TIME TRANSFER BY LASER LINK - T2L2: RESULTS OF THE FIRST YEAR OF OPERATION

摘要

The Time Transfer by Laser Link (T2L2) experiment is a joint CNES and OCA space mission that will perform ground-to-ground time transfer with an expected time stability of about 1 ps over 1,000 s and 10 ps over 1 day and a time accuracy in the 100 ps range. The T2L2 instrument is onboard the Jason-2 satellite launched in June 2008. It has been in operation for 18 months. After a short period devoted to the characterization and the calibration of the system, the mission is in its "operational" phase. First ground-to-space time transfers have demonstrated noise levels of some tens of picoseconds and a preliminary time stability of a few picoseconds over integration times of some tens of seconds, clearly limited by the onboard clock. The 2009 T2L2 experimental program has two major experiences. The first one is a common-clock time transfer between two co-located laser stations MeO and FTLRS. The second is the validation of a distant comparison between cold atoms fountain clocks and RF time transfer systems. This validation is done with 3 regular laser stations (France, Poland, Japan) and also the French transportable laser ranging system (FTLRS) based at Paris (Syrte). The availability on these sites of both a GPS and a TWSTFT station will allow a direct comparison of T2L2 with RF time transfer techniques.