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    510HOW IT WORKS

    BY NAVKALA ROY

    DESIGNED AND ILLU STRATED BY

    SUBIR ROY

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    TH E MAG C OF TELEVISION

    Bringing the world into the home ---

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    Imagine. Sunil Gavaskar broken down intothousands of small bits of electricity as hetakes an outswinger and pushes it to sillymid-on. Rushed through the air at thephenomenal speed of light. Down yourantenna. Through the wires. And into yourreceiving set. To be seen exactly as he is onthat cricket field thousands and thousandsofkilometres away in the West Indies!

    Imagine. But you don't have to. For, themagic of television does it fo r you everyday. It breaks up every picture intothousands of small charges of electricityand sends them through the air aselectromagnetic carrier waves at nearly

    300,000 kms. per second, to be picked up bythe antenna on your roof-top andconducted into your receiving set wherethey are amplified and converted back intoa picture.

    -.

    - - - - - - - - - - - - - - - - - - - - 8

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    Television takes you places indeed. Youcan go down to the bottom of the sea orright up into space as you sit munchingwafers before your TV set.

    Time was when grandmother gatheredher grandchildren around her to tell themstories about the man in the moon. Now,both grandmother and grandchild sit gluedto the TV set as they watch and listen to theman on the moon.

    -". . , . . /..

    The first 'waves'

    It began with sound broadcasting, in the

    early 1920's, after Alexander Graham.Bellhad invented the telephone and GuglielmoMarconi had made wireless transmissionsacross the Atlantic:/tlf we can use waves totransmit speech," said some /tcan we notalso use them to transmit movingpictures?"

    This set John Logie Baird, a Scotsman,thinking. One day, while in his bedroom, hepulled out some odd pieces of equipmentwhich included tw o cycle lamp lenses, atorch, an old electric motor, p a r t ~of an oldradio, string, wire, glue and sealing wax.Then he set about his task. The results,though not immediate, were dramatic. On

    January 27, 1926 he finally proved to t ~ eworld that television was indeed a reality.

    It was, of course, a combination of severaldiscoveries that helped Baird todemonstrate ho w moving pictures could be

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    Dur'ng th e war

    People did not take to televisionovernight. TV sets were expensive and not

    many could afford to buy them, Besides,people had to be convinced that televisionwas worth their money.

    And convinced they were in 1936, whenthe British Broadcasting Corporation(B.B.C.) set up the first regular televisionservice in the world. In the next couple of

    years television didgrow

    in popularity andwould have caught on in a big way, had thesecond world war not broken out.

    This is, of course, no t to suggest thatpeople abandoned television thereafter. Itwas, in fact, during this time that some

    scientists considered using television fo rmany purposes, fo r instance, to develop abomb. The idea was to fit a small TV camera

    and transmitter to the flying bomb so thatits course could be followed by the planewhich had launched it. In this way the bombwould be guided nearer and nearer to itstarget. However, this was an idea that neverreally took shape.

    The Germans, meanwhile, introduced apicture telegraph system fo r securityreasons. This system used the sameprinciples as television. Words in messageswere projected as images to the other endso that they could be read and understoodeasily,

    While Europe was at war, engineers inAmerica threw themselves into establishinga regular television service, Numerousstations were opened at many of the largecities and a national network of cable andradio links, or what is more familiarlyknown as a 'national hook-up', was set up.

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    Mickey's gala premiereAfter the war television spread. And

    perhaps it was Mickey Mouse who made itpopular! For, the friendly little mouseendeared himself as much to people then ashe does today. The last transmission madeby the B.B.C. on September 1, 1939 justbefore the war, was a cartoon called,'Mickey's Gala Premiere', and on June 7,1946, to everyone's delight, the firstprogramme televised after the war was thesame cartoon!

    Initially pictures could be transmitted

    only over a limited distance. Onetransmitter could not serve people livingbeyond a radius of about 160 kms. To senda programme across the Atlantic was out ofthe question.

