Performance Improvement of Dual-Pulse Heterodyne Distributed Acoustic Sensor for Sound Detection

Abstract

Phase fading is fatal to the performance of distributed acoustic sensors (DASs) influencing its capability of distributed measurement as well as its noise level. Here, we report the experimental observation of a strong negative correlation between the relative power spectrum density (PSD) at the heterodyne frequency and the noise floor of the detected phase for the heterodyne demodulated distributed acoustic sensor (HD-DAS) system. We further propose a weighted-channel stack algorithm (WCSA) to alleviate the phase fading noise via an enhancement of the relative PSD at the heterodyne frequency. Experimental results show that the phase noise of the demodulated signal can be suppressed by 13.7 dB under optimal condition. As a potential application, we exploited the improved HD-DAS system to retrieve a piece of music lasted for 205 s, demonstrating the reliability of detecting wideband sound signal without distortion.

Detection of Gas Pipeline Leakage Using Distributed Optical Fiber Sensors: Multi-Physics Analysis of Leakage-Fiber Coupling Mechanism in Soil Environment

“…By applying a proper demodulation algorithm, the waveform of the acoustic wave can be accurately retrieved [ 28 ]. DAS sensors can respond to the local strain variation with a sensitivity of nε [ 29 ]. In the distributed temperature sensor (DTS), Raman backscattered light is collected.…”

Scientific Applications of Distributed Acoustic Sensing: State-of-the-Art Review and Perspective

“…Distributed fiber sensors are used to measure the distribution of temperature [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ], stress/deformations [ 22 , 23 , 24 ], or vibro-acoustic properties [ 25 , 26 , 27 , 28 , 29 , 30 ] of various objects. The last application allows more information about the investigated object to be obtained in contrast to the static measurement of temperature or stress.…”

Review of a Specialty Fiber for Distributed Acoustic Sensing Technology

“…In addition, since a laser pulse with a narrow linewidth and high coherence is injected into the fiber, the interference between the Rayleigh scattering points in one pulse will produce interference cancellation, resulting in coherent fading of the backscattered light, forming a "dead zone" on the sensing fiber [11]. In recent years, in order to solve the defects of the poor SNR values and the sensitivity of phase demodulation in SMF-DAS systems, many suppression technologies for noise have been studied, such as coherent fading, while at the same time the complexity and cost of the systems has increased, leading to sacrifices in terms of the response frequency band and sensing distance [12][13][14][15][16][17][18]. Furthermore, it is also important to enhance the performance of the sensing fiber itself.…”