Research On The Theories And Algorithms Of Space Geodesy Data Fusing

Nowadays There’re mainly four kinds of space geodesy techniques: SLR, VLBI, GPS and DORIS. GPS, SLR and DORIS are satellite techniques, as they can all determinate the station coordinates, ERPs and Troposphere parameters, they are necessary techniques for computing, monitoring and maintaining the ITRF. On this paper, we mainly focus on the principles and methods of GPS, VLBI, SLR and DORIS inter-technique and intra-technique solution combination and multiple GNSS data fusing based on SINEX files, and also make preliminary research on algorithms of multi-GNSS data fusing as well as deeply research on the methods of troposphere time-series. The main work and contributions are summarized as follows:1. Based on the IGS analysis-center SINEX products, we do research on the combination of station coordinates and ERPs considering its systematic errors and relative weight factor,and have results in accordance with IGS final products. A weighted-combination method based on the polynomial fitting residuals is proposed for the pole motion parameters.Computations and comparisons are performed using the proposed methods, results show that the accuracy of ERP solution based on the SINEX file is higher than that of the weighted-combination method.2. As to the troposphere parameters combination, we focus on a method of Kalman filtering for sequential and high accurate combination of troposphere time series. Once given the time series from various analysis centers, with the theory of robust Kalman filtering and least-squares variance component estimation, we can get the lagging or real-time combined solution and its corresponding standard deviation, the average accuracy of the combined solution can approach 0.85 mm.3. We do studies on multi-GNSS PPP algorithms and realization on observation level and normal equation level and have described the time and space datum unification as well as the weight distribution for different satellite systems in detail. Both methods have higher accuracy positioning results than single system, but the combination method on normal equation level shows higher computing efficiency and can also adjust the weight within different systems more convenient, thus we may get the best positioning accuracy and reliability.4. We have a preliminary research on the combination of GPS/VLBI/SLR/DORIS solution for station coordinates, velocity and ERPs for the realization of terrestrial reference frame, after fully considering the key technologies of intre and inter technique combination,we have got the station coordinates, velocity and ERPs in ITRF08 and make both itsinner-accuracy test and comparison with ITRF08 results, they all show good consistency.The computation on this paper is large; all the methods put forward are tested with numerous data and get some useful conclusions, our results can be references and supplements for space geodesy data fusing and the terrestrial reference frame realization and maintainance.