Amplitude Modulation
Consists of a technique used most commonly for transmitting information via a radio carrier wave.
It consists of multiplying a signal (called "message signal"; i.e. the signal that is going to be transmitted) with a carrier signal, called modulation of the signal, then transmitting the modulated signal and retrieving the message signal, process called demodulation.
AM works by varying the strength (amplitude) of the transmitted signal in relation to the information being sent.
For example,
We have a message signal x(t) which is intended to be transmitted.
We also have a carrier signal c(t) which modulates the message signal.
So,
$ x(t) * c(t) = y (t) /<math> where y(t) is the modulated signal. $
