Recommendation 4 of the 15th CCTF (2001)

Calibration of time links for International Atomic Time

The Consultative Committee for Time and Frequency,

considering that

• previous recommendations of the Consultative Committee for the Definition of the Second (CCDS) and the Consultative Committee for Time and Frequency (CCTF) have stressed the importance of the calibration of time-transfer equipment to ensure the accuracy of time links,
• improvements in clock technology and in time transfer techniques have resulted in better stability for ensemble time scales, particularly for International Atomic Time (TAI),
• uncompensated changes of the hardware delays in a time link may cause a significant instability in an ensemble time scale like TAI;

recommends that

• absolute and differential calibration methods be continued to be developed and put into operation for all time transfer techniques used in TAI computation, with the aim of achieving 1 ns standard uncertainty,
• laboratories participating in TAI carry out regular calibration exercises and continuous monitoring of time-transfer equipment,
• techniques used for the time links of TAI be independently calibrated.

DOI : 10.59161/CCTF2001REC4E