Ionospheric Delay Model To Improve The Accuracy Of GPS Elevation Study Measurements

GPS because of its efficient and convenient, it obtained the rapid development, now it becomes the first choice of the topographic survey, deformation monitoring, low grade elevation control survey. Recently, GPS theory and the technology development, the quality of GPS in plane precision and elevation measurement precision have been greatly improved. In hardware, the using choke coil antenna, GPS multipath effect has been effectively eliminated; In theory, all sorts of troposphere, ionospheric delay correction model is proposed and applied, and many studies have shown that effective application of GPS to eliminate error theory, which makes many GPS error that between the satellite and the receiver is correct. So the GPS position in plane and elevation measurement precision is further improved, in the surface measurement, the accuracy is even less than1mm+1PPM. Due to GPS geodetic height needs to convert to normal high when applied to practical working, intermediate conversion need to solve in the process of height anomaly GPS error in elevation control survey has been further increased because this series of calculation, which affects the GPS elevation control survey in many applications. In this paper, on the basis of GPS dual-frequency observation, through calculating GPS observation data, it establishes a regional model of ionospheric delay correction,which replaces present, Klobuchar model, to eliminate the influence of the ionosphere on GPS and the influence of the ionosphere. It improves the accuracy of calculation of GPS data, and improves the precision of height measurement value. Establishment of Zone model adopts polynomial ionospheric delay correction model, the entire ionospheric is concentrated in a single layer, the electrons in the ionosphere single height is350km. In the vertically direction the monolayer of total electron content (VTEC) value as a function of the latitude and solar hour Angle.According to receive the satellite observation data that the receiver in a certain period of time, and TEQC software processing these data, restricting satellite altitude Angle, isolating needed data, it calculates the coefficient of polynomial and eliminating the system error amount between the formula for the difference. It uses the least squares fitting out these unknown terms of optimal solution, and establishes the regional ionospheric delay correction model. It compares the ionosphere delay amount from model calculating with actual amount of latency, to verify the effect of the model. On the basement of double-frequency observation value, it fixes electronic content of the above puncture point accurately, and retrodicts the coefficient of polynomial model to establish regional ionospheric delay correction model. To solve the local ionospheric delay it is more pertinence.Through practical application example to validate the advantage of article established polynomial model of ionospheric delay correction effect, it describes the polynomial model is more targeted, specificity. But due to congenital conditions of model, it also limits the model in the prediction of the ionosphere delay the shortfalls. Comprehensive comparison of the merits and drawback of the model, using the GPS dual-frequency observation set up the regional ionospheric delay correction polynomial model can well improve the measuring accuracy of GPS. GPS also makes application in elevation control survey widely.