Distributed Optical Fiber Acoustic Signal Acquisition And Playback

Phase-sensitive optical time-domain reflectometer(Φ-OTDR)is a kind of optical fiber sensing technology which can realize the sensing and measurement of external signals,by using Rayleigh scattering effect produced by optical pulse in the optical fiber to real-time sense the tiny disturbance at every point in the optical fiber link.This technology has prominent advantages in the application fields of perimeter security,seismic wave detection,pipeline safety monitoring and so on.Sound detection technology based on optical fiber sensing technology has important application prospects in underwater acoustic detection and environmental sound detection.Distributed optical fiber sensing technology has the advantage of large capacity compared with point sensing technology.At present,the distributed sound detection technology used in sound acquisition can not meet the requirements of signal-to-noise ratio and sensitivity.Therefore,this paper mainly studies two aspects: one is how to realize the special structure of high sensitivity perception of sound signal,so that the distributed optical fiber sound sensor system can obtain good sound acquisition quality;the other is how to denoise the noise-containing sound signal detected by the distributed sound sensor system,so as to improve the signal quality.This paper lays a foundation for the practicality of distributed sound sensing.The main work is as follows:Firstly,in order to realize multi-point distributed high sensitivity sound detection,we need to study a special structure to realize high sensitivity sound detection.Therefore,three kinds of distributed sound acquisition devices are designed in this paper.Based on the ANSYS finite element platform,the sound acquisition devices with different structures are modeled.The sound pressure distribution maps and sound field distribution nephograms of different structures are obtained by adding an excitation source of 0.01 kg/N·m3 at the origin.According to the sound pressure distribution curves of the three structures,the sound pressure distribution curves of the point source and the cylinder structure are obtained.The optimal simulation results are obtained by analyzing the sound pressure distribution curves of the three structures.The simulation structure device is used as the experimental device in subsequent experiments.Secondly,the distributed voice storage program and multi-channel voice signal storage program are completed on LabVIEW platform.The voice signal is stored as an offline wav file,and the offline file can be played.Then it introduces the design flow of real-time playback program module of sound signal,and completes the real-time playback program design of sound signal.Finally,based on the simulation design,a distributed optical fiber sound acquisition system is built.Based on the simulation structure,materials are selected through the contrast experiment of optical fiber sound signals,acrylic materials are selected as experimental materials,and tightly sleeved optical fibers are selected as experimental optical fibers.Based on this experimental device,the sound is used as the sound source,and the single-frequency and song signal acquisition experiments are carried out by using the distributed sound acquisition system.Then through the use of MATLAB platform and LabVIEW platform,the sound signal waveform file generated by LabVIEW is read by matlab,and then the sound song fragments are processed by wavelet denoising.After processing,the signal-to-noise ratio is increased by 26.38 dB,and the clear sound signal is replayed,which verifies the effectiveness of the sound acquisition device and denoising method.