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

摘要

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