A dual-ended 400 km OFDR for vibration detection

2022 ◽  
Author(s):  
Zujun Qin ◽  
Yiwei Hu ◽  
Yaoli Yue ◽  
Chao Tan
Keyword(s):  
Frequency Domain ◽  
Spatial Resolution ◽  
Cross Correlation ◽  
High Spatial Resolution ◽  
Vibration Monitoring ◽  
Optical Frequency ◽  
Detection Range ◽  
Vibration Detection

Abstract Optical frequency-domain reflectometer (OFDR) has been widely used in vibration detection because of its unique advantages of simple configuration and high spatial resolution. Based on remote fiber amplification, an unrepeatered OFDR is experimentally investigated for vibration monitoring. To locate the vibration, we present an algorithm by calculating segmental cross-correlation between the beating signals with and without disturbances on the sensing fiber. It is shown that the OFDR demonstrates the ability of detecting the vibration over 222 km testing distance (112 km + 110 km). After sensing the first spool fiber of 112 km, the remnant laser is amplified by a remote-pumped EDFA before proceeding to probe the vibration in the second spool one of 110 km. To be specific, the PZT-induced vibrations positioned at z=110.9 km and z=220.9 km are both detected. More importantly, the OFDR system can be extended to operate in bi-directional sensing mode and to double detection range from 200 km to 400 km.

scholarly journals Enhancement of the Performance and Data Processing Rate of an Optical Frequency Domain Reflectometer Distributed Sensing System Using A Limited Swept Wavelength Range

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3480 ◽  
Author(s):  
Kunpeng Feng ◽  
Jiwen Cui ◽  
Yihua Jin ◽  
Xun Sun ◽  
Dong Jiang ◽  
...  
Keyword(s):  
Data Processing ◽  
Frequency Domain ◽  
Spatial Resolution ◽  
Wavelength Range ◽  
Distributed Sensing ◽  
Optical Frequency ◽  
Local Similarity ◽  
Processing Rate ◽  
Spectrum Range ◽  
Measurable Range

A novel optical frequency domain reflectometer (OFDR) processing algorithm is proposed to enhance the measurable range and data processing rate using a narrow swept spectrum range and reducing the time consuming of the process distributed sensing results. To reduce the swept wavelength range and simultaneously enhance strain measurable range, the local similarity characteristics of Rayleigh scattering fingerprint spectrum is discovered and a new similarity evaluation function based on least-square method is built to improve the data processing rate and sensing performance. By this method, the strain measurable range is raised to 3000 µε under a highest spatial resolution of 3 mm when the swept spectrum range is only 10 nm and the data processing rate is improved by at least 10 times. Experimental results indicate that a nonlinearity of less than 0.5%, a strain resolution of better than 10 µε, a repeatability at zero strain of below ±0.4 GHz and a full-scale accuracy is lower than 0.85 GHz under a highest spatial resolution of 3 mm can be achieved. Advantages of this method are fast processing rate, large strain measurable range, high SNR, and applicability with current OFDR systems.

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