Impact of temporal correlations on GPS-derived relative point positions

Due to the steady progress in global positioning system (GPS) technology and methods of data evaluation, it is possible to obtain highly precise relative point positions also for extensive geodetic networks. However, some limiting influences such as temporal correlations of observational data are neglected in most of the GPS processing programs. Therefore, it is necessary to consider the impact of these neglected correlations on the coordinates and their accuracy measures. In this paper the sensitivity and reliability of GPS positioning over long baselines when temporal correlations are modelled with the aid of a correlation function are discussed. The implementation in the variance-covariance matrix and the subsequent evaluation process require a considerable amount of computing time and memory. Therefore it is necessary to use appropriate numerical methods such as approximated matrix inversion in order to reduce the numerical requirements. After the description of the methodical and numerical handling of the temporal correlations. exemplary results are given to illustrate the effects on position and accuracy of GPS stations.