In the communication system, the s/g to be transmitted is digitized during the digitization process the s/g need to be sampled first.

This sampling is to be done in a specified rate range such that the recovery is faithful.

This rate is governed by Nquist’s criteria which gives rise to sampling theorem which states that,

For faithful reconstruction at the receiver, the signal should be sampled at the transmitter at-least at twice the rate of maximum frequency.

$fs \geq 2fm$

Where,

Fs = sampling frequency.

Fm = maximum frequency component.