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The concept of television was the work of many individuals in the late 19th and early 20th centuries, with its roots initially starting from back even in the 18th century. The first practical transmissions of moving images over a radio system used mechanical rotating perforated disks to scan a scene into a time-varying signal that could be reconstructed at a receiver back into an approximation of the original image. Development of television was interrupted by the Second World War. After the end of the war, all-electronic methods of scanning and displaying images became standard. Several different standards for addition of color to transmitted images were developed, with different regions using technically incompatible signal standards. Television broadcasting expanded rapidly after World War II, becoming an important mass medium for advertising, propaganda, and entertainment.[1]

Television broadcasts can be distributed over the air by VHF and UHF radio signals from terrestrial transmitting stations, by microwave signals from Earth orbiting satellites, or by wired transmission to individual consumers by cable TV. Many countries have moved away from the original analog radio transmission methods and now use digital television standards, providing additional operating features and conserving radio spectrum bandwidth for more profitable uses. Television programming can also be distributed over the Internet.

Television broadcasting may be funded by advertising revenue, by private or governmental organizations prepared to underwrite the cost, or in some countries, by television license fees paid by owners of receivers. Some services, especially carried by cable or satellite, are paid by subscriptions.

Television broadcasting is supported by continuing technical developments such as long-haul microwave networks, which allow distribution of programming over a wide geographic area. Video recording methods allow programming to be edited and replayed for later use. Three-dimensional television has been used commercially but has not received wide consumer acceptance owing to the limitations of display methods.

Willoughby Smith, an English electrical engineer, discovered the photoconductivity of the element selenium in 1873. This led, among other technologies, towards telephotography, a way to send still images through phone lines, as early as in 1895, as well as any kind of electronical image scanning devices, both still and in motion, and ultimately to TV cameras.

As a 23-year-old German university student, Paul Julius Gottlieb Nipkow proposed and patented the Nipkow disk in 1884.[5] This was a spinning disk with a spiral pattern of holes in it, so each hole scanned a line of the image. Although he never built a working model of the system, variations of Nipkow's spinning-disk "image rasterizer" became exceedingly common.[6] 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 24, 1900. Perskyi's paper reviewed the existing electromechanical technologies, mentioning the work of Nipkow and others.[7] However, it was not until 1907 that developments in amplification tube technology, by Lee de Forest and Arthur Korn among others, made the design practical.[8]

The first demonstration of the instantaneous transmission of images was by Georges Rignoux and A. Fournier in Paris in 1909. A matrix of 64 selenium cells, individually wired to a mechanical commutator, served as an electronic retina. In the receiver, a type of Kerr cell modulated the light and a series of variously angled mirrors attached to the edge of a rotating disc scanned the modulated beam onto the display screen. A separate circuit regulated synchronization. The 8x8 pixel resolution in this proof-of-concept demonstration was just sufficient to clearly transmit individual letters of the alphabet. An updated image was transmitted "several times" each second.selenium cells, individually wired to a mechanical commutator, served as an electronic retina. In the receiver, a type of Kerr cell modulated the light and a series of variously angled mirrors attached to the edge of a rotating disc scanned the modulated beam onto the display screen. A separate circuit regulated synchronization. The 8x8 pixel resolution in this proof-of-concept demonstration was just sufficient to clearly transmit individual letters of the alphabet. An updated image was transmitted "several times" each second.[9]

In 1911, Boris Rosing and his student Vladimir Zworykin created a 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".[10]

By the 1920s, when amplification made television practical, Scottish inventor John Logie Baird employed the Nipkow disk in his prototype video systems. He created his prototype in a little village called Santa Cruz on the island of Trinidad where he was recovering from an illness. He also started work on the first color television. On March 25, 1925, Baird gave the first public demonstration of televised silhouette images in motion, at Selfridge's Department Store in London.[11] Since human faces had inadequate contrast to show up on his primitive system, he televised a talking, moving ventriloquist's dummy named "Stooky Bill", whose painted face had higher contrast. By January 26, 1926, he demonstrated the transmission of image of a face in motion by radio. This is widely regarded as being the world's first public television demonstration. Baird's system used the Nipkow disk for both scanning the image and displaying it. A brightly illuminated subject was placed in front of a spinning Nipkow disk set with lenses which swept images across a static photocell. The thallium sulphide (Thalofide) cell, developed by Theodore Case in the US, detected the light reflected from the subject and converted it into a proportional electrical signal. This was transmitted by AM radio waves to a receiver unit, where the video signal was applied to a neon light behind a second Nipkow disk rotating synchronized with the first. The brightness of the neon lamp was varied in proportion to the brightness of each spot on the image. As each hole in the disk passed by, one scan line of the image was reproduced. Baird's disk had 30 holes, producing an image with only 30 scan lines, just enough to recognize a human face.

