Tell FIR part and IIR part of a signal apart

1. How can you tell the difference between FIR and IIR filters?
2. How do you know if a system is IIR?
3. What are FIR and IIR systems their impulse responses and transfer functions?
4. Is Butterworth a FIR or IIR?

How can you tell the difference between FIR and IIR filters?

If the impulse response of the filter falls to zero after a finite period of time, it is an FIR (Finite Impulse Response) filter. However, if the impulse response exists indefinitely, it is an IIR (Infinite Impulse Response) filter.

How do you know if a system is IIR?

If both zeros and poles are present, then it is IIR.

What are FIR and IIR systems their impulse responses and transfer functions?

The transfer function of the system having an FIR filter contains only zeros. While in the case of IIR filters the transfer function contains both poles and zeros. FIR filters show non-recursive behaviour. But IIR filters show recursive behaviour.

Is Butterworth a FIR or IIR?

The classical IIR filters, Butterworth, Chebyshev Types I and II, elliptic, and Bessel, all approximate the ideal “brick wall” filter in different ways.