A time comparison experiment between Shangai and Paris via Symphonie satellite

Precise time differences between the time scales of Shanghai, Shaanxi, and the Paris Observatory were determined while satellite time comparison capability was tested. In order to get high precision and accuracy, the two-way transmission of a TV type second signal was used in the experiment, and a special calibration of the differences in delay at emission and on reception was made at Hong-Qiao station in Shanghai. During the experiment, the station clock was linked with the master clocks of Shanghai and Shaanxi observatories by special microwave link and long wave signals. In France, the link between the Paris Observatory and Pleumeur-Bodov station was realized by the passive TV method. Although the experiment only lasted 10 days and was the first international comparison by means of the satellite technique for China, precision in time comparison of 8 nsec is obtained, and accuracy is estimated to the within 100 nsec.