Analysis of the Ionosphere Regional Model (Mod_Ion) During the Period of Maximum Solar Activity: A Case Study in Brazil

Paulo O. Camargo, Joao F. G. Monico and Marcelo T. Matsuoka

Abstract:	Nowadays, one of the main drawbacks of the GPS accuracy for L1 users is the ionospheric refraction, which affects, mainly, the point positioning and ambiguity resolution in the relative positioning of medium and long baselines. The error associated with the ionospheric refraction depends on the Total Electrons Content (TEC) present in the ionospheric layer. Some techniques and models have been developed to estimate these systematic effects using data collected with double frequency GPS receivers. In Brazil, a regional model of the ionosphere (Mod_Ion) was developed, that makes use of GPS data collected at the active stations of RBMC (Brazilian Network for Continuous Monitoring of GPS satellites). In this model the ionosphere is represented analytically by a Fourier series type and the satellites and receivers interfrequency biases can be constrained or estimated in a bath adjustment by MMQ. The data input can be the pseudo range; pseudo range filtered by carrier phase or the carrier phase observables, collected on both carriers. Quality control based on the Chi-square (÷2) statistical test was implemented in the order to perform the quality analysis of the adjustment, as well as to test the significance parameters of the series. The objective of this paper is to test the Mod_Ion performance, through the discrepancies between the cartesian coordinates “ground truth” and the estimated ones by point positioning, using pseudorange corrected of the ionosphere effects, computed from the proposed model. The experiments will be accomplished with data collected during the period of maximum solar activity (2000 - 2001), mainly after the turn off the Selective Availability (SA). Tests carried out showed that this model provides, in relation to the point positioning carried out without correction, error reduction of the order of 86.1%, providing metric accuracy for most of the cases.
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:	2525 - 2530
Cite this article:	Camargo, Paulo O., Monico, Joao F. G., Matsuoka, Marcelo T., "Analysis of the Ionosphere Regional Model (Mod_Ion) During the Period of Maximum Solar Activity: A Case Study in Brazil," 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. 2525-2530.
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