A5070008023- Advanced Frequency and Time Standards
- Atomic and Subatomic Physics Research
- Particle accelerators and beam dynamics
- GNSS positioning and interference
- Cold Atom Physics and Bose-Einstein Condensates
- Geophysics and Sensor Technology
- Particle Accelerators and Free-Electron Lasers
- Advanced Fiber Laser Technologies
- Scientific Measurement and Uncertainty Evaluation
- Superconducting Materials and Applications
- Spacecraft Design and Technology
- Inertial Sensor and Navigation
- Satellite Communication Systems
- Network Time Synchronization Technologies
- Gyrotron and Vacuum Electronics Research
- Advanced Electrical Measurement Techniques
- Radio Astronomy Observations and Technology
- Magnetic confinement fusion research
- Precipitation Measurement and Analysis
- Cardiovascular Syncope and Autonomic Disorders
- Advanced Photonic Communication Systems
- Advancements in PLL and VCO Technologies
- Astronomy and Astrophysical Research
- Electric Motor Design and Analysis
- Geophysics and Gravity Measurements
National Institute of Information and Communications Technology
2013-2024
Kyoto University
1998-2024
Chukyo Hospital
2024
National Astronomical Observatory of Japan
2023-2024
Nippon Soken (Japan)
2019-2021
Japan Science and Technology Agency
2011
Shibaura Institute of Technology
2008
High Energy Accelerator Research Organization
1999-2003
Kyoto Bunkyo University
1999-2003
Kyoto University Institute for Chemical Research
1999-2002
Abstract This paper outlines the roadmap towards redefinition of second, which was recently updated by CCTF Task Force created in 2020. The main achievements optical frequency standards (OFS) call for reflection on but open new challenges related to performance OFS, their contribution time scales and UTC, possibility comparison, knowledge Earth’s gravitational potential ensure a robust accurate capacity realize definition at level 10 −18 uncertainty. mandatory criteria be achieved before...
Fiber-based remote comparison of 87Sr lattice clocks in 24 km distant laboratories is demonstrated. The instability the reaches 5×10-16 over an averaging time 1000 s, which two orders magnitude shorter than that conventional satellite links and limited by instabilities optical clocks. By correcting systematic shifts are predominated differential gravitational redshift, residual fractional difference found to be (1.0±7.3)×10-16, confirming coincidence between accurate speedy paves way for a...
We developed an all-optical link system for making remote comparisons of two distant ultra-stable optical clocks. An carrier transfer based on a fiber interferometer was employed to compensate the phase noise accumulated during propagation through link. Transfer stabilities $2\times10^{-15}$ at 1 second and $4\times10^{-18}$ 1000 seconds were achieved in 90-km active polarization control additionally introduced maintain transmitted light adequate polarization, consequently, stable reliable...
An rf dissemination system using an optical fiber link has been developed. The phase noise induced during transmission successfully cancelled what we believe to be a novel fiber-noise compensation with combination of electrical and compensations. We have performed transfer in 114 km urban telecom Tokyo stability 10(-18) level at averaging time 1 day. Additionally, high degree continuous operation robustness confirmed.
We have demonstrated a microwave transfer over 204-km noisy urban fiber link by cascaded system with 2 stages, which connected 10-GHz and 1-GHz systems in series. A diurnal phase-noise cancellation ratio of 45 dB was obtained use an electronic compensation system. Additionally, the stabilities reached 6 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-14</sup> at 1 s 5 xmlns:xlink="http://www.w3.org/1999/xlink">-17</sup> one-half day,...
In this paper we report that carrier-phase two-way satellite time and frequency transfer (TWSTFT) was successfully demonstrated over a very long baseline of 9,000 km, established between the National Institute Information Communications Technology (NICT) Physikalisch-Technische Bundesanstalt (PTB). We verified TWSTFT (TWCP) result agreed with those obtained by conventional GPS (GPSCP) techniques. Moreover, much improved short-term instability for $2\times10^{-13}$ at 1 s achieved, which is...
Advanced satellite-based frequency transfers by two-way carrier-phase (TWCP) and integer precise point positioning have been performed between the National Institute of Information Communications Technology Korea Research Standards Science. We confirm that disagreement them is less than at an averaging time several days. In addition, overseas ratio measurement Sr Yb optical lattice clocks was directly TWCP. achieved uncertainty mid-10-16 level after a total 12 h. The consistent with recently...
We have developed a radio-frequency (RF) dissemination system using optical fibers. The phase noise induced during the transmission is actively cancelled by compensation with voltage-controlled crystal oscillator. A first proving test was conducted on an urban telecom fiber link length of 10 km, and frequency stability 1 X <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-17</sup> achieved at averaging time one day. As application ultrastable...
We have demonstrated a direct frequency comparison between two ⁸⁷Sr lattice clocks operated in intercontinentally separated laboratories real time. Two-way satellite time and transfer technique, based on the carrier-phase, was employed for comparison, with baseline of 9000 km Japan Germany. A achieved 83,640 s, resulting fractional difference (1.1±1.6)×10⁻¹⁵, where statistical part is largest contributor to uncertainty. This measurement directly confirms agreement optical standards an...
