An Experiment of VLBI Clock-Signal Distribution through Optical Fibers Based on Signal-Delay Measurement Using a Digital Correlator

Pei Xin; Chen Maozheng; Li Jian; Yan Hao

Astronomical Research and Technology > 2015 > 12(3): 270-276.

Pei Xin, Chen Maozheng, Li Jian, Yan Hao. An Experiment of VLBI Clock-Signal Distribution through Optical Fibers Based on Signal-Delay Measurement Using a Digital Correlator[J]. Astronomical Research and Technology, 2015, 12(3): 270-276.

Citation:

PDF (1966 KB)

An Experiment of VLBI Clock-Signal Distribution through Optical Fibers Based on Signal-Delay Measurement Using a Digital Correlator

Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi 830011, China

More Information

Received Date: July 31, 2014
Revised Date: August 23, 2014
Published Date: July 14, 2015

Graphical Abstract

Abstract

Abstract

In a VLBI observation delays of clock signals used as timing and frequency standards fluctuate severely after long-distance propagation from a maser to a radio receiver. The fluctuations are worsened by variations of environmental temperatures. There is a need of a system to measure and compensate clock-signal delays with high precisions for a VLBI observation in the millimeter wavelength band. In this paper we present a system for the purpose. In the system clock signals are distributed through optical fibers and the system is based on signal-delay measurement using a digital correlator. With the high-performance digital correlator high-precision results of signal delay can be obtained by directly measuring phase differences between signals transmitted to and back from the optical receiver. Our test results show that the system can achieve measurement precisions better than the level of a picosecond, and the system is highly stable. Our test thus verifies the overall reliability of the system.
- Clock-signal distribution,
- Phase measurement,
- Correlator,
- Signal delay (during transmission),
- VLBI

FullText(HTML)

References (8)

References

[1]	D'Addario L R, Stennes M J. Transmission of timing references to sub-picosecond precision over optical fiber[C]//Proceedings of the SPIE. 1998: 691-701.
[2]	Stennes M J. GBT LO reference distribution system[R/OL]. 2004[2014-07-01]. http://www.gb.nrao.edu/electronics/gbttechreport/gbttechreport2.pdf.
[3]	Cotter T. LO/IF systems[M/OL]//EVLA Project Book. (2009-02-28) [2014-07-01]. http://www.aoc.nrao.edu/evla/admin/projbook/chap6.pdf.
[4]	Durand S J, Cotter T. Operational performance of the EVLA LO round-trip phase system[C]//Proceedings of the SPIE. 2002: 63-71.
[5]	王锦清, 韦文任. 一种基于相位的相对延迟变化测量方法[J]. 中国科学院上海天文台年刊, 2007(28): 119-127. Wang Jinqing, Wei Wenren. A relative measurement method based on phase delay[J]. Annals of Shanghai Astronomical Observatory Chinese Academy Sciences, 2007(28): 119-127.
[6]	张越成, 刘荣军, 马玉培, 等. CSRH光传输线的长度及相位测量[J]. 天文研究与技术——国家天文台台刊, 2011, 8(4): 334-337. Zhang Yuecheng, Liu Rongjun, Ma Yupei, et al. A measurement method of lengths and phases of transmission optical fibers for the CSRH[J]. Astronomical Research & Technology——Publications of National Astronomical Observatories of China, 2011, 8(4): 334-337.
[7]	钱志瀚, 邬林达. 甚长基线射电干涉测量[M]. 北京: 测绘出版社, 1983.
[8]	裴鑫, 李健, 陈卯蒸, 等. 基于ROACH的微波全息法相关机设计[J]. 天文研究与技术——国家天文台台刊, 2015, 12(1): 54-62. Pei Xin, Li Jian, Chen Maozheng, et al. Design of a microwave holography correlator based on the ROACH board[J]. Astronomical Research & Technology——Publications of National Astronomical Observatories of China, 2015, 12(1): 54-62.

Articles Related

[1]	Zhu Yali, Zheng Weimin, Tong Li, Tong Fengxian, Zhang Juan, Liu Lei. Simulation method of Probe VLBI Signal [J]. Astronomical Research and Technology, 2018, 15(1): 25-31.
[2]	Guo Shaoguang, Zhu Renjie, Zheng Weimin, Fan Qingyuan, Li Jiyun, Zhao Rongbing, Zhang Xiuzhong, Xu Zhijun, Gan Jiangying, Wu Yajun. The Progress of VLBI Data Acquisition System-Mark6 and Related Techenologies [J]. Astronomical Research and Technology, 2017, 14(3): 281-287.
[3]	Yang Wenjun, Zhao Rongbing, Nie Jun. The Improvement of a VLBI Monitoring System [J]. Astronomical Research and Technology, 2015, 12(3): 285-291.
[4]	Wang Lingling. Design and Implementation of a Time Frequency System with Auto-Switching Clocks at a VLBI Station [J]. Astronomical Research and Technology, 2015, 12(2): 166-173.
[5]	Xiang Binbin, Liu Zhiyong, Yang Wenjun. Measurement of the Antenna Characteristics of the VLBI Radio Telescope of the Urumqi Station [J]. Astronomical Research and Technology, 2014, 11(4): 343-349.
[6]	He Qingbao, Liu Qinghui, Zheng Xin, Wu Yajun, Tang Mingle. A Study of Difference Delay Rates Derived from Processing of Same-Beam VLBI Data [J]. Astronomical Research and Technology, 2014, 11(3): 247-254.
[7]	XIANG Ying, ZHANG Xiu-zhong. The Study of Digital Filtering on VLBI Data Acquisition [J]. Astronomical Research and Technology, 2003, 0(4): 19-27.
[8]	ZHENG Wei-ming, SHU Feng-chun, ZHANG Xiu-zhong. The Real-time VLBI Technology [J]. Astronomical Research and Technology, 2003, 0(1): 100-105.
[9]	JIANG Dong-rong. Progress in the VLBI observation of AGNs [J]. Astronomical Research and Technology, 2003, 0(1): 37-40.
[10]	Yang Xiaoning, Su Bumei, Wang Rui. Progress in VLBI Recording Systems [J]. Publications of the Yunnan Observatory, 1993, 0(4): 31-44.