Question

What is impulse response, why it is important? How else is it called?

Answer 1

Impulse Response:

Whenever a system (block) or a signal processor is given an input signal, it alters or processes the input to give the desired output signal depending on the system transfer function.
The output of the system to a unit input signal is the impulse response of the system.
Impulse response of the system helps in determining the main characteristics and response of the system (block) for any kind of input signal.

The impulse response of a system is important because the response of a system to any arbitrary input can calculated from the system impulse response using a convolution integral.

Convolution is a very powerful technique that can be used to calculate the zero state response (i.e., the response to an input when the system has zero initial conditions) of a system to an arbitrary input by using the impulse response of a system. It uses the power of linearity and superposition.