Study On The Methods Of Clock Bias Data Preprocessing And Performance Analysis For On-board Atomic Clocks Of BDS

Space-borne atomic clocks are the core part of the payload of satellite navigation system,of which the performance directly determine the user's accuracy of navigation positioning and timing.With the Beidou navigation satellite system comprehensively providing services for the asia-pacific region and the new-generation of global navigation satellite launch in succession,it is important to conduct comprehensive evaluation and analysis on the performance of the BDS atomic clocks.The existing public precise satellite clock data products of BDS derived from multi-satellite orbit determination contain many outliers.In order to get the accurate results of performance evaluation and analysis,the outliers of satellite clock data must be preprocessed.The outliers of precise satellite clock data products of BDS are studied,the main performance indicators of space-borne atomic clock is comprehensively analyzed by using the data preprocessed.The main research content and innication work are as follows:?1?The main abnormal situation of BDS clock bias data is studied,median gross error detection method based on sliding window is proposed.The principle of wavelet analysis is studied,and the clock bias gross error detection method based on wavelet analysis is put forward.According to the different types of situations,the gross error can be effectively eliminated by using the two methods.BDS clock bias data contain plenty of dead time,and the method with which dead time is added by using prediction model of the quadratic polynomial is proposed.At the same time,the influence of supplementary data for stability analysis is researched.?2?Frequency accuracy,frequency drift rate and random distribution noise of BDS are studied in depth.At present,the frequency accuracy of the BDS atomic clocks is 10-11 orders of magnitude,the frequency drift rate is 10^-18,the performance of the MEO statellite clocks is best and the frequency drift can achieve 10^-19.The random distribution of noise on BDS atomic clocks and the noise level assessment of BDS are evaluated,the GEO satellite and IGSO satellite have the same noise level,and the performance of the MEO is the best.The power law noise identification show that the BDS orbit atomic clocks are mainly influenced by Flicker FM noise,White noise and Flicker PM.Different satellite has the different influence of the noise.?3?Stability of time domain of BDS space-borne atomic clocks are analyzed,the influence of the different variance and smapling time in the stability evaluation of BDS is researched.The study result show that the frequency stability of 2 hours,4 hours,6 hours,12 hours and 24 hours for space-board atomic clock can achieve 10^-13,stability of GEO is worse,the volatility of 24hours for the GEO and IGSO is larger than that of MEO satellites.The consequence of the mid-long term stability anlalyse in total Hadamard variance is more obvious;the 5 min sampling interval data is used in frequency stability when the quality of precise satellite clock data is poor.If the quality is high,the result of frequency stability calculation in 15 min sampling interval is more accurate.?4?Based on data preprocessed of BDS,space-borne atomic clocks performance evaluation and clock bias prediction theory,the software prototype of space-borne atomic clocks performance evaluation and clock bias prediction is developed.The software has the functions of clock bais data preprocessing,evaluation on space-borne atomic clocks performance and clock bias prediction.