Research On Theory And Application Of Real Time Precise Point Positioning

Real-time precise point positioning (RT-PPP) has been one of research focus in current Global Navigation Satellite System (GNSS) community, and will be one of the main techniques for real-time precise kinematic positioning in the present or even for the future. In this thesis, satellite clock interpolation error, precise high-rate satellite clock bias computation method, real-time cycle slip detection and repair algorithm for PPP and establishment regional RT-PPP system based on regional GPS Continuously Operating Reference Stations(CORS) network and International GNSS Service(IGS) Ultra-rapid product have been studied comprehensively. The main conclusions and contribution are as following:1) PPP use undifferenced observation for data processing. In PPP, satellite clock interpolation error can not be eliminated as differential GPS positioning, and then deteriorate PPP positioning precision. After analysis of satellite clock interpolation error, the conclusion that satellite clock interpolation error should be included in the PPP error source is drawn, in order to make error analysis theory of PPP more perfect.2) An improved observation stochastic model considering satellite clock interpolation error has been proposed. Experiments shown that this model could reduce the satellite clock interpolation error dramatically for larger time interval clock product (e.g.5 minutes), and then improve the positioning precision while has little improvement for small time interval product (e.g.30 seconds).3) Using high-rate satellite clock is the most effective method to mitigate satellite clock interpolation error for PPP. An improved high-rate satellite clock calculation method was proposed. The new method has several advantages, such as less unknown parameters, simple algorithm, high computation efficiency and high accuracy, and could be used to compute long duration high-rate satellite clock bias for centimeter accuracy PPP. But it can not be used for time application, e.g. time transfer.4) Quality control is one of the key factors for high precision GPS positioning. Anew cycle slip detection and repair algorithm suitable for RT-PPP was put forward. The new algorithm makes full use of precise GPS satellite orbit and clock to detect and repair phase cycle slips using the observations of current and previous one (or several) epoch only. Experiments show that new algorithm can repair cycle slips correctly and rapidly for RT-PPP and has wide range of applications as it can process observation data for receivers of poor accuracy P code observation and non-P code.5) An approach to establish regional RT-PPP system using regional GPS Continuously Operating Reference Stations (CORS) network data and IGS ultra-rapid (IGU) product is proposed. Experiments show that the approach can be used to do centimeter precision RT-PPP positioning, has numerous advantages, such as simple algorithm, low-cost system software and hardware, and can extend PPP service area several hundreds kilometer away from CORS.6) A GPS Precise Point Positoning software was developed using Fortran programming language. The software can conduct post-processing or real-time static and kinematic precise point positioning and compute precise high-rate satellite clock bias. Numerical Results show that the software can achieve high precision PPP positioning result comparable to current international research.