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===Televisio===
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The development of television technology can be partitioned along two lines: those developments that depended upon both mechanical and electronic principles, and those which are purely electronic. From the latter descended all modern televisions, but these would not have been possible without discoveries and insights from the mechanical systems.
The word ''television'' is a hybrid word, created from both Greek and Latin. ''Tele-'' is Greek for "far", while ''-vision'' is from the Latin ''visio'', meaning "vision" or "sight". It is often abbreviated as '''TV''' in the U.S. and '''telly''' in the UK and Australia.
===Electromechanical television===
The German student '''Paul Gottlieb Nipkow''' proposed and patented the first electromechanical television system in 1885. Nipkow's spinning disk design is credited with being the first television image rasterizer. However, it wasn't until 1907 that developments in amplification tube technology made the design practical. Meanwhile, '''Constantin Perskyi''' had coined the word ''television'' in a paper read to the International Electricity Congress at the International World Fair in Paris on August 25, 1900. Perskeyi's paper reviewed the existing electromechanical technologies, mentioning the work of Nipkow and others.
[[Kuva:523ss82inch500x317.jpg|thumb|right|200px|Moderni, 82" (208 cm) LCD-televisio.]]
From 1907 to 1910, '''Boris Rosing''' and his student '''Vladimir Kosma Zworykin''' demonstrated a television system that used a mechanical mirror-drum scanner in the transmitter and the electronic Braun tube (cathode ray tube) in the receiver. Rosing disappeared during the Bolshevik revolution of 1917, but Zworykin later went to work for RCA to build a purely electronic television, the design of which was eventually found to violate patents by Philo Taylor Farnsworth.
A mechanically scanned analogue television system was first demonstrated by '''John Logie Baird''' in London in February 1924 with a silhouette image of Felix the Cat, and a moving picture image on October 30, 1925. But if television is defined as the transmission of live, moving, half-tone (grayscale) images, and not silhouette, still, or moving picture images, the world's first demonstration of a working television system was given by Baird to members of the Royal Institution and a newspaper reporter on January 26, 1926 at his laboratory in London. Unlike later electronic systems with several hundred lines of resolution, Baird's vertically scanned image had only 30 lines, and was about four inches high by two inches wide, just enough to reproduce a recognizable human face. Baird's electromechanical system reached a peak of 240 lines of resolution on BBC television broadcasts in 1936, before being discontinued in favor of a 405 line all-electronic system.
In 1928 Baird's company (Baird Television Development Company / Cinema Television) broadcast the first transatlantic television signal, between London and New York, and the first shore to ship transmission. He also demonstrated an electromechanical colour, infrared (dubbed "Noctovision"), and stereoscopic television, using additional lenses, disks and filters. In parallel he developed a video disk recording system dubbed "Phonovision"; a number of the Phonovision[http://www.tvdawn.com/tvimage.htm] recordings, dating back to 1927, still exist. In 1929 he became involved in the first experimental electromechanical television service in Germany. In 1931 he made the first live transmission, of the Epsom Derby. In 1932 he demonstrated ultra-short wave television.
In the U. S. '''Ernst Alexanderson''' demonstrated a mechanically scanned television broadcasting system in 1927.
===Electronic television===
[[Kuva:Family Watching TV in the 1950s.jpg|thumb|right|200px|An American family watching television in the 1950s.]]
Although the discoveries of Nipkow, Rosing, Baird and others were extraordinary, little of their technology is used in modern television. By 1934, all electromechanical television systems were outmoded, although electromechanical broadcasts continued on some stations until 1939.
'''A.A. Campbell-Swinton''' wrote a letter to ''Nature'' (journal) on the 18 June 1908 describing his concept of electronic television using the cathode ray tube, which had been invented in 1897 by the German physicist and Nobel prize winner Karl Ferdinand Braun. He proposed using an electron beam in both the camera and the receiver, which could be steered electronically to produce moving pictures. He lectured on the subject in 1911 and displayed circuit diagrams, but no one, including Swinton, knew how to realize the design. Although his system was never built, the cathode ray tube did come to be used to display images in almost all television sets and computer monitors until the invention of the LCD panel.
A fully electronic system was first achieved by '''Philo Taylor Farnsworth''' on September 7, 1927, although the low-resolution image was limited to a plate of glass painted black, with a straight line etched across it, rotated in front of a bright carbon arc lamp. Seven years later, on August 25, 1934, at the Franklin Institute in Philadelphia, Pennsylvania, Farnsworth gave the world's first public demonstration of a working, all-electronic television system. Over a three week period, vaudeville acts, athletes, politicians, and hundreds of ordinary citizens were captured on Farnsworth's cameras in the open air and simultaneously shown on his receiving sets.
