| Time and Frequency Activities at NICT, Japan |
Nov 2009 |
11 pages |
| Authors:
Yasuhiro Koyama; Kuniyasu Imamura; Tsukasa Iwama; Shin'ichi Hama; Jun Amagai; Ryuichi Ichikawa; Mizuhiko Hosokawa; NATIONAL INST OF INFORMATION AND COMMUNICATIONS TECHNOLOGY (NICT) TOKYO (JAPAN)
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 | At NICT, Japan, research and developments for the time and frequency standards are performed by the Space-Time Standards Group. The objectives of this group are to establish standards and reference of space and time as the fundamental basis for various fields of activities in science, engineering, and social activities, and to provide easy access to these foundations from wide range of communities. The recent activities and achievements of the group ... |
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| Development Of Frequency Transfer Via Optical Fiber Link at NICT |
01-Dec-2008 |
11 pages |
| Authors:
Mizuhiko Hosokawa; Motohiro Kumagai; Mihu Fujieda; Tadahiro Gotoh; NATIONAL INST OF INFORMATION AND COMMUNICATIONS TECHNOLOGY (NICT) TOKYO (JAPAN)
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| NICT in Japan has developed a radio frequency (RF) dissemination system using an optical fiber link. The phase noise induced during the transmission through the optical fiber is actively cancelled by a compensation system. A proving test has been conducted on the 114-km urban telecom optical fiber link in Tokyo. The transfer stability in the 10-18 level at an averaging time of 1 day was achieved. In the last few ... |
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| Single Ca+ Ion Trapping and Quadrupole Transition Measurement Towards an Optical Frequency Standard |
01-Nov-2007 |
13 pages |
| Authors:
Kensuke Matsubara; Ying Li; Hiroyuki Ito; Shigeo Nagano; Kazuhiro Hayasaka; Mizuhiko Hosokawa; NATIONAL INST OF INFORMATION AND COMMUNICATIONS TECHNOLOGY (NICT) TOKYO (JAPAN)
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| NICT in Japan is developing an optical frequency standard using a quadrupole transition of single Ca+. After our first measurement, reported at PTTI 2006, we have improved the experimental setup. We have performed laser cooling using two cooling lasers, improved vacuum pressure with an additional getter pump, and introduced a pulse-light sequence to the transition measurement. In consequence, we observed the quadrupole transition with a linewidth of approximately 25 kHz ... |
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| Time Transfer Experiment by TCE on the ETS-VIII Satellite |
Nov 2007 |
11 pages |
| Authors:
Fumimaru Nakagawa; Yasuhiro Takahashi; Jun Amagai; Ryo Tabuchi; Shin'ichi Hama; Mizuhiko Hosokawa; NATIONAL INST OF INFORMATION AND COMMUNICATIONS TECHNOLOGY (NICT) TOKYO (JAPAN)
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| ETS-VIII, a Japanese geo-stationary satellite, launched in December 2006, has been developed to obtain the fundamental technologies for satellite positioning systems using two onboard cesium atomic clocks. At NICT, we developed Time Comparison Equipment (TCE) both onboard ETS-VIII and in the Earth station for precise time transfer between the atomic clocks on the satellite and a ground reference clock. Using code and carrier-phase data measured by TCE, the time and ... |
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| Quadrupole Transition Spectrum Measurement of Single Ca+ Ions Toward Optical Frequency Standards |
Jan 2007 |
15 pages |
| Authors:
Kensuke Matsubara; Ying Li; Kyoya Fukuda; Hiroyuki Ito; Shigeo Nagano; Masatoshi Kajita; Kazuhiro Hayasaka; Shinji Urabe; Mizuhiko Hosokawa; OSAKA UNIV (JAPAN)
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| The National Institute of Information and Communications Technology in Japan is proceeding with development of an optical frequency standard using an electric quadrupole transition of Ca+ ions in a small radio-frequency trap. The single, trapped 40Ca+ ions are laser cooled to a temperature of 10 mK using extended-cavity diode lasers at 397 nm and 866 nm. In order to measure the electric quadrupole transition, the linewidth of the clock laser ... |
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| Overview of Research Activities on Time and Frequency at the National Institute of Information and Communications Technology |
Dec 2004 |
13 pages |
| Authors:
Mizuhiko Hosokawa; Yukio Takahashi; Shin'ichi Hama; Hiroshi Toriyama; Takao Morikawa; NATIONAL INST OF INFORMATION AND COMMUNICATION TECHNOLOGY (NICT) TOKYO (JAPAN)
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| A new organization, the National Institute of Information and Communications Technology (NICT), was founded in Japan in April 2004. The responsibility of the Communications Research Laboratory (CRL) for the national frequency standard and time dissemination has been succeeded by NICT. There are five time and frequency research and service groups. In this paper, we show the recent activities of these five groups. |
