《无线衰落信道中编码FSK的性能研究》》-毕业论文.doc

摘要 PAGE IV 精品 无线衰落信道中编码FSK的性能研究 摘 要 随着社会的不断发展,通信对我们来说越来越显的重要.对于通信技术来讲,通信的质量也就显的非常的关键.通信的根本任务是如何保证远距离传输信息的正确性，在这方面数字通信系统具有先天的优势。这主要是因为数字通信系统中传输的是离散的数字信号，由于信号是离散的，被噪声干扰后的信号只要没有超过门限，接收端就能够完全正确地判断出传输的信息；而对于模拟传输系统，只要有稍微的干扰都会使传输的信息产生错误。也正是由于这样的原因，数字通信系统才能在各方面逐渐代替模拟通信系统成为现代通信的最基本方式。为了便于区别信号与噪声，使通信不失真和不受干扰,往往给测量信号赋以一定特征，这就是调制的主要功能。调制就是用一个信号（称为调制信号）去控制另一作为载体的信号（称为载波信号），让后者的某一特征参数按前者变化。再将测量信号调制，并将它和噪声分离，放大等处理后，还要从已经调制的信号中提取反映被测量值的测量信号，这一过程称为解调。为了更好地利用通信信道的带宽并使信号能够传送更大的距离, 在数字载波通信中,我们采用了三种解调方式: 幅移键控（ASK）频移键控（FSK）和相移键控（PSK）。调制信号为二进制信号的调制称为二进制数字调制, 二进制调制又分为二进制幅移键控（2ASK）、二进制频移键控（2FSK）、二进制相移键控（2PSK）和差分二进制相移键控（2DPSK）等多种基本的类型，本文主要研究在MATLAB环境下建立编码FSK的调制的仿真系统，利用仿真系统对无线衰落信道中编码FSK性能进行仿真，并且和卷积编码FSK硬判决解调系统的性能进行对比。 关键词：数字通信，FSK信号，仿真，调制解调 英文摘要 ABSTRACT ?Along with society of continuously development, correspondence more and more show to us of importance. Speak for the correspondence technique, the quality of the correspondence also show very of key. Correspondence of root mission is how assurance long-distance leave to deliver an information of accuracy, in this aspect numeral correspondence the system have inborn of advantage. This main is because of numeral correspondence what to deliver be long-lost in the system of numeral signal, because of the signal be long-lost, drive Zao voice interference empress of signal want ～only have no exceed threshold, receive to carry can complete with accuracy judgment the information for deliver; But for imitate to deliver system, as long as have a little bit of the interference will make the information creation for deliver false. Is exactly also because of so of reason, numeral correspondence system then can in everyones noodles gradual replace imitate correspondence system to become modern correspondence of the most basic way. For the sake of easy to differentiation signal and Zao voice, make correspondence dont lose true with be free from interference, usually give diagraph signal to endow with certain characteristic, this be the main functio