Research On BDS/GNSS Combined Real-time Precision Single-point Positioning Method

Compared with traditional differential positioning,Real-Time Precise point positioning(RT-PPP)has the advantages of convenient positioning,high accuracy,and no limitation by reference stations.Therefore,it has become a research hotspot in the field of satellite navigation.The continuous development of the Global Navigation Satellite System(GNSS)and the real-time satellite orbit and clock difference data provided by the International GNSS Service(IGS)have laid the foundation for the development of RT-PPP.Multi-system combined positioning obviously increases the number of available satellites in the positioning process,improves the satellite space constellation geometry,and helps improve the positioning accuracy,convergence time,and reliability of RT-PPP.In the application research of RT-PPP,the accuracy assessment of GNSS satellite real-time orbit and clock difference is not comprehensive enough;real-time product acquisition is difficult;the positioning accuracy of single system is low,the convergence time is long,and it is susceptible to interference from the observation environment.Based on the theory of RT-PPP,through multiple experiments to study the above problems,the main work is as follows:(1)This paper sorts out and expounds the mathematical model of RT-PPP,random model,parameter estimation method,error source and processing method,satellite real-time orbit and clock difference calculation principle.(2)The real-time orbit and clock difference parameters of GPS ? BDS ?GLONASS and Galileo satellites are calculated through the SSR correction number and broadcast ephemeris broadcast by CNES received in real time;The accuracy of the real-time product was evaluated;and the GPS single-system RT-PPP positioning experiment was conducted based on the estimated real-time product,IGU forecast product,and IGS final precision product.Contrast and analyze the impact of the real-time products calculated on RT-PPP positioning results.(3)Under the support of the basic theory of RT-PPP,the single-system positioning function model is improved,and the BDS / GNSS combined RT-PPP positioning observation equation is established;the specific data processing methods and processes in the calculation process are given;The program performs GPS?BDS?GPS+BDS?GPS+BDS+Galileo?GPS+BDS+GLONASS?GPS+BDS+GLONASS+ Galileo pseudo-dynamic positioning solution for 32 IGS-MGEX station data The experiment analyzes the number of available satellites,positioning accuracy,and convergence time of the positioning solution results.(4)GPS ? GPS+Galileo ? GPS+GLONASS+Galileo RT-PPP positioning experiments were carried out before and after the Galileo service interruption,and a comparative analysis of the positioning effect of the Galileo system before and after the service interruption was carried out.The positioning accuracy performance of the end.Through the above work,this article draws the following conclusions:(1)The accuracy evaluation results of the calculated satellite real-time orbit and clock difference show that: the GPS real-time orbit accuracy of GPS?GLONASS and Galileo calculated in this paper is equivalent to the IGU forecast orbit accuracy,and the real clock difference accuracy is better than the IGU forecast clock difference;BDS The accuracy of the satellite real-time orbit and clock difference are lower than the IGU forecast clock difference;(2)The single-system GPS RT-PPP positioning experiment results show that: RT-PPP based on the real-time products calculated in this paper can obtain higher positioning accuracy and convergence time,which is slightly better than RT-PPP under IGU forecast products,but relative to The accuracy of RT-PPP of IGS final precision products needs to be improved.This also verifies the reliability of real-time orbit and clock error accuracy assessment.(3)BDS/GNSS combined RT-PPP positioning experiment results show that: the combined positioning method adopted in this paper can effectively increase the number of available satellites,improve the satellite space constellation geometry,improve RT-PPP positioning accuracy and accelerate the convergence speed.(4)RT-PPP positioning experiment results before and after Galileo service interruption show that: before and after service interruption,Galileo has improved the convergence time and positioning accuracy of GNSS combined RT-PPP,and the system can still be at the positioning end after service restoration Provide stable and reliable service.