RNT: National Timescales
Operational activity: two standard timescales available to users are established at LNE-SYRTE
- The coordinated universal time of the Observatoire de Paris UTC(OP) is realized from the pps signal delivered by a high performance
caesium clock coupled with a micro-phase stepper. The UTC(OP) timescale, maintained at less than 50 ns from UTC, is the physical realization
of UTC, which is the basis of the French legal time according to the decree of 1978;
- The French atomic time TA(F) is a scientific timescale built from the readings of free running atomic clocks disseminated in several French
laboratories. The daily clock data are recorded through GPS links. The frequency accuracy of TA(F) has been maintained at ±1,3.10-14
over the year 2006 and it is now better than ±5.10-15 thanks to the use of the SYRTE atomic fountains. Our time service continuously
broadcasts the French legal time with an accuracy better than 50 ms in the whole metropolitan France, through the talking clock (telephone dial
nr 36 99).
Picture: RNT control room, Observatoire de Paris.
Research & development: two projects are in progress:
- a timescale for the realization of UTC(OP) based on an active hydrogen maser signal steered by a group of clocks. It will enable us to improve
the short term stability of UTC(OP) and to reduce the uncertainty budget of the time transfer links;
- a timescale based on an ensemble of hydrogen masers available at LNE-SYRTE for which the goal is to improve the performance of the local
frequency reference used during the fountains contribution to TAI.
Data RNT (sur serveur syrte.obspm.fr)