IEEE Trans Ultrason Ferroelectr Freq Control. 2018 Jun;65(6):927-933. doi: 10.1109/TUFFC.2018.2804221.
The Time Transfer by Laser Link (T2L2) project allows for the synchronization of remote ultrastable clocks over intercontinental distances. The principle is derived from the satellite laser ranging technology with a dedicated space equipment designed to record arrival times of laser pulses at the satellite. The space segment was launched in 2008 as a passenger instrument on the ocean altimetry satellite Jason 2. For the first time, we have conducted by the end of 2016 a dedicated time transfer comparison campaign between Global Positioning System and T2L2 over intercontinental distances. The campaign was carried out between two laboratories in Europe and two in China. The campaign has demonstrated a consistency of the time transfer techniques at the 1-ns level, together with the confirmation of a subnanosecond level for continental distances.
激光链路时间传递（T2L2）项目允许通过洲际距离对远程超高稳时钟进行同步。其原理源自卫星激光测距技术，专门设计的空间设备用于记录激光脉冲到达卫星的时间。该空间部分于 2008 年作为海洋测高卫星 Jason 2 的乘客仪器发射。我们首次在 2016 年底在洲际距离上进行了 GPS 和 T2L2 之间的专门时间传递比对活动。该活动在欧洲的两个实验室和中国的两个实验室之间进行。该活动证明了时间传递技术在 1 纳秒级的一致性，同时确认了大陆距离的亚纳秒级水平。
