GPS/BDS Precise Point Positioning And Short-Term Clock Error Prediction

With the completion of the networking of Bei Dou satellite navigation system,China has the ability to provide global navigation positioning and timing service.Therefore,the precise point positioning and other related research of the GPS/BDS system will become a hot spot.Due to the network,station data quality and other reasons,the real-time clock error often occurs time delay or missing,so it is of great practical significance to improve the reliability of clock error products by short-term prediction of satellite clock error.Based on PPP theory,the inter system deviation(ISB)characteristics between GPS and BDS are studied,and estimated according to constant estimation,random walk process and white noise process respectively.The experimental results show that the effect of random walk is the best.Using 35 MGEX tracking stations around the world to evaluate the PPP performance of GPS/BDS and its combined system,the experimental results show that the BDS-2 system has the worst positioning accuracy and the longest convergence time regardless of whether it is static or dynamic PPP.The static positioning accuracy of the BDS-3 system in the E,N,and U directions is 1.21 cm,0.86 cm,and 2.84 cm,respectively.The dynamics are 2.96 cm,2.45 cm,and 5.65 cm,respectively,and the convergence time in the three directions is 43.31 min,31.23 min,and 55.57 min.The GPS/BDS-2/BDS-3system combination has the highest positioning accuracy.The static positioning accuracy of the three directions is 0.76 cm,0.54 cm,1.03 cm,and the dynamics reach 1.37 cm,1.05 cm,2.93 cm,and the convergence time is 23.79 min,respectively.12.15 min,23.24 min.By optimizing the clock error prediction strategy of GPS/BDS satellite,the best fitting time and extrapolation time of the clock error prediction experiment are determined to be 75 min and5 min respectively.The polynomial model,grey model and combination model are used to predict the satellite precise clock error.The experimental results show that the prediction accuracy of the three models is better than 0.2ns,and the combination model has the highest prediction accuracy.The rationality of the clock error prediction is verified by the simulated real-time PPP experiment.This paper has 38 pictures,33 tables,and 128 references.