An improved device and demodulation method for fiber-optic distributed acoustic sensor based on homodyne detection

Ma, Fai; Wang, Xiaxiao; Wang, Yizhen; Zhu, Rongtong; Yuan, Zhengguo; Wang, Peng; Yu, Jia; Song, Ningfang

doi:10.1016/j.yofte.2022.102925

Cited by 4 publications

(1 citation statement)

References 22 publications

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“…Moreover, its event response time is generally worse. At the same time, the necessity to use a highly coherent radiation source, a high-speed optical modulator [30], a photodetector, and ADC, as well as several optical amplifiers in DAS makes them rather expensive. Therefore, such systems are widespread only in top-financed areas of science and technology.…”

Section: Introductionmentioning

confidence: 99%

Enhancing the Distributed Acoustic Sensors’ (DAS) Performance by the Simple Noise Reduction Algorithms Sequential Application

et al. 2023

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Moving differential and dynamic window moving averaging are simple and well-known signal processing algorithms. However, the most common methods of obtaining sufficient signal-to-noise ratios in distributed acoustic sensing use expensive and precise equipment such as laser sources, photoreceivers, etc., and neural network postprocessing, which results in an unacceptable price of an acoustic monitoring system for potential customers. This paper presents the distributed fiber-optic acoustic sensors data processing and noise suppression techniques applied both to raw data (spatial and temporal amplitude distributions) and to spectra obtained after the Fourier transform. The performance of algorithms’ individual parts in processing distributed acoustic sensor’s data obtained in laboratory conditions for an optical fiber subjected to various dynamic impact events is studied. A comparative analysis of these parts’ efficiency was carried out, and for each type of impact event, the most beneficial combinations were identified. The feasibility of existing noise reduction techniques performance improvement is proposed and tested. Presented algorithms are undemanding for computation resources and provide the signal-to-noise ratio enhancement of up to 13.1 dB. Thus, they can be useful in areas requiring the distributed acoustic monitoring systems’ cost reduction as maintaining acceptable performance while allowing the use of cheaper hardware.

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Section: Introductionmentioning

confidence: 99%

Enhancing the Distributed Acoustic Sensors’ (DAS) Performance by the Simple Noise Reduction Algorithms Sequential Application

et al. 2023

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Highly sensitive acoustic detection system containing weak grating fiber based on spring sensitization

He,

Chen,

Sun

et al. 2024

SEG Workshop on Fiber Optics Sensing for Energy Applications, Xi'an, China, July 21-23, 2024

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Direct detection Φ-OTDR based on UWFBG array using linear-phase-modulated double-pulse

Hong,

Wang,

et al. 2024

Opt. Express

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We propose what we believe to be a novel direct detection phase-sensitive optical time-domain reflectometry (Φ-OTDR) based on ultra-weak fiber Bragg grating (UWFBG) array to achieve distributed vibration measurements with exceptional sensitivity and remarkable stability. Our system employs a pulse modulator to generate a double pulse and achieves linear phase modulation of one pulse by one cycle through a phase modulator. The phase change can be quantitatively demodulated using our proposed N-step phase-shifted demodulation algorithm. This method effectively mitigates the influence of phase noise of the laser and the pulse modulator, while also eliminating fluctuations in the half-voltage of the phase modulator. Compared with the existing phase modulation methods, our method avoids stringent requirements for the stability and precision of phase modulation. Moreover, we propose a phase-shifted approximation method, breaking the limitation of sensing length on the traditional differential approximation method and improving the accuracy significantly. The technique's effectiveness is experimentally demonstrated on a 1 km UWFBG array with a reflectivity of −40 dB to −45 dB and a spatial resolution of 10 m. Vibrations with different amplitudes are measured quantitatively with good linearity. The low-frequency self-noise is greatly suppressed and the overall self-noise is −54.3 dB rad2/Hz.

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An improved device and demodulation method for fiber-optic distributed acoustic sensor based on homodyne detection

Cited by 4 publications

References 22 publications

Enhancing the Distributed Acoustic Sensors’ (DAS) Performance by the Simple Noise Reduction Algorithms Sequential Application

Enhancing the Distributed Acoustic Sensors’ (DAS) Performance by the Simple Noise Reduction Algorithms Sequential Application

Highly sensitive acoustic detection system containing weak grating fiber based on spring sensitization

Direct detection Φ-OTDR based on UWFBG array using linear-phase-modulated double-pulse

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