SNR Enhancement By DWT For Improving The Performance Of Φ-OTDR In Vibration Sensing
Volume 5 - Issue 5, May 2022 Edition
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Atubga David Atia Ibrahim, Khushnood Abbas, Bonny Ernestina Linda
Phase-sensitive Optical Time Domain Reflectometry (Φ-OTDR), Discrete Wavelet Transform (DWT), Signal-to-Noise-Ratio (SNR)
The distributed optical vibration sensors (DOVS) have been extensively investigated with regards to their significant impact in sensor applications. The Phase-sensitive Optical Time Domain Reflectometry (Φ-OTDR) which is one of the most distinguished distributed optical fiber sensing technologies has lately attracted enormous research attention due to its merits of high precision measurements, fast speed response, long perimeter monitoring, capabilities in vibration detection abilities, among others. However, it becomes very stressful when data meant for the said sensing technology in vibration detection is impeded by harsh environmental conditions. Therefore, in order to successfully enhance effective vibration detection by the Φ-OTDR sensing technology, noise filtering becomes very crucial. As a result, we executed Hilbert transform to first retrieve both the real and imaginary parts of the complex signal of the Φ-OTDR sensing data. Then a discrete wavelet transform (DWT) was identified and carefully applied to achieve the denoised results. We further performed angle and phase unwrapping for the vibration detection. In the experiment, the Signal-Noise-Ratio (SNR) of the location information is greatly improved from 16.2 dB to 30.2 dB on a 3km sensing fiber range. The proposed method has the potentials of precisely extract intrusion location from any strong noise background. As proof of concept, the theoretical and experimental setup are equally presented.
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