Single-shot multi-sensitivity distributed acoustic sensing with hardware envelope retrieving acceleration

Abstract

Distributed acoustic sensing (DAS) can virtualize a fiber optic cable into an ultra-dense seismic network, offering long-term seismic wave observing capability and high-fidelity waveform recording performance. In practical applications, DAS systems still face two main challenges. Firstly, the large amount of raw data brings a burden on storage and demodulation speed. Secondly, the fixed strain sensitivity of DAS limits the dynamic measurement range of the actual seismic signal. In this work, we present a single-shot multi-sensitivity distributed acoustic sensing method with hardware assistance. A hardware filtering module is utilized to achieve equivalent sampling results at a lower sampling rate, thereby reducing the volume of raw data and accelerating the acquisition and demodulation process. The average processing time for a single-sideband pulse detection can be reduced from 214.79 s to 9.83 s, resulting in approximately a 20-time reduction. Meanwhile, multiple sidebands pulse with different bandwidths is generated to enable multi-sensitivity detection under hardware filtering. The different ranges of strain events can be recovered through a modulated pulse with 20 MHz, 40 MHz, and 80 MHz bandwidths. The hardware-assistance multi-sensitivity DAS method offers a potential solution to complex environments and real-time detection applications.