The Prediction of BeiDou Satellite Clock Bias Based on Periodic Term and Starting Point Deviation Correction

According to the physical characteristics of the BDS on-board atomic clocks, a spectral analysis method is used to detect the periodicity based on the products published by the IGS data Center of Wuhan University from January 1, 2016 to November 1, 2016. The results show that there are periodic fluctuations in the three types of satellite clocks. The main period of GEO and IGSO satellite clock bias is relatively obvious. The testing with nearly a year data showed that the main periods of GEO are 12, 24, 8 and 6 h, but for IGSO are 24, 12, 8 and 6 h, while those for MEO are 12.9, 6.4 and 24 h. Based on the periodic characteristics of different types of clocks and the correction of the starting point deviation of the clock bias, a modified prediction method of satellite clock bias is used to forecast the BeiDou satellite clock bias. The results show that the modified method can significantly improve the prediction accuracy, the 24 h, 12 h, 6 h average forecast accuracy can reach 6.55 ns, 3.17 ns and 1.76 ns respectively.