How to determine if an IIR filter is causal or non-causal?

1. Are IIR filters non causal?
2. How do you determine if a signal is causal or non causal?
3. Can FIR filter be non causal?
4. What is the difference between non causal and anti-causal systems?

Are IIR filters non causal?

(v) An IIR filter is linear and time-invariant. (vi) It is causal.

How do you determine if a signal is causal or non causal?

A system is said to be causal if it does not respond before the input is applied. In other words, in a causal system, the output at any time depends only on the values of the input signal up to and including that time and does not depend on the future values of the input.

Can FIR filter be non causal?

In all cases, the ROC includes the unit circle, i.e., FIR filters are always stable (but not necessarily causal).

What is the difference between non causal and anti-causal systems?

A system that has some dependence on input values from the future (in addition to possible dependence on past or current input values) is termed a non-causal or acausal system, and a system that depends solely on future input values is an anticausal system.