Generation and Validation of GPS Satellite Orbital Covariance Matrices for Integrity Determination

Yongchao Wang, Yanming Feng, Rui Li

Abstract:	The paper explores methods and algorithms used to generate, apply and validate covariance matrices of GPS orbits in the context of position solution. In general, the research of satellite orbit error is threefold. The first is covariance matrix generation of satellite orbit error which may include systematic orbit biases or sudden changes in the orbit solution. The next is to determine and test “Bad” satellites which have large orbit error with the highest probability. The third is to validate what integrity benefit can be obtained if orbit covariance matrices are considered in estimation of user positioning solutions. However, the existing integrity studies have not addressed these issues directly yet. The paper starts with a general description of a satellite integrity orbit monitoring problem and computing orbital covariance matrices from different orbital solutions in real time. Next the paper describes covariance propagations in the least square navigation solutions. The method to determine ‘bad’ satellites is then analyzed preliminarily. Experimental analysis with GPS orbits of several hours and several widely distributed ground GNSS stations are performed to demonstrate the proposed integrity concepts and determination algorithms. The results have shown that the effects of large broadcast orbital errors on the user solutions can indeed be effectively reduced by considering the orbital covariance matrices estimated.
Published in:	Proceedings of the 24th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2011) September 20 - 23, 2011 Oregon Convention Center, Portland, Oregon Portland, OR
Pages:	2723 - 2731
Cite this article:	Wang, Yongchao, Feng, Yanming, Li, Rui, "Generation and Validation of GPS Satellite Orbital Covariance Matrices for Integrity Determination," Proceedings of the 24th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2011), Portland, OR, September 2011, pp. 2723-2731.
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