| There are a variety of ways to monitor,electronic monitoring is a more common means.Traditional contact,active monitoring means With the development of modern anti-monitoring technology,gradually exposed to easily found,the installation process difficult and other defects in the technical and legal ethics encountered great difficulties,can not meet the use of personnel The demand.Among the many new listeners,the laser listener occupies the important position of the monitoring technology because of its simple device,strong concealment,long distance and good portability.In this paper,we mainly study the laser monitoring technology based on four-quadrant detectors,and study the radius and position of the four-quadrant detectors and the accuracy of the system noise to detect the accuracy of the focal spot.The main contents are as follows:(1)The outline structure,photoelectric effect and main performance parameters of the four-quadrant detector are introduced,and the evaluation parameters of the spot center position detection are analyzed.The algorithm of the centroid of the light spot under uniform distribution and Gaussian distribution is studied.(2)The noise of the system based on the four-quadrant monitoring system is analyzed.The influence of various noise on the accuracy of the spot center position detection is studied.The mathematical model of the standard deviation of the spot center position and the spot radius,the spot position and the signal-to-noise ratio The Simulation was carried out and the method of reducing noise in the experiment was obtained.(3)The hardware design was carried out for the front-end laser emitting unit,the reverse bias circuit of the four-quadrant detector and the transimpedance amplifier circuit,the focal spot position determination unit and the sound restoration circuit,and the simulation experiment was carried out in the laboratory.Based on the four-quadrant detector as a photosensitive element for sound detection and reduction of the feasibility. |
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