Selasa, 24 Mei 2011

HISTORY TELEVISION.

The history of television records the work of numerous engineers and inventors in several countries over many decades. The fundamental principles of television were initially explored using electromechanical methods to scan, transmit and reproduce an image. As electronic camera and display tubes were perfected, electromechanical television gave way to all-electronic systems in nearly all applications.

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[edit] Electromechanical television

The Nipkow disk. This schematic shows the circular paths traced by the holes, that may also be square for greater precision. The area of the disk outlined in black shows the region scanned.
The beginnings of mechanical television can be traced back to the discovery of the photoconductivity of the element selenium by Willoughby Smith in 1873, the invention of a scanning disk by Paul Gottlieb Nipkow in 1884 and John Logie Baird's demonstration of televised moving images in 1926.
As a 23-year-old German university student, Paul Nipkow proposed and patented the first electromechanical television system in 1884.[1] Although he never built a working model of the system, variations of Nipkow's spinning-disk "image rasterizer" for television became exceedingly common, and remained in use until 1939.[2] 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. Perskyi's paper reviewed the existing electromechanical technologies, mentioning the work of Nipkow and others.[3]
However, it was not until 1907 that developments in amplification tube technology, by Lee DeForest and Arthur Korn among others, made the design practical.[4] The first demonstration of the instantaneous transmission of still silhouette images was by Georges Rignoux and A. Fournier in Paris in 1909, using a rotating mirror-drum as the scanner and a matrix of 64 selenium cells as the receiver.[5]
In 1911, Boris Rosing and his student Vladimir Zworykin created a television system that used a mechanical mirror-drum scanner to transmit, in Zworykin's words, "very crude images" over wires to the "Braun tube" (cathode ray tube or "CRT") in the receiver. Moving images were not possible because, in the scanner, "the sensitivity was not enough and the selenium cell was very laggy".[6]
On March 25, 1925, Scottish inventor John Logie Baird gave the first public demonstration of televised silhouette images in motion, at Selfridge's Department Store in London.[7] AT&T's Bell Telephone Laboratories transmitted halftone still images of transparencies in May 1925. On June 13 of that year, Charles Francis Jenkins transmitted the silhouette image of a toy windmill in motion, over a distance of five miles from a naval radio station in Maryland to his laboratory in Washington, using a lensed disk scanner with a 48-line resolution.[8][9]
However, if television is defined as the live transmission of moving images with continuous tonal variation, Baird first achieved this privately on October 2, 1925. But strictly speaking, Baird had not yet achieved moving images on October 2. His scanner worked at only five images per second, below the threshold required to give the illusion of motion, usually defined as at least 12 images per second. By January, he had improved the scan rate to 12.5 images per second. Then he gave the world's first demonstration of a working television system 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, using a scanning disk embedded with a double spiral of lenses, had only 30 lines, just enough to reproduce a recognizable human face.[citation needed]
In 1927, Baird transmitted a signal over 438 miles (705 km) of telephone line between London and Glasgow. 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 color, infrared (dubbed "Noctovision"), and stereoscopic television, using additional lenses, disks and filters. In parallel, Baird developed a video disk recording system dubbed "Phonovision"; a number of the Phonovision recordings, dating back to 1927, still exist.[10] In 1929, he became involved in the first experimental electromechanical television service in Germany. In November of the same year, Baird and Bernard Natan of Pathé established France's first television company, Télévision-Baird-Natan. In 1931, he made the first outdoor remote broadcast, of the Epsom Derby.[11] In 1932, he demonstrated ultra-short wave television. Baird's electromechanical system reached a peak of 240 lines of resolution on BBC television broadcasts in 1936 though the mechanical system did not scan the televised scene directly. Instead a 35 mm film was shot, rapidly developed and then scanned while the film was still wet. This intermediate film system was discontinued within three months in favor of a 405-line all-electronic system developed by Marconi-EMI.[12]
Herbert E. Ives and Frank Gray of Bell Telephone Laboratories gave a dramatic demonstration of mechanical television on April 7, 1927. The reflected-light television system included both small and large viewing screens. The small receiver had a two-inch-wide by 2.5-inch-high screen. The large receiver had a screen 24 inches wide by 30 inches high. Both sets were capable of reproducing reasonably accurate, monochromatic moving images. Along with the pictures, the sets also received synchronized sound. The system transmitted images over two paths: first, a wire link from Washington to New York City, then a radio link from Whippany, New Jersey. Comparing the two transmission methods, viewers noted no difference in quality. Subjects of the telecast included Secretary of Commerce Herbert Hoover. A flying-spot scanner beam illuminated these subjects. The scanner that produced the beam had a 50-aperture disk. The disc revolved at a rate of 18 frames per second, capturing one frame about every 56 milliseconds. (Today's systems typically transmit 30 or 60 frames per second, or one frame every 33.3 or 16.7 milliseconds respectively.) Television historian Albert Abramson underscored the significance of the Bell Labs demonstration: "It was in fact the best demonstration of a mechanical television system ever made to this time. It would be several years before any other system could even begin to compare with it in picture quality."[13]
Meanwhile in the Soviet Union, Léon Theremin had been developing a mirror drum-based television, starting with 16 lines resolution in 1925, then 32 lines and eventually 64 using interlacing in 1926, and as part of his thesis on May 7, 1926 he electrically transmitted and then projected near-simultaneous moving images on a five foot square screen.[9] By 1927 he achieved an image of 100 lines, a resolution that was not surpassed until 1931 by RCA, with 120 lines.[citation needed]
On December 25, 1926, Kenjiro Takayanagi demonstrated a television system with a 40-line resolution that employed a Nipkow disk scanner and CRT display at Hamamatsu Industrial High School in Japan. This protype is still on display at the Takayanagi Memorial Museum in Shizuoka University, Hamamatsu Campus. His research in creating a production model were halted by the US after Japan lost World War II.[14]
Mechanical scanning systems, though obsolete for the more familiar television systems, nevertheless survive in long wave infra red cameras because there is no suitable all-electronic pickup device.[citation needed]

