Time Transfer by Laser Link - T2L2: First Results of the 2010 Campaign

Philippe Guillemot, P. Exertier, E. Samain, F. Pierron, C. Courde, Ph. Laurent, M. Abgrall, J. Achkar, D. Rovera, K. Djerroud, Sylvie Leon

Abstract:	The Time Transfer by Laser Link (T2L2) experiment, developed by both CNES and OCA, is aimed at performing ground to ground time transfer over intercontinental distances. The principle is derived from laser telemetry technology with dedicated space equipment designed to record arrival time of laser pulses at the satellite. Using laser pulses instead of radio frequency signals, T2L2 permits the realization of links between distant clocks with time stability of a few picoseconds and accuracy better than 100 ps. The T2L2 space instrument on board the satellite Jason 2 has been in operation since June 2008. Several campaigns were done to estimate both the ultimate time accuracy and time stability capabilities. It includes mainly two kinds of experiments: the first involves two SLR stations on the same site and using the same clock, the second involves two remote SLR stations (Grasse and Paris) in common view. These experiments allowed the demonstration of both a time stability lower than a few tens of picoseconds for integration times from 10 s to 100 s and an accuracy lower than 100 ps for the T2L2 time transfer. Some important work has also been done to accurately compare T2L2 with microwave time transfer GPS and TWSTFT. These comparisons are based on laser station calibrations with a dedicated T2L2 event timer designed to accurately set the optical reference of the laser station within the PPS reference of the microwave systems. This paper presents ground to ground time transfer both in common view and non common view configuration, and comparisons between T2L2, GPS and Two-Way systems. Results of the 2010 campaigns are described as well as an insight into the future working plan.
Published in:	Proceedings of the 43rd Annual Precise Time and Time Interval Systems and Applications Meeting November 14 - 17, 2011 Hyatt Regency Long Beach Long Beach, California
Pages:	271 - 282
Cite this article:	Guillemot, Philippe, Exertier, P., Samain, E., Pierron, F., Courde, C., Laurent, Ph., Abgrall, M., Achkar, J., Rovera, D., Djerroud, K., Leon, Sylvie, "Time Transfer by Laser Link - T2L2: First Results of the 2010 Campaign," Proceedings of the 43rd Annual Precise Time and Time Interval Systems and Applications Meeting, Long Beach, California, November 2011, pp. 271-282.
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