Mathematical models used in GPs Models needed for millimeter level positioning Review of basic estimation frame Data(phase and pseudorange) are collected at a sampling interval (usually 30-sec) over an interval usually a multiple of 24-hours. Typically 6-8 satellites are observed simultaneously a theoretical model is constructed to model these data. this model should be as complete as necessary and it uses apriori values of the parameters of the model An estimation is performed in which new values of some of the parameters determined that minimize some cost function(e.g, RMS of phase residuals) Results in the form of normal equations or covariance matrices may be combined to estimate parameters from many days of data (Dong D, T. A Herring, andR. W. King, Estimating egion al Deformation from a Combination of Space and terrestrial Geodetic Data, J. Geodesy, 72, 200-214, 1998 04/17/02 12.540Lec1804/17/02 12.540 Lec 18 3 Mathematical models used in GPS • Models needed for millimeter level positioning • Review of basic estimation frame: – Data (phase and pseudorange) are collected at a sampling interval (usually 30-sec) over an interval usually a multiple of 24-hours. Typically 6-8 satellites are observed simultaneously – A theoretical model is constructed to model these data. This model should be as complete as necessary and it uses apriori values of the parameters of the model. – An estimation is performed in which new values of some of the parameters are determined that minimize some cost function (e.g., RMS of phase residuals). – Results in the form of normal equations or covariance matrices may be combined to estimate parameters from many days of data (Dong D., T. A. Herring, and R. W. King, Estimating Regional Deformation from a Combination of Space and Terrestrial Geodetic Data, J. Geodesy, 72, 200–214, 1998.)