[edit] Electronic television

In 1908, Alan Archibald Campbell-Swinton, fellow of the Royal Society (UK), published a letter in the scientific journal Nature in which he described how "distant electric vision" could be achieved by using a cathode ray tube (or "Braun" tube, after its inventor, Karl Braun) as both a transmitting and receiving device,[15][16] apparently the first iteration of the electronic television method that would dominate the field until recently. He expanded on his vision in a speech given in London in 1911 and reported in The Times[17] and the Journal of the Röntgen Society.[18][19] In a letter to Nature published in October 1926, Campbell-Swinton also announced the results of some "not very successful experiments" he had conducted with G. M. Minchin and J. C. M. Stanton. They had attempted to generate an electrical signal by projecting an image onto a selenium-coated metal plate that was simultaneously scanned by a cathode ray beam.[20][21] These experiments were conducted before March 1914, when Minchin died,[22] but they were later repeated by two different teams in 1937, by H. Miller and J. W. Strange from EMI,[23] and by H. Iams and A. Rose from RCA.[24] Both teams succeeded in transmitting "very faint" images with the original Campbell-Swinton's selenium-coated plate. Although others had experimented with using a cathode ray tube as a receiver, the concept of using one as a transmitter was novel.[25] By the late 1920s, when electromechanical television was still being introduced, several inventors were already working separately on versions of all-electronic transmitting tubes, including Philo Farnsworth and Vladimir Zworykin in the United States, and Kálmán Tihanyi in Hungary.
On September 7, 1927, Farnsworth's Image Dissector camera tube transmitted its first image, a simple straight line, at his laboratory at 202 Green Street in San Francisco.[26][27] By September 3, 1928, Farnsworth had developed the system sufficiently to hold a demonstration for the press.[27] In 1929, the system was further improved by elimination of a motor generator, so that his television system now had no mechanical parts.[28] That year, Farnsworth transmitted the first live human images with his system, including a three and a half-inch image of his wife Elma ("Pem") with her eyes closed (possibly due to the bright lighting required).[29]
Meanwhile, Vladimir Zworykin was also experimenting with the cathode ray tube to create and show images. While working for Westinghouse Electric Corporation in 1923, he began to develop an electronic camera tube. But in a 1925 demonstration, the image was dim, had low contrast and poor definition, and was stationary.[30] Zworykin's imaging tube never got beyond the laboratory stage. But RCA, which had acquired the Westinghouse patent, asserted that the patent for Farnsworth's 1927 image dissector was written so broadly that it would exclude any other electronic imaging device. Thus RCA, on the basis of Zworykin's 1923 patent application, filed a patent interference suit against Farnsworth. The U.S. Patent Office examiner disagreed in a 1935 decision, finding priority of invention for Farnsworth against Zworykin. Farnsworth claimed that Zworykin's 1923 system would be unable to produce an electrical image of the type to challenge his patent. Zworykin received a patent in 1928 for a color transmission version of his 1923 patent application,[31] he also divided his original application in 1931.[32] Zworykin was unable or unwilling to introduce evidence of a working model of his tube that was based on his 1923 patent application. In September 1939, after losing an appeal in the courts and determined to go forward with the commercial manufacturing of television equipment, RCA agreed to pay Farnsworth US$1 million (the equivalent of $13.8 million in 2006) over a ten-year period, in addition to license payments, to use Farnsworth's patents.[33][34]
Drawing from Kálmán Tihanyi's 1926 patent application "Radioskop"
The problem of low sensitivity to light resulting in low electrical output from transmitting or "camera" tubes would be solved by Tihanyi beginning in 1924.[35] His solution was a camera tube that accumulated and stored electrical charges ("photoelectrons") within the tube throughout each scanning cycle. The device was first described in a patent application he filed in Hungary in March 1926 for a television system he dubbed "Radioskop".[36] After further refinements included in a 1928 patent application,[35] Tihanyi was awarded patents for the camera tube in both France and Great Britain in 1928, and applied for patents in the United States in June of the following year. Although his breakthrough would be incorporated into the design of RCA's "iconoscope" in 1931, the U.S. patent for Tihanyi's transmitting tube would not be granted until May 1939. The patent for his receiving tube had been granted the previous October. Both patents had been purchased by RCA prior to their approval.[37][38] The idea of charge & storage (with various and very different technological solutions) is still remained[39] as a basic requirement for all type of modern image sensors until this day.
