Characteristic Analysis Of BDS Satellite Atomic Clock And Modeling And Prediction Of Precise Clock Error

Satellite atomic clock is the core component of satellite navigation system,and its performance directly determines the accuracy and quality of navigation,positioning and timing.At the same time,with the rapid development of satellite navigation and positioning,the requirement of accuracy is also higher and higher.Therefore,clock error prediction is particularly important in practical scientific research and application.On the basis of summarizing the theory of satellite clock error,the following researches are carried out in this paper(1)The BDS satellite clock phase difference data is plotted,and the frequency data,frequency accuracy data and frequency drift rate data of the satellite clock are calculated and plotted.Comprehensive analysis shows that compared with BDS-2 satellite clock,BDS-3 satellite clock has better stability,performance and quality.(2)In view of the poor quality of clock error data,this paper uses the quartile method for data preprocessing,compares the similarities and differences between the quartile method and the conventional method,and finds that this method can effectively eliminate the gross error through experiments,which proves the feasibility and effectiveness of the quartile method in clock error preprocessing.(3)Aiming at the limitation of the traditional model,this paper combines the characteristics of BDS satellite clock,uses ELM model for clock error prediction,improves ELM model,and discusses the influence of excitation function and the number of hidden layer neurons on the performance of the model.Aiming at the shortcomings of ELM model,genetic algorithm is introduced to optimize the weights and thresholds of hidden layer to find the optimal random parameters.(4)In this paper,the bell difference prediction experiments of different types are designed by modeling length and forecast length respectively.The ex perimental results of improved ELM model and quadratic polynomial model,grey model and ELM model are compared to explore the influence of different modeling time and different prediction time on prediction accuracy.The experimental results show that the improved ELM model has obvious advantages over other models,and the prediction accuracy is the highest when the modeling time is 10 days.It shows that the improved ELM model has better feasibility and stability in clock difference prediction.The paper are 35 figures,21 tables,71 references.