Gas sensing using acoustic attenuation with improved resolution

Abstract

Sensors being used for gas sensing in underground coal mine require frequent recalibration due to highly humid and toxic environment prevalent in UG coal mines. If we intend to deploy a WSN which can continuously monitor the UG mine environment then we require sensors which are able to withstand the environment of UG coal mine. Acoustics gas sensors are more rugged and would be able to work for prolonged period in UG coal mine environment. Acoustic sensors work on the principle that acoustic signal velocity and amplitude are affected by changing composition of air. Attenuation of acoustics waves in presence of a target gas can be used to detect its presence and give its concentration level. We present an acoustic signal processing approach which can measure attenuation of acoustic signal with improved resolution. Proposed approach takes advantage of the fact that when triggered with a transmitted pulse of acoustic sensor resonance frequency, the receiver output is a damped ringing waveform. We measure the area under envelop of the received waveform to provide increased resolution.