Research On Precise Point Positioning Based On Unscented Kalman Filter

GPS Precise Point Positioning(PPP)using a single receiver with fixing precise satellite orbits and clocks can locate independently on a global scale.It can directly obtain decimeter-level to millimeter-level accuracy coordinates.PPP has widely used in the field of crustal deformation monitoring,high-precision navigation and positioning,LEO satellite orbit determination,meteorology,precise time transferring and so on because of simple operation?the implementation of freedom in field surveying and simple data processing.The paper round the data processing cycle of precise point positioning and establish parameter estimation method of PPP based on Unscented Kalman Filter(UKF).The main contents as follows:(1)The principle of GPS position principle and UKF are researched.At the same time,we have tested the degree of lagrange algorithm for interpolation of precise satellite orbits and the method of detecting cycle slips.(2)The symmetrical sampling is highest and fastest by simulation of symmetrical sampling,minimal skew simplex sampling and spherical simplex sampling.(3)The algorithm of PPP is established based on UKF.At the same time,we have contrasted with Least Squares(LS)and Extended Kalman Filter(EKF).The results show that UKF has the highest precision and the convergence rate is the same as EKF.(4)A adaptive factor is introduced in forgetting factor UKF solves the fall of ability for system mutation in filter convergence.The results show that this method improve the ability of track to prevent filter divergence and raise the problem of lower accuracy by forgetting factor.