Research On Laser Interferometric Speech Detection Technology And Its Demodulation Algorithm

As we all know,whether it is the country or the enterprise,or even the field of criminal investigation,the acquisition of information is a very important link.In the field of criminal investigation,the acquisition of voice information of criminals is an important means to guarantee the safety of people's lives.In this paper,a speech detection system based on laser interferometer is designed.The research contents the laser interference theory knowledge research and the research of the laser interferometric speech detection system.Then the selection of devices in the optical system part is introduced.What's more,it also contents the study on the backlight scattering and acoustic vibration characteristics of the target object.Finally,the design of orthogonal zero difference demodulation algorithm against optical intensity disturbance is introduced in this paper.Firstly,the basic theoretical knowledge of laser interference in speech detection technology is expounded.In the establishment of the whole system,factors need to be considered,including the Angle between two coherent beams,polarization state,light power,the Angle relationship between light path and detector,etc.Then the parameter values of each factor are obtained to maximize the efficiency of the system,and the system is in the best state when working.It is also to reduce the noise to the detector interference.Then the devices needed in the optical system are selected in order to improve the working efficiency of the detector.Secondly,the back correlation scattering and vibration characteristics of the target are studied and analyzed.The change of the object's back correlation scattering coefficient is studied when the surface roughness of the object is different and the incident Angle of the light wave is different.The purpose of doing this is to select the right target object and make the incident Angle of the light wave the best.This will make monitoring work best.Finally,we study the demodulation part of the received signal and design a new demodulation algorithm based on orthogonal zero difference.The equipment cost is reduced and the device performance is improved.The use of an acousto-optic modulator is avoided and high frequency reference signals are not required.