摘要：利用Matlab作为编程工具，对二进制数字调制系统进行了分析，设计了二进制数字调制系统模型，并对模型的仿真流程以及仿真结果进行具体分析，加强对理论知识的学习和掌握。随着通信系统的不断发展，通信技术越来越受到重视，其中二进制数字调制系统也得到了全面的发展，作为通信专业的学生更应该熟练地掌握通信的知识，但是仅仅通过书面的知识难免太过于抽象。
Matlab是一款功能强大的应用工具软件，Matlab提供了可视化的系统仿真环境，可以方便、灵活的建立各种形象的仿真模型，让抽象的理论通过图形形象的呈现在我们眼前。本文即利用Matlab建立通信仿真模型对理论知识加深学习。经过最近对通信原理的学习，本文中对通信系统中的二进制数字调制系统进行编程和仿真，并对结果进行比较和分析。
数字信号有两种传输方式，分别是基带传输方式和调制传输方式，即带通，在实际应用中，因基带信号含有大量低频分量不利于传送，所以必须经过载波和调制形成带通信号，通过数字基带信号对载波某些参量进行控制，使之随基带信号的变化而变化，这一过程即为数字调制。数字调制为信号长距离高效传输提供保障，现已广泛应用于生活和生产中。另外根据控制载波参量方式的不同，数字调制主要有振幅键控（ASK），频移键控(FSK)，相移键控(PSK) 三种基本形式。本次设计针对二进制的2ASK、2FSK、2PSK进行讨论，应用Matlab矩阵实验室进行仿真，分析和修改，通过仿真系统生成一个人机交互界面，以利于仿真系统的操作。通过对系统的仿真，更加直观的了解数字调制系统的性能及影响其性能的各种因素，以便于比较，评论和改进。
本文对数字调制信号的基础进行了详细的介绍，并利用M文件编程的方法做出了调制过程的仿真波形，接着又利用Simulink平台建立了功率谱密度的仿真模型，并得到了预期的仿真结果。通过总结BFSK的基本原理，运用MATLAB的Simulink仿真系统和运行程序完成对BFSK在三种传输信道中的传输性能的仿真。三种信道为高斯白噪声信道，多径瑞利信道和多径伦琴信道。又利用MATLAB 仿真了PSK DPSK的传输信能。对比3种方式的波形图，得到了想要的结果。在此期间，参数的设置和MATLAB的编译是两个重点也是难点。最后，在仿真的基础上分析了比较了各个环节对调制性能的影响及仿真模型的可行性。20591
毕业论文关键词：    MATLAB；Simulink；数字调制；分析与仿真；
 Matlab-based Digital Modulation Performance Simulation in Different Channels
Abstract:  Using Matlab as a programming tool for binary digital modulation system is analyzed, designed a binary digital modulation system model, simulation model and the simulation process and the results of a detailed analysis, to strengthen the theoretical knowledge to learn and master. With the continuous development of communication systems, communication technology more and more attention, which is also a binary digital modulation system has been fully developed as a communication professional students should proficient knowledge of communication, but only by a written knowledge inevitably too too abstract. Matlab is a powerful software application tools, Matlab provides a visual system simulation environment that can facilitate flexible simulation model to establish a variety of images, so that the abstract theory presented by graphic images in front of us. In this paper, namely the use of Matlab established communication simulation model to enhance the learning of theoretical knowledge. After the recent study on communication theory, this article on binary digital communication system modulation system for programming and simulation, and the results were compared and analyzed. A digital signal has two means of transmission, which are the base band transmission method and modulation transmission, i.e., band-pass, in practical applications, because the baseband signal contains a large low-frequency component is not conducive to transmit, it must go through the carrier and modulated bandpass signal is formed by The digital baseband signal to the carrier for controlling certain parameters, so as to vary with changes in the baseband signal, which is a digital modulation process. Efficient long-distance transmission of digital modulation signals provide protection, is now widely used in life and production. Also, according to the different parameters of the control mode of the carrier, there are digital modulation amplitude shift keying (ASK), frequency shift keying (FSK), phase shift keying (PSK) in three basic forms. The design for the binary 2ASK, 2FSK, 2PSK discuss the application matrix laboratory Matlab simulation, analysis and modification, to generate an interactive interface through simulation system to facilitate the operation of the simulation system. Through the system simulation, a more intuitive understanding of the performance of a digital modulation system and the factors that affect its performance in order to facilitate comparison, reviews and improvements.    Based on the knowledge learned in college, on the basis of digital modulation signals for a detailed description, and the M-file programming method to make a simulation waveform modulation process, and then they use the platform to build a Simulink simulation of the power spectral density model and get the desired simulation results. By summing BFSK basic principle, the use of MATLAB Simulink simulation systems and operational procedures to complete the simulation BFSK transmission performance of three transmission channels. Three kinds of channel is Gaussian white noise channel, multi-path Rayleigh channel and multi-path channel Roentgen. Also using MATLAB simulation PSK DPSK transmission channel capacity. Comparison of three methods of waveform, got the desired results. In the meantime, the compiler parameter settings and MATLAB are two key points is difficult. Finally, based on the analysis of simulation compares the performance of all aspects of the modulation effects and feasibility of the simulation model. 基于matlab的数字调制在不同信道中的性能仿真:http://www.751com.cn/zidonghua/lunwen_12430.html