Algorithm Reseach And Precision Analysis Of GNSS Precise Point Positioning

GNSS precise point positioning(PPP)technology requires only a single GNSS receiver to achieve centimeter-level positioning and navigation,and has broad application prospects and markets in military,traffic,engineering,and agricultural fields.The paper focuses on GPS+GLONASS+BDS PPP technology,focusing on PPP mathematical model and parameter estimation method,un-difference phase carrier observation for cycle slip detection and repair,robust Kalman filtering model,multi-system fusion model and precision analysis,etc.The main research contents and results are as follows:(1)For the problem of low success rate of cycle slip detection for un-difference observation data,especially under low sampling rate data or ionospheric active conditions.Based on the oblique path ionospheric delay prediction model to correct the observations of geometry-free phase combination.This study focus on the cycle slip detection and repair algorithm of GNSS dual-frequency observation data makes full use of the existing observation data to effectively improve the cycle slip detection and repair success rate.(2)For the influence of precise point positioning carrier and code unequal precision observations on the positioning results,this paper builds a GNSS robust Kalman filtering model based on the post-test residual vector.The results show that the proposed algorithm can effectively overcome the influence of carrier and code error on the positioning results.(3)Starting from two aspects of positioning accuracy and convergence speed,the effects of different system combinations and visible satellite numbers on the positioning results are studied.The results show that under the condition of a large number of satellites in a single GPS system,the introduction of other system data can significantly improve the positioning convergence speed of the dual system and the three system combination,but the positioning accuracy after convergence is not improved;when the single GPS system under the condition that the number of satellites is small,the introduction of other system data can significantly improve the positioning accuracy of the dual system and the three systems,and the positioning accuracy is also significantly improved.