TV - English version.pdf

Television “TV”redirects here. For other uses, see Television (dis- ambiguation) and TV (disambiguation). Television (TV) is a telecommunication medium that American family watching TV, 1958 is used for transmitting and receiving moving images and sound. Television can transmit images that are monochrome (black-and-white), in color, or in three dimensions. The word television comes from Ancient Greek τῆλε (tèle), meaning “far”, and Latin visio, meaning “sight”. Televisi
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  Television “ TV ” redirects here. For other uses, see Television (dis-ambiguation) and TV (disambiguation). Television  ( TV ) is a telecommunication medium that American family watching TV, 1958  is used for transmitting and receiving moving imagesand sound. Television can transmit images that aremonochrome (black-and-white), in color, or in three dimensions. The word  television  comes from AncientGreek τῆλε  (tèle) , meaning “ far ” , and Latin  visio ,meaning “ sight ” .  Television  may also refer specificallyto a television set, television program, or television trans- mission.First commercially available in very crude form on an ex-perimental basis in the late 1920s, then popularized ingreatly improved form shortly after World War II, thetelevision set has become commonplace in homes, busi-nesses, andinstitutions, particularlyasavehicleforenter-tainment, advertising, and news. During the 1950s, tele- vision became the primary medium for molding publicopinion. * [1] In the mid-1960s, color broadcasting andsales of color television sets surged in the US and beganin most other developed countries.The availability of storage media such as video cassettes(mid-1970s), laserdiscs (1978), DVDs (1997), and high- definitionBlu-rayDiscs(2006)enabledviewerstousethetelevision set to watch recorded material such as moviesand broadcast material. Internet television has seen therise of television programming available via the Internetthrough services such as iPlayer, Hulu, and Netflix. In 2009, 78% of the world ʼ s households owned at leastone television set, an increase of 5% from 2003. * [2]The replacement of bulky, high-voltage cathode ray tube(CRT) screen displays with compact, energy-efficient,flat-panel alternatives such as LCDs (both fluorescent- backlit and LED-backlit), plasma displays, and OLED displays was a major hardware revolution that began pen-etrating the consumer computer monitor market in thelate 1990s and soon spread to TV sets. In 2013, 87% oftelevisions sold had color LCD screens. * [3]The most common usage of television is for broadcasttelevision, which is modeled on the radio broadcast-ing systems developed in the 1920s. Broadcast televi-sion uses high-powered radio-frequency transmitters tobroadcast the television signal to individual television re-ceivers. The broadcast television system is typically dis-seminated via radio transmissions on designated channelsin the 54–890 MHz frequency band. * [4] Signals are of-ten transmitted with stereo or surround sound in many countries. Until the 2000s, broadcast television programswere generally transmitted as an analog television signal,butoverthecourseofthefollowingdecade, severalcoun-tries went almost exclusively digital. In addition to over-the-airtransmission,televisionsignalsarealsodistributedby cable and satellite systems. Astandardtelevisionsetiscomposedofmultipleinternalelectroniccircuits,includingcircuitsforreceivingandde- coding broadcast signals. A visual display device whichlacksatunerisproperlycalledavideomonitorratherthan a television. A television system may use different tech-nical standards such as digital television (DTV) and high- definition television (HDTV). Television systems are alsoused for surveillance, industrial process control, and the1  2  1 HISTORY  guidance of weapons in places where direct observationis difficult or dangerous. A 2004 study by the Children ʼ sHospital and Regional Medical Center in Seattle, Wash-ington, found a link between infant exposure to televisionand ADHD. * [5] 1 History Main article: History of televisionIn its early stages of development, television employed acombination of optical, mechanical, and electronic tech- nologies to capture, transmit, and display moving images.Modern broadcast TV systems do not involve mechanicalimage scanning methods, although the knowledge gainedfrom working on electromechanical systems was crucialin the development of fully electronic television. Braun HF 1 