Invertible System The system is invertible if by observing the output, we can determine its input i.e. we can construct an inverse system that when cascaded with the given system, as shown in figure1, yields an output equal to the

## Time-Varying & Time-Invariant Systems

Time-Invariant System The system is time invariant if the behaviour and characteristic of the system are fixed over time. In other words, a system is said to be time invariant if a time shift in the input signal causes an identical

## Linear and Non-Linear Systems

Linear System A system is said to be linear if superposition principle is applicable to the system. Superposition Principle The response resulting from several input signals can be computed as the sum of the responses resulting from each input signal

## Causal, Non-Causal & Anti-Causal Signals

Causal Signal A signal that does not start before t=0 is a causal signal i.e. x(t)=0, ∀ t<0. A system is causal or non-anticipatory if the output at any time to depends only on the values of the input at