Algorithm And Positioning Accuracy Analysis Of GPS/BDS/GLONASS Network RTK

With the modernization of the GPS system of the United States,Russia's GLONASS system full constellation operation again,China's BDS system begin to provide location services to the Asia Pacific Region and EU GALILEO system accelerate the process of networking,mutli-GNSS RTK has become an important development direction of network RTK technology.In this paper,GPS/BDS/GLONASS multi system network RTK algorithm as the main line.First,we introduces the basic theory of multi-GNSS network RTK system,includes the uniform time-space reference between different systems;in the process of network RTK data processing,the processing methods of the error,and the mathematical model and the observation equation which need to be used in the multi system network RTK positioning.Then this paper introduces the solution steps of GPS/BDS/GLONASS network RTK ambiguity between base stations,including the realization of the widelane ambiguity fixed by Melbourne-Wubbena;Ionosphere free combination ambiguity estimation using Kalman filter;the double difference integer ambiguity solution and fixed of L1 and L2 frequency.In the end,we introduces the atmosphere error modeling and modified theory of GPS/BDS/GLONASS network RTK,mainly includes:the extraction method of multi system network RTK atmosphere error;interpolation ionosphere delay error,troposphere delay error and residual error;and the observation generation of virtual reference station.And we use the CORS network in Wuhan city and Guiyang city respectively to verify the ambiguity fixing between base stations,the atmosphere error modeling and dynamic positioning performance in mid latitudes and low latitudes of the algorithm proposed in this paper.Through the analysis of the long time multi-system observation data of Guiyang CORS network,the accuracy of multi-system network RTK positioning is analyzed as:1)In six kinds of combination models composed by GPS,BDS,GLONASS,BDS single system network RTK can achieve the positioning accuracy of GPS single system network RTK,GPS/BDS/GLONASS network RTK system in the ENU direction positioning accuracy compared with the single GPS system network RTK increased by 14.16%,15.73%and 17.31%.2)we increasing the cut-off elevation angle to the analog signal shielding,the positioning performance of GPS single system network RTK with increasing elevation angle is pool,when the cut-off angle is 40 degrees,GPS RTK system has been unable to work properly;while the GPS/BDS/GLONASS three RTK system network can still be in 99.84%time of a day to reach plane 0.01 meters,height 0.025 meters positioning accuracy.Finally,in the absence of or do not use the GPS signal case,we can achieve plane 0.01 meters,height 0.025 meters positioning accuracy in the city of Guiyang CORS network coverage area using the BDS single system or BDS and GLONASS dual system network RTK.It is proved that the BDS system can provide high precision network RTK positioning service in the absence or absence of GPS signal.Finally,this paper summarizes and prospects the future research direction of network RTK.