Development continued around the world. At the Berlin Radio Show in August 1931, Manfred von Ardenne gave a public demonstration of a television system using a CRT for both transmission and reception. However, Ardenne had not developed a camera tube, using the CRT instead as a flying-spot scanner to scan slides and film.[40] Philo Farnsworth gave the world's first public demonstration of an all-electronic television system, using a live camera, at the Franklin Institute of Philadelphia on August 25, 1934, and for ten days afterwards.[41][42]
In 1933 RCA introduced an improved camera tube that relied on Tihanyi's charge storage principle.[43] Dubbed the Iconoscope by Zworykin, the new tube had a light sensitivity of about 75,000 lux, and thus was claimed to be much more sensitive than Farnsworth's image dissector.[citation needed] However, Farnsworth had overcome his power problems with his Image Dissector through the invention of a completely unique "multipactor" device that he began work on in 1930, and demonstrated in 1931.[44][45] This small tube could amplify a signal reportedly to the 60th power or better[46] and showed great promise in all fields of electronics. A problem with the multipactor, unfortunately, was that it wore out at an unsatisfactory rate.[47]
In Britain the EMI engineering team led by Isaac Shoenberg applied in 1932 for a patent for a new device they dubbed "the Emitron",[48][49] which formed the heart of the cameras they designed for the BBC. On November 2, 1936, a 405-line broadcasting service employing the Emitron began at studios in Alexandra Palace, and transmitted from a specially-built mast atop one of the Victorian building's towers. It alternated for a short time with Baird's mechanical system in adjoining studios, but was more reliable and visibly superior. This was the world's first regular high-definition television service.[50]
The original American iconoscope was noisy, had a high ratio of interference to signal, and ultimately gave disappointing results, especially when compared to the high definition mechanical scanning systems then becoming available.[51][52] The EMI team under the supervision of Isaac Shoenberg analyzed how the iconoscope (or Emitron) produces an electronic signal and concluded that its real efficiency was only about 5% of the theoretical maximum.[53][54] They solved this problem by developing and patenting in 1934 two new camera tubes dubbed super-Emitron and CPS Emitron.[55][56][57] The super-Emitron was between ten and fifteen times more sensitive than the original Emitron and iconoscope tubes and, in some cases, this ratio was considerably greater.[53] It was used for an outside broadcasting by the BBC, for the first time, on Armistice Day 1937, when the general public could watch in a television set how the King lay a wreath at the Cenotaph.[58] This was the first time that anyone could broadcast a live street scene from cameras installed on the roof of neighbor buildings, because neither Farnsworth nor RCA could do the same before the 1939 New York World's Fair.
On the other hand, in 1934, Zworykin shared some patent rights with the German licensee company Telefunken.[59] The "image iconoscope" ("Superikonoskop" in Germany) was produced as a results of the collaboration. This tube is essentially identical to the super-Emitron.[citation needed] The production and commercialization of the super-Emitron and image iconoscope in Europe were not affected by the patent war between Zworykin and Farnsworth, because Dieckmann and Hell had priority in Germany for the invention of the image dissector, having submitted a patent application for their Lichtelektrische Bildzerlegerröhre für Fernseher (Photoelectric Image Dissector Tube for Television) in Germany in 1925,[60] two years before Farnsworth did the same in the United States.[61] The image iconoscope (Superikonoskop) became the industrial standard for public broadcasting in Europe from 1936 until 1960, when it was replaced by the vidicon and plumbicon tubes. Indeed it was the representative of the European tradition in electronic tubes competing against the American tradition represented by the image orthicon.[62][63] The German company Heimann produced the Superikonoskop for the 1936 Berlin Olympic Games,[64][65] later Heimann also produced and commercialized it from 1940 to 1955,[66] finally the Dutch company Philips produced and commercialized the image iconoscope and multicon from 1952 to 1958.[63][67]
American television broadcasting at the time consisted of a variety of markets in a wide range of sizes, each competing for programming and dominance with separate technology, until deals were made and standards agreed upon in 1941.[68] RCA, for example, used only Iconoscopes in the New York area, but Farnsworth Image Dissectors in Philadelphia and San Francisco.[69] In September 1939, RCA agreed to pay the Farnsworth Television and Radio Corporation royalties over the next ten years for access to Farnsworth's patents.[70] With this historic agreement in place, RCA integrated much of what was best about the Farnsworth Technology into their systems.[69]
In 1941, the United States implemented 525-line television.[71][72] The world's first 625-line television standard was designed in the Soviet Union in 1944, and became a national standard in 1946.[73] The first broadcast in 625-line standard occurred in 1948 in Moscow.[74] The concept of 625 lines per frame was subsequently implemented in the European CCIR standard.[75]