Farnsworth, a Mormon farm boy from Rigby, Idaho, first envisioned his system at age 14. He discussed the idea with his high school chemistry teacher, who could think of no reason why it would not work (Farnsworth would later credit this teacher, '''Justin Tolman''', as providing key insights into his invention). He continued to pursue the idea at Brigham Young Academy (now Brigham Young University). At age 21, he demonstrated a working system at his own laboratory in San Francisco. His breakthrough freed television from reliance on spinning discs and other mechanical parts. All modern picture tube televisions descend directly from his design.
'''Vladimir Kosma Zworykin''' is also sometimes cited as the father of electronic television because of his invention of the iconoscope in 1923 and his invention of the kinescope in 1929. His design was one of the first to demonstrate a television system with all the features of modern picture tubes. His previous work with Rosing on electromechanical television gave him key insights into how to produce such a system, but his (and RCA's) claim to being its original inventor was largely invalidated by three facts: a) Zworykin's 1923 patent presented an incomplete design, incapable of working in its given form (it was not until 1933 that Zworykin achieved a working implementation), b) the 1923 patent application was not granted until 1938, and not until it had been seriously revised, and c) courts eventually found that RCA was in violation of the television design patented by [[Philo Taylor Farnsworth]], whose lab Zworykin had visited while working on his designs for RCA.
The controversy over whether it was first Farnsworth or Zworykin who invented modern television is still hotly debated today. Some of this debate stems from the fact that while Farnsworth appears to have gotten there first, it was RCA that first marketed working television sets, and it was RCA employees who first wrote the history of television. Even though Farnsworth eventually won the legal battle over this issue, he was never able to fully capitalize financially on his invention.
=== Color television ===
Most television researchers appreciated the value of color image transmission, with an early patent application in Russia in 1889 for a mechanically-scanned color system showing how early the importance of color was realized. John Logie Baird demonstrated color transmission in 1928.
'''Color television''' in the United States had a protracted history due to conflicting technical systems vying for approval by the Federal Communications Commission for commercial use. Color television was demonstrated by Bell Laboratories in 1928 during the mechanically scanned era. In the electronically scanned era, the first color television demonstration was on February 5, 1940, when RCA privately showed to members of the FCC at the RCA plant in Camden, New Jersey, a television receiver producing images in color by electronic and optical means without moving mechanism. CBS began live, non-broadcast color experiments in studio as early as August 28, 1940. The CBS "field sequential" color system was partly mechanical, with a disc made of red, blue, and green filters spinning inside the television camera at 1,200 rpm, and a similar disc spinning in synchornization in front of the cathode ray tube inside the receiver set. The RCA "dot sequential" color system had no moving parts, using a series of dichroic mirrors to separate and direct red, green, and blue light from the subject through three separate lenses into three scanning tubes, and electronic switching that allowed the tubes to send their signals in rotation, dot by dot. These signals were sorted by a second switching device in the receiver set and sent to red, green, and blue picture tubes, and combined by a second set of dichroic mirrors into a full color image.
The first field test (i.e., broadcast) of color television was by NBC (owned by RCA) on February 20, 1941. CBS began daily color field tests on June 1, 1941. These color systems were not compatible with existing black and white television sets, and as no color television sets were available to the public at this time, viewership of the color field tests was limited to RCA and CBS engineers and the invited press. The [[War Production Board]] halted the manufacture of television and radio equipment for civilian use from April 1, 1942 to October 1, 1945, limiting any opportunity to introduce color television to the general public.
The post-war development of color television was dominated by three systems competing for approval by the FCC as the U.S. color broadcasting standard: CBS's field sequential system, which was incompatible with existing black and white sets without an adaptor; RCA's dot sequential system, which in 1949 became compatible with existing black and white sets; and CTI's (Color Television, Inc.) system (also incompatible with existing black and white sets), which used three camera lenses, behind which were color filters that produced red, green, and blue images side by side on a single scanning tube, and a receiver set that used lenses in front of the picture tube (which had sectors treated with different phosphorescent compounds to glow in red, green, or blue) to project these three side by side images into one combined picture on the viewing screen.