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. In 1929, he became involved in the first experimental mechanical 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 Derby.[12] In 1932, he demonstrated 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. In 1929, he became involved in the first experimental mechanical 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 Derby.[12] In 1932, he demonstrated ultra-short wave television. Baird's mechanical system reached a peak of 240 lines of resolution on BBC television broadcasts in 1936, though for action shots (as opposed to a seated presenter) the mechanical system did not scan the televised scene directly. Instead, a 17.5mm film was shot, rapidly developed and then scanned while the film was still wet.

An American inventor, Charles Francis Jenkins, also pioneered the television. He published an article on "Motion Pictures by Wireless" in 1913, but it was not until December 1923 that he transmitted moving silhouette images for witnesses. On June 13, 1925, Jenkins publicly demonstrated the synchronized transmission of silhouette pictures. In 1925, Jenkins used a Nipkow disk and 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, D.C.), using a lensed disk scanner with a 48-line resolution.[13][14] He was granted U.S. patent 1,544,156 (Transmitting Pictures over Wireless) on June 30, 1925 (filed March 13, 1922).

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 prototype is still on display at the Takayanagi Memorial Museum at Shizuoka University, Hamamatsu Campus.[15] By 1927, Takayanagi improved the resolution to 100 lines, which was not surpassed until 1931.[16] By 1928, he was the first to transmit human faces in halftones. His work had an influence on the later work of Vladimir K. Zworykin.[17] By 1935, Takayanagi had invented the first all-electronic television.[18] His research toward creating a production model was halted by the US after Japan lost World War II.[15]

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 copper 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."[19]

In 1928, WRGB (then W2XB) was started as the world's first television station. It broadcast from the General Electric facility in Schenectady, NY. It was popularly known as "WGY Television".

Meanwhile, in the Soviet Union, Léon Theremin had been developing a mirror drum-based television, starting with 16-line resolution in 1925, then 32 lines and eventually 64 using interlacing in 1926. As part of his thesis on May 7, 1926, Theremin electrically transmitted and then projected near-simultaneous moving images on a five-foot square screen.[14] By 1927 he achieved an image of 100 lines, a resolution that was not surpassed until 1931 by RCA, with 120 lines.[citation needed]

Because only a limited number of holes could be made in the disks, and disks beyond a certain diameter became impractical, image resolution in mechanical television broadcasts was relatively low, ranging from about 30 lines up to about 120. Nevertheless, the image quality of 30-line transmissions steadily improved with technical advances, and by 1933 the UK broadcasts using the Baird system were remarkably clear.[20] A few systems ranging into the 200-line region also went on the air. Two of these were the 180-line system that Compagnie des Compteurs (CDC) installed in Paris in 1935, and the 180-line system that Peck Television Corp. started in 1935 at station VE9AK in Montreal.[21][22]

Anton Codelli (22 March 1875 – 28 April 1954), a Slovenian nobleman, was a passionate inventor. Among other things, he had devised a miniature refrigerator for cars and a new rotary engine design. Intrigued by television, he decided to apply his technical skills to the new medium. At the time, the biggest challenge in television technology was to transmit images with sufficient resolution to reproduce recognizable figures. As recounted by media historian Melita Zajc, most inventors were determined to increase the number of lines used by their systems – some were approaching what was then the magic number of 100 lines. But Baron Codelli had a different idea. In 1929, he developed a television device with a single line – but one that formed a continuous spiral on the screen. Codelli based his ingenious design on his understanding of the human eye. He knew that objects seen in peripheral vision don't need to be as sharp as those in the center. The baron's mechanical television system, whose image was sharpest in the middle, worked well, and he was soon able to transmit images of his wife, Ilona von Drasche-Lazar, over the air. Despite the backing of the German electronics giant Telefunken, however, Codelli's television system never became a commercial reality. Electronic television ultimately emerged as the dominant system, and Codelli moved on to other projects. His invention was largely forgotten.[23][24]

The advancement of all-electronic television (including image dissectors and other camera tubes and cathode ray tubes for the reproducer) marked the beginning of the end for mechanical systems as the dominant form of television. Mechanical TV usually only produced small images. It was the main type of TV until the 1930s. The last mechanical television broadcasts ended in 1939 at stations run by a handful of public universities in the United States.