[edit] Color television

[edit] Broadcast television

[edit] Overview

Programming is broadcast by television stations, sometimes called "channels", as stations are licensed by their governments to broadcast only over assigned channels in the television band. At first, terrestrial broadcasting was the only way television could be widely distributed, and because bandwidth was limited, i.e., there were only a small number of channels available, government regulation was the norm.
In the U.S., the Federal Communications Commission (FCC) allowed stations to broadcast advertisements beginning 1941, but required 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 British Broadcasting Corporation (BBC), which had public service as part of its Royal Charter.
Practically every country in the world now has at least one broadcast television station. Television has grown up all over the world, enabling nearly every country to share aspects of its culture and society with others.

[edit] United States

Television antenna on a rooftop
The first regularly scheduled television service in the United States began on July 2, 1928. The Federal Radio Commission authorized C.F. Jenkins to broadcast from experimental station W3XK in Wheaton Maryland, a suburb of Washington, D.C. For at least the first eighteen months, 48-line silhouette images from motion picture film were broadcast, although beginning in the summer of 1929 he occasionally broadcast in halftones.[76][77]
Hugo Gernsback's New York City radio station began a regular, if limited, schedule of live television broadcasts on August 14, 1928, using 48-line images. Working with only one transmitter, the station alternated radio broadcasts with silent television images of the station's call sign, faces in motion, and wind-up toys in motion.[78][79] Speaking later that month, Gernsback downplayed the broadcasts, intended for amateur experimenters. "In six months we may have television for the public, but so far we have not got it."[80] Gernsback also published Television, the world's first magazine about the medium.
General Electric's experimental station in Schenectady, New York, on the air sporadically since January 13, 1928, was able to broadcast reflected-light, 48-line images via shortwave as far as Los Angeles, and by September was making four television broadcasts weekly. It is considered to be the direct predecessor of current television station WRGB. The Queen's Messenger, a one-act play broadcast on September 11, 1928, was the world's first live drama on television.[81]
Radio giant RCA began daily experimental television broadcasts in New York City in March 1929 over station W2XBS. The 60-line transmissions consisted of pictures, signs, and views of persons and objects.[82] Experimental broadcasts continued to 1931.[83]
General Broadcasting System's WGBS radio and W2XCR television aired their regular broadcasting debut in New York City on April 26, 1931, with a special demonstration set up in Aeolian Hall at Fifth Avenue and Fifty-fourth Street. Thousands waited to catch a glimpse of the Broadway stars who appeared on the six-inch (15 cm) square image, in an evening event to publicize a weekday programming schedule offering films and live entertainers during the four-hour daily broadcasts. Appearing were boxer Primo Carnera, actors Gertrude Lawrence, Louis Calhern, Frances Upton and Lionel Atwill, WHN announcer Nils Granlund, the Forman Sisters, and a host of others.[84]
CBS's New York City station W2XAB began broadcasting their first regular seven days a week television schedule on July 21, 1931, with a 60-line electromechanical system. The first broadcast included Mayor Jimmy Walker, the Boswell Sisters, Kate Smith, and George Gershwin. The service ended in February 1933.[85] Don Lee Broadcasting's station W6XAO in Los Angeles went on the air in December 1931. Using the UHF spectrum, it broadcast a regular schedule of filmed images every day except Sundays and holidays for several years.[86]
