Airborne Sound Sensing System Based on DAS and Ultra-Simple Transducer Structure

Abstract

Fiber-distributed optical fiber acoustic sensor (DAS) is generally used in distributed long-distance acoustic/vibration measurement. Recently, DAS is also used in weak airborne sound detection. To improve the sensitivity of DAS, using a state-of-the-art acoustic transducer or a special enhanced scattering fiber, which are uncommon in the industrial site, is often essential, according to the previous research. In this work, the fading of DAS is suppressed by the multi-frequency probes and polarization-diversity-receiver scheme. The self-noise of DAS is further lowered by the phase averaging of multiple acoustic channels wound on the transducer. We found that, supported by this high-performance DAS, even if the transducer is made with an ultra-simple plastic structure in daily life, the system can achieve high-sensitivity airborne sound sensing. The proposed simple acoustic transducer can reach the sensitivity level of −106.5 dB re. 1 rad/μPa at a sensing range of 5.1 km, which can meet many demands on the industrial site.

Detection and Recognition of Voice Commands by a Distributed Acoustic Sensor Based on Phase-Sensitive OTDR in the Smart Home Concept

“…3.3. The fiber was wound on an elastic core made of a plastic bottle, as proposed in [37], with a diameter of 140 mm. The bottle, as well as the metal plate in the previous experiment 3.2, made it possible to increase the amplitude of vibration transmission to the fiber.…”

“…At the moment, long-distance DAS are most in demand. Therefore, the issue of ensuring high recognition quality at sampling frequencies of less than 10 kHz remains quite important, and this problem can be solved by increasing the system sensitivity [37].…”