In 1897, J. J. Thomson, an English physicist, in his three famous experiments was able to deflect cathode rays, a fundamental function of the modern Cathode Ray Tube (CRT). The earliest version of the CRT was invented by the German physicist Karl Ferdinand Braun in 1897 and is also known as the Braun tube.[25][26] It was a cold-cathode diode, a modification of the Crookes tube with a phosphor-coated screen. A cathode ray tube was successfully demonstrated as a displaying device by the German Professor Max Dieckmann in 1906, his experimental results were published by the journal Scientific American in 1909.[27] 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) as both a transmitting and receiving device.[28][29] He expanded on his vision in a speech given in London in 1911 and reported in The Times[30] and the Journal of the Röntgen Society.[31][32] 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.[33][34] These experiments were conducted before March 1914, when Minchin died.[35] They were later repeated in 1937 by two different teams, H. Miller and J. W. Strange from EMI,[36] and H. Iams and A. Rose from RCA.[37] 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.[38] The first cathode ray tube to use a hot cathode was developed by John B. Johnson (who gave his name to the term Johnson noise) and Harry Weiner Weinhart of Western Electric, and became a commercial product in 1922.[citation needed]

The problem of low sensitivity to light resulting in low electrical output from transmitting or "camera" tubes would be solved with the introduction of charge-storage technology by the Hungarian engineer Kálmán Tihanyi in the beginning of 1924.[39] In 1926, Tihanyi designed a television system utilizing fully electronic scanning and display elements and employing the principle of "charge storage" within the scanning (or "camera") tube.[4

The problem of low sensitivity to light resulting in low electrical output from transmitting or "camera" tubes would be solved with the introduction of charge-storage technology by the Hungarian engineer Kálmán Tihanyi in the beginning of 1924.[39] In 1926, Tihanyi designed a television system utilizing fully electronic scanning and display elements and employing the principle of "charge storage" within the scanning (or "camera") tube.[40][41][42][43] 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".[44] After further refinements included in a 1928 patent application,[39] Tihanyi's patent was declared void in Great Britain in 1930,[45] and so he applied for patents in the United States. 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.[41][42] Charge storage remains a basic principle in the design of imaging devices for television to the present day.[44]

On December 25, 1926, Kenjiro Takayanagi demonstrated a TV system with a 40-line resolution that employed a CRT display at Hamamatsu Industrial High School in Japan.[15] This was the first working example of a fully electronic television receiver. Takayanagi did not apply for a patent.[46]

On September 7, 1927, Philo Farnsworth's image dissector camera tube transmitted its first image, a simple straight line, at his laboratory at 202 Green Street in San Francisco.[47][48] By September 3, 1928, Farnsworth had developed the system sufficiently to hold a demonstration for the press. This is widely regarded as the first electronic television demonstration.[48] In 1929, the system was further improved by elimination of a motor generator, so that his television system now had no mechanical parts.[49] 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).[50]

Meanwhile, Vladimir Zworykin was also experimenting with the cathode ray tube to create and show images. While working for Westinghouse Electric 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.[51] Zworykin's imaging tube never got beyond the laboratory stage. But RCA, which 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,[52] he also divided his original application in 1931.[53] 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 over a ten-year period, in addition to license payments, to use Farnsworth's patents.[54][55]

In 1933 RCA introduced an improved camera tube that relied on Tihanyi's charge storage principle.[56][57] 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, a

In 1933 RCA introduced an improved camera tube that relied on Tihanyi's charge storage principle.[56][57] 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.[58][59] This small tube could amplify a signal reportedly to the 60th power or better[60] and showed great promise in all fields of electronics. A problem with the multipactor, unfortunately, was that it wore out at an unsatisfactory rate.[61]

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.[62] 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.[63][64]

In Britain the EMI engineering team led by Isaac Shoenberg applied in 1932 for a patent for a new device they dubbed "the Emitron",[65][66] which formed the heart of the cameras they designed for the BBC. In November 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.[67]

