What is Signal ?

Signals

  A signal is an quantity or indication through which some amount of information is conveyed. Generally information is all about, what actually we are looking for. Information may be temperature at any specific place at any time or  pressure at any point on a body or electrical voltage or current in any conductor at a specific time.

Signals are generally functions of an independent variable. Here independent variable may be time or space or any other quantity. e.g. x(t), V(t), I(t), Img(x,y) etc. Few examples of Signal is given below: 

• Speech Signal: 1 independent Variable i.e time signal or 1 Dimensional (1D) signal.
• Image Signal: It is two variable of Space signal i.e.  I(x,y) i.e. 2D signal
• TV Picture: It is Three Variable signal i.e. I(x,y,t). It is 3D signal
• Room temperature at any time: It is 4 Variable signal i.e. T(x,y,z,t). It is 4D signal.