Algorithm Research Of Satellite Epherimers And Clock Differential Corretions And Integrity In GPS/BDS Wide Area Differential System

In this paper,the method of calculating the differential corrections of epherimers and satellite clocks in GPS/BDS wide area differential system is analyzed by studying the algorithm of epherimers and satellite clock differential corrections in GPS wide area differential system.Combine with the instability of Beidou satellite broadcast ephemeris orbit,This paper adopt a new method to comput the differential corrections of ephemeris errors which based on the short-term(3 days)statistical satellite orbit accuracy,then,the ultrafast precision ephemeris are introducded as constraint information,this method will be referred as PIOEU method.At the same time,this paper also divides the traditional method of computing ephemeris differential corrections into two kinds according to the difference of the prior information.One is based on the satellite orbit accuracy of long-term data statistics as a priori information,this method will be referred as PIOE method;the other is based on the satellite orbit accuracy of short-term data(3 days)statistics as a priori information,this method will be referred as PIOE3D Method,Finally,the three methods are compared at the system end and the user terminal.The main work of this paper is as follows:(1)The current situation of GPS wide area differential system algorithm and system construction is briefly introduced,and the difference between wide area differential system and wide area precision positioning system is analyzed,and then The significance of building GPS/BDS wide area differential system combined with the development status of civil aviation field in China is described.(2)The GPS/BDS wide area differential system data preprocessing,reference station receiver clock error computation,ephemeris and satellite clock differential corrections and its integrity computation are analyzed in detail.the results of the method proposed in this paper show that,in terms of accuracy,regardless of which satellite system is,PIOEU method can effectively improve the accuracy of broadcast ephemeris compared with PIOE,PIOE3D method,The PIOEU method can also significantly improve the integrity of the BDS satellites than the PIOE3D method,and the PIOE method is the worst,but for the GPS satellites,There is no obvious difference between the three methods.(3)The application algorithm of GPS/BDS epherimers and satellite clock differential corrections in terminal location is introduced in detail,and the differential corrections of PIOE,PIOE3D and PIOEU are respectively used to implement static and dynamic standard single-point positioning experiment,Then,the experimental results are compared with the broadcast ephemeris(BRDC)and precision ephemeris(PREC)standard single-point positioning results,The results show that,in terms of accuracy,the PIOEU/PIOE/PIOE3D is the same in the horizontal or elevation direction,the PREC method is slightly worse and the BRDC is the worst.In terms of integrity,the PIOEU method can significantly improve the system availability probability of BDS satellites in the elevation direction The PIOE method is the worst,but there are no obvious differences between the three methods for the horizontal direction of the BDS satellite and the horizontal direction and elevation direction of the GPS satellite.