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The Japanese term "タイムビジネス", time business, describes the time authentication and time distribution services required for ensuring safety and reliability in a digital society.

The "e-documents law"[1] came into effect in Japan in April 2005 to address the need to store legal documents in electronic form rather than on paper. This law requires electronic documents to be time stamped in a way that shows they have not been altered. The Information Technology (IT) community has also been encouraged to adopt precise and accurate timing records everywhere.

In February 2005[2] NICT began distributing Japan Standard Time (JST) in an easy-to-use format to respond to this need of society. Initially, the time stamps issued based on this time information were certified through a voluntary organization. However, a national certification system was launched in July 2021, in line with developments in other countries.

Careful evaluation of all individual steps creates a traceability chain from the national standard time to the time stamp applied to the end user’s document.

Within this system, NICT serves as the National Time Authority (NTA), and it provides JST and the underlying UTC(NICT) to authorized time certification service providers. This is often realized by a GPS common view method, using measurement data that NICT publishes on the Time Business web pages. Other options include JJY Standard Time and Frequency signals, Telephone JJY, Hikari Telephone JJY and Time Dissemination by Leased Line. The authorized providers are then responsible for maintaining their own timescale such that the difference between their clocks and Japan Standard Time remains within one second. This creates a system where the time stamps provided to users are traceable to JST.

To ensure that each step in this traceability chain is carefully examined and reliable, NICT continues to promote[3,4] the relevant national and international industrial standards, such as JIS X 5094 and ISO/IEC 18144.

Time business policies

As the National Time Standards Agency (NTA), the National Institute of Information and Communications Technology (NICT) provides a number of services in the field of Time Business. The policies for each of these services are provided below, together with the unique object identifier (OID) assigned to the service.

Time comparison by GPS-CV data exchange operation policy

OID: 0.2.440.200168.1.1.1 (download) (Japanese)
Data and additional information (Japanese)

Portable clock operation policy

OID: 0.2.440.200168.1.1.2 (download) (Japanese)

Time Dissemination by Leased Line

OID: 0.2.440.200168.1.1.3 (download) (Japanese)
Operation reports are available here.

Telephone JJY and Hikari Telephone JJY Operation Policy

OID: 0.2.440.200168.1.1.4 (download) (Japanese)
Operation reports are available here.

Standard time and frequency transmission (JJY) Operation Policy

OID: 0.2.440.200168.1.1.5 (download) (Japanese)
Operation reports are available here.

The party responsible for the provision of these services is the Space-Time Standards Laboratory, Electromagnet Standards Research Center, National Institute of Information and Communications Technology. Please see our statement on exemption from liability in the event of emergency or malfunction.

Email : jst-service@ml.nict.go.jp
Phone : 042-327-6985

We are available 8:30 to 12:00 and 13:00 to 17:00 on weekdays, except for public holidays and the period from December 28 to January 3.

Time Dissemination by Leased Line (NTP service)

Implementation of Time Dissemination by Leased Line. Orange items are supplied by the user, blue items are provided by NICT.

Time dissemination by leased line is available for users that require access to the time information distributed by NICT’s NTP, but do not want to access it over the public internet. This service is intended for public institutions, certified time distributors, internet providers and other users with special requirements.

To realize access, a dedicated communications line will be established between NICT and the user’s site, creating a direct connection from NICT’s stratum 1 NTP server and a stratum 2 server on the user side.

While access to the NTP server is free, the user is required to provide the necessary equipment and is responsible for the cost of the connection and the installation of the required equipment at NICT. Applications are reviewed at the end of March, June, September and December, and following the review it will be necessary to conclude a contract with NICT.

Related documents
  • Network time service (Time Dissemination by Leased Line) usage guide
    Download (PDF, Japanese)
  • Documentation for Time Dissemination by Leased Line service
    ・Application for use
    ・Connection information sheet
    ・Equipment requirements
    ・Contract
    Download (PDF, Japanese)
  • Annual report of operation for submission to NICT
    Download (PDF, Japanese)


Time comparison by GPS common-view

In a GPS common view time comparison, the time signals broadcast by the GPS satellites are simultaneously recorded at NICT and the user site.

A standard technique for time synchronization is the observation of the time signals broadcast by the satellites of GPS or other global navigational satellite systems.

Comparing the observations then allows the time bases at multiple sites to be adjusted for synchronization. In this method, the internet is typically used to share observation data, which does not require a high-bandwidth or low-latency connection. The common-view (CV) method is typically used when the two sites are close enough to simultaneously observe the same satellites according to a pre-planned schedule.

As part of OID: 0.2.440.200168.1.1.1, NICT continuously publishes its daily GPS satellite observation results at

Daily observation data (Japanese)

Further data, including flash results of GPS satellite observations updated at an hourly rate, is available at:

Database of observation data (Japanese)
Additional data and operation manuals (Japanese)


Further Information

If you are looking for information on the previously offered services, please check the previous webpage. If you have urgent questions, please contact us directly at

jst-service@ml.nict.go.jp .

References

1) Use of Information and Communication Technology in the Storage of Documents Conducted by Private Businesses, etc. Available at elaws.e-gov.go.jp (Japanese)

2) H. Saito, Japan Standard Time and Time Business, NICT News 344, 3 (2004)

3) T. Iwama, H. Saito, A. Machizawa and H. Toriyama, Trend of Time Business in Japan, Journal of NICT 57, 69 (2010)

4) T. Iwama, Introducing Japan's Time-stamping Technologies to the Global Market, NICT News 394, 1 (2010)