Fading noise reduction in coherent OTDR

Izumita, Hisashi; Furukawa, Shoei; Koyamada, Yahei; Sankawa, I.

doi:10.1109/68.122361

Cited by 78 publications

(25 citation statements)

References 7 publications

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“…In order to obtain the accurate location of the perturbation in Φ-OTDR systems, we should figure out the center of the vibration segment. However, some subsections of the fiber vibration segment may be in insensitive states due to the coherent fading problem [23]. Figure 2a shows 100 consecutive averaged Rayleigh traces, which were acquired by our Φ-OTDR system.…”

Section: Methodsmentioning

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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Section: Methodsmentioning

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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“…The phase signals are extracted from the sampled signals according to (4). The phase variance is used to characterize the noise level, since the phase signal varies at [0, 2] so that the SNR is not applicable.…”

Section: Phase Noise Analysismentioning

confidence: 99%

“…In -OTDR, highly coherent pulses from a narrow linewidth laser are launched into the fiber under test (FUT), and the Rayleigh backscattering (RBS) lightwaves from individual scattering centers within a pulse length interfere coherently, resulting in RBS traces in a jagged form [4]. With a frequency stabled laser and an undisturbed fiber, a stable RBS trace can be obtained, since the phase of backscattered lightwave from each scattering center is dependent on the wavelength of laser source and the distance of scattering centers [5].…”

Section: Introductionmentioning

confidence: 99%

Long-Range Distributed Vibration Sensing Based on Phase Extraction From Phase-Sensitive OTDR

et al. 2016

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Distributed fiber-optic vibration sensors based on phase-sensitive optical timedomain reflectometry (-OTDR) have found many applications in various fields. In this paper, we analyze the phase noise of -OTDR, which is the main limiting factor of the measurement range. We found that the laser phase noise and phase extraction error caused by the intensity noise in photodetection contribute to the total phase noise. By introducing a series of auxiliary weak reflection points along the fiber, we develop a phase-noise-compensated -OTDR and realize a long-range distributed vibration sensing based on the phase extraction. Furthermore, a statistical analysis was proposed to maintain the vibration measurement sensitivity along the whole fiber. In the experiment, vibrations at 30 km were measured with a linear response, which confirmed the validity of our proposed system.

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“…Coherent OTDR (COTDR) is the one developed for this situation. Many researchers have conducted analysis and experiments on it, but most of them focused on synchronous demodulation of Rayleigh backscattered signal [2][3][4][5][6][7] . In this paper, we demonstrate a COTDR based on direct demodulation using log-detector.…”

Section: Introductionmentioning

confidence: 99%