A new realization strategy for the time scale UTC(PTB)

The time scale UTC(PTB) is to be realized with an active hydrogen maser steered in frequency in a way that the maser's short-term frequency stability is preserved and that the medium-term stability is provided by the primary time references of PTB (Physikalisch-Technische Bundesanstalt). UTC(PTB) remains steered to UTC in the long term. Based on real data, we analyzed the possible ways of establishing this, searching for the best combination of data from two hydrogen masers, the primary reference clocks, CS1, CS2 and CSF1, and frequency prediction. Differences between UTC and a fictitious time scale UTCf(PTB) were calculated for various combinations, and these time differences were analyzed in terms of their time instability and their forward predictability for 45 days. It turned out that the properties of the masers during the study period were not particularly suited for the purpose. UTCf(PTB) would outperform UTC(PTB), as it has been realized up to now, only if the maser frequency was steered towards CSF1 very tightly, daily or once every two days. We discuss the properties of UTC(PTB) now and in the future, also in view of its use as a reference for steering the system time of the European satellite navigation system, Galileo, towards TAI.

[1]  G. Petit.  A New Realization of Terrestrial Time , 2003 .

[2]  Judah Levine,et al.  First comparison of remote cesium fountains , 2001, Proceedings of the 2001 IEEE International Frequncy Control Symposium and PDA Exhibition (Cat. No.01CH37218).

[3]  Judah Levine,et al.  Introduction to time and frequency metrology , 1999 .

[4]  Pascale Defraigne,et al.  Time transfer to TAI using geodetic receivers , 2003 .

[5]  Andreas Bauch,et al.  Discussion of the uncertainty budget and of long term comparison of PTB's primary frequency standards CS1, CS2 and CSF1 , 2003 .

[6]  Andreas Bauch,et al.  Comparisons of the PTB primary clocks with TAI in 1999 , 2000 .

[7]  Gerard Petit,et al.  PTB primary clocks: performance and comparison with TAI in 2000 , 2001 .

[8]  Andreas Bauch,et al.  The Atomic Caesium Fountain CSF1 of Ptb , 2002 .

[9]  Andreas Bauch,et al.  Design of the Galileo Precise Time Facility (PTF) , 2004 .

[10]  A. Bauch,et al.  Time comparisons between USNO and PTB: a model for the determination of the time offset between GPS time and the future Galileo system time , 2004, Proceedings of the 2004 IEEE International Frequency Control Symposium and Exposition, 2004..

[11]  T. Polewka,et al.  Time Transfer Between USNO and PTB: Operation and Calibration Results , 2004 .

[12]  D. W. Allan,et al.  Time and Frequency (Time-Domain) Characterization, Estimation, and Prediction of Precision Clocks and Oscillators , 1987, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[13]  Andreas Bauch,et al.  Experimental Verification of the Shift of the Cesium Hyperfine Transition Frequency due to Blackbody Radiation , 1997 .