Research On Time Synchronization Method Based On Ka Inter-Satellite Link

With the continuous development of space technology,human exploration of science extends from the ground to the deep space.The number of space station and spacecraft is increasing.The precise orbit determination and precise measurement of spacecraft require high-precision time reference as support,and high-precision time transfer and synchronization technology become the bottleneck of high-precision timefrequency reference in space science and technology applications.Studying the higherprecision time synchronization method can help to realize the high-precision timing requirements of spacecraft users,and it can provide technical accumulation for the construction of integrated space-air-ground time synchronization network in China.This thesis focuses on the time synchronization method between spacecraft users.The main contents are as follows:(1)The time synchronization method between space users based on Ka intersatellite link is studied.The measurement error in the two-way time synchronization process of inter-satellite links is analyzed.The motion delay error has the greatest influence on time synchronization accuracy,which reaches the microsecond level.(2)In this thesis,two methods of pseudo-range epoch conversion are studied,including Lagrange interpolation method and power polynomial fitting method.The simulation data is used to analyze the accuracy of pseudo-range epoch conversion of the two methods,and the advantages and disadvantages of the two epoch conversion methods are compared.(3)A motion delay correction method based on single-point pseudo-range epoch conversion is proposed.The method only needs to synchronize the movement speed of one of the two sides and the position of both sides to correct the motion delay error.The advantage of this method is that the two-way time synchronization accuracy is not affected by the speed error of the one with poor speed accuracy.(4)The motion delay correction algorithm proposed in this thesis is verified by the measured data of the inter-satellite link between Beidou-3 and Xian Ka ground station.The accuracy of the time synchronization of the satellite-ground is better than 0.1 ns.It is verified that the satellite velocity calculated by the Beidou broadcast ephemeris can make the motion delay correction accuracy based on single-point pseudo-range epoch conversion better than 0.01 ns.