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.[68][69] 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.[70][71] They solved this problem by developing and patenting in 1934 two new camera tubes dubbed super-Emitron and CPS Emitron.[72][73][74] 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.[70] 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.[75] 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.[76] The "image iconoscope" ("Superikonoskop" in Germany) was produced as a result 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,[77] two years before Farnsworth did the same in the United States.[78] 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.[79][80] The German company Heimann produced the Superikonoskop for the 1936 Berlin Olympic Games,[81][82] later Heimann also produced and commercialized it from 1940 to 1955,[83] finally the Dutch company Philips produced and commercialized the image iconoscope and multicon from 1952 to 1958.[80][84]

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.[85] RCA, for example, used only Iconoscopes in the New York area, but Farnsworth Image Dissectors in Philadelphia and San Francisco.[86] 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.[87] With this historic agreement in place, RCA integrated much of what was best about the Farnswor

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.[85] RCA, for example, used only Iconoscopes in the New York area, but Farnsworth Image Dissectors in Philadelphia and San Francisco.[86] 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.[87] With this historic agreement in place, RCA integrated much of what was best about the Farnsworth Technology into their systems.[86] In 1941, the United States implemented 525-line television.[88][89]

The world's first 625-line television standard was designed in the Soviet Union in 1944, and became a national standard in 1946.[90] The first broadcast in 625-line standard occurred in 1948 in Moscow.[91] The concept of 625 lines per frame was subsequently implemented in the European CCIR standard.[92]

In 1936, Kálmán Tihanyi described the principle of plasma display, the first flat panel display system.[93][94]

In 1978, James P Mitchell described, prototyped and demonstrated what was perhaps the earliest monochromatic flat panel LED television display LED Display targeted at replacing the CRT.

The basic idea of using three monochrome images to produce a color image had been experimented with almost as soon as black-and-white televisions had first been built. Older televisions have the RGB (Red-Green-Blue) color scheme while modern televisions focus on LEDs to create the image. Among the earliest published proposals for television was one by Maurice Le Blanc in 1880 for a color system, including the first mentions in television literature of line and frame scanning, although he gave no practical details.[95] Polish inventor Jan Szczepanik patented a color television system in 1897, using a selenium photoelectric cell at the transmitter and an electromagnet controlling an oscillating mirror and a moving prism at the receiver. But his system contained no means of analyzing the spectrum of colors at the transmitting end, and could not have worked as he described it.[96] Another inventor, Hovannes Adamian, also experimented with color television as early as 1907. The first color television project is claimed by him,[97] and was patented in Germany on March 31, 1908, patent No. 197183, then in Britain, on April 1, 1908, patent No. 7219,[98] in France (patent No. 390326) and in Russia in 1910 (patent No. 17912).[99]

Scottish inventor John Logie Baird demonstrated the world's first color transmission on July 3, 1928, using scanning discs at the transmitting and receiving ends with three spirals of apertures, each spiral with filters of a different primary color; and three light sources at the receiving end, with a commutatorScottish inventor John Logie Baird demonstrated the world's first color transmission on July 3, 1928, using scanning discs at the transmitting and receiving ends with three spirals of apertures, each spiral with filters of a different primary color; and three light sources at the receiving end, with a commutator to alternate their illumination.[100] Baird also made the world's first color broadcast on February 4, 1938, sending a mechanically scanned 120-line image from Baird's Crystal Palace studios to a projection screen at London's Dominion Theatre.[101]

Mechanically scanned color television was also demonstrated by Bell Laboratories in June 1929 using three complete systems of photoelectric cells, amplifiers, glow-tubes and color filters, with a series of mirrors to superimpose the red, green and blue images into one full color image.

The first practical hybrid system was again pioneered by John Logie Baird. In 1940 he publicly demonstrated a color television combining a traditional black-and-white display with a rotating colored disc. This device was very "deep", but was later improved with a mirror folding the light path into an entirely practical device resembling a large conventional console.[102] However, Baird was not happy with the design, and as early as 1944 had commented to a British government committee that a fully electronic device would be better.

