Performance Analysis of Two-Way Time Comparison of Eurasian Satellites Based on 1Mcps/s Code

The bandwidth leased on Earth satellites directly affects the operation cost of TWSTFT (Two-Way Satellite Time and Frequency Transfer). %(Or satellite channel leasing fee is one of the main costs of two-way satellite time transfer at present.) Until May 2017, the Ku-band TWSTFT between Asian-European laboratories involved in UTC (Coordinated Universal Time) computing had been using the 2.5Mcps/s pseudo-random codes with a bandwidth of 2.5MHz. In order to reduce the cost without affecting the performance of time and frequency, a pseudo-random code with 1Mcps/s bandwidth of 1.7MHz is first attempted to transmit time bidirectionally between Eurasian and Asian satellites in China. An indirect calibration for the bidirectional links by using the calibrated GPS PPP (Global Position System Precise Point Positioning) links reduces the link uncertainty. The TWSTFT link data of December 2018 are selected to analyze the link performance. It is found that the daily frequency stability and time stability of the satellite bidirectional time comparison link constructed with 1Mcps/s code rate reach 10^-15