Correct Answer - Option 2 : 1 and 2 only
Impulse response defines the characteristics of a system. If the system consists of an infinite number of impulses, then it is called an infinite impulse response system. If the number of impulses is finite, then it is called a finite impulse response system. Hence two major classes of the systems are:
- If a system is said to be an infinite duration impulse response (IIR) if the output samples of the system depend on the present input sample, past input samples and past output samples.
- If a system is said to be a finite duration impulse response (FIR) if the output samples of the system depend only on the present input sample and a finite number of past or previous input samples, i.e. the FIR system does not consider past or previous output samples.
Recursive discrete time system:
- If a system output y(n) at time n depends on any number of past output value y(n – 1), y(n – 2), …, it is called a recursive system.
- This system requires two multiplication, one addition, and one memory location. This is a recursive system which means the output at time n depends on any number of a past output values.
- So, a recursive system has feedback output of the system into the input. This feed back loop contains a delay element.
Non-Recursive discrete time system:
If y(n) depends only on the present and past input, it is called non-recursive. It does not exhibit the necessity of any feedback.
