Time and Frequency Activities at NICT, Japan

Transcription

1 Time and Frequency Activities at NICT, Japan Yasuhiro Koyama, Kuniyasu Imamura, Tsukasa Iwama, Shin'ichi Hama, Jun Amagai, Ryuichi Ichikawa, and Mizuhiko Hosokawa National Institute of Information and Communications Technology 1

2 Organization of NICT NICT New Generation Network Research Center Network Architecture Group Photonic Network Group Advanced Device Research Group Space-Time Standards Group Quantum ICT Group New Generation Wireless Communications Research Center Information Security Research Center Applied Electromagnetic Research Center Kobe Advanced ICT Research Center Knowledge Creating Communication Research Center Universal Media Research Center

3 Four Research Projects Japan Standard Time Project Generation and maintenance of high quality Japan Standard Time (JST) and UTC (NICT) Dissemination of standard time by various methods (LF radio, NTP, dial-up,... etc.). Atomic Frequency Standards Project Develop and operate primary frequency standard and optical frequency standard systems. Satellite Time Control Projects Precise T&F transfer between ground and satellites (ETS-8 and Quasi-Zenith Satellite System). Space-Time Measurement Project R&D for precise T&F transfer and establishment of spatial reference frame by using TWSTFT, optical fiber transfer methods, and space geodetic techniques such as GPS and VLBI

4 Generation and Dissemination of Space, Time and Frequency Standards Space, Time and Frequency are the fundamental physical quantities in the field of Science and Technology. They are the important indexes of any kinds of digital information and are very important for safety and security of everybody s life. Developments of Next Generation Frequency Standards Emission of light from trapped Sr atoms. Trap Chamber New Frequency Standards in the Optical Region Precise Time and Frequency Transfer Methods and Space Geodesy ETS-8 (Engineering Test Satellite) QZSS (Quasi Zenith Satellite System) BIPM, National Timing Laboratories, Station A Station B + Ca Single Ion Trap Satellite T&F Transfer Precise T&F Transfer e-vlbi Towards better frequency standards International time and frequency transfer and satellite navigation Generation and Dissemination of Stable and Accurate Japan Standard Time (JST) Primary Frequency Standard LF Radio Dissemination of Frequency (10-12 ) and Time (10μs) Telephone Line JST System Internet (NTP Services) Atomic Clocks Determination and maintenance of UTC(NICT) to be consistent with UTC within 10nsec of difference and 5ns of variance. Frequency Calibration Services Time Business Services High Quality Frequency Calibration (5x10-14 ) Establish integrated space and time infrastructure to provide and certificate position and time. Integration of Space and Time Information Pedestrian navigation, certification of time and position of various information. Integrated Space and Time Infrastructure Provide accurate and reliable spatial and timing information to support secure and safe ICT. Protection of intellectual properties and electric commerce. Secure infrastructure for s, GIS, etc. 4

5 nsec Time Keeping Date UTC-UTC(k) Contribution Factors for UTC Average of the period Oct.2008-Sep.2009

6 Frequency difference ( x10-15 ) Primary Frequency Standard Cesium atomic fountain primary frequency standard (NICT-CsF1) Instead of the previous optically pumped cesium primary frequency standard (NICT- O1 ~June 2006), NICT-CsF1 is in operational use. International official recognition was obtained in September Ramsey fringe linewidth : 0.9Hz Frequency stability : 4 x /t 1/2 Current total frequency uncertainty : 1.3 to 2.2 in CsF1 SI second on geoid Ref: M. Kumagai et al, Metrologia 45 (2008) MJD NICT-CsF1 contributes to determination of TAI.

7 Number of of measurement Ion Trap Histogram of the measured frequency Std. Deviation: 28.6 Hz Std. Error: 4.1 Hz N total = 50 Magnetic-shielded chamber Ion pump (55 l/s) Titan sublimation pump Frequency Absolute Frequency Measurement of the 40 Ca + Clock Transition Our Results: (5) Hz Innsbruck/LNE-SYRTE: (1.0) Hz Twofold magnetic shield (Permalloy t=1.5 mm) S. F. (at 50 Hz): 1/240 radial, 1/25 axial 0.4 m

8 Optical Lattice Clock Sr Oven Zeeman slower Ion Pump 5 cm MOT Coil Succeeded to load 87 Sr atoms in the lattice potential and observe the clock transition.

9 Precise T&F Transfer T&F Transfer by Using Satellites T&F Transfer by VLBI (Very Long Baseline Interferometry) T&F Transfer by Using Optical Fiber

10 T&F Transfer by TWSTFT and VLBI Development of a new modem VLBI = Very Long Baseline Interferometry Based software-defined radio technology. - Waveform signal generator - Versatile A/D sampler Digital signal processing is performed by software on the host computer Common clock two-way exp. after removing linear trend GPS: day boundary : 94 ps - GPS + VLBI GPS-VLBI ±200ps Post-fit RMS 30.6 ps. Clock difference between Onsala and Wettzell

11 Overlapping Allan deviation 114km, free run 204km, free run NICT Air part Hakusan 45 km 12 km Otemachi km Google map km: 1GHz, compensated 90km: 10GHz, compensated 204km: cascade of 1GHz & 10GHz, compensated Averaging time [s] *A stable microwave signal was transferred over 204- km urban optical fiber link, named JGN2+, in Tokyo. *The transfer length was the longest among actual fiber links reported so far. *The frequency stability reached 5x10-17 at 0.5 day.

12 Operations of TWSTFT links IS-4 on 72 E IS-8 on 166 E GE23 on 172 E PTB OP VSL NTSC NMIJ KRISSNICT USNO TL Hawaii A*STAR NMIA Operating Planning October 2009

13 Operations of TWSTFT links Asia Link = IS-8 Current Users : NICT, KRISS, TL, NTSC, and 2 LF stations of NICT. Switched from JCSAT-1B since April Asia-Hawaii-US Link = GE-23 A new ground station is in construction at Kauai (Hawaii) to establish a new link between NICT and USNO. Asia-EU Link = IS-4 Link share scheme started with NICT, TL, NTSC, NMIJ, KRISS, NIM, PTB, OP, and VSL since April VNIIFTRI (Russia) has an intension to join the link.

14 Dissemination Hardware SNTP Server Ohtakadoya-yama Hagane-yama Frequency 40 khz 60 khz E.I.R.P 13 kw 23 kw Antenna 250 m height 200 m height Latitude 37 22' N 33 28' N Longitude ' E ' E JJY LF radio stations Network Space-Time server

15 Calibration Services FPGA based GPS receiver unit for remote calibration Prototype remote calibration unit using LF radio signal

16 Training Program for Time and Frequency Date : October 15-23, 2009 Number of Participants : 12 (9 Institutes) National Time Service Center (China) National Institute of Metrology (China) Kazakhstan Institute of Metrology (Kazakhstan) KIM-LIPI (Indonesia) National Institute of Metrology Thailand (Thai) National Institute of Standards and Industrial Technology (Papua New Guinea) Department of Measurement Units, Standards and Service (Sri Lanka) National Standards & Calibration Laboratory (Syria) National Metrology Laboratory, ITDI (Philippines) National Metrology Centre, A*STAR (Singapore)