A Long Distance Phase-Sensitive Optical Time Domain Reflectometer with Simple Structure and  High Locating Accuracy

Shi, Yi; Feng, Hao; Zeng, Zhoumo

doi:10.3390/s150921957

Cited by 45 publications

(25 citation statements)

References 12 publications

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“…6,26 In this technique, the backscattered light is mixed with the laser source to extract the absolute phase of the backscattered light relative to the light source and this is used to detect perturbation along the fibre. In the current subsection, however, the term ϕ-OTDR is used to describe the systems which use the phase-difference between two adjacent sections of the sensing fibre rather than the absolute phase of the backscattered light.…”

Section: A Optical Time Domain Reflectometry (Otdr)mentioning

confidence: 99%

Contributed Review: Distributed optical fibre dynamic strain sensing

Masoudi

Newson

2016

Review of Scientific Instruments

206

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Extensive research on Brillouin- and Raman-based distributed optical fibre sensors over the past two decades has resulted in the commercialization of distributed sensors capable of measuring static and quasi-static phenomena such as temperature and strain. Recently, the focus has been shifted towards developing distributed sensors for measurement of dynamic phenomena such as dynamic strain and sound waves. This article reviews the current state of the art distributed optical fibre sensors capable of quantifying dynamic vibrations. The most important aspect of Rayleigh and Brillouin scattering processes which have been used for distributed dynamic measurement are studied. The principle of the sensing techniques used to measure dynamic perturbations are analyzed followed by a case study of the most recent advances in this field. It is shown that the Rayleigh-based sensors have longer sensing range and higher frequency range, but their spatial resolution is limited to 1 m. On the other hand, the Brillouin-based sensors have shown a higher spatial resolution, but relatively lower frequency and sensing ranges.

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Section: A Optical Time Domain Reflectometry (Otdr)mentioning

confidence: 99%

Contributed Review: Distributed optical fibre dynamic strain sensing

Masoudi

Newson

2016

Review of Scientific Instruments

206

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“…In Φ-OTDR systems, the accurate location of perturbations can be figured out by [7]:

z = z_{c e n t} - \frac{T_{p} v}{4},

where

z_{c e n t}

is the center of the vibration response segment,

T_{p}

is the optical pulse width, and v is the light velocity in fiber. In order to obtain the accurate location of the perturbation in Φ-OTDR systems, we should figure out the center of the vibration segment.…”

Section: Methodsmentioning

confidence: 99%

“…Qin et al introduced a wavelet denoising method to reject the random noises induced by varied polarization states in different position and detectors [6]. Shi et al [7] and Qin et al [8] proposed using empirical mode decomposition (EMD) to improve the signal-to-noise ratio (SNR) of location information for the vibration events. Qin et al also proposed a curvelet denoising method to reduce the time domain noise and improve the detection performance of Φ-OTDR systems [9].…”

Section: Introductionmentioning

confidence: 99%

Localization and Discrimination of the Perturbation Signals in Fiber Distributed Acoustic Sensing Systems Using Spatial Average Kurtosis

Jiang

Zhang

et al. 2018

Sensors

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Location error and false alarm are noticeable problems in fiber distributed acoustic sensing systems based on phase-sensitive optical time-domain reflectometry (Φ-OTDR). A novel method based on signal kurtosis is proposed to locate and discriminate perturbations in Φ-OTDR systems. The spatial kurtosis (SK) along the fiber is firstly obtained by calculating the kurtosis of acoustic signals at each position of the fiber in a short time period. After the moving average on the spatial dimension, the spatial average kurtosis (SAK) is then obtained, whose peak can accurately locate the center of the vibration segment. By comparing the SAK value with a certain threshold, we may to some degree discriminate the instantaneous destructive perturbations from the system noise and certain ambient environmental interferences. The experimental results show that, comparing with the average of the previous localization methods, the SAK method improves the pencil-break and digging locating signal-to-noise ratio (SNR) by 16.6 dB and 17.3 dB, respectively; and decreases the location standard deviation by 7.3 m and 9.1 m, respectively. For the instantaneous destructive perturbation (pencil-break and digging) detection, the false alarm rate can be as low as 1.02%, while the detection probability is maintained as high as 95.57%. In addition, the time consumption of the SAK method is adequate for a real-time Φ-OTDR system.

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“…In a simple distributed measurement using this technique, a number of raw traces are acquired, and their difference with a reference trace is calculated for the entire length of the fiber. The resulting differential trace set will have nonzero values at points of disturbance while being near zero at locations without disturbance, as shown in Figure 2(b) [9]. The evolution of the change at a disturbed location can then be monitored to extract information such as frequency and amplitude of the external impact.…”

Section: Basic Principle Of Distributed Sensing In ϕ-Otdrmentioning

confidence: 99%

Recent Advances in Distributed Acoustic Sensing Based on Phase-Sensitive Optical Time Domain Reflectometry

Muanenda

2018

Journal of Sensors

120

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Distributed acoustic sensing (DAS) using coherent Rayleigh backscattering in an optical fiber has become a ubiquitous technique for monitoring multiple dynamic events in real time. It has continued to constitute a steadily increasing share of the fiber-optic sensor market, thanks to its interesting applications in many safety, security, and integrity monitoring systems. In this contribution, an overview of the recent advances of research in DAS based on phase-sensitive optical time domain reflectometry (ϕ-OTDR) is provided. Some advanced techniques used to enhance the performance of ϕ-OTDR sensors for measuring backscattering intensity changes through reduction of measurement noise are presented, in addition to methods used to increase the dynamic measurement capacity of ϕ-OTDR schemes beyond conventional limits set by the sensing distance. Recent ϕ-OTDR configurations which significantly enhance the measurement spatial resolution, including those which decouple it from the probing pulse width, are also discussed. Finally, a review of recent advances in more precise quantitative measurement of an external impact based on frequency shift and phase demodulation methods using simple direct detection ϕ-OTDR schemes is given.

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A Long Distance Phase-Sensitive Optical Time Domain Reflectometer with Simple Structure and High Locating Accuracy

Cited by 45 publications

References 12 publications

Contributed Review: Distributed optical fibre dynamic strain sensing

Contributed Review: Distributed optical fibre dynamic strain sensing

Localization and Discrimination of the Perturbation Signals in Fiber Distributed Acoustic Sensing Systems Using Spatial Average Kurtosis

Recent Advances in Distributed Acoustic Sensing Based on Phase-Sensitive Optical Time Domain Reflectometry

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