Research On The Doppler-free And Gain Acquisition Characteristics Of Parabolic Acoustic Mirror For Moving Sound Source Signal

This paper first discovered and theoretically explained that the parabolic acoustic mirror has Doppler-free acquisition characteristics for the sound signal of the moving sound source,which was verified by simulation and preliminary experiments.The parabolic acoustic mirror can solve the Doppler distortion problem and strong noise problem in the sound signal of the moving sound source in signal acquisition.It can effectively solve the problems of Doppler distortion and strong noise in the wayside acoustic fault diagnosis of the train bearing.It is also expected to be used in the field of sound source localization,noise assessment,etc.involving the sound collection from moving sound sources.The specific research contents are as follows:(1)Theoretical analysis: First,the principle of Doppler distortion is theoretically analyzed,that is,the Doppler effect is caused by the time-varying distance between the moving sound source and the receiver.Secondly,the factors affecting the degree of Doppler distortion are analyzed.Finally,the distorted acoustic signal acquisition mechanism,signal gain acquisition mechanism and directional denoising mechanism of parabolic acoustic mirrors for linearly moving sound sources are elaborated in detail.(2)Simulation analysis: First,the acoustic module of COMSOL Multiphysics software is introduced,and the "static/dynamic sound source-acoustic mirror" simulation model is established.Then,through static and dynamic simulation comparison analysis,with-mirror and without-mirror simulation comparison analysis,the characteristics of Doppler-free and amplified-gain signal acquisition of the parabolic acoustic mirror under the uniform linear motion of the sound source in the speed range of 150m/s and the uniform acceleration linear motion of 10m/s2 was verified.Finally,the amplitude-frequency response characteristic curve from 1000 Hz to 5000 Hz is given.(3)Experimental verification: First,through the static and the dynamic experiment comparison analysis,the parabolic acoustic mirror's Doppler-free acquisition characteristics and amplified-gain acquisition characteristics of the linear moving sound source acousticsignal are verified.Secondly,based on the directional miniature microphone(BO6027ULA42C)and high-performance low-noise dual operational amplifier(NE5532),a signal collector at the focal of the paraboloid was designed,and a prototype was trial-produced to lay the foundation for subsequent experiments and applications.