Performance Evaluation on C-Band TWSTFT Network of National Time Service Center

A C-band two-way comparison network is built at National Time Service Center (NTSC), Chinese Academy of Sciences, which is respectively used to orbit determination and time comparison between ground stations. This paper mainly evaluates the time comparison performance of the two-way comparison network of NTSC. Before the performance evaluation experiment, the equipment delay between ground stations is calibrated by mobile station, and then the delay difference between the receiving channels for multi-channel modem at each ground station is calibrated by using of satellite simulator. And three stations in the NTSC two-way comparison network, Xi'an, Kashi, and Sanya, are carried out TWSTFT and GPS Precise Point Positioning (PPP) time transfer experiments between them. The two-way time comparison performance of the system is evaluated by the method of closure difference and the method of time transfer difference between TWSTFT and GPS PPP. The experiment results showed that the influence of equipment delay is obvious. After the equipment delay is deducted, the triangle closure difference of TWSTFT is about 0.3ns, and the difference between TWSTFT and GPS PPP is less than 0.5ns.