Experiment of Asia-Europe TWSTFT Link using new satellite Express-80

The two-way satellite time and frequency transfer (TWSTFT) was recommended by ITU in 1999 and has been officially used for the calculation of Coordinated Universal Time (UTC) and widely adopted by major timekeeping laboratories around the world. In view of the unstable and frequent interruptions of the Asia-Europe TWSTFT link uses the Russian ABS-2A satellite, the Consultative Committee on Time and Frequency (CCTF) proposed to stop the operation of the current TWSTFT link, and quickly organized laboratories to conduct new satellite network access tests two months later. The uplink and downlink test of the Russian Express-80 satellite was passed successfully, reconstructed the Asia-Europe TWSTFT link, and restored the data transmission work of long-distance TWSTFT link for UTC calculation. In order to enable the Asia-Europe link to be used for UTC calculation as soon as possible and operate stably for a long time, it is necessary to carry out performance testing on the Express-80 based Asia-Europe link as soon as possible. Select the observation data of two TWSTFT links for the long and short baselines of the newly established Asia-Europe network in January 2024, use the GPS PPP link that is completely independent of the TWSTFT link as a reference, and use the Allan variance as a stability indicator to analyze the link performance. The results show that the stability of the new Asia-Europe TWSTFT link constructed by the Express-80 satellite can reach the order of magnitude of 1×10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-15</sup>d-1, and the standard deviation between the TWSTFT and the calibrated GPS PPP link is less than 0.5ns, which is consistent with the GPS PPP time transfer result, indicating that the newly established TWSTFT link can be used for UTC calculation.