Research And Implementation Of GPS Precise Point Positioning Key Algorithms

GPS Precise Point Positioning(PPP) refers to a GPS data processing technology which can get the decimeter, cm or mm level positioning results by processing the un-differenced GPS pseudorange and phase observation data of a single station under the support of external high-precision GPS satellite orbit and clock bias products. Under the support of real-time precise satellite orbit and clock products, precise point positioning technology can realize real-time data processing to get real-time positioning results, referred to as real-time precise point positioning technology. The thesis presents a study of the PPP and precision satellite clock bias estimation methods, and the main works are as follows:The basic theories of GPS precise point positioning technology are introduced. Function models, stochastic models and various parameter models are introduced. Sequential adjustment, parameter weighted adjustment and Kalman filter theory are studied as well as their application feature in PPP.A variety of errors which can affect the accuracy of GPS PPP are analyzed in detail. These errors can be classified into errors related to satellite, errors related to signal transmission and errors related to GPS receiver. And the corresponding correction formula or correction measures are introduced too.The features of satellite clock bias interpolation error and the corresponding eliminating methods are studied. Firstly, the thesis studies the features of satellite clock bias interpolation error of PPP. Then, current methods to reduce the influence of satellite clock bias interpolation error are introduced and discussed, and on base of that, a stochastic modeling of observations considering satellite clock bias interpolation error is provided. And by experiment validation, prove the modeling to be true.Calculation methods of high sampling frequency satellite clock bias are studied. Firstly, current calculation methods of satellite clock bias are introduced and discussed, which include the conventional method, CODE method and Han method. Then, on base of Han method, a revised calculation method of high sampling frequency satellite clock bias is provided. And by experiment validation, prove the method to be true.Algorithm implementation is achieved based on the theoretical studies of PPP with object-oriented design technique using C++ programming language. Technical issues are solved such as interpolation of precise orbit and precise clock bias data, access to coordinates of perturbation celestials, error correction modeling et al. Error equation, stochastic models, parameter modeling and initial values of filtering are key researches during the programming and centimeter-level positioning result is achieved within the preliminary test.