Breaking through the bandwidth barrier in distributed fiber vibration sensing by sub-Nyquist randomized sampling

TL;DR

This paper introduces a sub-Nyquist randomized sampling technique for phase-sensitive optical time domain reflectometry, enabling detection of high-frequency vibrations over long distances beyond traditional bandwidth limits.

Contribution

The authors propose a novel random sampling method that breaks the bandwidth restriction of { extphi}-OTDR systems, allowing for wideband vibration detection with lower sampling rates.

Findings

Successfully detected MHz-range vibrations over 9.6 km fiber

Identified over a dozen frequency components in resonance vibrations

Achieved clear detection of 1.153 MHz single-frequency vibrations

Abstract

The round trip time of the light pulse limits the maximum detectable frequency response range of vibration in phase-sensitive optical time domain reflectometry ({\phi}-OTDR). We propose a method to break the frequency response range restriction of {\phi}-OTDR system by modulating the light pulse interval randomly which enables a random sampling for every vibration point in a long sensing fiber. This sub-Nyquist randomized sampling method is suits for detecting sparse-wideband-frequency vibration signals. Up to MHz resonance vibration signal with over dozens of frequency components and 1.153MHz single frequency vibration signal are clearly identified for a sensing range of 9.6km with 10kHz maximum sampling rate.