Overall Activities of Time and Frequency Metrology in NICT

Abstract

Space-Time Standards laboratory in National institute of Information and Communications Technology (NICT), Japan, has various activities of time and frequency metrology. NICT generates and disseminates Japan Standard Time (JST. In addition to the headquarter in Koganei, Tokyo, we built a substation of JST in Kobe, which is in western part of Japan. Every place in Japan has a potential to be attacked by a large earthquake. The combination of two stations provides a resilience. Two optical frequency standards are being developed. One is a strontium lattice clock and the other is a single In+ trap. The lattice clock is recognized as a secondary represenataion of the Second. Various technique of the time and frequency transfer is under developing, including GNSS, TWSTFT, VLBI and fiber link. We developed the two-way carrier phase technique and developed a modem for it, which is now commercially available in Japan. VLBI does not need satellites. We can compare the clocks without depending on GNSS providers or communication satellites. These various activity will be briefly introduced.