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调制解调(非专业人士学习)

2010年1月3日 / 86次阅读

调制分为模拟调制和数字调制,现在基本上都是数字调制系统,承载的都是数字信号。

调制解调原理

In electronics, modulation is the process of varying one or more properties of a high-frequency periodic waveform, called the carrier signal, with respect to a modulating signal (which typically contains information to be transmitted).

This is done in a similar fashion to a musician modulating a tone (a periodic waveform) from a musical instrument by varying its volume, timing and pitch. The three key parameters of a periodic waveform are its amplitude ("volume"), its phase ("timing") and its frequency ("pitch"), all of which can be modified in accordance with a low frequency signal to obtain the modulated signal. Typically a high-frequency sinusoid waveform is used as carrier signal, but a square wave pulse train may also occur.

A modem's purpose is to convert digital information to analog signals (modulation), and to convert analog signals back into useful digital information (demodulation).

调制解调器简明教程(En)

A Brief Introduction to Modem Technology

http://www.physics.udel.edu/~watson/student_projects/scen167/thosguys/index.html

调制解调过程图解

调制解调过程图解

QAM调制解调

[Kwa:m] / /kæm/ Quadrature amplitude modulation.

Quadrature amplitude modulation, or QAM, is a big name for a relatively simply technique. It is simply a combination of amplitude modulation and phase shift keying.

The most common forms are 16-QAM, 64-QAM and 256-QAM. By moving to a higher-order constellation, it is possible to transmit more bits per symbol.

QAM16_动画详细示例

QAM16_动画详细示例

 

这个gif动画太棒了,清楚的说明了调制解调的原理。

本文链接:https://www.maixj.net/ict/modem-2964

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