    With the launching of space satellites, thiswas made possible. On July 11, 1962 thefirst

    transatlantic transmission took placefrom Andover, U.S.A., via the satelliteTelstar 1, to Pleumeur, France. Baird'sdream had at last come true. Television hadby now become an accomplished fact inmany countries.

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    Doordarshan

    In India television was introduced in 1959.Known as J D o o r d a r s h a n ~the programmesinitially were entirely educational. The firstgeneral service on a regular basis wasstarted from Delhi in August 1965.

    Now, besides having gone colour,television has reached practically everycorner of the country. This offers ustremendous prospects for development. TVhas great potential in the field of education,particularly basic education, and in othervital spheres such as transforming the

    social environment, bringing us culturallynearer and generating a scienceconsciousness. Television has placed us in

    the unique position of being able toJexperience simultaneously the sameenvironment.'

    In 1963, people wh o had their TV setson, in the United States, saw Jack Ruby kill

    PresidentJohn

    Kennedy's presumedassassin, Lee Harvey Oswald, in thebasement of Dallas Police headquarters asit happened. Within hours the rest oftheworld also saw it - thanks to the SatelliteTelstar.

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    F P

    Today, television is shrinking the world.In

    fact, it has gone far beyond the stageof

    simply being one ofthe communicationmedia. TV has extended itself to manycomplex and intricate areas - fromunderground pipes to spacecraft, fromsupermarkets to operation theatres, andfrom police stations to your front door. Itcan go places where man perhaps cannot.

    It was a television camera that showedthe world the first pictures ofthe moon longbefore Neil Armstrong set foot on it.

    With possibilities of 3-D television takingshape, it may not be long before you cansee your favourite star reaching outtowards you as it were!

    In a closed circuit TV system the signalsfrom the camera are not broadcast to all,but are transmitted through cables toselected receivers. It helps students watchthe surgeon perform his delicate task

    without crowding into the operationtheatre. Similarly it helps the police toregulate traffic and spot thieves insupermarkets. And if you place one of thesecameras outside your front door, you caneven check who is calling!

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    The cameraThe camera comes first in our bag of

    television equipment. In this case, we take ablack and white one. Remember this is a TVcamera and not an ordinary one that youma y use to take photographs.

    Several cameras are normally used fo r anoutside telecast, as in a studio transmission.You have a team of people operating the

    equipment.One camera is so arranged that it takes in

    the entire picture. Another camera showsclose-ups of the scene, and others arepositioned elsewhere to give differentviews of the same scene.

    The producer positions the camerassuitably before the shooting is done. Theoverall effect is observed on a monitorwhich is placed before the producer. He canswitch from one camera to another during

    the broadcast, in order to get the bestpossible coverage.The inside of a black and white TV camera .1. Object 2. Light from the object 3. Screen of photoelectriccells 4. Electron gun 5. Stream of electrons

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    Th image-makerThe TV camera does no t have a film as in

    the ordinary camera. The subject on whichit focuses - a monkey, let us say, throws animage on a plate inside the camera. This isknown as the signal plate. It is made up ofthousands of tiny dots of a special material.These dots are actually photo-cells. Whenlight falls on them, an electric charge isgenerated on each cell. The stronger the

    light, the stronger the electrical charge.There are actually two images on the signalplate. One is visible, being formed by thescene in f ront o f the camera - in this caseth e monkey. The other is an invisibleelectrical 'image'. This image has strong

    Television microscopes are used fo rbiological research. With ultra-violet lightthe microscope magnifies the object beingstudied more than a thousand times.

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    1. Object 2. Lens 3. Photoelectric screen 4. A close-up ofscreen, showing ho w picture is broken into dots of varyingintensity

    electrical charges where the scene beforethe camera is bright, and weaker electricalcharges where th e scene is less bright. Inplaces where the scene is dark, there is nocharge.

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    Th e control r o o m - a close-up1. Monitors 2 C on tr ol p an el

    Shooting in a TV studio1 Microphone 2 Cameras 3. Cameraman4. Sound engineer 5. Floor manager6. Director 7. Control gallery