Study On Troposphere Model And Arithmetic In VRS

GPS technology caused a revolution in the field of navigation and positioning, with the rapid increase of GPS application, the world economically developed countries and some developed cities in China have already built or are going to built multi-functions GNSS(Global Navigation Satellite System). VRS(Virtual Reference Station) is a new technique with great prospect.Firstly, all kinds of error sources affecting GPS positioning precision are analyzed in this thesis and it is concluded that troposphere delay effect is one of the bottlenecks limiting VRS positioning precision. At the same time troposphere delay is also the focus of GPS meteorology and numerical weather forecasting. Therefore the research on troposphere delay has great significance in theory study or engineering application. The troposphere delay model is, through analysis, classified into two kinds in this thesis:1. Base station troposphere delay which is gained by troposphere parameters;2. VRS(Virtual Reference Station) troposphere delay which is gained by interpolation between base stations.Secondly, several standard atmosphere models are introduced and corresponding error sources are analyzed. It is thought that standard atmosphere models can not meet the needs of VRS. The analysis showed that the wet component which comprise of 10% of troposphere delay varies quickly in temporal and space and is a studying difficulty of troposphere delay.Then, to combine with GAMIT software, the troposphere delay estimation methods of single-parameter, multi-parameters, piece-line and random process are analyzed. The variedly parameter-estimating results and the effects on relative positioning are discussed. The GAMIT solutions showed that the random process method has higher accuracy and especial great improvement in vertical repeatability.That the semi-parameter estimation method is applied to estimatetroposphere delay are put forward in the thesis, thus solved the problem that coefficients matrix of normal equation is ill-conditioned for introducing too many parameter. At the mean time, some parts which are difficult to model in troposphere delay are estimated as modeling errors.Finally, some conductive suggestions are concluded and some problems to be further studied are pointed out.Generally, a variety of parameter estimation methods of troposphere delay are discussed in details through introducing latest development in troposphere delay. The semi-parameter estimation method is put forward in this thesis and the results have significant theoretical and practical values.