television receiver, Germany, 1958  The first images transmitted electrically were sentby early mechanical fax machines, including thepantelegraph, developed in the late 19th century. Theconcept of electrically powered transmission of TVimages in motion was first sketched in 1878 as thetelephonoscope shortly after the invention of the tele-phone. At the time, it was imagined by early science fic-tion authors that someday light could be transmitted overcopper wires as sounds were at that time.The concept of using scanning to transmit images wasput to actual practical use in 1881 in the pantelegraphthrough the use of a pendulum-based scanning mecha-nism. From this period forward, scanning in one form oranother has been used in nearly every image transmissiontechnology to date, including TV. This is the concept ofextquotedblrasterization extquotedbl, the process of con-verting a visual image into a stream of electrical pulses.In 1884, Paul Gottlieb Nipkow, a 23-year-old univer-sity student in Germany, * [6] patented the first electrome-chanical TV system which employed a scanning disk, aspinning disk with a series of holes spiraling toward thecenter, for rasterization. The holes were spaced at equalangular intervals such that, in a single rotation, the diskwould allow light to pass through each hole and onto alight-sensitive selenium sensor which produced the elec-trical pulses. As an image was focused on the rotatingdisk, each hole captured a horizontal “ slice ” of the en-tire image. * [7]Nipkow ʼ s design was not practical until advances inamplifier tube technology became available. Later de-signs used a rotating mirror-drum scanner to capture theimage and a cathode ray tube (CRT) as a display device,but moving images were still not possible due to the poorsensitivity of the selenium sensors. In 1907, Russian sci-entistBorisRosingbecamethefirstinventortouseaCRTin the receiver of an experimental television system. Heused mirror-drum scanning to transmit simple geometricshapes to the CRT. * [8]Using a Nipkow disk, Scottish inventor John Logie Bairdsuccessfullydemonstratedthetransmissionofmovingsil-houette images in London in 1925 * [9] and of moving,monochromatic images in 1926. Baird ʼ s scanning diskproduced an image of 30 lines resolution, just enough todiscernahumanface,fromadoublespiraloflenses. * [10]This demonstration by Baird is generally agreed to bethe world ʼ s first true demonstration of TV, albeit a me-chanical form no longer in use. Remarkably, in 1927,Baird also invented the world ʼ s first video recording sys-tem, extquotedblPhonovision; extquotedbl because thesignalproducedbyhis30-lineequipmentwasintheaudiofrequency range, he was able to capture it on 10-inchgramophone records using conventional audio recording  3 Vladimir Zworykin demonstrates electronic television (1929). technology. A handful of Baird ʼ s Phonovision record-ings survive and were finally decoded and rendered intoviewable moving images in the 1990s using modern dig-ital signal-processing technology. * [11]In 1926, Hungarian engineer Kálmán Tihanyi designeda television system utilizing fully electronic scanningand display elements and employing the principle of “ charge storage ” within the scanning (or “ camera ” )tube. * [12] * [13] * [14] * [15]On 25 December 1926, Kenjiro Takayanagi demon-strated a TV system with a 40-line resolution that em-ployed a CRT display at Hamamatsu Industrial HighSchool in Japan. * [16] This was the first working exam-ple of a fully electronic television receiver. Takayanagidid not apply for a patent. * [17]By 1927, Russian inventor Léon Theremin developed amirror-drum-based TV system which used interlacing toachieve an image resolution of 100 lines. * [18]In 1927, Philo Farnsworth made the world ʼ s first work-ing television system with electronic scanning of both thepickup and display devices, * [19] which he first demon-strated to the press on 1 September 1928. * [19] * [20] Philo Farnsworth WRGB claims to be the world ʼ s oldest television sta-tion, tracing its roots to an experimental station foundedon13January1928, broadcastingfromtheGeneralElec-tric factory in Schenectady, NY, under the call letters W2XB. * [21] It was popularly known as “ WGY Televi-sion ” after its sister radio station. Later in 1928, GeneralElectric started a second facility, this one in New YorkCity, which had the call letters W2XBS and which todayis known as WNBC.The two stations were experimental in nature and had noregular programming, as receivers were