Abstract
In the simulation of communication systems, generated by the analog source carrying amessag
e through the sensor into electrical signals. Analog baseband signal after the modul- -ation of t
he low pass spectrum to carrier frequency to adapt to the channel, the final reducti- -on into el
ectrical signal demodulation. This paper applied the frequency modulation method to generat
e the signal modulation and demodulation. Mainly through the study and use of SIMULINK to
olbox in this thesis, with its rich template and undergraduate course on comm- -unication theo
ry knowledge,the modulation and demodulation of FM signal, as well asthe design and simul
ation with SIMULINK. Firstly, sine wave signal generator is simple asthe source, simulation F
M modulation anddemodulation principle of analogue signals. Then, using the song as the sour
ce.
Keywords:modulation and demodulation；FM; MATLAB; SIMULINK simulation
1 FM 调制与解调原理
1.1 模拟通信系统的简介
通信的目的是传输信息。通信系统的作用就是将信息从信息源发送到一个或多个目的地。
通信系统对信号进行两种基本变换：
第一、要把发送的消息要变换成原始电信号。
第二、将原始电信号调制到频率较高的载频上，使其频带适合信道的传输。
调制前和解调后的信号称为基带信号，已调信号也称为频带信号。
对于任何一个通信系统，均可视为由发送端、信道和接收端三大部分组成（如图 2-1 所
示）。
信息源
发送端
信道
信 道
噪声源
接收端
发 送 设 接 受 设 信息源
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