical Meeting of The Institute of Navigation January 26 - 28, 2000 Pacific Hotel Disneyland Anaheim, CA
Pages:	464 - 473
Cite this article:	Sparks, L., Iijima, B.A., Mannucci, A.J., Pi, X., Wilson, B.D., "A New Model for Retrieving Slant TEC Corrections for Wide Area Differential GPS," Proceedings of the 2000 National Technical Meeting of The Institute of Navigation, Anaheim, CA, January 2000, pp. 464-473.
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