We performed measurements of carrier-phase-based two-way satellite time and frequency transfer (TWST-FT) with an A/D sampler conventional TWSTFT system. found that instability resulting from a local signal at the transponder was negligible. The short-term stability 4 × 10(-13) 1 s achieved in short-baseline measurement. results showed good agreement GPS carrier phase.
In the global network of institutions engaged with realization International Atomic Time (TAI), atomic clocks and time scales are compared by means Global Positioning System (GPS) employing telecommunication satellites for two-way satellite frequency transfer (TWSTFT). The frequencies state-of-the-art primary caesium fountain can be at level 10e-15 (relative, 1 day averaging) synchronized an uncertainty one nanosecond. Future improvements worldwide clock comparisons will require also...
To keep national time accurately coherent with coordinated universal time, many metrology institutes (NMIs) use two-way satellite and frequency transfer (TWSTFT) to continuously measure the difference other NMIs over an international baseline. Some have ultra-stable clocks stability better than 10−16. However, current operational TWSTFT can only provide uncertainty of 10−15 1 ns, which is inadequate. The dominated by short-term diurnals, i.e. measurement variation a period one day. aim this...
Two-way satellite time and frequency transfer (TWSTFT) is a primary technique for the generation of coordinated universal (UTC). About 20 timing laboratories around world continuously operate TWSTFT using ranging equipment (SATRE19) modems remote comparisons in this context. The precision SATRE as observed today limited by an apparent daily variation pattern (diurnal) results. peak-to-peak have been found high 2 ns some cases. Investigations into origins diurnals so far provided no complete...
We have developed a new two-way time transfer modem to improve the precision of remote clock comparison. As timing signal, we apply binary offset carrier, which is similar those signals used for next-generation Global Navigation Satellite Systems. took advantage versatile A/D and D/A converters, most digital signal processing stages were realized by software, running on an off-the-shelf PC. This enabled us realize complete system with cheaper equipment, leading affordable low-cost modem. For...
Two-way satellite time and frequency transfer (TWSTFT) is one of the major techniques to compare atomic scales between timing laboratories. As more TWSTFT measurements have been performed, large number point-to-point 2-way links has grown be a complex network. For future improvement performance, it important reduce measurement noise results. One method using network transfer. The Asia-Pacific an exceptional case simultaneous measurements. Some indirect through relay stations show better...
Two-way satellite time and frequency transfer (TWSTFT) is one of the main techniques used to compare atomic scales over long distances. To both improve precision TWSTFT decrease link fee, a new software-defined modem with dual pseudo-random noise (DPN) codes has been developed. In this paper, we demonstrate first international DPN-based experiment period 6 months. The results DPN exhibit excellent performance, which competitive Global Positioning System (GPS) precise point positioning (PPP)...
Very high field-gradient has become available by a new magnetic alloy (MA)-loaded cavity developed for intensity proton synchrotrons. The RF voltage per core is ten times larger than that of the ordinary ferrite core. maximum 20 kV been achieved high-field gradient (HGC) 40 cm in length. Because intrinsic Q-value MA low, acceleration without any tuning system also becomes possible. first beam test using HGC performed successfully at HIMAC (Heavy Ion Medical Accelerator Chiba). Furthermore,...
Delays in signal transmission and reception paths of an Earth station must be calibrated accurately, their variation should reduced the two-way satellite time frequency transfer (TWSTFT). We have developed a portable TWSTFT using modem built by National Institute Information Communications Technology (NICT) performed calibration between NICT Telecommunication Laboratories. An uncertainty about 1 ns differential was achieved. In addition, we monitored delay measurement system installed at to...
We have developed a means for accurate time transfer using optical fibers and aim at the synchronization of clocks located different places on an institute campus with overall uncertainty 100 ps or better. Such installation shall be used as part infrastructure connecting ground station setups during forthcoming T2L2 ACES experiments local installations PTB laboratory. Our target transmission length is less than 1 km. To time, code-domain-multiple-access (CDMA) signal modulation laser....
Carrier-phase measurement is one of the ways to improve resolution two-way satellite frequency transfer. We introduce two possible methods for carrier-phase measurement: direct detection identified by Two-Way Carrier-Phase (TWCP) and use carrier-frequency information Carrier Frequency (TWCF). performed former using an arbitrary waveform generator analog-to-digital sampler latter a conventional modem. The TWCF modem had 10-13 result agreed with that obtained GPS transfer in 1500 km baseline....
A dual frequency GPS and a geostationary communication satellite based time transfer network have been established for the Asia-Pacific region. Some stations link to Europe with both methods. Consequently, we can compare performance of carrier phase or two-way transfer, vice versa. The difference between two methods shows good consistency in regional network. On other hand, intercontinental links there is an obvious variation diurnal secular changes.
During the last years transfer of frequency signals through optical fibers has shown ultra low instabilities in various configurations. The outstanding experimental results such point-to-point connections is motivation to develop a means extend accurate time transfer. We aim at synchronization clocks located different places PTB campus with an over-all uncertainty less than 100 ps. Such installation can be used as part infrastructure connecting local scales ground station setup during...