After a series of hearings beginning in September 1949, the FCC found the RCA and CTI systems fraught with technical problems, inaccurate color reproduction, and expensive equipment, and so formally approved the CBS system as the U.S. color broadcasting standard on October 11, 1950. An unsuccessful lawsuit by RCA delayed the world's first network color broadcast until June 25, 1951, when a musical variety special titled simply ''Premiere'' was shown over a network of five east coast CBS affiliates. Viewership was again extremely limited: the program could not be seen on black and white sets, and ''Variety'' (magazine) estimated that only thirty prototype color receivers were available in the New York area. Regular color broadcasts began that same week with the daytime series ''The World Is Yours'' and ''Modern Homemakers''.
While the CBS color broadcasting schedule gradually expanded to twelve hours per week (but never into prime time), and the color network expanded as far west as its Chicago, Illinois affiliate, its commercial success was doomed by the lack of color receivers on which to watch the programs, the refusal of television manufacturers to create adaptor mechanisms for their existing black and white sets, and the unwillingness of advertisers to sponsor broadcasts seen by almost no one. In desperation, CBS bought a television manufacturer, and on September 20, 1951, production began on the first and only CBS color television model. But it was too little, too late. Only 200 sets had been shipped, and only 100 sold, when CBS pulled the plug on its color television system on October 20, 1951, and bought back all the CBS color sets it could to prevent law suits by disappointed customers.
The first publicly announced experimental TV broadcast of a program using RCA's "compatible color" system was an episode of ''Kukla, Fran and Ollie'' on August 30, 1953. NBC made the first coast-to-coast color broadcast when it covered the Rose Bowl Parade on New Years Day, 1954. Television's first prime time network color series was ''The Marriage'', a situation comedy broadcast live by NBC in the summer of 1954. NBC's anthology series ''Ford Theatre'' became the first color filmed series that October.
NBC was naturally at the forefront of color programming because its parent company RCA manufactured the most successful line of color sets in the 1950s. CBS and American Broadcasting Company (ABC), which were not affiliated with set manufacturers, and were not eager to promote their competitor's product, dragged their feet into color, with ABC delaying its first color series (''The Flintstones'' and ''The Jetsons'') until 1962. The Du Mont network, although it did have a television-manufacturing parent company, was in financial decline by 1954 and was dissolved two years later. Thus the relatively small amount of network color programming, combined with the high cost of color television sets, meant that as late as 1964 only 3.1 percent of television households in the U.S. had a color set. NBC provided the catalyst for rapid color expansion by announcing that its prime time schedule for fall 1965 would be entirely in color. All three broadcast networks were airing full color prime time schedules by the 1966–67 broadcast season. But the number of color television sets sold in the U.S. did not exceed black and white sales until 1972, which was also the first year that more than fifty percent of television households in the U.S. had a color set.
In '''Mexico''', Guillermo González Camarena (1917–1965), invented the an early color televsion transmission system. He received patents for color television systems in 1940 (U.S. Patent 1942 (2296019), 1960 and 1962. The 1942 patent was for a mechanically scanned color filter adapter for an existing monochrome electronic transmission system.
In August 31, 1946 he sent his first color transmission from his lab in the offices of The Mexican League of Radio Experiments in Lucerna St. #1, in Mexico City. The video signal was transmitted at a frequency of 115 MHz. and the audio in the 40 metre band.
'''European color television''' was developed somewhat later and was hindered by a continuing division on technical standards. Having decided to adopt a higher-definition 625-line system for monochrome transmissions, with a lower frame rate but with a higher overall bandwidth, Europeans could not directly adopt the U.S. color standard, which was widely perceived as ''wanting'' anyway, because of its tint control problems. There was no urgency either, since there were still few sets overall and no commercial motivations, European television broadcasters being state-owned at the time.
As a consequence, although work on various color encoding systems started already in the 1950s, with the first SECAM patent being registered in 1956, many years had passed till the first broadcasts actually started in 1967. Unsatisfied with the performance of NTSC and of initial SECAM implementations, the Germans decided to create PAL (phase alternating line) at the beginning of the 1960s, staying closer to NTSC but borrowing some ideas from SECAM. The French continued with SECAM, notably involving Russians in the development.
The first color broadcast in Europe was by BBC Two in the UK in the summer of 1967, using PAL. Germans did their first broadcast in September (PAL), while the French in October (SECAM).
PAL was eventually adopted by West Germany, the United Kingdom, Australia, New Zealand, much of Africa, Asia and South America, and most Western European countries except France.
