【作者】 王爱华；

【导师】 郑建生； 艾勇；

【作者基本信息】 武汉大学 ， 通信与信息系统， 2004， 硕士

【摘要】 随着无线激光通信的技术进步，应用的范围也越来越广，激光作为一种可信赖的载波，已经成为一种无线宽带接入手段逐步为人们所认可，并作为一种新的“最后一公里”解决方案的主导技术。传统的微波方法受到电台频率的限制，而光纤网铺设较复杂，费用高，而且不能适用于临时的网络。本文借助半导体激光器，提出了一种基于USB接口的激光无线通信系统。 本文将USB接口的优点和激光通信的优点有机结合起来。首先从USB接口入手，介绍了USB接口的协议和通信规范，提出了一种无线激光通信的新方法，该方法利用两台计算机之间的USB接口电路可完成远距离激光无线通信任务。该接口电路安装方便、通信速度快、占用主机资源少，特别适合那些临时搭建的军用网络和不需耗资、耗时地铺设光纤就能满足对办公大楼或商业集中区大容量接入的需要以及自然条件限制铺设光纤网的情况。设计包括接口电路的设计，AN2131Q芯片固件程序设计，USB设备驱动程序的编写以及Windows程序的编写。 接着提出了一种为半导体激光器的调制驱动电路，能够在大气激光通讯中稳定工作。电路选用现有大规模集成芯片，设计力求简单、实用、成本低及高性能。然后研究了大气信道的特点，综合讨论了大气信道对信号的吸收，散射和湍流影响，给出了衰减的因子，结合信道编码定理，讨论了适于在大气中传输的码型，特别是RS码，得出了适合大气信道的编码码长和码率的选择方法和依据，对实验中激光束宽的旋涡的形态进行了讨论，并做了大量实验，就实验中出现的干涉条纹问题提出了新的光斑中心点的判断方式。为后续编码解码的研究和PAT系统提供了参考依据。最后给出了实验的数据和图像。更多还原

【Abstract】 With the development of technologies on wireless laser communication, the application of laser becomes more and more popular. Meanwhile the laser has been the reliant carrier, accepted as a method of access in wireless Broad Band, and the magisterial technology in resolving "last mile" problem as a new method. Conventional method of microwave is licensed by the frequency of broadcasting station. Fiber network is so expensive and complexity, and it is not suitable for temp network. The paper put forward a method of wireless laser communication system based on the interface of USB with the semiconductor LD.The paper combines the advantages of laser communication and the interface of USB. First introduce the protocol and communication standard of interface of USB, put forward a new method of wireless communication, which use the interface to settle the task of remote wireless laser communication. The circuit is easy to fix and speeding in transferring with little resource in host, special to the situation of temporarily network in war, shopping mart and office block using lots of connection without much money and time, or the instance limited by nature condition. The design is including circuit of interface, compiling the program of AN2131Q, compiling USB device driver and Windows application program.Then the paper puts forward a driver and modulator for circuit of LD, which can work steady in wireless communication. The circuit chooses the cosmically integration chip to make the design simple, practicality and low cost with high capability. Then give the characteristic of atmosphere channel, This paper mainly discuss the influence on the laser transmission for its stochastic behavior, analyze the scatter , absorption and turbulence of atmosphere channel, and calculate the atmosphere attenuation ratio by visible, with theorem of channel coding, we discuss the style of code in transmission, especially RS coding, inducing the way and gist to choose the length and ratio of code suitable for atmosphere channel, and discuss the shape of burble laser beam in lots of experiments. Bringing up a new opinion in judging the facular center of interferential stripes in experiment. We provide some reference for later coding and decoding and PAT system. At last we give some data and images and we give some advice for the future work.更多还原