Electrical Engineering ⇒ Topic : Causal and Non-causal Systems

Causal and Non-causal Systems

A system is said to be causal if its output depends on the present and past values of the input but it does not depend on the future values of input. Therefore, a causal system cannot produce an output before the application of input. A causal system is non-anticipatory. On the other hand, a system whose output depends on the future input is known as non-causal system.

The output y(t) = x(t) + 2x (t - 1) + x(t -  2) and y(t) = x(t) + 1/2 ∫ x(t) dt represent a causal system. On the other hand, y(t) = x(t + 3), y(t) = x(t) + 2x(t + 1) and y(t) = dx(t)/dt represent a non-causal system.