operated by en-gineers within the company. The image of a Felix theCat doll rotating on a turntable was broadcast for 2 hoursevery day for several years as new technology was beingtested by the engineers. Milton Berle claimed that he wasinvolved in a very early television experiment in Chicago,Illinois, in 1929. * [22]At the Berlin Radio Show in August 1931, Manfred vonArdenne gave the world ʼ s first public demonstration of aTV system using a cathode ray tube for both transmissionand reception. The world ʼ s first electronically scannedTV service began in Berlin in 1935. In August 1936, the  4  1 HISTORY  Olympic Games in Berlin were carried by cable to TVstationsinBerlinandLeipzigwherethepubliccouldviewthe games live. * [23]In 1935, the German firm of Fernseh A.G. and theUnited States firm Farnsworth Television owned by PhiloFarnsworth signed an agreement to exchange their tele-vision patents and technology to speed development ofTV transmitters and stations in their respective coun-tries. * [24]On 2 November 1936, the BBC began transmitting theworld ʼ s first public regular high-definition service fromthe Victorian Alexandra Palace in north London. * [25] Ittherefore claims to be the birthplace of TV broadcastingas we know it today.In 1936, Kálmán Tihanyi described the principleof plasma display, the first flat panel display sys- tem. * [26] * [27]Mexican inventor Guillermo González Camarena alsoplayed an important role in early TV. His experimentswith TV (known as telectroescopía at first) began in 1931and led to a patent for the “ trichromatic field sequentialsystem ” color television in 1940. * [28]Although TV became more familiar to the general pub-lic in the US at the 1939 World ʼ s Fair, the outbreak ofWorld War II prevented it from being manufactured on alarge scale until after the war ʼ s end. True regular com-mercial television network programming did not begin inthe US until 1948. During that year, conductor ArturoToscanini made his first of ten TV appearances conduct-ing the NBC Symphony Orchestra, * [29] and  Texaco Star Theater  , starring comedian Milton Berle, became tele-vision ʼ s first gigantic hit show. * [30] Since the 1950s,television has been the main medium for molding publicopinion. * [1]Amateur television ( ham TV   or  ATV  ) was developed fornon-commercial experimentation, pleasure, and publicservice events by amateur radio operators. Ham TV sta-tions were on the air in many cities before commercialTV stations came on the air. * [31]In 2012, it was reported that TV revenue was growingfaster than film for major media companies. * [32] 1.1 Color TV Color TV is part of the history of television, thetechnology of television, and practices associated with Title card for  NBC  , promoting their broadcast  “   in RCA color  ” . television ʼ s transmission of moving images in colorvideo.In its most basic form, a color broadcast can be createdby broadcasting three monochrome images, one each inthe three colors of red, green and blue (RGB). When dis-played together or in either rapid succession or opticallyoverlapped, these images will blend together to producea full color image as seen by the viewer.Oneofthegreattechnicalchallengesofintroducingcolorbroadcasttelevisionwasthedesiretoconservebandwidthpotentially three times that of the existing black-and-white standards and not use an excessive amount of radiospectrum. In the US, after considerable research, theNational Television Systems Committee (NTSC) * [33]approved an all-electronic system developed by RCAwhich encoded color difference information (renderingthe hue and saturation of colors) separately from thebrightness information (rendering the lightness and dark-ness of colors) and greatly reduced the resolution of thecolor difference information in order to conserve band-width. The brightness image remained compatible withexisting black-and-white television sets at full resolution,while color TVs could decode both the extra informa-tion (low resolution color difference) and the brightnessimage and then combine the brightness image with thecolordifferenceimagetoproduceafull-colorimage. Thehigher resolution black-and-white and lower resolutioncolor-difference images combine in the eye to producea seemingly high-resolution full-color image. The NTSCstandard represented a major technical achievement.Although all-electronic color was introduced in the US in


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Jul 23, 2017
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