By 1935, low-definition electromechanical television broadcasting had ceased in the United States except for a handful of stations run by public universities that continued to 1939. The Federal Communications Commission (FCC) saw television in the continual flux of development with no consistent technical standards, hence all such stations in the U.S. were granted only experimental and not commercial licenses, hampering television's economic development. Just as importantly, Philo Farnsworth's August 1934 demonstration of an all-electronic system at the Franklin Institute in Philadelphia pointed out the direction of television's future.
On June 15, 1936, Don Lee Broadcasting began a one month-long demonstration of high definition (240+ line) television in Los Angeles on W6XAO (later KTSL) with a 300-line image from motion picture film. By October, W6XAO was making daily television broadcasts of films. RCA and its subsidiary NBC demonstrated in New York City a 343-line electronic television broadcast, with live and film segments, to its licensees on July 7, 1936, and made its first public demonstration to the press on November 6. Irregularly scheduled broadcasts continued through 1937 and 1938.[87] Regularly scheduled electronic broadcasts began in April 1938 in New York (to the second week of June, and resuming in August) and Los Angeles.[88][89][90][91] NBC officially began regularly scheduled television broadcasts in New York on April 30, 1939 with a broadcast of the opening of the 1939 New York World's Fair. By June 1939, regularly scheduled 441-line electronic television broadcasts were available in New York City and Los Angeles, and by November on General Electric's station in Schenectady. From May through December 1939, the New York City NBC station (W2XBS) of General Electric broadcast twenty to fifty-eight hours of programming per month, Wednesday through Sunday of each week. The programming was 33% news, 29% drama, and 17% educational programming, with an estimated 2,000 receiving sets by the end of the year, and an estimated audience of five to eight thousand. A remote truck could cover outdoor events from up to 10 miles (16 km) away from the transmitter, which was located atop the Empire State Building. Coaxial cable was used to cover events at Madison Square Garden. The coverage area for reliable reception was a radius of 40 to 50 miles (80 km) from the Empire State Building, an area populated by more than 10,000,000 people (Lohr, 1940).
The FCC adopted NTSC television engineering standards on May 2, 1941, calling for 525 lines of vertical resolution, 30 frames per second with interlaced scanning, 60 fields per second, and sound carried by frequency modulation. Sets sold since 1939 which were built for slightly lower resolution could still be adjusted to receive the new standard. (Dunlap, p31). The FCC saw television ready for commercial licensing, and the first such licenses were issued to NBC and CBS owned stations in New York on July 1, 1941, followed by Philco's station WPTZ in Philadelphia. After the U.S. entry into World War II, the FCC reduced the required minimum air time for commercial television stations from 15 hours per week to 4 hours. Most TV stations suspended broadcasting. On the few that remained, programs included entertainment such as boxing and plays, events at Madison Square Garden, and illustrated war news as well as training for air raid wardens and first aid providers. In 1942, there were 5,000 sets in operation, but production of new TVs, radios, and other broadcasting equipment for civilian purposes was suspended from April 1942 to August 1945 (Dunlap).
The Philco Predicta, 1958. In the collection of The Children's Museum of Indianapolis
By 1947, when there were 40 million radios in the U.S., there were about 44,000 television sets (with probably 30,000 in the New York area).[92] Regular network television broadcasts began on the DuMont Television Network in 1946, on NBC in 1947, and on CBS and ABC in 1948. By 1949, the networks stretched from New York to the Mississippi River, and by 1951 to the West Coast. Commercial color television broadcasts began on CBS in 1951 with a field-sequential color system that was suspended four months later for technical and economic reasons. The television industry's National Television System Committee developed a color television system that was compatible with existing black and white receivers, and commercial color broadcasts reappeared in 1953.

