The method and experiment analysis of two-way common-view satellite time transfer for compass system

Time synchronization between ground and satellites is a key technology for satellite navigation system. With dual-channel sat- ellite, a method called Two-Way Common-View （TWCV） satellite time transfer for Compass system is proposed, which com- bines both characteristics of satellite common-view and two-way satellite-ground time transfer. By satellite-ground two-way pseudo-range differencing and two stations common-view differencing, this TWCV method can completely eliminate the in- fluence of common errors, such as satellite clock offset, ephemeris errors, troposphere delay and station coordinates errors. At the same time, ionosphere delay related to signal frequency is also weakened significantly. So the precision of time transfer is improved much more greatly than before. In this paper, the basic principle is introduced in detail, the effect of major errors is analyzed and the practical calculation model in the Earth-fixed coordinate system for this new method is provided. Finally, experiment analysis is conducted with actual Compass observing data. The results show that the deviation and the stability of the satellite dual channel can be better than 0.1 ns, and the accuracy of the two-way common-view satellite time transfer can achieve 0.4 ns. All these results have verified the correctness of this TWCV method and model. In addition, we compare this TWCV satellite time transfer with the independent C-band TWSTFT （Two-Way Satellite Time and Frequency Transfer）. It shows that the result of the TWCV satellite time transfer is in accordance with the C-band TWSTFT result, which further sug- gests that the TWCV method is a remote high precision time transfer technique. The research results in this paper are very im- portant references for the development and application of Compass satellite navigation system.