Systems Important Definitions

 Systems

Definition of a System: A Signal is a one which produces an output signal when an input signal is processed. 

These Systems are classified into Six types they are:

    Continuous time and Discrete time system

    Linear and Non-Linear system

    Static and Dynamic system

    Time invariant and Time variant system

    Causal and Non-Causal system

    Stable and Unstable system

Continuous System: Continuous time system will operate on a continuous time signal (input or excitation) and produces another continuous time signal (output or response). The

signal x(t)is transformed by the system into signal y(t).

Discrete Time System:

Discrete time system will  operate on a discrete time signal (input or excitation) and

produces another discrete time signal (output or response).

Linear System:

    Any system is said to be linear if obeys superposition theorem. Superposition theorem will state that the response of a system to a weighted sum of the signals is equal to the corresponding weighted sum of responses to each of the individual input signals.

Non Linear System:

Any system is said to be Non linear if that does not obeys superposition theorem.

Static system:

A system called as memoryless or static if the response of the system is due to present input alone.

Dynamic system:

A system called as memory or dynamic if the response of the system depends on

factors other than present input also.

Time variant and Invariant System: 

Time invariant system:

A system is said to time invariant if the relationship between the input and output does

not change with time.

Time variant system:

A system is said to time variant if the relationship between the input and output changes

with time.