Research On BDS/GPS Network Pseudo-range Differential Global Navigation Satellite System

Since the eighties of the last century, differential GNSS system has been widely used in the world, and the differential GNSS technology has also made great progress, the development of the reference station model、differential correction interpolation model and the data transmission format are very fast. In which, differential GNSS system is developed from the original single reference station to the local difference system based on the multi reference station; In the method of interpolation correction; In the method of interpolation correction, there are a variety of methods to choose, include inverse distance weighted interpolation model、linear interpolation model、adjustment allocation algorithm and the low order surface model method; In the data transmission format, the differential correction signal have been amended several times in the data structure and coding format in order to achieve progress.At present, China’s BeiDou Navigation Satellite System has been providing services in the Asia Pacific region, and the construction of the Continuous Operational Reference Stations has been improved gradually, the BDS/GPS network pseudo range differential positioning method will play an important role in both the vehicle navigation and traffic control. In order to make up the disadvantage of the limited number of available satellites in the GPS single system in special environment and promote the application and development of BDS satellite navigation industry in the civil field, taking BDS assisted GPS to position has become the trend of the navigation and positioning.In this paper, In order to get real-time, safe and high-precision positioning effect, the BDS/GPS network pseudo range differential positioning method is studied in detail based on the static and dynamic data of BDS/GPS, a lot of experiments and analysis on the BDS/GPS network pseudo range difference method are carried out by the CORS station and the vehicle test data, and some useful conclusions are obtained. The main research contents and results of this paper are as follows:1. BDS and GPS system are different in time system、space coordinate system、 satellite constellation type and space layout and other aspects, through the detailed research and analysis of each system, the BDS/GPS network pseudo range differential positioning model is derived through the modification of the single point positioning of GPS satellite.2. In order to avoid the leakage of reference station coordinate information when the differential correction information transmission in the network, the reference station coordinate information, based on the traditional network pseudo range differential positioning theory, a pseudo range differential positioning method based on grid virtual reference station is proposed for the first time, and the pseudo range differential positioning model based on the grid virtual reference station of BDS/GPS is derived. This improvement ensures the national geodetic points safety, also due to the coordinates of the grid points being broadcasted is fixed, the amount of data calculation of data processing center is reduced to a certain extent, thus the amount of user increasees3. Based on the static data collected by the CORS network in Sichuan Province, a detailed analysis and research on the BDS/GPS dual system and single system network pseudo range difference model is made in detail.4. Based on the static data collected by the CORS network in Sichuan Province, the influence of the distance between the reference station and the mobile station on the positioning accuracy is studied.5. Write the real time network pseudo range differential positioning program, using the real time data flow of CORS test network of BDS/GPS in Sichuan Province and Hebei Province, the network pseudo range differential positioning method and the pseudo range differential positioning method based on grid virtual reference station were compared and analyzed, it is verified that there is no difference between the pseudo range differential positioning method based on the grid virtual reference station and the traditional network pseudo range differential positioning method in the accuracy whether in the static mode or dynamic mode.