Time Transfer by Laser Link - T2L2: Results of the First Year of Operation

Philippe Guillemot, Pierre Exertier, Etienne Samain, Francis Pierron, Jean-Marie Torre, and Sylvie Leon

Abstract:	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. After summarizing the principle, the exploitation plan, and the objectives of the mission, the paper will present first results of these experiences and others validations of the T2L2 system.
Published in:	Proceedings of the 41st Annual Precise Time and Time Interval Systems and Applications Meeting November 16 - 19, 2009 Hyatt Regency Tamaya Resort Santa Ana Pueblo, New Mexico
Pages:	67 - 80
Cite this article:	Guillemot, Philippe, Exertier, Pierre, Samain, Etienne, Pierron, Francis, Torre, Jean-Marie, Leon, Sylvie, "Time Transfer by Laser Link - T2L2: Results of the First Year of Operation," Proceedings of the 41st Annual Precise Time and Time Interval Systems and Applications Meeting, Santa Ana Pueblo, New Mexico, November 2009, pp. 67-80.
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