Research On GPS/BDS Dual Mode Satellite Positioning Algorithm

Although the single-system positioning has developed very maturely,the satellites of different systems have different coverage rates in various regions,resulting in differences in positioning accuracy,and combined systems can reduce this difference between regions.With the completion of the Beidou system's global networking in 2020,the combined positioning research of Beidou and other satellite navigation systems has more advantages and practical significance,especially the combination with the most mature GPS system,which will strongly promote the global application of Beidou system.Therefore,this article studies the GPS/BDS dual-mode satellite positioning algorithm.Firstly,after analyzing the basic theory of GPS/BDS combined positioning,it is considered that the determination of the weights of different systems during combined positioning directly affects the accuracy of the positioning results,and GPS and BDS are different systems with different observation values and accuracy.The observation values of the three BDS orbiting satellites are not the same,so the GPS/BDS combination is classified and weighted,namely GPS,GEO,MEO,IGSO,and the altitude angle model and the post-test Helmert variance in the priori weighting model are used.Component fixed weight model for analysis and comparison.Secondly,through the least square algorithm and Kalman filter algorithm,the advantages of GPS/BDS combined positioning compared to GPS or BDS singlesystem positioning are analyzed in terms of the number of visible satellites,precision factors,and internal and external coincidence accuracy.On this basis,in order to improve the positioning accuracy,the positioning performance of the robust adaptive Kalman filter algorithm in higher-precision positioning is studied,and the extended Kalman,robust Kalman and adaptive Kalman filter algorithms are in E,N,U compares the positioning errors in the three directions.Finally,in the data preprocessing part of the carrier phase smoothing pseudorange algorithm,cycle slip detection is performed through the relationship between Doppler and phase change rate to avoid cycle slips affecting the continuity and reliability of the carrier phase;at the same time,ionization is considered.The layer error will cause the divergence and accuracy of the carrier phase smoothing pseudorange results.For single-frequency receivers,the Klobuchar model is used to correct the ionospheric error,and the effectiveness of the carrier phase smoothing pseudorange algorithm is proved through experiments.