In addition to France and Luxembourg, SECAM was adopted by Soviet Union, much of Eastern Europe, much of Africa and of the Middle East. Both systems broadcast on ultra high frequency (UHF) frequencies, the very high frequency (VHF) being used for legacy black and white, 405 lines in UK or 819 lines in France, till the beginning of the eighties.
===Broadcast television===
[[Image:Television Antenna.jpg|thumb|200px|Television antenna on a rooftop]]
The first long distance [[public television]] broadcast was from [[Washington, DC]] to [[New York City]] and occurred on [[April 7]], [[1927]]. The image shown was of then Commerce Secretary [[Herbert Hoover]]. The first analogue service was WGY, [[Schenectady]], [[New York]] inaugurated on [[May 11]] [[1928]]. The first British Television Play, "The Man with the Flower in his Mouth", was transmitted in July [[1930]]. [[CBS]]'s [[New York City]] station began broadcasting the first regular seven days a week television schedule in the U. S. on [[July 21]], [[1931]]. The first broadcast included Mayor [[James J. Walker]], [[Kate Smith]], and [[George Gershwin]]. The first all-electronic television service was started in Los Angeles, CA by Don Lee Broadcasting. Their start date was [[December 23]], [[1931]] on W6XAO—later KTSL. Originally, mechanical equipment was used, but in June of 1936 a 300-line all-electronic service was started.
In [[Germany]], regular service started on [[March 22]], [[1935]], and one year later, the [[Berlin]] [[Summer Olympic Games]] were televised to places in Berlin and [[Hamburg]].
In [[1932]] the [[BBC]] launched a service using Baird's 30-line system and these transmissions continued until [[11 September]] [[1935]]. On [[November 2]], [[1936]] the [[BBC]] began broadcasting a dual-system service, alternating on a weekly basis between Marconi-EMI's high-resolution (405 lines per picture) service and Baird's improved 240-line standard from [[Alexandra Palace]] in [[London]]. Six months later, the corporation decided that Marconi-EMI's electronic picture gave the superior picture, and adopted that as their standard. This service is described as "the world's first regular high-definition public television service", since a regular television service had been broadcast earlier on a 180-line standard in Germany. The outbreak of the [[Second World War]] caused the service to be suspended. TV transmissions only resumed from Alexandra Palace in [[1946]].
[[Image:Braun HF 1.jpg|thumb|210px|Braun HF 1, [[Germany]], [[1958]] ]]
The first regular television transmissions in [[Canada]] began in [[1952]] when the [[Canadian Broadcasting Corporation|CBC]] put two stations on the air, one in [[Montreal, Quebec]] on [[September 6]], and another in [[Toronto, Ontario]] [[September 8|two days later]].
[[Image:Early portable tv.jpg|thumb|210px|left|Early portable television set]]
The first live transcontinental television broadcast took place in [[San Francisco, California]] from the [[Japanese Peace Treaty Conference]] on [[September 4]], [[1951]]. In [[1958]], the CBC completed the longest television network in the world, from [[Sydney, Nova Scotia]] to [[Victoria, British Columbia]]. Reportedly, the first continuous live broadcast of a breaking news story in the world was conducted by the CBC during the [[Springhill Mining Disaster]] which began on [[October 23]] of that year.
Programming is broadcast on [[television station]]s (sometimes called channels). At first, terrestrial broadcasting was the only way television could be distributed. Because bandwidth was limited, government regulation was normal. In the U.S., the [[Federal Communications Commission]] allowed stations to broadcast advertisements, but insisted on public service programming commitments as a requirement for a license. By contrast, the [[United Kingdom]] chose a different route, imposing a [[television licence]] fee on owners of television reception equipment, to fund the [[BBC]], which had public service as part of its [[Royal Charter]]. Development of cable and satellite means of distribution in the [[1970s]] pushed businessmen to target channels towards a certain audience, and enabled the rise of subscription-based television channels, such as [[Home Box Office|HBO]] and [[British Sky Broadcasting|Sky]]. Practically every country in the world now has developed at least one television channel. Television has grown up all over the world, enabling every country to share aspects of their culture and society with others.
By the late [[1980s]], 98% of all homes in the U.S. had at least one TV set. On average, Americans watch four hours of television per day. An estimated two-thirds of Americans got most of their news about the world from TV, and nearly half got all of their news from TV. These figures are now estimated to be significantly higher.-->
===Tietokoneet===
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