The New Generation System of Japan Standard Time at NICT

Hanado, Yuko; Imamura, Kuniyasu; Kuboyama, Noboru; Nakagawa, Fumimaru; Shimizu, Yoshikazu; Tabuchi, Ryo; Lam, Quoc Tung; Takahashi, Yasuhiro; Hosokawa, Mizuhiko; Morikawa, Takao

doi:10.1109/freq.2007.4319101

Cited by 10 publications

(4 citation statements)

References 5 publications

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“…UTC(NICT) is an atomic time scale that is used as the origin of Japan Standard Time (JST). The phases of HM1, HM2, and TA(Sr) with respect to UTC(NICT) are continuously monitored by a precise phase measurement system (DMTD, dual mixer time difference system) 21 contained in the JST system 22 . The time difference of UTC(NICT) relative to other UTC(k) is routinely measured by satellite-based precision time and frequency transfer methods 1 .…”

Section: Comparison With Reference Time Scalesmentioning

confidence: 99%

Months-long real-time generation of a time scale based on an optical clock

Hachisu

Nakagawa

Hanado

et al. 2018

Sci Rep

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Time scales consistently provide precise time stamps and time intervals by combining atomic frequency standards with a reliable local oscillator. Optical frequency standards, however, have not been applied to the generation of time scales, although they provide superb accuracy and stability these days. Here, by steering an oscillator frequency based on the intermittent operation of a 87Sr optical lattice clock, we realized an “optically steered” time scale TA(Sr) that was continuously generated for half a year. The resultant time scale was as stable as International Atomic Time (TAI) with its accuracy at the 10−16 level. We also compared the time scale with TT(BIPM16). TT(BIPM) is computed in deferred time each January based on a weighted average of the evaluations of the frequency of TAI using primary and secondary frequency standards. The variation of the time difference TA(Sr) – TT(BIPM16) was 0.79 ns after 5 months, suggesting the compatibility of using optical clocks for time scale generation. The steady signal also demonstrated the capability to evaluate one-month mean scale intervals of TAI over all six months with comparable uncertainties to those of primary frequency standards (PFSs).

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Section: Comparison With Reference Time Scalesmentioning

confidence: 99%

Months-long real-time generation of a time scale based on an optical clock

Hachisu

Nakagawa

Hanado

et al. 2018

Sci Rep

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“…As the next step, we have developed the atomic fountain type primary frequency standard for the purpose of contribution to the accuracy of TAI at the level of 10 −15 and improving Japan Standard Time (JST). JST has been responsibly maintained for a long time by NICT [10]. Recently, we have developed a new atomic fountain frequency standard named 'NICT-CsF1' [11,12].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of caesium atomic fountain NICT-CsF1

Kumagai¹,

Ito²,

Kajita³

et al. 2008

Metrologia

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In this paper, we describe the first caesium atomic fountain primary frequency standard NICT-CsF1 of National Institute of Information Communications Technology (NICT) in Tokyo, Japan. The structure of the NICT-CsF1 system and evaluation procedure of the systematic frequency shifts and their uncertainties are presented. Typically, NICT-CsF1 has a frequency stability of 4 × 10 −13 /τ 1/2 and a frequency uncertainty of 1.9 × 10 −15 .

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“…The output voltage from the mixer is monitored via an analog to digital converter and the frequency of the DDS is steered to make the output voltage constant over the long-term. By this slow stabilization, the frequency difference between the output signal from the down-converter and the hydrogen maser becomes zero, making it traceable to Japan Standard Time (JST) [10] and International Atomic Time (TAI).…”

Section: Ghz Down-convertermentioning

confidence: 99%

Synthesis chains based on ultra-stable cryogenic sapphire oscillator at NICT

Kumagai

Ito

Nagano

et al. 2009

2009 IEEE International Frequency Control Symposium Joint With the 22nd European Frequency and Time Forum

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A synthesis chain based on a cryogenic sapphire oscillator (CSO) has been developed at NICT. The 11.2005GHz output of the CSO is down-converted to 1-GHz for laboratory distribution. The short-term frequency stability of the downconverter itself is better than 1×10 -15 at an averaging time of 1 second. The long-term drift of the CSO is suppressed by referencing it to a hydrogen maser linked to Japan Standard Time. For microwave interrogation to the cesium atom, a 9.192-GHz up-converter was developed.

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The New Generation System of Japan Standard Time at NICT

Cited by 10 publications

References 5 publications

Months-long real-time generation of a time scale based on an optical clock

Months-long real-time generation of a time scale based on an optical clock

Evaluation of caesium atomic fountain NICT-CsF1

Synthesis chains based on ultra-stable cryogenic sapphire oscillator at NICT

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