Research On BDS Satellite Clock Offset Prediction And Real-Time Precise Point Position

Real-time Precise Point Positioning(RT-PPP)is one of the important development directions in the current Global Navigation Satellite System(GNSS).It is widely applied in the positioning,navigation and timing(PNT).With the completion of the global constellation deployment of China's BeiDou Navigation satellite System(BDS),BDS begins to formally provide global services.The real-time precise positioning service based on BDS is of great significance to economic development and national defense construction.Generally,the realization of RT-PPP depends on the acquisition of external real-time precision products,such as ultra-fast precision orbit,real-time precision satellite clock difference,atmospheric delay correction and satellite hardware delay,etc.,among which the quality of real-time precision satellite clock difference has a huge impact on the positioning performance of RT-PPP.At present,there are few public real-time products including BDS,which restricts the application expansion of BDS real-time PPP to some extent.Therefore,with the establishment of BDS real-time precise point positioning service system as the main research objective,this paper focuses on the performance analysis of BDS new generation satellite atomic clock,clock difference data modeling and prediction,and positioning performance evaluation and research of BDS RT-PPP.The main research work and contributions of this paper are as follows:1)Based on the BDS precision satellite clock data solved for a long time,the phase,frequency,frequency drift and clock difference model noise of the beidou new generation.satellite clock were solved by using the quadratic polynomial fitting model,and the long-term variation characteristics were analyzed.At the same time,the periodic characteristics of different atomic clocks in different orbits of BDS were analyzed by using spectrum analysis method.The Hadamard variance is used to calculate the frequency stability index of satellite clock,and the long-term variation of frequency stability is discussed.Combined with the above experimental results,we have comprehensively evaluated the long-term performance of BDS-2/BDS-3 onboard atomic clocks.2)Analyze the accuracy of BDS satellite clock error prediction,and discuss the applicability of the BDS-3 hydrogen clock and the new rubidium clock to different models.Based on the BDS precision clock error data,the article analyzes the linear model(LPM),the quadratic polynomial model(QPM),the gray model GM(1,1)(GM)and the integrated moving average autoregressive model(ARIMA)model under different forecast time lengths.Statistical analysis of forecast accuracy is carried out to compare the forecast accuracy of BDS satellite rubidium clock,new type rubidium clock and passive hydrogen clock under each model.The results show that the BDS-3 hydrogen clock has the best results in terms of forecast accuracy and forecast stability,and the 12h forecast result is still at 0.5ns;in addition,the BDS-3 hydrogen clock is suitable for the use of LPM for clock error data forecasting,while the BDS-3 The new rubidium clock is more suitable for using QPM to predict the clock error data.This conclusion can provide a favorable reference for the further refinement of the BDS clock error model.3)Based on the real-time service products provided by CNES,the article analyzes the quality of the CLK93 BDS real-time satellite orbit and clock error products;based on the quality analysis,it studies the static and dynamic real-time PPP under the three schemes of BDS,GPS and BDS/GPS combination Positioning performance,and present BDS dynamic RT-PPP positioning performance with real dynamic data.Experiments show that the accuracy of BDS MEO and IGSO real-time orbit products can be maintained within 10cm,and the accuracy of the real-time clock difference product is 0.3ns,which is equivalent to GPS;while the GEO orbit accuracy reaches m level,and the clock error accuracy is in the order of Ins.In terms of BDS real-time PPP positioning performance,under static and imitation dynamic conditions,the BDS convergence time is about 50 minutes,and the positioning accuracy is decimeter level;under real dynamic conditions,the BDS positioning accuracy in the E,N,and U directions is 1.3m and 1.6,respectivelym and 1.7m.Since CNES only broadcasts BDS-2 satellite real-time products,only BDS-2 participates in RT-PPP parameter estimation,which makes the positioning performance slightly worse.The addition of BDS-3 real-time products in the future will further improve the BDS real-time service performance.Figure[35]table[20]reference[103]...