Analysis of Two-way Time Synchronization Error Caused by Satellite Motion

Abstract

In a navigation satellite system, the two-way satellite time and frequency transfer (TWSTFT) is mainly used for time synchronization at earth stations, and system time tracing, etc. The reason why the TWSTFT can realize high-precision time synchronization is its path symmetry; however, in practical applications, satellite motion leads to a deviation from the distance between base station and satellite and a time synchronization error between two base stations, which affect the path symmetry of the TWSTFT and further influence the precision of two-way satellite time synchronization. In this paper, the calculation method of the two-way time synchronization error caused by satellite motion was studied, and the influence of satellite motion on the precision of two-way time synchronization was analyzed for three base stations, i.e., Sanya, Chengdu and Kashi, selected at low, medium and high latitudes, respectively, with Beijing station as a reference station, using the orbital data of different satellites on one day. In the two-way time synchronization technology research for and construction of the BeiDou Navigation Satellite System, if geosynchronous earth orbit (GEO) satellites are used for two-way time transfer with precision of 1 ns, the influence of satellite motion can be neglected; however, if it is expected to realize time comparison with higher precision or to use satellites with faster motion velocity, the research results from this paper will have important reference function.