The Study On Laser Communication System

This thesis discusses detailedly the process on the research and design of laser communication system, and describes the outlook on the development of laser communication. The thesis introduces the principle on laser emitting system, studies some problems about laser emitting circuits design, pulse distributing circuits design, laser power-supply design. Author takes some safeguard measures for the laser apparatus. The article analyses wide angle laser signal receiving system and the receive sensitivity of system, and studies the problems on circuits designing of laser receiving system.The thesis analyses the problems on the noise of APD photoelectric receiving system. Author designs APD laser signal receiving system circuits, front amplify circuit, controlling time-series logic circuits, DC/DC transform circuits. And takes APD bias voltage fuzzy control. Author takes some technological measures in the circuits designing in order to increase the sensitivity of detection and to reduce the rate of error coding. The thesis offers APD signal amplify circuit chart and controlling time-series logic circuit principle chart bearing practical applied value.The thesis studies the principle on the PPM modulation and demodulation, and analyses the performance of the PPM signal demodulation circuits and designs corresponding circuits. It presents the mathematical models for the PPM modulation and demodulation circuits system. Author gives out the conditions of linear modulation and demodulation, and educes its connection between the modulation factor and maximal laser frequency excursion.Analyses and calculate the sensitivity of the system, and the interference of the laser emitting system to the weak signal detection system11is restricted, the error rate of the system is reduced, and the sensitivity of the laser communication system is enhanced by the means of the electromagnetism compatible technique.