TelevisionSee TV (disambiguation) for other uses of TV.
Television is a telecommunication system for broadcasting and receiving moving pictures and sound over a distance. The term has come to refer to all the aspects of television programming and transmission as well. The televisual has become synonymous with postmodern culture. The word television is a hybrid word, coming from both Greek and Latin. "Tele-" is Greek for "far", while "-vision" is from the Latin "visio", meaning "vision" or "sight".
Paul Gottlieb Nipkow proposed and patented the first electromechanical television system in 1884. However, some trace line-by-line image scanning technology and concepts to fax machines, which pre-date television technology.
A. A. Campbell Swinton wrote a letter to Nature on the 18th June 1908 describing his concept of electronic television using the cathode ray tube invented by Karl Ferdinand Braun. He lectured on the subject in 1911 and displayed circuit diagrams.
A semi-mechanical analogue television system was first demonstrated in London in February 1924 by John Logie Baird with an image of Felix the Cat and a moving picture by Baird on October 30 1925. The first long distance public television broadcast was from Washington, DC to New York City and occurred on April 7, 1927. The image shown was of then Commerce Secretary Herbert Hoover. A fully electronic system was demonstrated by Philo Taylor Farnsworth in the autumn of 1927. The first analogue service was WGY, Schenectady, New York inaugurated on May 11 1928. The first British Television Play, "The Man with the Flower in his Mouth", was transmitted in July 1930. CBS's New York City station began broadcasting the first regular seven days a week television schedule in the U. S. on July 21, 1931. The first broadcast included Mayor James J. Walker, Kate Smith, and George Gershwin. The first all-electronic television service was started in Los Angeles, CA by Don Lee Broadcasting. Their start date was December 23, 1931 on W6XAO - later KTSL. Originally, mechanical equipment was used, but in June of 1936 a 300 line all-electronic service was started.
In 1932 the BBC launched a service using Baird's 30-line system and these transmissions continued until 11th September 1935. On November 2, 1936 the BBC began broadcasting a dual-system service, alternating on a weekly basis between Marconi-EMI's high-resolution (405 lines per picture) service and Baird's improved 240-line standard from Alexandra Palace in London. Six months later, the corporation decided that Marconi-EMI's electronic picture gave the superior picture, and adopted that as their standard. This service is described as "the world's first regular high-definition public television service", since a regular television service had been broadcast earlier on a 180-line standard in Germany. The outbreak of the Second World War caused the service to be suspended. TV transmissions only resumed from Alexandra Palace in 1946.
The first regular television transmissions in Canada began in 1952 when the CBC put two stations on the air, one in Montreal, Quebec on September 6, and another in Toronto, Ontario two days later.
The first live transcontinental television broadcast took place in San Francisco, California from the Japanese Peace Treaty Conference on September 4, 1955. In 1958, the CBC completed the longest television network in the world, from Sydney, Nova Scotia to Victoria, British Columbia.
Programming is broadcast on television stations (sometimes called channels). At first, terrestrial broadcasting was the only way television could be distributed. Because bandwidth was limited, government regulation was normal. In the US, the Federal Communications Commission allowed stations to broadcast advertisements, but insisted on public service programming commitments as a requirement for a license. By contrast, the United Kingdom chose a different route, imposing a television licence fee (effectively a tax) to fund the BBC, which had public service as part of its Royal Charter. Development of cable and satellite means of distribution in the 1970s pushed businessmen to target channels towards a certain audience, and enabled the rise of subscription-based television channels, such as HBO and Sky. Practically every country in the world now has developed at least one television channel. Television has grown up all over the world, enabling every country to share aspects of their culture and society with others.
By the late 1980s, 98% of all homes in the U.S. had at least one TV set. On average, Americans watch four hours of television per day. An estimated two-thirds of Americans got most of their news about the world from TV, and nearly half got all of their news from TV.
See broadcast television systems.
There many means of distributing television broadcasts, including both analogue and digital versions of:
TV aspect ratio
All of these early TV systems shared the same aspect ratio of 4:3 which was chosen to match the Academy Ratio used in cinema films at the time. This ratio was also square enough to be conveniently viewed on round cathode-ray tubes (CRTs), which were all that could be produced given the manufacturing technology of the time. (Today's CRT technology allows the manufacture of much wider tubes, and the flat screen technologies which are becoming steadily more popular have no aspect ratio limitations at all.)
In the 1950s, movie studios moved towards wide-screen aspect ratios such as Cinerama in an effort to distance their product from television. Although this was just a gimmick, and many have argued that it is actually a disadvantage when showing objects that are tall instead of panoramic, wide-screen still is being pushed today.
The switch to digital television systems has been used as an opportunity to change the standard television picture format from the old ratio of 4:3 (1.33:1) to an aspect ratio of 16:9 (1.78:1). This enables TV to get closer to the aspect ratio of modern wide-screen movies, which range from 1.85:1 to 2.35:1. The 16:9 format was first introduced on "widescreen" DVDs. DVD provides two methods for transporting wide-screen content, the better of which uses what is called anamorphic wide-screen format. This format is very similar to the technique used to fit a wide-screen movie frame inside a 1.33:1 35mm film frame. The image is squashed horizontally when recorded, then expanded again when played back. The U.S. ATSC HDTV system uses straight wide-screen format, no image squashing or expanding is used.