[edit] Canada

The Canadian Broadcasting Corporation (CBC) adopted the American NTSC 525-line B/W 60 field per second system as its broadcast standard. It began television broadcasting in Canada in September 1952. The first broadcast was on September 6, 1952 from its Montreal, Quebec station CBFT. The premiere broadcast was bilingual, spoken in English and French. Two days later, on September 8, 1952, the Toronto, Ontario station CBLT went on the air. This became the English-speaking flagship station for the country, while CBFT became the French language flagship after a second English language station was licensed to CBC in Montreal later in the decade. The CBC’s first privately owned affiliate television station, CKSO in Sudbury, Ontario, launched in October 1953 (at the time, all private stations were expected to affiliate with the CBC, a condition that was relaxed in 1960–61 when CTV, Canada's second national English language network, was formed).

[edit] France

The first experiments in television broadcasting began in France in the 1930s, but the French were slow to employ the new technology.
In November 1929, Bernard Natan established France's first television company, Télévision-Baird-Natan. On April 14, 1931, there took place the first transmission with a thirty-line standard by René Barthélemy. On December 6, 1931, Henri de France created the Compagnie Générale de Télévision (CGT). In December 1932, Bathélemy carried out an experimental program in black and white (definition: 60 lines) one hour per week, "Paris Télévision", which gradually became daily from early 1933.
The first official channel of French television appeared on February 13, 1935, the date of the official inauguration of television in France, which was broadcast in 60 lines from 8:15 to 8:30 pm. The program showed the actress Béatrice Bretty in the studio of Radio-PTT Vision at 103 rue de Grenelle in Paris. The broadcast had a range of 100 km (62 miles). On November 10, George Mandel, Minister of Posts, inaugurated the first broadcast in 180 lines from the transmitter of the Eiffel tower. On the 18th, Susy Wincker, the first announcer since the previous June, carried out a demonstration for the press from 5:30 to 7:30 pm. Broadcasts became regular from January 4, 1937 from 11:00 to 11:30 am and 8:00 to 8:30 pm during the week, and from 5:30 to 7:30 pm on Sundays. In July 1938, a decree defined for three years a standard of 455 lines VHF (whereas three standards were used for the experiments: 441 lines for Gramont, 450 lines for the Compagnie des Compteurs and 455 for Thomson). In 1939, there were about only 200 to 300 individual television sets, some of which were also available in a few public places.
With the entry of France into World War II the same year, broadcasts ceased and the transmitter of the Eiffel tower was sabotaged. On September 3, 1940, French television was seized by the German occupation forces. A technical agreement was signed by the Compagnie des Compteurs and Telefunken, and a financing agreement for the resuming of the service is signed by German Ministry of Post and Radiodiffusion Nationale (Vichy's radio). On May 7, 1943 at 3:00 evening broadcasts. The first broadcast of Fernsehsender Paris (Paris Télévision) was transmitted from rue Cognac-Jay. These regular broadcasts (5 1/4 hours a day) lasted until August 16, 1944. One thousand 441-line sets, most of which were installed in soldiers' hospitals, picked up the broadcasts.
In 1944, René Barthélemy developed an 819-line television standard. During the years of occupation, Barthélemy reached 1015 and even 1042 lines. On October 1, 1944, television service resumed after the liberation of Paris. The broadcasts were transmitted from the Cognacq-Jay studios. In October 1945, after repairs, the transmitter of the Eiffel Tower was back in service. On November 20, 1948, Mitterrand decreed a broadcast standard of 819 lines; broadcasting began at the end of 1949 in this definition. France was the only European country to adopt it (others will choose 625 lines).

[edit] Germany

Electromechanical broadcasts began in Germany in 1929, but were without sound until 1934. Network electronic service started on March 22, 1935, on 180 lines using telecine transmission of film, intermediate film system, or cameras using the Nipkow Disk. Transmissions using cameras based on the iconoscope began on January 15, 1936. The Berlin Summer Olympic Games were televised, using both all-electronic iconoscope-based cameras and intermediate film cameras, to Berlin and Hamburg in August 1936. Twenty-eight public television rooms were opened for anybody who did not own a television set. The Germans had a 441-line system on the air in February 1937, and during World War II brought it to France, where they broadcast from the Eiffel Tower.
The American Armed Forces Radio Network at the end of World War II, wishing to provide US TV programming to the occupation forces in Germany, used US TV receivers made to operate at 525 lines and 60 fields. US broadcast equipment was modified; they changed the vertical frequency to 50 Hz in accordance to the European mains frequency standard to avoid power line wiggles, changed the horizontal frequency from 15,750 Hz to 15,625 Hz a 0.5 microsecond change in the length of a line. With this signal, US TV receivers with only an adjustment to the vertical hold control had a 625 line (= 576 visual lines + 49 lines of non-visual synch and burst data), 50 field scan, which became the German standard. This AFN system, however, was not the later PAL standard native to Germany, as the displays themselves were not capable of displaying any more than the standard NTSC 486 visual lines, which effectively were even only 243 visible lines due to display-internal deinterlacing by means of alternatively discarding one field and applying line doubling on the result. Additionally, it still took until the 1960s for the PAL-specific YUV color system to be invented by Walter Bruch, with PAL operating at 576 visual lines.

