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The transmission stations at Otakadoya-yama (40kHz) and Hagane-yama (60kHz) broadcast standard time and frequency signals 24 hours a day. Notification No. 382 of the Ministry of Internal Affairs and Communications (1999) stipulates that the transmitted frequency signal shall have an uncertainty of one part in 1012 or less. The time information is required to agree with international time to 1/100,000 of a second.

NICT continuously monitors the transmitted JJY signals, the results can be accessed from web pages as shown below. The character encoding is EUC-JP.

Deviation of standard frequency at transmission station

We publish here the frequency deviation of the standard frequency signals transmitted by the JJY stations. The reported value is a 24-hour average of the relative difference of the frequency reference at the transmission station from the frequency standards at NICT’s Koganei headquarters. It is determined by satellite-based time transfer.

After selecting the period and station, please click on “Show data”. The data will be shown in a new window. Each report covers one month.