Research On Transmission Characteristics Of Atmospheric Laser Communication System

Atmospheric laser communication is an awfully good wireless communication technology.since laser occurred,numerous scholars have made the research on theory and practice.In recent years,such technology has made rapid progress,but it is affected by atmospheric aspects seriously.Many factors such as atmospheric scattering, refraction and turbulence cause attenuation of laser energy,laser scintillation and laser beam random deflection.The key point whether turns it into actually or not and expand application is that whether can overcome the effect of climatic factors or not.In virtue of atmospheric random channel, it is vital to study the character of channel itself on the communication system performance.This thesis has done some research after searching and reading lots of relative documentary,which also has accomplished the following work:Firstly, systematically describing atmospheric attenuation and turbulence,at the same time,on the basis of it and communication theory,the atmospheric channel model is designed.And then channel model is proposed for this technical programs,such as the APT system technology and adaptive optics technology. According to photoelectric detection theory, BER(bit error rate) of system affected by attenuation and turbulence are studied.Especially,system BER modulated by the way of OOK and PPM is studied.There is a comparison with particle scattering.A conclusion is drawn that particle scattering influences system average BER whereas turbulence affects system instantaneous BER.In case of such two BER,this thesis tries to give some suggestions.Secondly,the relationship can be known through emulational model according to laser scintillation and wavelength.Channel loss is important to study communication system.The optium value of laser beam divergence angle and lens aperture when the loss is the minimum can be drawn in virture of the emulational model Furthermore,it verifes the correctness of laser beam divergence angle. This is the key point of our project.The research on laser transmission character is useful to the design of communication s...