Abstract
A curvelet denoising method has been proposed to reduce the time domain noise to improve the detection performance in the distributed fiber vibration sensing system based on phase-sensitive optical time domain reflectometry. The raw Rayleigh backscattering traces are regarded as a gray image and the random noise can be eliminated by the curvelet transform; hence, the amplitude difference induced by the external vibration can be extracted. The detection of a vibration event with 10 m spatial resolution along a 4 km single mode fiber is demonstrated. The signal-to-noise ratio (SNR) of location information for 50 Hz and 1 kHz vibration based on this new method increases to as high as 7.8 dB and 8.0 dB, respectively, compared to the conventional method, showing the remarkable denoising capability of this new approach.
Highlights
Fiber-optical vibration sensors have attracted significant interest in recent years owing to their immunity to electromagnetic interference, high detection sensitivity, fast response, and low cost.In general, fiber-optical vibration sensors can be categorized into two main types: point and distributed sensors
Distributed vibration sensors based on the scattering effects inside the optical fiber have been demonstrated, which includes polarization optical time domain reflectometry (P-OTDR) [7], phase-sensitive OTDR (φ-OTDR) [8,9,10,11,12,13], and Brillouin scattering-based sensors [14,15]
Considering the feature of distributed fiber vibration sensor based on the φ-OTDR system, the acquired data contains repeated structures of information in a two-dimensional (2D) domain, which means that the signal-to-noise ratio (SNR) of the location information can be improved by processing the raw data in a two-dimensional way [21]
Summary
Fiber-optical vibration sensors have attracted significant interest in recent years owing to their immunity to electromagnetic interference, high detection sensitivity, fast response, and low cost. A large variety of interferometric architectures for distributed vibration sensing, including the Sagnac interferometer, dual Mach–Zehnder interferometer, and Sagnac interferometer merged with Mach–Zehnder interferometer [4,5,6], have been proposed and demonstrated This kind of sensor has high sensitivity and wide frequency response range, the spatial resolution is usually poor. Considering the feature of distributed fiber vibration sensor based on the φ-OTDR system, the acquired data contains repeated structures of information in a two-dimensional (2D) domain (time and position), which means that the SNR of the location information can be improved by processing the raw data in a two-dimensional way [21]. This new curvelet denoising method shows great potential in retrieving the vibration position precisely under the condition of strong background noise in a distributed vibration sensor with a φ-OTDR system
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