Periodic and non periodic signals

Periodic signals :

  • A CT signal which repeats it self after a fixed time period is called as a periodic signal. The periodicity of a CT signal can be defined mathematically as follows :
x(t) = x(t+T0)
Where ; 
T= periodic of signal x(t) 

periodic signal are sine wave, cosine wave, square wave etc.

Periodic signal

Non periodic signals :
  • A CT signal which does not repeat itself after a fixed time period or does not repeat at all is called as a non periodic signal.
The non periodic signal do not satisfy the condition of periodicity stated in equation :

x(t) ≠  x(t+T0)

Sometimes it is said that an aperiodic signal has a periodic T = ∞. Figure shows a decaying exponential signal.

This exponential signal is non periodic but it is deteministic because we can mathematically express it as x(t) = e-ɖt.
Non periodic signal