光脉冲传输时延受近海大气信道影响的研究(34页).docx

海南大学毕业论文（设计）题目：光脉冲传输时延受近海大气信道影响的研究学号014 姓名：汪云龙年级：2008级学院：信息科学技术学院系别：通信工程专业：通信工程指导教师：张涛完成日期：2012年5 月 4 日摘 要自由空间光通信具有传输速率高、工程周期短、抗干扰性强、传输必威体育官网网址性好等特点。这些优点使其在通信领域具有重要地位及良好的应用前景且已成为解决“最后一千米”的主要技术方案之一。但激光通过大气信道会产生光脉冲传输时延，而光脉冲传输时延严重影响传输误码率。因此需要采用有效的方法来衡量脉冲传输时延效应，为减小探测误差提供依据。论文首先对自由空间光通信的发展历程及各国研究现状，关键技术，优缺点及应用前景进行了概述。然后总结分析了大气衰减效应和大气湍流效应。并应用经典电子散射理论，分析了激光信号通过大气随机信道时的时延特性，得出了光脉冲传输时延与传输距离、单程散射反照率和能见度的关系。通过MATLAB仿真，结果表明，传输距离越大，脉冲时延越大；单程散射反照率越大，脉冲传输时延越大；能见度越小，脉冲时延越大。最后，从大气信道方面介绍了提高自由空间光通信系统性能的有效方法。关键词大气信道；大气散射；多径传播；脉冲传输时延；能见度Abstract?Free space optical communications systemhas a high transmission rate with the short project cycle, strong anti-jamming, high security and many other characteristics.?These advantages make it an important position and a good prospect in the field of communication. It has become one of the main technical program of solving the the last one thousand meters”.?However, through the atmospheric channel, the laser will produce the pulse transmission delay which seriously affect the transmission bit error rate .?Therefore adopting effective way to measure the effects of pulse transmission delay is needed in order togetthe basis for emendation?of detection .Firstly, the course of development , national research status, key techniques, advantages or disadvantages and the application prospects of free space optical communications are introduced in this paper .And then summarizes and analyzes the atmospheric attenuation and the atmospheric turbulence effects are analyzed and summarized.? Appling the classical electron scattering theory, delay characteristics of the random channel is analyzed when he laser signal spread through the atmosphere.Relationship between optical pulse transmission delay and transmission distance, one-way scattering albedo and visibility. By MATLAB , the simulation result show that the greater the transmission distance is , the longer the pulse transmission delay time is . the greater one-way scattering