| With the growing demand for mobile devices,low-cost single-frequency receivers occupy the main GNSS market.Therefore,the precision point positioning technology based on single-frequency receiver has attracted more and more attention.In this paper,the GNSS single frequency PPP algorithm is implemented on the C++ platform.Combined with the MGEX tracking station and measured data,the data quality,positioning accuracy and convergence speed of single-frequency PPP of GPS,Galileo and BDS are compared,and analyze the application effects of single-frequency PPP under different conditions.The research contents and results of this paper are as follows:(1)29 MGEX stations evenly distributed all over the world are selected to analyze the data integrity and SNR quality of each frequency point.The statistical results show that the integrity rate of L5 frequency points is only 46.88%,and the integrity rate of E1,L1,L2,B1 I and B3 I frequency points is more than 85%;The SNR of the three systems is better than 30 db·HZ and has strong signal strength.(2)A set of single-frequency PPP processing algorithm is realized.MGEX station is used to carry out single system and multi system single-frequency PPP positioning experiments,and the stations are grouped according to latitude to explore the positioning performance of single-frequency PPP in different latitudes;Then,the measured receiver and smartphone data are further explored.The experimental results show that:The positioning accuracy and convergence speed of GPS and Galileo are better than BDS as a whole.The static positioning accuracy of single system is in centimeter level,and the elevation positioning accuracy of individual frequency points is in decimeter level;The grouping experiments of stations at different latitudes show that the positioning accuracy of middle latitudes is better than that of high and low latitudes.Compared with the single system,the static positioning accuracy of multi system single-frequency PPP is improved by about 60%,and the kinematic positioning accuracy is improved by about 35%.The positioning performance of smart phones is poor,and the static and kinematic positioning accuracy are decimeter and meter respectively.(3)In order to explore the impact of different environmental conditions on single-frequency PPP,the positioning performance of single-frequency static PPP in ionospheric active period,haze period and typhoon period is experimentally analyzed.The results show that: the positioning accuracy of GNSS can be reduced by 0.046 cm and the convergence time can be extended by 5min;In haze weather,the elevation positioning accuracy decreases significantly,up to 0.051 m,and the convergence time can be extended by up to 5min;In typhoon weather,the positioning accuracy of GNSS can be reduced by 0.015 m at most,and the convergence time can be extended by 30 min at most.This paper has 59 figures,33 tables,and 103 references... |