Mexican inventor Guillermo González Camarena also played an important role in early TV. His experiments with TV (known as telectroescopía at first) began in 1931 and led to a patent for the "trichromatic field sequential system" color television in 1940.[103]

In 1939, Hungarian engineer Peter Carl Goldmark introduced an electro-mechanical system while at CBS, which contained an Iconoscope sensor. 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 synchronization in front of the cathode ray tube inside the receiver set.[104] The system was first demonstrated to the Federal Communications Commission (FCC) on August 29, 1940, and shown to the press on September 4.[105][106][107][108]

CBS began experimental color field tests using film as early as August 28, 1940, and live cameras by November 12.[109] NBC (owned by RCA) made its first field test of color television on February 20, 1941. CBS began daily color field tests on June 1, 1941.[110] 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, viewing of the color field tests was restricted 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 22, 1942, to August 20, 1945, limiting any opportunity to introduce color television to the general public.[111][112]

As early as 1940, Baird had started work on a fully electronic system he called the "Telechrome". Early Telechrome devices used two electron guns aimed at either side of a phosphor plate. Using cyan and magenta phosphors, a reasonable limited-color image could be obtained. He also demonstrated the same system using monochrome signals to produce a 3D image (called "stereoscopic" at the time). A demonstration on August 16, 1944 was the first example of a practical color television system. Work on the Telechrome continued and plans were made to introduce a three-gun version for full color. This used a patterned version of the phosphor plate, with the guns aimed at ridges on one side of the plate. However, Baird's untimely death in 1946 ended development of the Telechrome system.[113][114]

Similar concepts were common through the 1940s and 1950s, differing primarily in the way they re-combined the colors generated by the three guns. The Geer tube was similar to Baird's concept, but used small pyramids with the phosphors deposited on their outside faces, instead of Baird's 3D patterning on a flat surface. The Penetron used three layers of phosphor on top of each other and increased the power of the beam to reach the upper layers when drawing those colors. The Chromatron used a set of focusing wires to select the colored phosphors arranged in vertical stripes on the tube.

One of the great technical challenges of introducing color broadcast television was the desire to conserve bandwidth, potentially three times that of the existing black-and-white standards, and not use an excessive amount of radio spectrum. In the United States, after considerable research, the National Television Systems Committee[115] approved an all-electronic Compatible color system developed by RCA, which encoded the color information separately from the brightness information and greatly reduced the resolution of the color information in order to conserve bandwidth. The brightness image remained compatible with existing black-and-white television sets at slightly reduced resolution, while color televisions could decode the extra information in the signal and produce a limited-resolution color display. The higher resolution black-and-white and lower resolution color images combine in the brain to produce a seemingly high-resolution color image. The NTSC standard represented a major technical achievement.

Although all-electronic color was introduced in the U.S. in 1953,[116] high prices and the scarcity of color programming greatly slowed its acceptance in the marketplace. The first national color broadcast (the 1954 Tournament of Roses Parade) occurred on January 1, 1954, but during the following ten years most network broadcasts, and nearly all local programming, continued to be in black-and-white. It was not until the mid-1960s that color sets started selling in large numbers, due in part to the color transition of 1965 in which it was announced that over half of all network prime-time programming would be broadcast in color that fall. The first all-color prime-time season came just one year later. In 1972, the last holdout among daytime network programs converted to color, resulting in the first completely all-color network season.

Early color sets were either floor-standing console models or tabletop versions nearly as bulky and heavy, so in practice they remained firmly anchored in one place. The introduction of GE's relatively compact and lightweight Porta-Color set in the spring of 1966 made watching color television a more flexible and convenient proposition. In 1972, sales of color sets finally surpassed sales of black-and-white sets.

Color broadcasting in Europe was also not standardized on the PAL format until the 1960s.

By the mid-1970s, the only stations broadcasting in black-and-white were a few high-numbered UHF stations in small markets, and a handful of low-power repeater stations in even smaller markets such as vacation spots. By 1979, even the last of these had converted t

Early color sets were either floor-standing console models or tabletop versions nearly as bulky and heavy, so in practice they remained firmly anchored in one place. The introduction of GE's relatively compact and lightweight Porta-Color set in the spring of 1966 made watching color television a more flexible and convenient proposition. In 1972, sales of color sets finally surpassed sales of black-and-white sets.

Color broadcasting in Europe was also not standardized on the PAL format until the 1960s.

By the mid-1970s, the only stations broadcasting in black-and-white were a few high-numbered UHF stations in small markets, and a handful of low-power repeater stations in even smaller markets such as vacation spots. By 1979, even the last of these had converted to color, and by the early 1980s black-and-white sets had been pushed into niche markets, notably low-power uses, small portable sets, or use as video monitor screens in lower-cost consumer equipment. By the late 1980s even these areas switched to color sets.

