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本科毕业设计-基于MATLAB常用数字信号调制与解调，共22页，8613字，附任务书、答辩PPT、外文翻译
数字信号是现在民用与军用通信中常用的信号。通信的目的是传送信息。信号的调制就是将信号变成适合信道传输的信号，而信号的解调则是将信号恢复成原始信号，这是信息传输中非常重要的两个步骤。本次课题主要是研究连续波调制中的ASK，FSK，PSK信号的调制与解调的过程。
要求：
1、理解ASK信号的调制原理，并能够用程序实现；
2、理解ASK信号的解调原理，并能够用程序实现两种解调方法，做出性能比较；
3、理解FSK信号的调制原理，并能够用程序实现；
4、理解FSK信号的解调原理，并能够用程序实现两种解调方法，做出性能比较；
5、理解PSK信号的解调原理，并能够用程序实现；
理解PSK信号的解调原理，并能够用程序实现两种解调方法，做出性能比较。

中英文翻译 Frequency Modulation（调频）
摘要：数字通信与模拟通信系统相比有着灵活性、高效性和保密性等突出特点。数字通信系统仿真对于系统分析起着越来越重要的作用。数字调制，是一种用数字基带信号对高频载波的幅度、频率和相位进行控制的技术，使高频载波的幅度，相位或频率随数字基带信号的变化而变化。在信号调制中常以一个高频正弦信号作为载波信号。一个正弦信号有幅度、频率、相位三个参数，可以对这三个参数进行调制，分别称为调幅、调频和调相。也可以用脉冲信号作为载波信号。可以对脉冲信号的不同特征参数作解调，最常用的是对脉冲的宽度进行调制，称为脉冲调宽。数字信号调制的三种基本方式，有振幅监控、频率键控和相位监控。
在信号的解调中首先已调信号中检出调制信号的过程称为解调或检波。幅度调制就是让已调信号的幅度随调制信号的值变化，因此调幅信号的包络线形状与调制信号一致。只要能检出调幅信号的包络线即能实现解调。这种方法称为包络检波。检波后的信号，再经低通滤波，滤除高频信号，即可获得所需调制信号，实现解调。
本文首先介绍了ASK、FSK、PSK各种调制与解调的原理；其次，以MATLAB为仿真工具，实现并比较了三种调制解调方式；仿真中可以改变仿真参数，此仿真参数可以进行相应地时域和频域比较分析。

关键词：数字通信；MATLAB，ASK，PSK，FSK，调制与解调

Common used Digital Signal Modulation and Demodulation Based on MATLAB

Abstract:Digital communication and simulation of communication system than have flexibility and efficiency, and confidentiality such prominent characteristics. Digital communication system simulation analysis to system plays a more and more important role. Digital modulation is a kind of digital baseband signal of high frequency carrier of the amplitude, frequency and phase to control technology, and to make high frequency carrier of the amplitude, phase or frequency with digital baseband signal changes. In the signal with a high frequency modulation in sine signal as carrier signal. A sine signal amplitude, frequency and phase has three parameters and can be to the three parameters for modulation, respectively called an am, FM and jamming. Also can use the pulse signal as carrier signal. To the different characteristics of the pulse signal parameters demodulation, the most common is to pulse width modulation on, called the pulse width. Digital signal modulation of the three basic way, have the amplitude, frequency control and monitoring key phase monitoring. In signal demodulation signal in the first has modulated signal detection of the process is called demodulation or detection. Amplitude modulation is to make already the amplitude of a signal with the value of the modulated signal changes and therefore the amplitude modulated signal envelope shape and modulation signal consistent. As long as can be detected amplitude modulated signal that can realize the envelope demodulation. This method is called modulated envelope. After the signal detection, then the low-pass filter, half signal, can obtain modulation signal, realize demodulation.
This paper first introduced the ASK, FSK, PSK various modulation and demodulation of the principle; Second, with MATLAB simulation tools for, realize and compared the three demodulation method; Simulation can change the simulation parameters, the simulation parameters can be accordingly, time domain and frequency domain comparison analysis.
目 录

摘要 I
Abstract II
第一章 绪论 1
第二章 ASK信号调制与解调 3
2.1二进制数字幅度调制与解调 3
2.1.1二进制振幅键控(2ASK)原理 3
2.1.2仿真结果分析 3
2.1.3 二进制振幅键控(2ASK)的解调 3
2.1.4仿真结果分析 4
2.2四进制数字幅度调制与解调 4
2.2.1四进制振幅键控(4ASK)原理 4
2.2.2仿真结果分析 4
2.2.3四进制振幅键控(4ASK)的解调 5
2.2.4仿真结果分析 5
第三章 FSK信号调制与解调 6
3.1二进制数字频率调制与解调 6
3.1.1 二进制频移键控(2FSK)原理 6
3.1.2仿真结果分析 7
3.1.3 二进制频移键控(2FSK)的解调 7
3.1.4仿真结果分析 8
3.2四进制数字频率调制与解调 10
3.2.1四进制频移键控(4FSK)原理 10
3.2.2仿真结果分析 10
3.2.3 四进制频移键控(4FSK)的解调 11
3.2.4仿真结果分析 11
第四章 PSK信号调制与解调 12
4.1 二进制数字相位调制与解调 12
4.1.1 二进制相移键控(2PSK)原理 12
4.1.2仿真结果分析 13
4.1.3二进制相移键控的解调 13
4.1.4仿真结果分析 14
4.2四进制数字相位调制 14
4.2.1四进制相移键控(4PSK)原理 14
4.2.2仿真结果分析 16
4.2.3四进制相移键控的解调 16
第五章 结论 17
参考文献 18
致 谢 19