| With the development of GNSS satellite navigation system,the applications related to GNSS have been widely applied in the field of science,engineering,transportation and navigation.The requirement of GNSS positioning accuracy is higher and higher.The accuracy of satellite orbit is bound to have a great impact on the positioning results.For the multi day positioning such as deformation observation,the continuity of the position is concerned when the orbit is used for positioning,so the satellite trajectory is also required to be continuous.If using a single day orbit determination results,one day can not provide the precise location of satellite orbit,because that one day orbit solution has the end effector,both ends of the orbit error is relatively large,and each single day solution orbit is not continuous.In order to further improve the orbit precision and reduce the orbit error,In this paper,a method of long arc orbit determination is used to synthesize a multi daily arc solution orbit of a single day arc section solution orbit.Then,the middle part of the solution arc is taken as the final orbit.The middle track after synthesizing is higher than the accuracy of the corresponding single day orbit.More than 500 multi-mode GNSS tracking stations have been provided by international GNSS services and nearly one hundred MGEX stations are compatible with the Beidou satellite navigation system(BDS).Although the development of the global satellite system continues to strengthen the GNSS base station construction and some stations with a certain size and reasonable distribution can meet various location services,but too many stations will increase the burden of computer and reduce the calculation efficiency.At the same time,the BDS system has three kinds of MEO/IGSO/GEO satellites and the global distribution of stations is not reasonable,which leads to poor accuracy of Beidou orbit determination.How to improve the orbit determination accuracy of BDS on the existing basis is the key.In order to solve the above problems,the optimization of ground tracking station and the improvement of orbit determination accuracy through multi arc days are studied in this paper.The main research contents and innovations are as follows:1)The accuracy of satellite orbit fitting for broadcast ephemeris and precise ephemeris is analyzed,especially the accuracy of BDS satellite orbit fitting,and theinfluence of initial orbit information on precise orbit determination is analyzed by an example.2)The number and distribution of ground stations effect on the orbit determination accuracy of GPS/BDS satellite is analyzed,proposes a method of quantitative selection of base station and station distribution evaluation standard,and the preparation of the base station selection software.Through the different ground station number and distribution methods comparison methods of quantitative calculation efficiency and accuracy are better than the traditional GNSS ground station selection method,but also verify the reliability of station distribution of the evaluation standard.3)Study the GPS satellite long arc orbit model,analyzes the influence of two strategy on different regions and different arc beam to GPS long arc orbit,and studied the bidirectional Calman filter for long arc orbit determination for long arc,and the results were compared with one-way track Calman filtering,analysis its superiority.4)Aiming at BDS' three kinds of orbital satellites,the influence of different calculation strategy on orbit determination of BDS satellite is analyzed. |
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