電波時計による長波標準電波のタイムコードの遅延測定

概要

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Two JJY stations are disseminating time and frequency signals prepared by NICT (National Institute of Information and Communications Technology) with low frequencies of 40kHz and 60kHz. One of the stations, placed on Mt. Otakadoya, has been operational since 10th of June 1999 with a frequency of 40kHz. A set of time codes modulates the amplitude of LF radio wave by the amplitude shift keying (ASK) so that the time of the radio-controlled clock can be adjusted automatically. The time-codes of JJY signal are very low rate of 1 bps using pulse width modulation. The authors measured the delay of the decoded time-code, sent from the JJY station on Mt. Otakadoya and received by a radio-controlled clock. The PPS (pulse per second) signal from GPS receiver with an accuracy of 1×10^<-6> and Rubidium frequency standard with a stability of 5×10^<-11>/month are used for the time standard and the delay measurement counter respectively. The clock will be adjusted accurately enough in the daily life as the delay is up to around 100ms, though depending on the distance from the station, with the standard deviation of less than 1ms.
社団法人日本航海学会の論文
2004-09-25