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## Saturday, 20 July 2013

### Amplitude modulation notes | Principles of communication IT 2202 Unit 1 - Fundamentals of analog communication | Modulation | Demodulation | Amplitude modulation & its mathematical equation | Bandwidth

Principles of communication - IT 2202 Notes

Amplitude Modulation

Modulation:
The process of impressing low-frequency information signals onto a high frequency carrier signal is called Modulation.

Demodulation:

Demodulation is the reverse process where the received signals are transformed back to their original form.

Amplitude Modulation:

Amplitude modulation is the process of changing the amplitude of a relatively high frequency carrier signal in proportion with the instantaneous value of the modulating signal (information).Amplitude modulation is relatively inexpensive. It is used in two-way mobile communications.

Mathematical Equation of Amplitude modulation:

Em(t) = Emsinwmt   ------>  Em = amplitude of message signal

Ec(t) = Ecsinwct    ------>  Ec = carrier signal amplitude.

EAM(t) =Ec  +  Emsinwmt

EAM(t) = EAMsinwct

= Ec(1+masinwmt)sinwct

=Ecsinwct  + maEcsinwct.sinwmt

Bandwidth:

Bandwidth ( B.W ) is calculated as Upper Cutoff frequency  - Lower cut off frequency
= fc + fm – ( fc – fm)
B.W        = 2 fm