Provide Definition of Signals

A continuous-time signal x(t) is a signal that is a function of real number t. For a discrete-time signal x[n], it is a method of discrete time instants which is defined by integer n. Sampled signals processed by using digital computers are discrete-time signals. The variation between a continuous-time and discrete-time signal is displayed in Diagram. A discrete-time signal is considered periodic if the sunsequent conditions are true

x [n] = c [n+N]                                                                   - ∞ < n < ∞                  

in which N is an arbitrary interval in time. If not, the signal is considered aperiodic.