Digital television (DTV) is the transmission of audio and video by digitally processed and multiplexed signal, in contrast to the totally analog and channel separated signals used by analog television. Digital TV can support more than one program in the same channel bandwidth.[117] It is an innovative service that represents the first significant evolution in television technology since color television in the 1950s.[118]

Digital TV's roots have been tied very closely to the availability of inexpensive, high-performance computers. It wasn't until the 1990s that digital TV became a real possibility.[119]

In the mid-1980s Japanese consumer electronics firm Sony Corporation developed HDTV technology and the equipment to record at such resolution, and the MUSE analog format proposed by Digital TV's roots have been tied very closely to the availability of inexpensive, high-performance computers. It wasn't until the 1990s that digital TV became a real possibility.[119]

In the mid-1980s Japanese consumer electronics firm Sony Corporation developed HDTV technology and the equipment to record at such resolution, and the MUSE analog format proposed by NHK, a Japanese broadcaster, was seen as a pacesetter that threatened to eclipse U.S. electronics companies. Sony's system produced images at 1125-line resolution (or in digital terms, 1875x1125, close to the resolution of Full HD video[120]) Until June 1990, the Japanese MUSE standard—based on an analog system—was the front-runner among the more than 23 different technical concepts under consideration. Then, an American company, General Instrument, demonstrated the feasibility of a digital television signal. This breakthrough was of such significance that the FCC was persuaded to delay its decision on an ATV standard until a digitally based standard could be developed.

In March 1990, when it became clear that a digital standard was feasible, the FCC made a number of critical decisions. First, the Commission declared that the new ATV standard must be more than an enhanced analog signal, but be able to provide a genuine HDTV signal with at least twice the resolution of existing television images. Then, to ensure that viewers who did not wish to buy a new digital television set could continue to receive conventional television broadcasts, it dictated that the new ATV standard must be capable of being "simulcast" on different channels.The new ATV standard also allowed the new DTV signal to be based on entirely new design principles. Although incompatible with the existing NTSC standard, the new DTV standard would be able to incorporate many improvements.

The final standard adopted by the FCC did not require a single standard for scanning formats, aspect ratios, or lines of resolution. This outcome resulted from a dispute between the consumer electronics industry (joined by some broadcasters) and the computer industry (joined by the film industry and some public interest groups) over which of the two scanning processes—interlaced or progressive—is superior. Interlaced scanning, which is used in televisions worldwide, scans even-numbered lines first, then odd-numbered ones. Progressive scanning, which is the format used in computers, scans lines in sequences, from top to bottom. The computer industry argued that progressive scanning is superior because it does not "flicker" in the manner of interlaced scanning. It also argued that progressive scanning enables easier connections with the Internet, and is more cheaply converted to interlaced formats than vice versa. The film industry also supported progressive scanning because it offers a more efficient means of converting filmed programming into digital formats. For their part, the consumer electronics industry and broadcasters argued that interlaced scanning was the only technology that could transmit the highest quality pictures then feasible, that is, 1080 lines per picture and 1920 pixels per line. William F. Schreiber, who was a director of the Advanced Television Research Program at the Massachusetts Institute of Technology from 1983 until his retirement in 1990, thought that the continued advocacy of interlaced equipment originated from consumer electronics companies that were trying to get back the substantial investments they made in the interlaced technology.[121]

Digital television transition started in the late 2000s. All the governments across the world set the deadline for analog shutdown by the 2010s. Initially the adoption rate was low. But soon, more and more households were converting to digital televisions. The transition was expected to be complete worldwide by the mid to late 2010s.

Advent of digital television allowed innovations like smart TVs. A smart television, sometimes referred to as connected TV or hybrid television, is a television set with integrated Internet and Web 2.0 features, and is an example of technological convergence between computers and television sets and set-top boxes. Besides the traditional functions of television sets and set-top boxes provided through traditional broadcasting media, these devices can also provide Internet TV, online interactive media, over-the-top content, as well as on-demand streaming media, and home networking access. These TVs come pre-loaded with an operating system.[122][123][124][125]

Smart TV should not to be confused with Internet TV, IPTV or with Web TV. Internet television refers to the receiving television content over internet instead of traditional systems (terrestrial, cable and satellite) (although internet itself is received by these methods). Internet Protocol television (IPTV) is one of the emerging Internet television technology standards for use by television broadcasters. Web television (WebTV) is a term used for programs created by a wide variety of companies and individuals for broadcast on Internet TV.

