Accurate time link calibration for UTC time transfer - Status of the BIPM pilot study on the UTC time link calibration

To continue and improve the earlier studies by different authors [1-4], in 2011 the BIPM launched a pilot study on the accurate calibration for the UTC time links [5]. The goal is to unify the UTC time link calibration uncertainties ≤ 2 ns. This is attainable with the `one for all' METODE scheme and a dedicatedly designed travelling calibrator (StdB). The METODE calibration result (CM) can be easily converted to the classic equipment internal delays INTDLY(P1/P2). Nine laboratories participated in the project [6-16]. An operational guideline is drafted and used to guide the calibration tours and data processing. This paper reviews the status of the study and gives the preliminary calibration results of the UTC time link calibrations of GNSS PPP, P3, L1C, TWSTFT and TWOTFT.