what is modulation techniques and types with applications

10/3/2014 What is Modulation Techniques and Types with Applications

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In our day-to-day life, we communicate with many people using various communicationtechniques. We frequently use television, radio, internet, newspaper, mobile and so on assource of different types of communication. Electronic communication comprises TV, radio,internet, etc. Here, when we need to transmit signal from one location to another, then we needto strengthen the signal. So, that the signal travels for long distances. This is called modulationand this article gives an overview of modulation and types of modulation techniques.

Communication is the process of exchanging (two way communication) or passing (one waycommunication) information from one person to another. The basic electronic communicationsystem consists of these components such as transmitter, receiver and communicationchannel.

Communication System

A transmitter is a group of electronic circuits which is designed to convert the information intoa signal for transmission over a given communication medium.

A receiver is a group of electronic circuits which is designed to convert the signal back to theoriginal information.

The communication channel is the medium which is designed to transmit the electronic signalfrom one place to another.

What is Modulation?



Modulation is nothing but, carrier signal varies in accordance with the message signal.Modulation technique is used to change the signal characteristics. Types of modulationtechniques are classified into two types such as

Modulation Techniques

Analog ModulationDigital Modulation

Analog ModulationIn analog modulation, analog signal (sinusoidal signal) is used as a carrier signal thatmodulates the message signal or data signal. The general function Sinusoidal waves is shownin the figure below, in which, three parameters can be altered to get modulation they areamplitude, frequency and phase, so the types of analog modulation are:



Analog Modulation

Amplitude Modulation (AM)Frequency Modulation (FM)Phase Modulation (PM)

Amplitude ModulationAmplitude modulation was developed beginning of the 20th century and it was the earliestmodulation technique used to transmit voice by radio. This type of modulation technique is usedin electronic communication. In this modulation, the amplitude of the carrier signal varies inaccordance with the message signal, and other factors like phase and frequency remainconstant.

The modulated signal is shown in the below figure, and its spectrum consists of the lowerfrequency band, upper frequency band and carrier frequency components. This type ofmodulation requires more power, greater bandwidth and filtering is very difficult. Amplitudemodulation is used in computer modems, VHF aircraft radio and portable two way radio

Frequency ModulationIn this type of modulation, frequency of the carrier signal varies in accordance with themessage signal, and other parameters like amplitude and phase remain constant. Frequencymodulation is used in different applications like radar, radio and telemetry, seismic prospectingand monitoring newborns for seizures via EEG, etc.

This type of modulation is commonly used for broadcasting music and speech, magnetic taperecording systems, two way radio systems and video transmission systems. When noise occursnaturally in radio systems, frequency modulation with sufficient bandwidth provides anadvantage in cancelling the noise.



Phase ModulationIn this type of modulation, phase of the carrier signal varies in accordance with the messagesignal. When the phase of the signal is changed, then it affects the frequency. So, for thisreason this modulation is also coming under frequency modulation.

Generally, phase modulation is used for transmitting waves and is an essential part of manydigital transmission coding schemes that underlie a wide range of technologies like GSM, WiFi,and satellite television. This type of modulation is used for signal generation in al synthesizers,such as the Yamaha DX7 to implement FM synthesis.

Types of Analog Modulation

Therefore, Analog modulation includes AM, FM and PM and these are more sensitive to noise.If noise enters into a system, it persists and gets carried till the end receiver. So, this drawbackcan be overcome by the digital modulation technique.

Digital ModulationFor a better quality and efficient communication, digital modulation technique is employed. The



main advantages of the digital modulation over analog modulation include available bandwidth ,high noise immunity and permissible power. In digital modulation, a message signal isconverted from analog to digital message, and then modulated by using a carrier wave.

Digital Modulation

The carrier wave is switched on and off to create pulses such that the signal is modulated.Similar to the analog, here the type of the digital modulation is decided by the variation of thecarrier wave parameters like amplitude, phase and frequency.

The most important digital modulation techniques are based on keying such as

Amplitude Shift Keying, Frequency Shift Keying, Phase Shift Keying, Differential Phase ShiftKeying, Quadrature Phase Shift Keying, Minimum Shift Keying, Gaussian Minimum ShiftKeying, OrthogonalFrequency Division Multiplexing, etc., as shown in the figure.

In Amplitude shift keying, the amplitude of the carrier wave changes based on the messagesignal or the base band signal, which is in digital format. It is sensitive to noise and used forlow-band requirements.

In frequency shift keying, the frequency of the carrier wave is varied for each symbol in thedigital data. It needs larger bandwidths as shown in the figure. Similarly, the phase shift keying



changes the phase of the carrier for each symbol and it is less sensitive to noise.

Types of Digital Modulation

Communication Based Project IdeasCommunication based projects mainly covers a wide range of areas such as GSM, GPS,Bluetooth, RFID, DTMF, Mobile, Ethernet, RF, XBEE, Networking, Data Acquisition and SmartCard. Here is the list of communication based project ideas for engineering students is listedbelow.



Communication Based Project

Cell Phone Based DTMF Controlled Garage Door Opening SystemZigbee Technology Based Industrial AutomationDisplay of Dialed Telephone Numbers on Seven Segment DisplaysAutomatic Dialing to any Telephone Using I2C Protocol on Detecting BurglaryDTMF Based Load Control SystemCell Phone Controlled Robotic VehicleGSM Based Energy Meter Reading with Load ControlRailway Track Security SystemGSM Based Wireless Electronic Notice BoardRFID Technology Based Device Control and Authentication system using PICMicrocontrollerTheft Intimation of Vehicle Over SMS to OwnerGSM Based Energy Meter Reading With Load Control Using PIC MicrocontrollerRF Controlled Robotic Vehicle With Laser Beam ArrangementAutomatic Bus Location Announcement System using Microcontroller and GPSPick N Place Robot With Soft Catching GripperFire Fighting Robotic VehicleWar Field Spying Robot with Night Vision Wireless CameraWireless Power TransferSpeed Synchronization of Multiple Motors in IndustriesRF based Unique Office Communication SystemTouch Screen Based Home Automation SystemRFID Security Access Control SystemRFID Based Attendance SystemRFID Based Passport Details



Device Control and Authentication using RFIDWireless Message Communication between Two ComputersXBEE Based Remote Monitoring of 3 Parameters on Transformer / Generator HealthXBEE Based Remote Monitoring of 3 Parameters on Transformer / Generator Healthwith Voice Announcement and Wireless PC InterfaceRemote AC Power Control by Android Application with LCD DisplayAdvanced Embedded System Based Remote Robot using RFWar Field Spying Robot with Night Vision Wireless Camera by Android ApplicationsRemote Induction Motor Control by Android Application with 7 Segment DisplayRemote Operated Domestic Appliances Control by Android ApplicationRemote Password Operated Load Control by Android ApplicationsDensity Based Auto Traffic Signal Control with Android Based Remote OverrideFour Quadrant Operation of DC Motor Remotely Controlled by Android Applications.Wireless Data Communication Project on Data Encryption and Decryption UsingZigbee

These are the different types of modulation in communication system and communicationbased projects. Therefore, the readers, can share their ideas, suggestions and comments in thecomment section below.