A first patent was filed in 1994[126] (and extended the following year)[127] for an "intelligent" television system, linked with data processing systems, by means of a digital or analog network. Apart from being linked to data networks, one key point is its ability to automatically download necessary software routines, according to a user's demand, and process their needs.

Major TV manufacturers have announced production of smart TVs only, for middle-end and high-end TVs in 2015.[128][129][130]

3D televisionInternet TV, IPTV or with Web TV. Internet television refers to the receiving television content over internet instead of traditional systems (terrestrial, cable and satellite) (although internet itself is received by these methods). Internet Protocol television (IPTV) is one of the emerging Internet television technology standards for use by television broadcasters. Web television (WebTV) is a term used for programs created by a wide variety of companies and individuals for broadcast on Internet TV.

A first patent was filed in 1994[126] (and extended the following year)[127] for an "intelligent" television system, linked with data processing systems, by means of a digital or analog network. Apart from being linked to data networks, one key point is its ability to automatically download necessary software routines, according to a user's demand, and process their needs.

Major TV manufacturers have announced production of smart TVs only, for middle-end and high-end TVs in 2015.[128][129][130]

Stereoscopic 3D television was demonstrated for the first time on August 10, 1928, by John Logie Baird in his company's premises at 133 Long Acre, London.[131] Baird pioneered a variety of 3D television systems using electro-mechanical and cathode-ray tube techniques. The first 3D TV was produced in 1935. The advent of digital television in the 2000s greatly improved 3D TVs.

Although 3D TV sets are quite popular for watching 3D home media such as on Blu-ray discs, 3D programming has largely failed to make inroads among the public. Many 3D television channels that started in the early 2010s were shut down by the mid-2010s.[[citation needed]

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.

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 station CBFT. The premiere broadcast was bilingual, spoken in English and French. Two days later, on September 8, 1952, the Toronto station CBLT went on the air. This became the English-speaking flagship station for the country,

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 station CBFT. The premiere broadcast was bilingual, spoken in English and French. Two days later, on September 8, 1952, the Toronto 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).

Czechoslovakia

The first experiments in television broadcasting began in France in the 1930s, although the French did not immediately 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, Barthélemy 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 th

The first experiments in television broadcasting began in France in the 1930s, although the French did not immediately 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, 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, Barthélemy 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 mi). 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​14 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. These Nazi-controlled television broadcasts from the Eiffel Tower in Paris were able to be received on the south coast of England by R.A.F. and BBC engineers,[132] who photographed the station identification image direct from the screen.

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, François Mitterrand decreed a broadcast standard of 819 lines; broadcasting began at the end of 1949 in this definition. Besides France, this standard was later adopted by Algeria, Monaco, and Morocco. Belgium and Luxembourg used a modified version of this standard with bandwidth narrowed to 7 MHz.[133]

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.

After the end of World War II, the victorious Allies imposed a general ban on all radio and television broadcasting in Germany. Radio broadcasts for information purposes were soon permitted again, but television broadcasting was allowed to resume only in 1948.

In East Germany, the head of broadcasti

After the end of World War II, the victorious Allies imposed a general ban on all radio and television broadcasting in Germany. Radio broadcasts for information purposes were soon permitted again, but television broadcasting was allowed to resume only in 1948.

In East Germany, the head of broadcasting in the Soviet occupation zone, Hans Mahler, predicted in 1948 that in the near future ‘a new and important technical step forward in the field of broadcasting in Germany will begin its triumphant march: television.’ In 1950, the plans for a nationwide television service got off the ground, and a Television Centre in Berlin was approved. Transmissions began on December 21, 1952 using the 625-line standard developed in the Soviet Union in 1944, although at that time there were probably no more than 75 television receivers capable of receiving the programming.[134][135]

In West Germany, the British occupation forces as well as NWDR (Nordwestdeutscher Rundfunk), which had started work in the British zone straight after the war, agreed to the launch of a television station. Even before this, German television specialists had agreed on 625 lines as the future standard.[136] This standard had narrower channel bandwidth (7 MHz) compared to the Soviet specification (8 MHz), allowing three television channels to fit into the VHF I band.

