where z is the set of integer number, can represent a discrete-time signal where each number x(n) corresponds to the amplitude of the signal at an instant nT. Since n is an integer, T represents the interval between two consecutive points at which the signal is defined. It is important to note that T is not necessarily a time unit. For example, if x(n) represents the temperature at sensors placed uniformly along a metal rod, then Y is a length unit.