# Types of Signals

Dec 5 • General • 2655 Views • 2 Comments on Types of Signals

Signal is the energy that carries some information.”A signal is a physical quantity that varies with time,space or any other independent variable.by which information can be conveyed”. A signal can be represented as a function x(t) of an independent variable t which usually represents time. If t is a continuous variable, x(t) is a continuous-time signal, and if t is a discrete variable, defined only at discrete values of t, then x(t) is a discrete-time signal. A discrete-time signal is often identified as a sequence of numbers, denoted by x[n], where n is an integer. Signals and Systems together forms the basis for the subject known as digital signal processing.This post include Signals and Systems Notes on Types of Signals with examples.

“A signal is a source of information generally a physical quantity which varies with respect to time, space, temperature like any independent variable”.

Signal example: An electrical circuit signal may represent a time-varying voltage measured across a resistor.

Signals can be categorized in various ways. The most common distinction is between discrete and continuous spaces that the functions are defined over, for example discrete and continuous time domains. Discrete time signals are often referred to as  time series in other fields. Continuous time signal are often referred to as continuous signals even when the signal functions are not continuous; an example is a square-wave signal.

Various types of signals are as follows

1. Continuous Time Signal:  If the independent variable (t) is continuous, then the corresponding is continuous signal. The signal not be continuous in amplitude as shown in fig 1.2.

2. Discrete Time Signal: If the independent variable (t) takes on only discrete values. For example: +-1, +-2 etc. Discrete time signal is shown in the following figure.

3. Periodic Signal: If the transformed signal is same as x (t+nT), then the signal is periodic signal.

4. Even Signal: One of characteristics of signal is symmetry that may be useful for signal analysis. Even signals are symmetric around vertical axis, and Odd signals are symmetric about origin. A signal is referred to as an even if it is identical to its time-reversed.

for example: sinusoidal waves are the example of even signal.

5. Odd Signal: A signal is odd if x(t) = -x(-t). An odd signal must be 0 at t=0, in other words, odd signal passes the origin. Waveform of cos is an example of odd signal.