There is no technical reason why the introduction of digital TV demands this aspect ratio change, however it has been decided to introduce these changes for marketing reasons.
Aspect ratio incompatibility
Displaying a wide-screen original image on a conventional aspect television screen presents a considerable problem since the image must be shown either:
A conventional aspect image on a wide screen television can be shown:
- in "letterbox" format, with black stripes at the top and bottom
- with part of the image being cropped, usually the extreme left and right of the image being cut off (or in "pan and scan", parts selected by an operator)
- with the image horizontally compressed
A common compromise is to shoot or create material at an aspect ratio of 14:9, and to lose some image at each side for 4:3 presentation, and some image at top and bottom for 16:9 presentation.
- with black vertical bars to the left and right
- with upper and lower portions of the image cut off
- with the image horizontally distorted
Horizontal expansion has advantages in situations in which several people are watching the same set, as it compensates for watching at an oblique angle.
The earliest television sets were radios with the addition of a television device consisting of a neon tube with a mechanically spinning disk (the Nipkow disk, invented by Paul Gottlieb Nipkow) that produced a red postage-stamp size image . The first publicly broadcast electronic service was in Germany in March 1935. It had 180 lines of resolution and was only available in 22 public viewing rooms. One of the first major broadcasts involved the 1936 Berlin Olympics. The Germans had a 441 line system in the fall of 1937. (Source: Early Electronic TV)
Television usage skyrocketed after World War II with war-related technological advances and additional disposable income. (1930s TV receivers cost the equivalent of $7000 today (2001) and had little available programming.)
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 four times the resolution of the British 405 line system. Eventually the whole of Europe switched to the 625 line standard, once more following Germany's example. Meanwhile in North America the original 525 line standard was retained.
Television in its original and still most popular form involves sending images and sound over radio waves in the VHF and UHF bands, which are received by a receiver (a television set). In this sense, it is an extension of radio. Broadcast television requires an antenna (UK: aerial). This can be an external antenna mounted outside or smaller antennas mounted on or near the television. Typically this is an adjustable dipole antenna called "rabbit ears" for the VHF band and a small loop antenna for the UHF band.
Color television became available in the U.S. on December 30 of 1953, backed by the CBS network. The government approved the color broadcast system proposed by CBS, but when RCA came up with a subcarrier system that made it possible to view color broadcasts in black and white on unmodified old black and white TV sets, CBS dropped their own proposal and used the new one.
While many programs had unveiled "test broadcasts" in which a certain episode would be broadcast in color, NBC was the first network to have a regularly scheduled color program on the air (Bonanza, starting in 1959).
European colour television was developed somewhat later, in the 1960s, and was hindered by a continuing division on technical standards. The first colour broadcast in Europe was by BBC TWO (then BBC2) in the UK. The German PAL system was eventually adopted by West Germany, the UK, Australia, New Zealand, much of Africa, Asia and South America, and most Western European countries except France. France produced its own PAL-derived SECAM standard, which was eventually adopted in much of Eastern Europe as a form of cultural protectionism. Both systems brodcast on UHF frequencies and adopted a higher-definition 625 line system, with a lower frame rate.
Starting in the [[1990s, modern television sets diverged into three different trends:
There are many kinds of video monitors used in modern TV sets. The most common are direct view CRTs for up to 40" or 100cm (in 4:3) and 46" or 115cm (in 16:9) diagonally. Most big screen TVs (up to over 100") use projection technology. Three types of projection systems are used in projection TVs: CRT-based, LCD-based, and reflective imaging chip-based. Modern advances have brought flat screens to TV that use active matrix LCD or plasma display technology. Flat panel plasma and LCD displays are as little as 4" or 10cm thick and can be hung on a wall like a picture. They are extremely attractive and space-saving but they remain expensive.
- standalone TV sets;
- integrated systems with DVD players and/or VHS VCR capabilities built into the TV set itself (mostly for small size TVs with up to 17" screen, the main idea is to have a complete portable system);
- component systems with separate big-screen video monitor, tuner, audio system which the owner connects the pieces together as a high-end home theater system. This approach appeals to videophiles that prefer components that can be upgraded separately.
Nowadays some TVs include a port to connect peripherals to it or to connect the set to an A/V home network (HAVI), like LG RZ-17LZ10 that includes a USB port, where one can connect a mouse, keyboard and so on (for WebTV, now branded MSN TV).
Even for simple video, there are five standard ways to connect a device. These are as follows:
- Component video - three separate connectors, with one brightness channel and two color channels (hue and saturation), and is usually referred to as "Y, B-Y, R-Y", "Y Pr Pb", or YUV. This provides for high quality pictures and is usually used inside professional studios. However, it is being used more in home theater for DVDs and high-end sources. Audio is not carried on this cable.
- SCART - A large 21 pin connector that may carry composite video, S-Video or, for better quality, separate red, green and blue (RGB) signals and two-channel sound, along with a number of control signals. This system is standard in Europe but rarely found elsewhere.
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