[edit] United Kingdom

The first British television broadcast was made by Baird Television's electromechanical system over the BBC radio transmitter in September 1929. Baird provided a limited amount of programming five days a week by 1930. During this time, Southampton earned the distinction of broadcasting the first-ever live television interview, which featured Peggy O'Neil, an actress and singer from Buffalo, New York.[93] On August 22, 1932, BBC launched its own regular service using Baird's 30-line electromechanical system, continuing until September 11, 1935. On November 2, 1936 the BBC began broadcasting a dual-system service, alternating between Marconi-EMI's 405-line standard and Baird's improved 240-line standard, from Alexandra Palace in London, making the BBC Television Service (now BBC One) the world's first regular high-definition television service. The government, on advice from a special advisory committee, decided that Marconi-EMI's electronic system gave the superior picture, and the Baird system was dropped in February 1937. TV broadcasts in London were on the air an average of four hours daily from 1936 to 1939. There were 12,000 to 15,000 receivers. Some sets in restaurants or bars might have 100 viewers for sport events (Dunlap, p56).The outbreak of the Second World War caused the BBC service to be suspended on September 1, 1939, resuming from Alexandra Palace on June 7, 1946. At the end of 1947 there were 54,000 licensed television receivers, compared with 44,000 television sets in the United States at that time.[92]
The first transatlantic television signal was sent in 1928 from London to New York by the Baird Television Development Company/Cinema Television, although this signal was not broadcast to the public. The first live satellite signal to Britain from the United States was broadcast via the Telstar satellite on July 23, 1962.
The first live broadcast from the European continent was made on August 27, 1950.

[edit] Soviet Union (USSR)

The Soviet Union began offering 30-line electromechanical test broadcasts in Moscow on October 31, 1931, and a commercially manufactured television set in 1932.
The first experimental transmissions of electronic television took place in Moscow on March 9, 1937, using equipment manufactured and installed by RCA. Regular broadcasting began on December 31, 1938. It was quickly realized that 343 lines of resolution offered by this format would have become insufficient in the long run, thus a specification for 441-line format was developed in 1940, superseded by a 625-line standard in 1944. This format was ultimately accepted as a national standard.
The experimental transmissions in 625-line format started in Moscow from November 4, 1948. Regular broadcasting began on June 16, 1949. Details for this standard were formalized in 1955 specification called GOST 7845-55, basic parameters for black-and-white television broadcast. In particular, frame size was set to 625 lines, frame rate to 25 frames/s interlaced, and video bandwidth to 6 MHz. These basic parameters were accepted by most countries having 50 Hz mains frequency and became the foundation of television systems presently known as PAL and SECAM.
Starting from 1951 broadcasting in the 625-line standard was introduced in other major cities of the Soviet Union.
Color television broadcast started in 1974, using SECAM color system.[73]

[edit] Technological innovations

The first live national television broadcast in the U.S. took place on September 4, 1951 when President Harry Truman's speech at the Japanese Peace Treaty Conference in San Francisco, California was transmitted over AT&T's transcontinental cable and microwave radio relay system to broadcast stations in local markets.[94][95][96]
The first live coast-to-coast commercial television broadcast in the U.S. took place on November 18, 1951 during the premiere of CBS's See It Now, which showed a split-screen view of the Brooklyn Bridge in New York City and the Golden Gate Bridge in San Francisco. 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.
The development of cable and satellite television in the 1970s allowed for more channels and encouraged businessmen to target programming toward specific audiences. It also enabled the rise of subscription television channels, such as Home Box Office (HBO) and Showtime in the U.S., and Sky Television in the U.K.

