The maximum detectable frequency response in phase-sensitive optical time domain reflectometry (Φ-OTDR) vibration sensing is limited by the detection distance due to the Nyquist sampling theorem. Nonuniform sampling can bypass this limitation, but it often suffers from a low signal-to-noise ratio (SNR) due to the low sampling rate. In this paper, edge detection and Otsu threshold optimization are adopted jointly to address this issue. Experiments employing additive random sampling show that vibration of 150 kHz is successfully retrieved with an average sampling rate of 3.92 kHz along 6 km sensing distance, and simultaneous multiple high-frequency vibration events can be recognized.
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Zhang et al. (2025) studied this question.
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