Signals and Systems Introduction

Hi Friend's, Here i am going to write about signals, systems and classification of signals. Signal and systems is a subject of engineering. In this subject we study about the signals, types of signals, classification of signals, systems, classification of systems, linear time invariant systems, fourier series, fourier Transform and It's applications, fourier analysis of discrete-time signals and systems, time and frequency characterization of signals and systems, sampling, z-Transform and it's applications, state variable analysis, etc. Here i am going to write about the signals, systems and classification of signals. I am writing this topic in my own language which is easy to read, learn and understand. comment on this hub to improve if needed. so here we go.....

The concepts of signals arise in a wide variety of fields of science and technology as communication, aeronautics, circuit design, seismology, biomedical engineering and speech processing etc.

Signals:- What is signal? "A detectable physical quantity or impulse (as a voltage, current, or magnetic field strength) by which messages or information can be transmitted." Signal is the energy that carries some information. Signals are meaningless without systems to interpret them, and systems are useless without signals to process. A signal is a function representing a physical quantity, which maybe a function of one or more independent variables like time, position, distance, temperature, force, etc and contains information about the behaviors or nature of some phenomenon. Or in simple words, a signal is a physical quantity, which contain information or a function of one or more independent variables which contain some information is called Signal. In general, signal is a function of time. some example of signal which is a function of time are voltage and current. These signals (voltage and current) are in electrical form. Some other signals are music speech, audio speech, sine wave, cosine wave, triangular wave, square wave, etc. Signals maybe one-dimensional or multidimensional. When the signal depends on only one variable, the signal is said to be one-dimensional and when the signal depends on two or more variables, the signal is said to be multidimensional. To discuss more about signals, we are going to read about classification of signals....! But before that i am going to tell you about Systems.

Systems:- A system is combination and interaction of several components to perform a desired task. These components may be physical (Hardware realization) or may be algorithm (software realization). Systems may be interconnected with each other to form other systems. In such cases, the component systems are referred to as sub-systems. A system is characterized by its inputs (or excitation or causes), its outputs (or responses or effects) and the rules of operations adequate to describe it's behavior. A system is a physical set of components that takes a signal, and produces a signal.

On the basis of nature and characteristics in the time-domain, the signals are broadly classified into two groups as continuous-time signals and discrete-time signals. But signals are classified in fourteen types.

1. Continuous-Time signals
2. Discrete-Time signals.
3. Even signals.
4. Odd signals.
5. Periodic Signals.
6. Unperiodic signals.
7. Deterministic signals.
8. Random signals.
9. Energy signals.
10. Power signals.
11. Casual signals.
12. Non-casual signals.
13. Analog signals.
14. Digital signals.

Description of these signals are given in my next hub which i will publish soon....thanks :)