COMMUNICATION GADGETS

BYU.N.BHASKARA

ASSISTANT TEACHERGOVERNMENT JUNIOR COLLEGE

ALURHASSAND DISTRICT

What is Communication?

It is process by which information is exchanged between individuals through a common system of symbols,signs or behaviours.

World-Village?

Yes,our global world has become a village with the help of fast growing technology.Now a days communication has become much easier and it reaches with the speed of light.emails,Teleconferences,skype calls all these communication gadgets had made our world a global village.

Electro Magnetic Waves

These are the waves which has very long or short wave length which are not visible ot our eyes.Mutually perpendicular electric and Magnetic fields which are also perpendicular to the line of propagation are known asa electromagnetic waves.They trave with the speed of light.

Why should we Study EM Waves?

It is because they act like vehicles in most of the modren communication devices.Here you can see the photograps of scientis who worked for em waves

James Clerk Maxwell1864

Heinrich Rudolf Hertz1887

Theory Behind the study of Electromagnetic Waves

Electromagnetic wave theory was first proposed by James Clerk Maxwell,in the year 1864.They were first experimentally produced and demonstrated by Hertz in the year 1887.They are also called as Hertizian Waves

The use of electromagnetic waves in sending wireless messages or radio communications was first demonstrated by the Indian scientists Acharya Sir J.C.Boase.

RADIO

Very Old Radio Guglielmo Marconi1874-1937

Radio is still the most popular electronic device used to listen to music,speeches and weather bulletins.The lowcost device namely radio does not require much technical skills to operate.

Radio

Radio Communication Involves two things1.Radio Transmitter.

2.Radio reciever.

1.Radio Transmitter.

Music,Speech or weather bulletins consists of sound waves which are produced by vibrations.This information is called intelligence. These sound waves are converted into electrical signals,called Audio Frequency Waves. Micophones convert the vibrations into AF.

Working Of Radio Transmitter

Microphone AF SignalsAmplified

AFSignals

Modulations AF+RF

RF Waves

Amplification

Antenna

When the sound is input to the microphone the membrane inside it virbates there by converting the audio signals into electrical input called as AF waves. This AF is amplifed in amplifier.The process of superimposing or mixing AF signals on RF waves is called modulation.The modulated waves are further amplified and transmitterd by transmitting towers or antennas.

Radio Receiver

Modulated Waves Demodulator Amplifier

Antenna

Speaker

Antenna receives the modulated waves.Demodulator seperates RF from Af signals the process is called demodulation.The signals are amplifed and fed to the speaker to rpoduce the original sound.

Television

It is an electronic device which not only gives audio but also video signals thereby entertaining crores of poeple arround the world. The credirt of this must go the the Physist JHON LOGIE BAIRD.

Working of Television Transmitter

Photo cells V.F.Signals Amplification

Light

T.V.Camera

ModulationVF+RF Amplifier

Antenna

RF

The image of an object is made fall on a plate using T.V.camera.This plate is called signal plate.The plate consits of many phot cells.The light from the object is converted in to video signals or video frequency waves or VF in short. Before this process the image is scanned as dots and lines by the scanner.The VF signals are amplified and modulated as RF waves and then amplified and transmitted through antennas.Sound is transmitted as in a radio.

T.V.Receiver

Modulated Waves Demodulator Amplifier

Antenna

Speaker

Antenna receives the modulated waves. Channel selection is nothing but selection of frequency of a T.V.station.after demodulation the VF signals are fed to the picture tube called cathode ray tube. The cathode ray tube prdouces original picture. The sound is reproduced as in the radio receiver.

FAXAlexander Bain is the inenvter of FAX.He is a technician and clock maker.

The long form of FAX is facsimile transmission.

(Telecommunications) an international system of transmitting a written, printed, or pictorial document over the telephone system by scanning it photoelectrically and reproducing the image after transmission. Often shortened to: fax

Working of FAX

A fax machine scans the document by light and image and the image is changed into electrical signals by photo cells. The message travels through the telephone lines and received by the fax machine at the other end. After decoding, machine produces the copy of the original document. Every FAX machine has a number like a telephone. This has tobe dialled before sending the message.

Working of Telephone

Telephone was invented by Alexander Graham Bell.He was a British inventor,Scientist,Engineer and Proffessor

The sound waes are converted into electrical signals by the mouth piece. The signals reach the ear piece at the other end by cables.

Working of MobileIt is a two way radio system.It consists of both radio transmitter and receiver.It also consists of a portable microchip called Sim card.(SUBSCRIBER INDXE MODULE).Sound waves are converted into radio frequency waves and travel without the help of the cable and reach the reciever at nearby base station. The base station sends the radio waves which are detected by the receiver.

Advantages of mobile

Communication between two persons even if they are moving. Communication to and from land line phone.Voice message, text message facicilitiesIt can be used as a mini computer.Linking of entire globe by tlelcommunication usinf geostationary satellites.

Internet

A means of connecting a computer to any other computer anywhere in the world via dedicated routers and servers. When two computers are connected over the Internet, they can send and receive all kinds of information such as text, graphics, voice, video, and computer programs.

Read more: http://www.businessdictionary.com/definition/internet.html

Founder of Internet

Vint Cerf