Research On Ionospheric Model And Influencing Factors Based On GPS

The error caused by ionosphere has become the largest fraction which influencethe accuracy of GPS positioning, especially after the USA government declared offthe SA policy. In this paper, we researched the principles and methods of calculatingionospheric electron content based on observational data published by IGS, analyzedthe accuracy of several models to calculate the satellite DCB, and on this basis,analysis the differences on calculating TEC between spherical harmonic functionmodel and inverse distance weighting method. In addition, this paper focused on therelationship between the ionospheric electron content and solar XUV radiation, anddraw some useful conclusions. The main contents can be generalized as follows:(1)Introduced detailedly the structural characteristics of the ionosphere, analyzedthe influence of ionosphere on the P or C/A code and carrier L1or L2; deduced theformula of calculating VTEC using GPS observation equation and the latitude andlongitude of the puncture point.(2)Studied the method of GPS positioning based on observation equation, andanalyzed factors influencing the positioning accuracy.(3) By using the observational data published by the eight IGS stations in China,we calculated the satellite DCB through the polynomial function model, trigonometricseries function model and spherical harmonics model, then comparative the accuracyin the calculation of these three models of. A comparison of the accuracy of the resultsof this three models is carried out.(4)Studied the method of using inverse distance weighting method to calculatethe electronic content of grid points, and then results were compared with the resultscalculated by spherical harmonic model, we can find that the electronic contentdistribution graph and electronic content residuals all have a high accuracy to meetthe general needs.(5)This paper payed more attention on the relationship between the electroncontent and solar XUV radiation. Write a program in c++to calculate the solar XUV radiation intensity of upper bound of the atmosphere after the formula’s derivation ofsolar XUV radiation, we got some conclusions by compared the calculated electroncontent with solar radiation data.