Research Of Tropospheric Delay Model And Applications Based On The GPS Data Processing

When GPS signal transmit in the troposphere of the earth, it may produce speed delay and inflecting delay on account of atmosphere refraction, called signal transmission delay. Tropsopheric delay is the main errors of improving the precision of GPS positioning. Based on basic knowledge of the troposphere, this paper study on the influence of GPS positioning by tropsopheric delay, Analysis the theoretic and method of tropospheric delay correction; the establishment of regional tropospheric zenith delay model; the application of troposphere delay in the data processing. Some experiments are given, the research purpose is, can be able to correct the troposphere better, and provide a helpful foundation to improve the accuracy of positioning.The main research contents are as follows:1, Study on the tropospheric delay correction method of parameter estimation and correction model. Use measured GPS data, analysis the method of parameter estimation in single-model, single-parameter, piecewise constant, piecewise linear and random process by GPS relative positioning, in order to compare the results of kinds of parameter estimation, and the impact of differential positioning. Evaluate the precision and applicability about three commonly used zenith delay model at present, including Hopfield model, Saastamoinen model and EGNOS model which don't need measured meteorological parameters. Troposphere mapping function is an important component of the delay correction. Deal with actual data by using five mapping functions set in GAMIT software, compare and analysis results of these functions.2, Regional tropospheric zenith delay model is established by using the radiosonde date in city of Xi'an. How to analyses meteorological data and establish a regional atmospheric model are discussed in detail. Use regional model and other classical model respectively in precision-point positioning and relative positioning, compare the results of the regional model with the classical model by calculating the IGS observation data, some useful conclusions are obtained. 3, Estimate tropospheric refraction gradient by measured GPS data, study the relation between horizontal gradient and satellite elevation cut-off angle, as well as the level of gradient estimate impact on coordinate; different software calculated the zenith delay, and the positioning results are took under a comparative analysis; discusses announced accuracy of variety of satellite ephemeris, in a experiment, use ultra-rapid ephemeris instead of final-ephemeris, compare their coordinate and zenith delay differences; derive formula about the impact of station coordinate error on GPS Double-Difference, and look at its zenith delay estimates influence; introduce two different antenna phase center correction model: the relative phase center model and the absolute phase center model, compare the calculated coordinates and tropospheric delay by these two models; GPS station vertical variety exists a strong correlation with zenith delay, study the effects of ocean tide on tropospheric zenith delay through data processing.