Time transfer by laser link (T2L2): characterization and calibration of the flight instrument

The T2L2 project (time transfer by laser link) allows for the synchronization of remote ultra-stable clocks over intercontinental distances (Fridelance et al 1997 Exp. Astron. 7, Samain and Fridelance 1998 Metrologia 35 151–9). The principle is derived from satellite laser ranging technology with dedicated space equipment designed to record arrival times of laser pulses at the satellite. The space segment has been launched in June 2008 as a passenger experiment on the ocean altimetry satellite Jason 2. T2L2 had been specified to yield a time stability of better than 1 ps over 1000 s integration time and an accuracy of better than 100 ps. This level of performance requires a rigorous data processing which can be performed only with a comprehensive calibration model of the whole instrumentation. For this purpose, several experimental measurements have been performed before and during the integration phase of the T2L2 space instrument. This instrument model is one of the cornerstones of the data reduction process which is carried out to translate the raw information to a usable picosecond time transfer. After providing a global synopsis of the T2L2 space instrument, the paper gives a description of the experimental setup for the instrument characterization. It then details the different contributions within the calibration model and concludes with an applied example of a space to ground time transfer.

[1]  C. Tourain,et al.  DORIS system: The new age , 2010 .

[2]  Nikita P. Zelensky,et al.  DORIS time bias estimated using Jason-1, TOPEX/Poseidon and ENVISAT orbits , 2006 .

[3]  S. Leon,et al.  Time Transfer by Laser Link — T2L2: Current status and future experiments , 2011, 2011 Joint Conference of the IEEE International Frequency Control and the European Frequency and Time Forum (FCS) Proceedings.

[4]  E Samain.  Timing of optical pulses by a photodiode in the geiger mode. , 1998, Applied optics.

[5]  Patrick Vrancken,et al.  TIME TRANSFER BY LASER LINK – THE T2L2 EXPERIMENT ON JASON-2 AND FURTHER EXPERIMENTS , 2008 .

[6]  P. Vrancken,et al.  The T2L2 Metrological Test Bed , 2007, 2007 IEEE International Frequency Control Symposium Joint with the 21st European Frequency and Time Forum.

[7]  Richard Dewhurst,et al.  Measurement Science and Technology: a historical perspective , 2012 .

[8]  Ivan Prochazka,et al.  Single photon counting module for space applications , 2007 .

[9]  E. Samain,et al.  T2L2 Flight Model Metrological Performances , 2007, 2007 IEEE International Frequency Control Symposium Joint with the 21st European Frequency and Time Forum.

[10]  Bruno Sopko,et al.  Recent achievements in single photon detectors and their applications , 2004 .

[11]  C. Veillet,et al.  T2L2 - Time transfer by Laser link: a new optical time transfer generation , 1997 .

[12]  P. Vrancken.  Characterization of T2L2 (time transfer by laser link) on the Jason 2 ocean altimetry satellite and micrometric laser ranging , 2008 .

[13]  Jean-Michel Lemoine,et al.  A corrective model for Jason-1 DORIS Doppler data in relation to the South Atlantic Anomaly , 2006 .

[14]  P Fridelance,et al.  Time Transfer by Laser Link (T2L2) experiment on Mir , 1998 .