Signals and Systems

1.12 CLASSIFICATIONS OF DISCRETE TIME SYSTEMS

The discrete time systems can be classified as follows:

• Static/Dynamic
• Causal/Non-Causal
• Time invariant/Time variant
• Linear/Non-Linear
• Stable/Unstable

1.12.1 Static and Dynamic Systems

The system is said to be static if its output depends only on the present input. On the other hand, if the output of the system depends on the past input, the system is said to be dynamic.

For example, y(n) = 5x(n) and y(n) = 2x²(n) +3x(n) are the static systems whereas y(n) = x(n) + 2x(n–1) represents the dynamic system.

1.12.2 Causal and Non-Causal Systems

If the output of the system depends on the past and presents input only, the system is said to be a causal system. On the other hand, if the output of the system ...