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

Abstract

The bandwidth leased on Earth satellites directly affects the operation cost of TWSTFT (Two-Way Satellite Time and Frequency Transfer). Until May 2017, the Ku-band TWSTFT between Asian-European laboratories involved in UTC (Coordinated Universal Time) computing had been using the 2.5 Mcps/s pseudo-random codes with a bandwidth of 2.5 MHz. In order to reduce the cost without affecting the performance of time and frequency, a pseudo-random code with 1 Mcps/s and bandwidth of 1.7 MHz 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 TWSTFT link constructed with 1 Mcps/s code rate reach 10−15 and 0.3 ns respectively through the ABS-2A satellite. The results show that it is feasible to use 1 Mcps/s code rate for ultra-long distance TWSTFT. Compared with the traditional methods, the system has a low cost, and the time transfer performance can meet the needs of international atomic time calculation.