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TELEVISION. This is the invention that almost everyone has, it involves sending and receiving pictures and sound by the means of signals and is transmitted through the use of optical fibers. These messages are transmitted from the main source the television station back to the television in our homes. The Television is regarded as one of the most wide spread forms of communication in the World, though many people don't travel, meet the leader of there country or even travel to the moon all these can be experienced by watching Television. The Television is not only used to gain information watch news, sport, and weather programs it can also be used to monitor certain things like the work place, public facilities, or even corner stores to monitor thieves. One other example would be doctors as they use cameras to look through the human body to see what is wrong. The United States is well none for having the most television sets per person then any other country, in 1994 a survey showed that for every 1000 people there were 814 Television sets, more than 98% of hose holds have televisions. Canada, Japan, Denmark, and Finland follow the United States. The Television works by focusing the television camera on a scene then the camera changes light from the scene into an electronic signal that is feed out to the Television sets in your home. These signals are called video signals, which vary depending on the brightness of the scene. Then Carrier Waves consisting of electric currents that carry information, carry waves that are combined and sent to an antenna which is usually in or on the tallest structure in a given broadcast area. Then electromagnetic waves are formed and sent horizontally throughout the atmosphere, the waves excite weak electric currents in all television-receiving antennas within range. The currents then flow down the antenna to the television receiver where they are separated into audio and video signals these signals are sent to the picture tube and speakers, were they create the picture and sound of the program. The frequency of carrier waves is measured in hertz; this is the total amount of peaks, which pass by a point every second. Television stations which broadcast in the same area send out carrier waves on different bands of frequencies, each called a channel so that the signals from different stations do not mix, for example channel 10 is on 10, Prime is on 7, the A.B.C is on channel 3, and Win is on channel 6. It was realized as early as 1904 that instead of black and white television color television was possible, by using the three primary colors of light: red, green and blue. In 1928 Baird demonstrated color television by using a Nipkow disk where three sets of openings scanned the scene. In New York City 1940 an American inventor Peter Goldmark introduced a fairly refined color television system. In 1951 public broadcasting of color television began, using Goldmarks system. This system was incompatible with monochrome television, this was perfected in 1953. When television had been around for a few years they started to try and develop them more by making bigger screens and better technology for broadcasting and transmitting signals. The first television screens were 18or25 cm (7or10inch) diagonally across. The televisions now come in a wide range of sizes but many of them measure to be 81or89 cm (32or35inch) diagonally. Manufactures have built television sets from 2m (7ft) diagonally, and a small one from 7.6 cm (3inch). The screen is formed by coating the inner end of the tube with any type of substance known as Phosphors which when struck by the electrons will glow. In the Kinescope the electrons beam is moved for scanning by means of two pairs of deflection plates. The first pair of plate deflects the beam up and down where as the second pair deflects it from side to side. I would have to say that the television is the most advanced type of technology there is today, not only do we use it for pleasure needs like watching sport and shows we use it to gain information about overseas troubles, and if we didn't have the television we would be well behind the times. | |||||||||||||||||||||||
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| BIBLIOGRAPHY. 1) Encarta 97 Encyclopedia 2) Funk & Wagnall's New Encyclopedia 4th Edition.
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