The Research Of Atomic Clock Performance And Prediction Model

Global navigation and positioning system based on high precision time system as the backing,to carry out real time positioning system.Satellite clock as a core part of the global navigation system,its performance directly determines the time and frequency precision of the satellite navigation,which affect the navigation and positioning.Navigation satellite by satellite clock performance evaluation,performance assessing index generally includes the performance of satellite clock frequency accuracy,frequency stability and frequency drift rate.At the same time,high precision satellite clock error prediction model is established for satellite navigation and positioning also has a very important role.High precision clock difference prediction model can improve the real-time dynamic positioning accuracy of precise point positioning(PPP),in addition to autonomous navigation satellite also need satellite prediction model of empirical data.Based on the analysis of satellite clock data before,first of all to the analysis of the data preprocessing,satellite clock performance and forecast analysis,in this paper,the main research contents and results are as follows:1.Based on the analysis the clock difference data preprocessing methods,namely median detection method.Clock difference analysis and processing of data in the drawing,simple reflect the quality of the clock error data and the general trend.In drawing analysis conducted on the basis of the clock difference data preprocessing,through graphic analysis,examine the simple median gross error detection method is effective.Aimed at the limitations of the method is simple and zero processing,put forward the Newton interpolation method is adopted to improve the abnormal values,got very good treatment2.Using GPS data to satellite clock related performance analysis,obtained the spaceborne atomic clocks and frequency accuracy,frequency deviation,frequency drift about satellite clock stability research,choose the overlapping Allan variance satellite clock stability index were analyzed.The results show that the BLOCK IIF rubidium standard with the best comprehensive performance and the performance indexes of the same kind of satellite clock under similar,early BLOCK type IIA type satellite clock poor overall performance.On the analysis of the stability of satellite clock type,BLOCK ? R-M type satellite clock stability is best,followed by the BLOCK ? R,BLOCK ? A worst,the stability of the BLOCK ? R/M type stability is higher than the other three types of clock an order of magnitude.3.Introduces the principle of GA-BP model and grey model and modeling method,using both linear and nonlinear model of short-term forecast accuracy of satellite clock were compared.Results show that increasing as the amount of initial fitting data,the forecast precision of GA-BP model gradually improved,compared with the grey model prediction accuracy of the opposite trend.When the initial fitting data for six hours,the precision of GA-BP prediction model is generally higher than the gray model;And when the initial fitting data for 24 hours,grey model to forecast the overall accuracy is higher than the GA-BP model 1 to 2 orders of magnitude.Overall,the grey model for the prediction accuracy is higher,the GA-BP model in fitting under the condition of insufficient data and forecast data more forecast quality is not high.