scholarly journals Simultaneous OTDR Dynamic Range and Spatial Resolution Enhancement by Digital LFM Pulse and Short-Time FrFT

2019 ◽  
Vol 9 (4) ◽  
pp. 668 ◽  
Author(s):  
Pu Zhang ◽  
Qiguang Feng ◽  
Wei Li ◽  
Qiang Zheng ◽  
You Wang
Keyword(s):  
Spatial Resolution ◽  
Dynamic Range ◽  
Fractional Fourier Transform ◽  
Resolution Enhancement ◽  
Time Domain Reflectometry ◽  
Optical Time Domain Reflectometry ◽  
Reflection Peak ◽  
Working Principle ◽  
Optical Time ◽  
Short Time

This paper proposes a novel optical time domain reflectometry (OTDR) method based on the digital linear frequency modulation (LFM) pulse, which can achieve a tradeoff between maximum measurable distance and spatial resolution. Direct modulation and detection are adopted at the transmitting and receiving ends, respectively, which is simple in construction and does not require additional optics. The short-time fractional Fourier transform (STFrFT) is introduced for the signal processing and noise filtering. The theoretical analysis of the working principle confirmed that the spatial resolution is determined by the sweep frequency range of the digital LFM signal rather than the pulse width. The influence of the STFrFT window on the peak sidelobe ratio of the reflection peak is also studied. By combining STFrFT and sidelobe suppression, the dynamic range and spatial resolution can be appreciably enhanced simultaneously. In the demo experiments testing the proposed method on a conventional OTDR development board for comparison, a 7-dB improvement in the dynamic range and an approximately 10-times improvement in the spatial resolution are simultaneously achieved.

scholarly journals Sub-Meter Spatial Resolution Phase-Sensitive Optical Time-Domain Reflectometry System Using Double Interferometers

2018 ◽  
Vol 8 (10) ◽  
pp. 1899 ◽  
Author(s):  
Shengwen Feng ◽  
Tuanwei Xu ◽  
Jianfen Huang ◽  
Yang Yang ◽  
Lilong Ma ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Time Domain ◽  
Time Domain Reflectometry ◽  
Bilateral Filtering ◽  
Rayleigh Backscattering ◽  
Detection Frequency ◽  
Optical Time Domain Reflectometry ◽  
Phase Sensitive ◽  
Optical Time ◽  
Phase Generated Carrier

An improved phase-sensitive optical time-domain reflectometry (φ-OTDR) system with sub-meter spatial resolution is demonstrated. Two Michelson interferometers (MIs) with different path length differences are used in the proposed system. One is 10 m, the other is 9.2 m. Two Rayleigh backscattering phase traces with different spatial resolution are obtained by a phase generated carrier (PGC) algorithm at adjacent times. After using differencing and adaptive 2-D bilateral filtering algorithms, a 0.8-m spatial resolution over 2 km is achieved. Experimental results indicate that the system shows an extraordinary linearity as high as 99.94% with amplitude-modulation and acquires a detection frequency from 5 to 500 Hz.

Chaos Raman optical time-domain reflectometry for millimeter-level spatial resolution temperature sensing

2021 ◽  
pp. 1-1
Author(s):  
Xinxin Zhou ◽  
Jian Li ◽  
Yang Xu ◽  
Zitong Yin ◽  
Chenyi Wang ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Time Domain ◽  
Time Domain Reflectometry ◽  
Temperature Sensing ◽  
Optical Time Domain Reflectometry ◽  
Optical Time

scholarly journals Distributed Fiber Birefringence Measurement Using Pulse-Compression Φ-OTDR

2020 ◽  
Author(s):  
Yongxiang Chen ◽  
Yun Fu ◽  
Ji Xiong ◽  
Zinan Wang
Keyword(s):  
Spatial Resolution ◽  
Pulse Compression ◽  
Single Mode ◽  
Single Mode Fiber ◽  
Time Domain Reflectometry ◽  
Coherent Detection ◽  
Compression Phase ◽  
Optical Time Domain Reflectometry ◽  
Fiber Birefringence ◽  
Optical Time

Abstract In this paper, a novel birefringence measurement method through the Rayleigh backscattered lightwave within single-mode fiber is proposed, using a single chirped-pulse with arbitrary state of polarization. Numerical analysis is carried out in detail, then pulse-compression phase-sensitive optical time domain reflectometry (PC-Φ-OTDR) with polarization-diverse coherent detection is employed to verify this method. A 2km spun single-mode fiber is tested with 8.6 cm spatial resolution, and the average birefringence of the fiber under test is measured as 0.234rad/m, which is consistent with previous literatures about single-mode fiber. Moreover, the relationship between the measured birefringence and the spatial resolution is also studied for the first time, and the results show that spatial resolution is crucial for fiber birefringence measurement.