[edit] Television sets

In television's electromechanical era, commercially made television sets were sold from 1928 to 1934 in the United Kingdom,[97] United States, and the Soviet Union.[98] The earliest commercially made sets sold by Baird in the UK in 1928 were radios with the addition of a television device consisting of a neon tube behind a mechanically spinning disk (the Nipkow disk) with a spiral of apertures that produced a red postage-stamp size image, enlarged to twice that size by a magnifying glass. The Baird "Televisor" was also available without the radio. The Televisor sold in 1930–1933 is considered the first mass-produced set, selling about a thousand units.[99]
Typical 1950s United States television set
The first commercially made electronic television sets with cathode ray tubes were manufactured by Telefunken in Germany in 1934,[100][101] followed by other makers in France (1936),[102] Britain (1936),[103] and America (1938).[104][105] The cheapest of the pre-World War II factory-made American sets, a 1938 image-only model with a 3-inch (8 cm) screen, cost US$125, the equivalent of US$1,863 in 2007. The most expensive model with a 12-inch (30 cm) screen was $445 ($6,633).[106]
An estimated 19,000 electronic television sets were manufactured in Britain, and about 1,600 in Germany, before World War II. About 7,000–8,000 electronic sets were made in the U.S.[107] before the War Production Board halted manufacture in April 1942, production resuming in August 1945.
Television usage in the United States skyrocketed after World War II with the lifting of the manufacturing freeze, war-related technological advances, the gradual expansion of the television networks westward, the drop in set prices caused by mass production, increased leisure time, and additional disposable income. In 1947, Motorola introduced the VT-71 television for $189.95, the first television set to be sold for under $200, finally making television affordable for millions of Americans. While only 0.5% of U.S. households had a television set in 1946, 55.7% had one in 1954, and 90% by 1962.[108] In Britain, there were 15,000 television households in 1947, 1.4 million in 1952, and 15.1 million by 1968.
For many years different countries used different technical standards. France initially adopted the German 441-line standard but later upgraded to 819 lines, which gave the highest picture definition of any analogue TV system, approximately double the resolution of the British 405-line system. However this is not without a cost, in that the cameras need to produce four times the pixel rate (thus quadrupling the bandwidth), from pixels one-quarter the size, reducing the sensitivity by an equal amount. In practice the 819-line cameras never achieved anything like the resolution that could theoretically be transmitted by the 819 line system, and for color, France reverted to the 625-line CCIR system used by most European countries.
With advent of color television most Western European countries adopted PAL standard. France, Soviet Union and most Eastern European countries adopted SECAM. In North America the original NTSC 525-line standard was augmented to include color transmission with slight slowing down of frame rate.
Throughout the 1960s, television sets used exclusively vacuum tube electronics. This resulted in relatively heavy and unreliable TVs. In addition, vacuum tubes were poorly-suited to color television, as it required a large amount of tubes which caused further reliability problems. Because vacuum tubes only allowed for very simple NTSC/PAL filtering, the picture quality of early color sets was rather poor. The tint control that is still found on NTSC televisions originally was meant to correct the color burst phase's drifting when channels were changed. In addition, the large number of vacuum tubes required for color prevented the use of it in portable TVs.
By the early 1970s, solid-state electronics appeared and quickly displaced vacuum tubes in color TVs (black and white sets generally continued to be tube-based). This allowed for significantly more reliable TVs and better picture quality. 1971 was the first year that sales of color TVs in the US exceeded B&W ones. In other countries, color was slower to arrive and did not become common in Western Europe until the '80s.
In 1972, the FCC began requiring UHF tuners in all TVs sold in the United States. At this time, there were only 130 UHF stations in the country, mostly low-power ones that carried local programming. Up to this point, UHF support from TV manufacturers was sporadic. Most sets did not come factory-equipped with them, and often merely included an empty slot in the cabinet where an optional UHF tuner could be installed.
During the 1970s, electronic tuners began appearing in high-end TVs in place of traditional dials, and they would gradually become standard along with remote controls. Remotes had first appeared in the 1950s with Zenith's Space Command Control, but these were mechanical devices that emitted a high-pitched audio frequency that the TV detected. The first electronic remote controls did not appear until the 1980s.
1980s TV developments mainly centered around the above-mentioned features. Electronic tuners also went hand-in-hand with the rise of cable television. Analog comb filters, first introduced in the '70s on high-end sets, gradually became more common. Black-and-white TVs virtually disappeared from the American market except for 5-inch, battery-powered models.
The first LCD TVs were introduced in 1988, small, handheld devices with a B&W screen that could not display the full NTSC resolution of 480 lines.
In the 1990s, 3-line digital comb filters appeared on high-end TVs. In addition, composite and S-video inputs began appearing to support devices like video games and VCRs.
Analog television broadcasting in the United States ended on June 12, 2009 in favor of Digital terrestrial television or digital-only broadcasting.

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