scholarly journals Key technology of high-precision time frequency transfer via 200 km desert urban fiber link

2019 ◽  
Vol 68 (6) ◽  
pp. 060602
Author(s):  
Kang Ying ◽  
You-Zhen Gui ◽  
Yan-Guang Sun ◽  
Nan Cheng ◽  
Xiao-Feng Xiong ◽  
...  
Keyword(s):  
High Precision ◽  
Key Technology ◽  
Time Frequency ◽  
Precision Time ◽  
Fiber Link ◽  
Frequency Transfer

scholarly journals Long-Distance Time Transfer in Optical Fiber Networks Using a Cascaded Taming Technology

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Ding Chen ◽  
Jiangning Xu ◽  
Yifeng Liang ◽  
Shan Jiang ◽  
Hongyang He
Keyword(s):  
Optical Fiber ◽  
High Precision ◽  
Wavelength Division Multiplexing ◽  
Time Synchronization ◽  
Atomic Clock ◽  
Process Time ◽  
Long Distance ◽  
Time Service ◽  
Time Frequency ◽  
Fiber Link

In order to meet the time service needs of high-precision, long-distance, and multinode optical network, this paper proposes a new time synchronization solution, which combines the wavelength division multiplexing (WDM) technology with cascaded taming clock technology. The WDM technology is used for time synchronization between each pair of master-slave nodes. In the system, there are two wavelengths on the fiber link between the master node and the slave node for transmitting signals. 1 plus per second (PPS) signal, time code signal, and 10 MHz signal are, respectively, and successively, sent to the optical fiber link. By solving the one-way delay through analysis of error contribution and link characteristics of the time transmission process, time synchronization of the master-slave nodes pair is achieved. Furthermore, the authors adopt cascaded taming clock technology to ensure accurate time synchronization of each node. A 700 km long-distance time-frequency synchronization system is constructed in the laboratory. The system uses a cesium atomic clock as the reference clock source and transmits the signals through 8 small rubidium atomic clocks (RB clocks) hierarchically. Results from the experiment show that the long-term time stability is 47.5 ps/104 s. The system’s structural characteristics and the experiment results meet the requirements to allow practical use of high-precision time synchronization in networks. This proposed solution can be applied in various civil, commercial, and military fields.

scholarly journals A Method of FPGA-Based Extraction of High-Precision Time-Difference Information and Implementation of Its Hardware Circuit

Sensors ◽  
2019 ◽  
Vol 19 (23) ◽  
pp. 5067
Author(s):  
Li ◽  
Yan ◽  
Li ◽  
Meng ◽  
Yan
Keyword(s):  
High Precision ◽  
High Speed ◽  
Source Location ◽  
Blast Waves ◽  
Time Difference ◽  
P Wave ◽  
Sensor Data ◽  
Time Interval ◽  
Time Frequency ◽  
Precision Time

Abstract: The positioning technology to find shallow underground vibration sources based on a wireless sensor network is receiving great interest in the field of underground position measurements. The slow peaking and strong multi-waveform aliasing typical of the underground vibration signal result in a low extraction accuracy of the time difference and a poor source-positioning accuracy. At the same time, the transmission of large amounts of sensor data and the host computer’s slow data processing speed make locating a source a slow process. To address the above problems, this paper proposes a method for high-precision time-difference measurements in near-field blasting and a method for its hardware implementation. First, based on the broadband that is typical of blast waves, the peak frequency of the P-wave was obtained in the time–frequency domain, taking advantage of the difference in the propagation speed of the P-wave, S-wave, and the surface wave. Second, the phase difference between two sensor nodes was found by means of a spectral decomposition and a correlation measurement. Third, the phase ambiguity was eliminated using the time interval of the first break and the dynamic characteristics of the sensors. Finally, following a top-down design idea, the hardware system was designed using Field Programmable Gate Array(FPGA). Verification, using both numerical simulations and experiments, suggested that compared with generalized cross-correlation-based time-difference measurement methods, the proposed method produced a higher time-difference resolution and accuracy. Compared with the traditional host computer post-position positioning method, the proposed method was significantly quicker. It can be seen that the proposed method provides a new solution for solving high-precision and quick source-location problems, and affords a technical means for developing high-speed, real-time source-location instruments.

