Research On Real-time Ionospheric Delay Modeling And Differential Code Bias Solution Analysis Of GNSS

As the requirement of high precision real-time position and positioning accuracy is becoming higher and higher,real-time ionospheric correction parameters have become an urgent need of users,which is of great significance to improve the accuracy of single-frequency PPP and accelerate the convergence speed of dual-frequency PPP.The main contents of this paper are as follows:(1)Formulas for calculating high-precision ionospheric TEC and inter-frequency deviation based on GNSS dual-frequency observation data and combined pseudorange and carrier phase observations are deduced in detail,which lays a theoretical foundation for the study of regional,global ionospheric model and inter-frequency deviation between satellites and receivers.(2)According to the theory of ionospheric delay modeling,the VTEC polynomial function modeling and accuracy analysis of China’s regional ionosphere are carried out based on the data of national reference stations,and the global ionospheric spherical harmonic function modeling and accuracy analysis are carried out using iGMAS,MGEX and IGS observation data.(3)Based on the global ionospheric spherical harmonic function model,the accuracy and reliability of the inter-code frequency deviations of GPS,GLONASS,BDS satellites and receivers are analyzed,including the DCB of P1C1,C1P2 and P1P2 of GPS satellites,P1C1,C1P2,P1P2 of GLONASSS satellites,B1B3,B1B2,B2B3 of BDS system,GPS receivers C1P2,P1P2 and BDS receivers B1B3.The influence of satellite end frequencydeviation correction on SPP and PPP positioning is analyzed.(4)Aiming at the research of regional real-time ionospheric delay modeling,this paper summarizes the process of real-time ionospheric deployment,analyses the scientific application method of BNC software,verifies the feasibility of the software by receiving and processing real-time data streams,compares the accuracy of the results with the products released by CODE on the same day,and applies the results of real-time ionospheric modeling to positioning test.