A Study On The Algorithms Of BDS And GNSS Precise Point Positioning

Recently, our national BeiDou satellite navigation system(BDS) has been officially available in Asia Pacific area, and it can offer normal PNT service which is short for Position、Navigation、Timing, and the European Union satellite navigation system called Galileo has also more than four satellites being normally operating. With the global GPS system and GLONASS system, the number of the operating satellites has been over 75. Comparing with the mature GPS and GLONASS system, our national BDS system is still in its early stage of development, and its navigation and positioning performance needs further verification and test, at the same time between BDS and other system compatible with interoperability is important problem to be solved at present. Based on this, this paper studies BDS single system of dynamic and static precise point positioning(PPP) technology and BDS/GNSS system integration technology of PPP.The main contents are as follows:1. This paper introduces the observation equation and error sources of precise point positioning, and it does some detailed research and analysis about the processing schemes of error correction of PPP data processing.2. Taking into account positioning monitoring of the slow variable carrier, it can obtain relatively precise priori coordinate information, at the same time the state of slow variable carrier may be considered as stationary state in a fixed length of time(e.g. 2 hours). Based on this, we propose a algorithm of additional priori coordinate information and epoch constraint information dynamic PPP. Based on prior information and epoch constraints information rational use, significantly improving the dynamic PPP positioning accuracy of the slow variable carrier;3. This paper proposes an improved correction information based on the base station regional augmentation precise point positioning algorithm. The algorithm still uses the traditional PPP ionosphere-free combined observations model, the process of solution is consistent with the traditional PPP model, but it can obtain the approximate equivalent results with the differential positioning and conventional base station corrections of Precise Point Positioning, and the improved base station corrections information without loss of positioning accuracy and convergence time is more favorable for data transmission and short-term forecast information;4. We research on the multi-system integration of positioning theory and method of parametric equations reduction method and propose a algorithm of multi-system integration of precise point positioning based on robust estimation and Helmert variance component estimation, and this algorithm use variance component estimation to ensure weights adaptation among different systems, while using the robust estimation method eliminates and weakens the influence of gross errors within a single system. Finally we use BDS / GLONASS / GPS measured datum of the three systems to verify the performance and accuracy of the proposed method.