## 13 Aug 2018

### What is a Signal - Types of Signals and Examples of Signals

Here we will discuss- what is a signal, definitions of signal, interesting examples of signals in our daily life and different types of signals.
Do you know, whether you are walking, singing, speaking or dancing... You are producing signals !!! Our whole universe is mathematical...

## Definition of Signal

1. Any physical quantity that varies with time and space is a Signal.

2. A Signal may be defined as a function of one or more independent variables like time, distance, position or temperature etc. that has some information about the phenomena (event) that produced it.

A signal can be a Motion signal, Sound signal, Image signal or Video signal etc. Now let's discuss each type of the signals-

## Types of Signals

### 1. Motion signal

Any object that moves has a signal associated with it.
To make it clear let's take an example-
The mathematical equation given below tells the position of a particle at any time instant-

x = 3t + 5

Here 'x' is the position and 't' is time

With the help of this equation you can easily find out the position of this particle at any time instant.

e.g.  x = 5      at t = 0
x = 11    at t = 2
and so on...

One important example of the motion signal is RADAR which displays the motion of any aircraft as an electromagnetic signal.

### Sound signal

When any medium (ex. air) vibrates it produces sound.
Sound signal Associates a pressure value to every value of time and space coordinates.

### Image signal

Do you know that image is also a signal !!!
An image or a picture has a color or brightness signal; a function of two dimensional location. Any object's appearance is represented as a reflected or emitted electromagnetic wave which is a type of electronic signal.
So any image has two components-
Color and brightness

### Video signal

A video signal is just a sequence of images. A Point in a video can be identified as its two dimensional position and time of its occurrence. This makes the video a three-dimensional entity having two dimensional position and time as the third dimension.

FREQUENCY SPECTRUM OF AMPLITUDE MODULATION (WAVEFORMS AND EQUATIONS DERIVATION)

AMPLITUDE MODULATION (TIME DOMAIN EQUATIONS AND WAVEFORMS)

STEP INDEX OPTICAL FIBER (MULTIMODE AND SINGLE MODE STEP INDEX FIBERS)

PULSE MODULATION TECHNIQUES (PAM, PWM, PPM, PCM)

OPTICAL FIBER: STRUCTURE AND WORKING PRINCIPLE

PULSE AMPLITUDE MODULATION (PAM)

COMPARISON OF PAM, PWM, PPM MODULATION TECHNIQUES

PULSE WIDTH MODULATION (PWM)

CONTINUOUS TIME AND DISCRETE TIME SIGNALS (C.T. AND D.T. SIGNALS)

NEED AND BENEFITS OF MODULATION

PULSE POSITION MODULATION (PPM)

OPTICAL FIBERS IN COMMUNICATION: COVERS ALL IMPORTANT POINTS

OPTICAL FIBER SOURCES (DESIRABLE PROPERTIES)

SAMPLING THEOREM AND RECONSTRUCTION (SAMPLING AND QUANTIZATION)

SUPERPOSITION THEOREM (BASICS, SOLVED PROBLEMS, APPLICATIONS AND LIMITATIONS)

Digital Modulation Techniques (ASK, FSK, PSK, BPSK)/ Amplitude, Frequency and Phase Shift Keying

Conventional AM Vs DSB-SC Vs SSB-SC Vs VSB (Comparison of AM Systems)

What are Microwaves and their Applications (Uses) in various fields

Basic Structure of Bipolar Junction Transistor (BJT) - BJT Transistor - Working and Properties

Polar Plots of Transfer Functions in Control Systems (How to Draw Nyquist Plot Examples)

Generation of Binary Phase Shift Keying (BPSK Generation) - Block Diagram of Binary Phase Shift Keying (BPSK)

Low Level and High Level Modulation Block Diagram (AM Transmitter Block Diagram)

Block Diagram of CRO (Cathode Ray Oscilloscope), Components of CRO and CRT with Structure and Working

Slope Overload Distortion and Granular (Idle Noise), Quantization Noise in Delta Modulation

Frequency Translation/Frequency Mixing/Frequency Conversion/Heterodyning (Basic Concepts and Need)

Quadrature Phase Shift Keying Modulation (QPSK) Basics, Waveform and Benefits

Pulse Code Modulation (PCM) Vs Differential Pulse Code Modulation (DPCM)