Research On The Algorithm And Realization Of Post-processing For GPS Precise Positioning And Orbit Determination

Satellite precise orbit determination(POD) play a very important role in Earth Observing System (EOS). Precise positioning can't be done without advanced POD technique and software, which ensure to achieve the accurate orbit of satellite. In the past twenty years, the technology of satellite positioning has been widely developed and applied in china. But the software of precise orbit determination and precise positioning we used always comes from foreign country. Such situation will impede us to make outstanding and creative achievement. Just relying on the imported software can't meet the practical need of developing the satellite plan in our country, and also make against national defense safety guarantee. In a word, we should develop the satellite precise orbit determination and precise positioning software with our own property and characteristic as soon as possible.Research on satellite precise positioning and orbit determination includes two main parts: The first part is to process the raw observation data of tracking stations on the earth to get the baseline single day solution and single day orbit determination. The second one is post-processing part, which use the single day orbit resolutions and baseline solutions to estimate the parameters and integrate orbit. The parameters to be estimated in the post-processing include orbit parameters, geodynamic model parameters, station coordinate and velocity parameters, tropospheric parameters, ambiguity parameters, satellite and receiver clock parameters and so on. Complicated functional correlation and error correlation between these parameters cause complex post-processing.The post-processed part of precise position and precise orbit determination is mainly studied in the dissertation. Using the single day solution orbit and the single day baseline solution to estimate various parameters such as station coordinate parameters, station velocity parameters, earth rotation parameters, orbit parameters and to integrate the satellite orbit is investigated in detail. Such study has not been developed systematically yet in our country before. The main achievements and concerned items of the dissertation are as following:(1) Using SINEX(Solution INdependent EXchange Format) files as the main input files in post-processing of GPS POD and precise positioning is proposed in the dissertation. The SINEX file structure and transformation between SINEX file and the normal equation are discussed. SINEX file is the standard format of solution file, baseline solutions derived from GPS, VLBI, SLR etc. and points coordinates, points covariance, aâ–  priori coordinates and a priori variance information can be found in SINEX file. Data processing combined multi-stages, multi-types and multi-subnets can be done by adding normal equations recovered from SINEX files.(2) Based on the analysis of traditional GPS network adjustment model with baseline pattern, a new generalized network adjustment model with coordinate pattern is brought forward, station coordinates, earth rotation parameters (ERP) etc. are used directly as observations in the new model. The relationship and the different of the two models are analyzed. The advantages of the generalized network adjustment model with coordinate pattern in parameters estimation of multi-types and multi-stages are summarized. The common ways of dada processing of the ne.w model are generalized. The robustified least squares estimator on equivalent variance-covariance method is used to solve the outliers problem on the generalized network adjustment model with coordinate pattern.(3) The influence of the a priori constraint in parameter estimation are analyzed in detail with consideration of function model error and stochastic model error. The influence of the error of the a priori constraint value and the a priori constraint covariance on estimated parameters is derived. This study also demonstrates that the elimination of the a priori constraint is the inverse process of additional constraint. The algorithm of elimination the a priori constraint is presented.(4) Based on indirect adjustment model with additional constraint condition, the influence of additional extra constraint conditions on adjustment results is deduced. With the condition of decreasing the variance of unit weight (variance factor)