scholarly journals Comparison of VLBI and GNSS common view for time transfer

2019 ◽  
Vol 10 ◽  
pp. 15 ◽  
Author(s):  
Pingli Wang ◽  
Guangli Wang ◽  
Yuping Gao ◽  
Hongbing Cai ◽  
Na Liu
Keyword(s):  
High Precision ◽  
Rapid Development ◽  
Next Generation ◽  
Time Transfer ◽  
Position Measurement ◽  
Common View ◽  
Practical Applications ◽  
Time Frequency ◽  
Frequency Standards ◽  
Frequency Transfer

With the rapid development of optical clock, the stability and system uncertainty of optical clocks has reached a 1.0e–18 level. Optical clocks will likely constitute the next generation of time-frequency standards for redefining the SI second. Because time and frequency transfer services that rely on satellite systems are not always reliable and currently available technologies are insufficient for comparing the next generation of frequency standards, high-precision time and transfer techniques are strongly desired. Very Long Baseline Interferometry (VLBI) is one of the space geodetic techniques that measure the arrival time delays between multiple stations utilizing radio signals from distant celestial radio sources. Not only can VLBI obtain the angle position measurement of the radio source with sub-millisecond accuracy and the station coordinate measurement with millimeter accuracy, but also, it can provide high-precision information regarding inter-station atomic clock differences. Therefore, it is theoretically feasible to use the VLBI technology to do the remote time transfer. Because of this characteristic of VLBI technology, VLBI has significant application potential in the field of remote time transfer. To confirm the suitability of VLBI to time-frequency transfer for future practical applications, the results of VLBI and GPS common view time transfer were compared using a Kunming-Urumqi baseline. The performance characteristics of time transfer based on VLBI are then analyzed. Experimental results show that VLBI technology can accurately measure the variation of clock differences between stations as same as the GPS common view time comparison technology. It briefly describes the challenges of future VLBI technology for practical applications of time transfer.

High-precision time transfer over a local ring fiber link

2020 ◽  
Vol 466 ◽  
pp. 125636
Author(s):  
Rongrong Xu ◽  
Faxing Zuo ◽  
Liang Hu ◽  
Jianping Chen ◽  
Guiling Wu
Keyword(s):  
Local Ring ◽  
High Precision ◽  
Time Transfer ◽  
Precision Time ◽  
Fiber Link

scholarly journals A High Precision Time-frequency Analysis Method

2015 ◽  
Vol 8 (7) ◽  
pp. 255-264
Author(s):  
Wenxin Zhang ◽  
Xiaojun Liu ◽  
Xiuwei Chen ◽  
Qing Liu ◽  
Guangyou Fang
Keyword(s):  
High Precision ◽  
Frequency Analysis ◽  
Analysis Method ◽  
Time Frequency Analysis ◽  
Time Frequency ◽  
Precision Time

High Precision Time and Frequency Transfer on 275 km Beijing—Shanghai Fiber Backbone

2016 ◽  
Vol 43 (7) ◽  
pp. 0706001
Author(s):  
陈炜 Chen Wei ◽  
程楠 Cheng Nan ◽  
刘琴 Liu Qin ◽  
王家亮 Wang Jialiang ◽  
冯子桐 Feng Zitong ◽  
...  
Keyword(s):  
High Precision ◽  
Precision Time ◽  
Frequency Transfer

scholarly journals High-Precision Time Transfer Over 2000-km Fiber Link

2015 ◽  
Vol 7 (6) ◽  
pp. 1-9 ◽  
Author(s):  
Hao Zhang ◽  
Guiling Wu ◽  
Liang Hu ◽  
Xinwan Li ◽  
Jianping Chen
Keyword(s):  
High Precision ◽  
Time Transfer ◽  
Precision Time ◽  
Fiber Link
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