Augmentation with low Earth orbit(LEO)satellites has become a hot topic in future po-sitioning,navigation and timing services,and high-precision LEO satellite clock product is an es-sential condition for the realization the LEO-augmentation.Using the data from the Sentinel-6A satellite,this paper analyzed its clock characteristics,explained the clock determination method and influencing factors,and introduced an LEO satellite clock prediction method that considers the clock characteristics.Experiments show that the LEO satellite clocks contain multiple periodic terms,which brings difficulties to clock modeling and prediction.Compared with the case using the kinematic precise orbit determination(POD)model,the reduced-dynamic POD model can sig-nificantly improve the LEO satellite clock precision.In the case of using the kinematic POD mod-el,the multi-GNSS scenario delivers better LEO satellite clock precision than the GPS-only sce-nario.The research result shows that Sentinel-6A satellite clock accuracy based on GPS and Galileo observation is improved by 36％compared with GPS single system clock error accuracy.The precision of the LEO satellite clocks is also found to be closely related to that of the GNSS products used.Using the LEO satellite clock prediction method that considers the satellite clock characteristics,the RMSE of the predicted and estimated clocks is within 0.1 ns and 0.3 ns,re-spectively,for a prediction time shorter than 1 min and 5 min.The prediction precision degrades significantly with the increasing prediction time.
维普
万方数据