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| Detection of the Gravitational Redshift of the Cesium Frequency Standard at CRL |
01-Nov-2000 |
9 pages |
| Authors:
Mizuhiko Hosokawa; Noboru Kotake ;Kuniyasu Imamura; Noriyuki Kurihara; COMMUNICATIONS RESEARCH LAB TOKYO (JAPAN)
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| We have detected the gravitational redshift of a Cs frequency standard that has been transported from CRL Tokyo headquarters, at an altitude of 80 m, to Mt. Ohtakadoya LF standard frequency station, located at an altitude of 794 m, about 250 km far from the CRL Tokyo headquarters. In the Mt. Ohtakadoya LF station, three Cs clocks are equipped to be the references of standard frequency radio signal emission, and ... |
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| Overview of Research Activities on Time and Frequency at the Communications Research Laboratory |
Dec-1999 |
7 pages |
| Authors:
Mizuhiko Hosokawa; Michito Imae; Takao Morikawa; Noriyuki Kurihara; Ken'ichi Okamoto; COMMUNICATIONS RESEARCH LAB TOKYO (JAPAN)
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| Communications Research Laboratory (CRL) is a national institute, which is responsible for the national frequency standards in Japan. For this mission CRL has been conducting many research and development projects in the field of time and frequency standards. To introduce these projects, we will present following topics: - Development of primary frequency standards, such as an optically pumped cesium-beam frequency standard and a fountain type cesium frequency standard, - Time ... |
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| Precise Time-Transfer Experiment Using Two-Way Carrier-Phase Method Planned for ETS-VIII Satellite |
Dec-1999 |
8 pages |
| Authors:
Michito Imae; Mizuhiko Hosokawa; Yukio Takahashi; Hitoshi Kiuchi; Yasuhiro Takahashi; Hiroyuki Noda; Naokazu Hamamoto; COMMUNICATIONS RESEARCH LAB TOKYO (JAPAN)
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| A precise time and frequency transfer between the satellite-onboard atomic clocks and the ground reference clocks has been planned for the Engineering Test Satellite-VIII (ETS-VIII) under the collaboration between the Communications Research Laboratory (CRL) and the National Space Development Agency (NASDA). We will show the plan and the status report of this experiment. ETS-VIII is a Japanese Geostationary Satellite, which will be launched in 2002. It has missions for mobile ... |
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| Two-Way Satellite Time Transfer Activities in Asian-Pacific Region |
Dec-1998 |
10 pages |
| Authors:
Michito Imae; Li Zhang; Colin T Coles; Michael J Wouters; John S Thorn; Malcolm A Lawn; Steve Quigg; Peter T Fisk; Yasubisa Shibuya; Hirotaka Yukawa; Kuniyasu Imamura; Mizuhiko Hosokawa; Kazuhiro Nakadan; COMMUNICATIONS RESEARCH LAB TOKYO (JAPAN)
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| Two-Way Satellite Time Transfer (TWSTT) is one of the most precise time transfer techniques, and time transfer using this method has been used between European and North American Time and Frequency laboratories on a regular basis. In the Asia-Pacific region four Time and Frequency laboratories have been involved in establishing a precise time transfer network using the TWSTT technique. After several continuous 24-hour TWSTT experiments between Communications Research Laboratory (CRL) ... |
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| Time and Frequency Keeping and Its Distribution System at CRL |
Dec 1996 |
14 pages |
| Authors:
Michito Imae; Mizuhiko Hosokawa; Yuko Hanado; Kuniyasu Imamura; Atsushi Otsuka; Takao Morikawa; COMMUNICATIONS RESEARCH LAB TOKYO (JAPAN)
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| As a national frequency standards laboratory in Japan, Communications Research Laboratory (CRL) is doing research and development work on a primary frequency standard. Besides the primary standard, CRL is in charge of the generation of local UTC, UTC(CRL), and its time and frequency distribution via HF and LF radio signals, telephone line, and computer network. CRL contributes to TAI not only atomic clock data, but also as one of the ... |
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| Update of Research Activities on Time and Frequency at the National Institute of Information and Communications Technology (NICT) |
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7 pages |
| Authors:
Mizuhiko Hosokawa; Shin'ichi Hama; Yukio Takahashi; Hiroshi Toriyama; Takao Morikawa; NATIONAL INST OF INFORMATION AND COMMUNICATIONS TECHNOLOGY (NICT) TOKYO (JAPAN)
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| The National Institute of Information and Communications Technology (NICT) in Japan has five time and frequency research and service groups. Those are: Atomic Frequency Standards Group, Time and Frequency Measurements Group, Japanese Standard Time Group, Quasi-Zenith Satellite System Group, and Time Applications Group. In this paper, we introduce the recent activities of these five groups. |
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