When color was introduced, West Germany chose a variant of the NTSC color system, modified by Walter Bruch and called PAL. East Germany accepted the French SECAM system, which was used in Eastern European countries. With the reunification of Germany, it was decided to switch to the PAL color system. The system was changed in December 1990.

In Italy, the first experimental tests on television broadcasts were made in Turin since 1934. The city already hosted the Center for Management of the EIAR (lately renamed as RAI) at the premises of the Theatre of Turin. Subsequently, the EAIR established offices in Rome and Milan. On July 22, 1939 comes into operation in Rome the first television transmitter at the EIAR station, which performed a regular broadcast for about a year using a 441-line system that was developed in Germany. In September of the same year, a second television transmitter was installed in Milan, making experimental broadcasts during major events in the city.

The broadcasts were suddenly ended on May 31, 1940, by order of the government, allegedly because of interferences encountered in the first air navigation systems. Also, the imminent participation in the war is believed to have played a role in this decision. EIAR transmitting equipment was relocated

The broadcasts were suddenly ended on May 31, 1940, by order of the government, allegedly because of interferences encountered in the first air navigation systems. Also, the imminent participation in the war is believed to have played a role in this decision. EIAR transmitting equipment was relocated to Germany by the German troops. Lately, it was returned to Italy.

The first official television broadcast began on January 3, 1954 by the RAI.

Television broadcasting in Japan started on August 28, 1953,[137] making the country one of the first in the world with an experimental television service. The first television tests were conducted as early as 1926 using a combined mechanical Nipkow disk and electronic Braun tube system, later switching to an all-electronic system in 1935 using a domestically developed iconoscope system.[138] In spite of that, because of the beginning of World War II in the Pacific region, this first full-fledged TV broadcast experimentation lasted only a few months. Regular television broadcasts would eventually start in 1953.

In 1979, NHK first developed a consumer high-definition television with a 5:3 display aspect ratio.[139] The system, known as Hi-Vision or MUSE after its [139] The system, known as Hi-Vision or MUSE after its Multiple sub-Nyquist sampling encoding for encoding the signal, required about twice the bandwidth of the existing NTSC system but provided about four times the resolution (1080i/1125 lines). Satellite test broadcasts started in 1989, with regular testing starting in 1991 and regular broadcasting of BS-9ch commenced on November 25, 1994, which featured commercial and NHK television programming.

Sony first demonstrated a wideband analog high-definition television system HDTV capable video camera, monitor and video tape recorder (VTR) in April 1981 at an international meeting of television engineers in Algiers. The Sony HDVS range was launched in April 1984, with the HDC-100 camera, HDV-100 video recorder and HDS-100 video switcher all working in the 1125-line component video format with interlaced video and a 5:3 aspect ratio.

The first testing television station in Mexico signed on in 1935. When KFMB-TV in San Diego signed on in 1949, Baja California became the first state to receive a commercial television station over the air. Within a year, the Mexican government would adopt the U.S. NTSC 525-line B/W 60-field-per-second system as the country's broadcast standard. In 1950, the first commercial television station within Mexico, XHTV in Mexico City, signed on the air, followed by XEW-TV in 1951 and XHGC in 1952. Those three were not only the first television stations in the country, but also the flagship stations of Telesistema Mexicano, which was formed in 1955. That year, Emilio Azcárraga Vidaurreta, who had signed on XEW-TV, entered into a partnership with Rómulo O'Farrill who had signed on XHTV, and Guillermo González Camarena, who had signed on XHGC. The earliest 3D television broadcasts in the world were broadcast over XHGC in 1954. Color television was introduced in 1962, also over XHGC-TV. One of Telesistema Mexicano's earliest broadcasts as a network, over XEW-TV, on June 25, 1955, was the first international North American broadcast in the medium's history, and was jointly aired with NBC in the United States, where it aired as the premiere episode of Wide Wide World, and the Canadian Broadcasting Corporation. Except for a brief period between 1969 and 1973, nearly every commercial television station in Mexico, with exceptions in the border cities, was expected to affiliate with a subnetwork of Telesistema Mexicano or its successor, Televisa (formed by the 1973 merger of Telesistema Mexicano and Television Independiente de Mexico). This condition would not be relaxed for good until 1993, when Imevision was privatized to become TV Azteca.

Soviet Union (USSR)