QZSS Augmentation Service Performance Analysis And Research On PPP-RTK Terminal Location Algorithm

One of the core and most concerned functions and services of the GNSS(Global Navigation Satellite System)are its positioning services.PPP-RTK(real-time kinematic precise point positioning)combines the advantages of both PPP(Precise Point Positioning)and RTK(Real-time Kinematic),and can achieve high precision,fast convergence,and broadcast location services with wide coverage,it can meet the growing demand for high-precision positioning in emerging and traditional industries in the current market,so PPP-RTK is the current research hotspot.It is of practical significance to study PPP-RTK technology.CLAS(Centimeter Level Augmentation Service)is a centimeter-level positioning augmentation service provided by QZSS(Quasi-Zenith Satellite System)on the L6 signal.The study of QZSS's enhancement service construction ideas and methods and analysis of its enhanced service performance can provide some experience for our satellite-based enhancement system construction.The key of PPP-RTK positioning is ambiguity resolution.Studying the partial ambiguity resolution strategy in the CLAS PPP-RTK terminal algorithm,shortening the solution time,and ensuring a high success rate are important content for achieving high-precision PPP-RTK positioning.The main work and conclusions of this thesis are as follows:(1)The bottlenecks and problems of the current high-precision positioning technology are summarized.With the GNSS original observation equation,the common processing methods for various errors on the satellite end,propagation path and user end in GNSS positioning are given.(2)The GPS and GPS+QZSS visible satellite number and PDOP maps were drawn through precise ephemeris,and the coverage of QZSS and the enhancement of GPS were analyzed.The results show that in the Asia-Pacific region,QZSS can increase 3 to 4 visible satellites,which can effectively reduce the PDOP(Position Dilution Of Precision).(3)This paper describes the functional model and stochastic model of the CLAS PPP-RTK terminal algorithm.The method of calculating the virtual observation value of a certain position from the correction information broadcast by the L6 information is introduced.The PPP-RTK positioning is realized by using the CLAS correction information,and the positioning results show that CLAS PPP-RTK can achieve fast ambiguity resolution.The positioning accuracy in horizontal and vertical directions are both less than 10cm;(4)The existing commonly used ambiguity resolution and validation methods are introduced,and different ambiguity subset screening methods are briefly reviewed and analyzed.The ambiguity subset selection method in this article is given.In the screening method,the ambiguity of the first time participate in the solution is considered to avoid the failure of the complete set ambiguity resolution caused by the poor observation quality of one single satellite.Experiments show that applying the partial ambiguity resolution strategy selected in this article to PPP-RTK positioning can improve the ambiguity resolution success rate,and obtain a more stable and highprecision positioning result.(5)Different system combination were set up to analyze the enhancement of the QZSS system on the positioning solution.The experimental results show that QZSS can improve the ambiguity fixation rate and positioning accuracy to a certain extent,especially in dynamic scenarios.