Modulation

Modulation is the addition of information to an electronic or optical carrier signal.It is a process of mixing a signal with a sinusoid to produce a new signal. 

Basic types of modulation

There are three main ways in which a radio communications or RF signal can be modulated:

Amplitude modulation(AM)

As the name implies, this form of modulation involves modulating the amplitude or intensity of the signal.Amplitude modulation was the first form of modulation to be used to broadcast sound.

Frequency modulation(FM)

This form of modulation varies the frequency in line with the modulating signal. As a result is form of modulation has been used for many applications including high quality analogue sound broadcasting. 

 

Phase modulation(PM)

As the name indicates, phase modulation varies the phase of the carrier in line with the modulating signal.