Signal and System

The concept of signal and system arise in a wide variety of fields and the ideas, techniques associated with these concept plays and important role in such diverse area of science and technology as communications, aeronautics and astronautics, circuit design, acoustics, seismology, biomedical engineering, power generation and disturbance systems, chemical process control, and speech processing that is voice recognition. Although the physical nature of signals and systems that arise in these various disciplines may be drastically different, they all have two very basic features in common.
The signals which are function of one or more independent variables contain information about the behavior or nature of some phenomena.
System respond to particularly signals by producing other signals or some desired behavior.
 Voltages and currents as a function of time in an electrical circuit are examples of signals and a circuit is itself an example of system which in this case responds to applied voltages and currents.
Few more examples of signals and systems :-

  1. When an automobile driver depresses the accelerator pedal, the automobile responds by increasing the speed of the vehicle. In this case, the system is the automobile, the pressure applied on the accelerator pedal is the input to the system and automobile speed is the response of applied signal. 
    Automobile exapmple - Signal and Sytem
    Photo Credit -
  2. A computer program for the automated diagnosis of electrocardiograms (E.C.G.) can be viewed as a system which has its input a digitized electrocardiogram and which produces estimation of parameters such as heart rate as output.
  3. A camera can be considered as a system that receives light from different sources and reflected from objects produces a photograph.
  4. A robot arm is a system whose movements are the response to control inputs.
Scope :-
Signal and system courses are frequently found in Electrical Engineering curricula, the concepts and techniques that form the core of the subject are of fundamental importance in all engineering disciplines.The scope of potential and actual applications of the methods of signals and systems analysis continue to expand as engineers are confronted with new challenges involving the synthesis and analysis of complex processes. For this reasons, a course in signal and system is not only an essential element in an engineering program but also can be one of the most rewarding, exciting and useful courses that engineering students take during their undergraduate education.