【作者】 焦荣；

【导师】 柯熙政；

【作者基本信息】 西安理工大学 ， 通信与信息系统， 2008， 硕士

【摘要】 近年来,人们对宽带多媒体业务的需求促进了整个通信网络的宽带化发展,光波是宽带信息的最佳载体,光纤通信的发展已证明了这一点。与光纤通信相比,大气激光通信更适合于宽带无线接入。我们将大气激光通信技术与视音频压缩处理、电话线传输系统、点对点通信技术结合在一起,搭建了一个多业务大气激光通信系统。本文概述了多业务大气激光通信的发展状况及基本原理,介绍了其特点和用途。研制了一种能够实现语音、数据、图像双向传送的大气激光通信系统,传输速率为20Mbps,传输距离1000m,工作在全双工的工作模式。本文从激光发射子系统、光电接收子系统、通信端机子系统等方面阐述了其基本原理、组成结构及关键技术。主要工作包括:1.激光发射子系统的设计及其实现。根据激光器件的特点,对半导体激光器调制的原理及特性进行了详细的分析,设计了其硬件实现电路,并对纠错编码及光学发射天线进行简单说明。2.光电接收子系统的设计及其实现。包括光探测器件的选择,高灵敏度和高抗干扰性的光信号接收技术以及接收到信号后处理部分,最后还对纠错译码器及光学接收天线略作介绍。3.通信端机子系统。主要包括电源模块、多业务信号同步问题及多业务信息的压缩编码与传输。在通信系统的设计中,利用FPGA的现场可编程技术,结合电话线传输系统,实现交换系统中数字与话音复合接口,完成了10路电话交换;图像编码算法采用ISO MPEG-2标准;并提供并口、串口等常用数字接口,实现了1路串、并口数据、2路MPEG-2图像的稳定传输。实验结果表明,该系统稳定可靠,能够实现多业务功能。因此,该系统的研制对国内实用大气激光通信机的推广使用是很有意义的。最后对全文提出的理论和所做的实际工作进行总结,指出了在今后工作中有待于完善的问题。更多还原

【Abstract】 In recent years, the requirement of broadband multimedia service promotes the development of the communication network; light wave is considered as the best carrier, which has been proved by the development of optical communication. Compare with optical communication, the atmospheric laser communication is more suitable for broadband wireless attachment. In this paper, Video coding technique, telephone line transmission system and point-to-point communication are combined together to build a multi-service atmospheric laser communication system.State of development and basis principle of multi-service atmospheric laser communication are presented, and its features and applications are also illustrated in this thesis. We develop atmospheric laser communication equipment which has 20Mbps transmission rate and 1000m transmission distance in full-duplex mode. The system could achieve the bidirectional transiting of phone, data and image. The key technique, system architecture and basis principle of the equipment are demonstrated from the semiconductor laser modulation, the photo detection and communication terminal device. This thesis carried through the following aspects of study:1. Design and implement of laser transmitting subsystem. Laser’s modulation principle and character are analyzed in detail, and the hardware circuit is designed. Then the optical mission antenna and Golay code are simply declared.2. Design and implement of photo electricity receiving subsystem. The choice of photo detector, optical signal detection and processing are firstly introduced. Then, the optical receiver antenna and decode operation are asserted respectively.3. Design of multi-service communication subsystem. The system consists of three parts: power module, synchronism module of different signal and encoding and transmitting of multi-service information module. Connecting to the telephone line transmission system, the compound interface between digital signal and voice was implemented in FPGA, and then 10 channels telephone switching are realized. Image compression technique employs MPEG-2. The system is rich in peripheral interface, including parallel port and serial port. Transmission of one channel data and binary channel MPEG-2 image are achieved.And the experiment results show that the system can implement the communication with stability. So its developing will play an important role in practical equipment’s popularizing. At last, the theory and actual working are generalized, and furthermore, some problems should be studied and analyzed in-depth in future.更多还原