What is Modulation? | Demodulation | Need & Advantage of Modulation | Demodulation | Communication Theory | EC8491

 Modulation

        Modulation is defined as the process by which some characteristics, usually amplitude, frequency or phase of a carrier wave is varied in accordance with instantaneous value of some other voltage or message signal.

Need For Modulation (Advantages)

1. Easy of Radiation
2. Adjustment of Bandwidth 
3. Reduction in height of Antenna
4. Avoid mixing  of Signals
5. Increases the range of Communication
6. Multiplexing
7. Improves Quality of Reception

Carrier Signal

        Carrier Signal doesn't contain any information it only carries an information after modulation.

Demodulation

        It is defined as the process of extracting a  modulating or baseband signal from the modulated signal.

Modulation Index

        The ratio of maximum amplitude of modulating signal to maximum amplitude of carrier signal.

ma = Vm / Vc           Vm  < Vc   --> Avoid Distortion

Hence the Value of ma  is between 0 to 1. If ma  = 1, then Vm  = Vc

Types of Modulation

• Amplitude Modulation
• Phase Modulation
• Frequency Modulation 

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