An Empirical Approach for the Estimation of GPS Covariance Matrix of Observations

Rodrigo Leandro, Marcelo Santos, Karen Cove

Abstract:	"The covariance matrix of observations plays an important role in GPS data processing. For example, the weighting of the observations are based on the covariance matrix of the observations. The covariance matrix of the observations also plays a role in the estimation of the covariance matrix of the parameters. In this paper we present an empirical stochastic approach to create covariance matrices for GPS. Our approach aims at a more realistic and complete information about the stochastic behavior of GPS observations. As a result, improvement in quality and quality control of estimated coordinates using GPS measurements is obtained. In the present case study, baselines are processed using pseudoranges. The observations are considered as a time series after double differencing. The advantages and disadvantages of this empirical stochastic approach are explored, comparing it with more usual methods used for building observations covariance matrix. An analysis is made in terms of obtained coordinates where baselines between points with known coordinates were processed. Two baselines with length of approximately 2 km and 20 km were processed using three different weighting schemes for observations. In general, when the empirical approach was used a good improvement in the bias was obtained. The mean biases were at least 44 % smaller in the 2 km baseline case and at least 21 % in the 20 km baseline case. The model certainly brings improvement to the solution, with better results achieved for height determination, with improvements up to 72 % in mean bias for the shorter baseline."
Published in:	Proceedings of the 61st Annual Meeting of The Institute of Navigation (2005) June 27 - 29, 2005 Royal Sonesta Hotel Cambridge, MA
Pages:	1098 - 1104
Cite this article:	Leandro, Rodrigo, Santos, Marcelo, Cove, Karen, "An Empirical Approach for the Estimation of GPS Covariance Matrix of Observations," Proceedings of the 61st Annual Meeting of The Institute of Navigation (2005), Cambridge, MA, June 2005, pp. 1098-1104.
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