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Mission of Japan Standard Time Group

New Initiatives for an IT Society

The concept relating to time in the IT society is defined as new words “Time Business.” Consequently disseminating precise time to the IT society and spreading its use for time stamp and others have been encouraged. The E-documents law, put into operation from April 2005, require time stamps to be put on electronic documents to certify that there is no alteration on them, and the precise time information is inevitable for the time stamps.
Our Group started to disseminate Japan Standard Time to the general public from Feb 2005, which is traceable with the Coordinated Universal Time (UTC). This makes it possible to use precisely-and-socially authorized electronic time information.
A system, in practice, is constructed as shown in the figure below: NICT, as the National Time Authority (NTA), publishes the measured data using GPS common-view method on the web, and then provide users the precise time which is traceable to Japan Standard Time via Time Assessment Authority "TAA" and Time Stamp Authority “TSA.”
Since the time comparison method using GPS common-view is possible to measure 1 second with accuracy of 10 nanoseconds but not possible to measure time label itself, Telephone JJY, NTP, and JJY which are performed by NICT are used in order to adjust time label.
In addition, the JSTG has promoted the use of traceability chains of UTC (NICT) to the TSA and the structure of the time dissemination and the audit carried out by the TAA. Technical requirements for the TAA have already been established in Japanese Industrial Standards (JIS X 5094) and also established in ISO/IEC 18014-4 by the International Organization for Standardization in 2015.

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