New Timekeeping System and Its Time Link Calibration at NIM

NIM has started to switch formally generating of UTC(NIM) to the new campus since Oct 14th 2012. After that, 6 H-masers (Symmetricom MHM-2010) and 7 industrial Cs clocks (Symmetricom 5071A) at the two campuses have been involved in TAI corporation. One calibration of the time transfer link between National Institute of Metrology (NIM), P. R. China, and Physikalisch-Technische Bundesanstalt (PTB), Braunschweig, Germany, has been implemented successfully and based on this, BIPM has aligned TWSTFT (Two Way Satellite Time and Frequency Transfer) link to GPS link for calibration of TWSTFT link. From the Cir.T, for UTC(NIM) the link uncertainty of type B has been maintained as 5.2 ns.