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The Japan Standard Time generated by NICT is made available throughout Japan by various means. It is an important social infrastructure, and its many users and applications rely on it. It was long implemented as a centralized system using atomic clocks operated at NICT headquarters in Koganei, Tokyo, but such a system is prone to interruption by local damage, for example from the earthquakes that are common in Japan.

Following the Tōhoku earthquake on March 11, 2011, NICT initiated the construction of a resilient distributed system to reduce the impact of such a disaster. We created a substation for the generation of Japan Standard Time at NICT's Advanced ICT Research Institute, which has been in operation since June 10, 2018.

A parabolic antenna for two-way satellite time comparison, and the time-keeping facilities at NICT's Kobe sub-station for Japan Standard Time generation.

Two hydrogen masers and five cesium atomic clocks are installed at the substation, which constantly generates Standard Time in parallel with the headquarters. It is equipped with an NTP server and Hikari Telephone JJY system to provide an alternative in case the services provided by NICT headquarters become unavailable.

In addition to improved resilience, calculating an average over additional clocks is an advantage for the generation of Japan Standard Time. To determine the time difference between distributed clocks with the required accuracy, we maintain and continue the development of a time transfer link using geostationary satellites as well as global navigational satellite systems.

To reduce the impact of a disaster, the generation of Japan Standard Time has been changed from centralized system located at a single site to a distributed system with atomic clocks in separate locations that are connected by satellite time comparison links.

Besides the Kobe sub-station, the transmission facilities for the JJY Standard Radio Signal also house atomic clocks. The decentralized system makes it possible to include these in the generation of Japan Standard Time, too.

The time difference between the UTC(KGNI) and UTC(KOBE) signals generated in Koganei and Kobe to form the basis of Japan Standard Time.

The time difference of the signals generated at Koganei and Kobe has been continuously monitored since the substation started operation in June 2018. The difference typically remains below 5ns, with a fractional instability of the frequency instability that reaches 2×10-15 after measuring for 10 to 30 days.