Cost-effective high-spatial-resolution photon-counting optical time-domain reflectometry at 850  nm

2018 ◽  
Vol 57 (30) ◽  
pp. 8824 ◽  
Author(s):  
Bin Li ◽  
Qiang Zhou ◽  
Ruiming Zhang ◽  
Junyi Li ◽  
Heng Zhou ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Time Domain ◽  
High Spatial Resolution ◽  
Photon Counting ◽  
Cost Effective ◽  
Time Domain Reflectometry ◽  
Optical Time Domain Reflectometry ◽  
Optical Time

Strain variation measurement with short‐time Fourier transform‐based Brillouin optical time‐domain reflectometry sensing system

2014 ◽  
Vol 50 (22) ◽  
pp. 1624-1626 ◽  
Author(s):  
Guojie Tu ◽  
Xuping Zhang ◽  
Yixin Zhang ◽  
Zhoufeng Ying ◽  
Lidong Lv
Keyword(s):  
Fourier Transform ◽  
Time Domain ◽  
Time Domain Reflectometry ◽  
Strain Variation ◽  
Short Time Fourier Transform ◽  
Sensing System ◽  
Optical Time Domain Reflectometry ◽  
Optical Time ◽  
Short Time

scholarly journals Performance Optimization for Phase-Sensitive OTDR Sensing System Based on Multi-Spatial Resolution Analysis

Sensors ◽  
2018 ◽  
Vol 19 (1) ◽  
pp. 83 ◽  
Author(s):  
Yuanyuan Shan ◽  
Wenbin Ji ◽  
Qing Wang ◽  
Lu Cao ◽  
Feng Wang ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Performance Optimization ◽  
Signal To Noise Ratio ◽  
Time Domain Reflectometry ◽  
Sensing System ◽  
Optical Time Domain Reflectometry ◽  
Resolution Analysis ◽  
Phase Sensitive ◽  
Optical Time ◽  
Qualitative Relationship

This paper proposes and demonstrates a phase-sensitive optical time domain reflectometry (Φ-OTDR) sensing system with multi-spatial resolution (MSR) analysis property. With both theoretical analysis and an experiment, the qualitative relationship between spatial resolution (SR), signal-to-noise ratio (SNR) and the length of the vibration region has been revealed, which indicates that choosing a suitable SR to analyze the vibration event can effectively enhance the SNR of a sensing system. The proposed MSR sensing scheme offers a promising solution for the performance optimization of Φ-OTDR sensing systems, which can restore vibration events of different disturbance range with optimum SNR in merely a single measurement while maintaining the same detectable frequency range.

scholarly journals Analysis of Phase-Shift Pulse Brillouin Optical Time-Domain Reflectometry

Sensors ◽  
2019 ◽  
Vol 19 (7) ◽  
pp. 1497 ◽  
Author(s):  
Tsuneo Horiguchi ◽  
Yuki Masui ◽  
Mohd Zan
Keyword(s):  
Spectral Analysis ◽  
Phase Shift ◽  
Spatial Resolution ◽  
Optical Fibers ◽  
Time Domain ◽  
Time Domain Reflectometry ◽  
Frequency Resolution ◽  
Optical Time Domain Reflectometry ◽  
Depth Analysis ◽  
Optical Time

Distributed strain and temperature can be measured by using local Brillouin backscatter in optical fibers based on the strain and temperature dependence of the Brillouin frequency shift. The technique of analyzing the local Brillion backscatter in the time domain is called Brillouin optical time domain reflectometry (BOTDR). Although the best spatial resolution of classic BOTDR remains at around 1 m, some recent BOTDR techniques have attained as high as cm-scale spatial resolution. Our laboratory has proposed and demonstrated a high-spatial-resolution BOTDR called phase-shift pulse BOTDR (PSP-BOTDR), using a pair of probe pulses modulated with binary phase-shift keying. PSP-BOTDR is based on the cross-correlation of Brillouin backscatter and on the subtraction of cross-correlations obtained from the Brillouin scatterings evoked by each phase-modulated probe pulse. Although PSP-BOTDR has attained 20-cm spatial resolution, the spectral analysis method of PSP-BOTDR has not been discussed in detail. This article gives in-depth analysis of the Brillouin backscatter and the correlations of the backscatters of the PSP-BOTDR. Based on the analysis, we propose new spectral analysis methods for PSP-BOTDR. The analysis and experiments show that the proposed methods give better frequency resolution than before.

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