Televisiontelecommunication 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.
|Table of contents|
2 TV Standards
3 TV Aspect Ratio
4 Aspect Ratio Incompatibility
5 New Developments
6 TV Sets
8 US Networks
9 Colloquial Names
10 Related Articles
11 Further Reading
Paul Gottlieb Nipkow proposed and patented the first electromechanical television system in 1884.
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 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. Los Angeles was the only major U. S. city that avoided the false start with mechanical television.
In 1932 the BBC launched a service using Baird's 30-line system and these transmissions continued until 11th September 1935. It was replaced by the world's first regular high-resolution (405 lines per picture) television service, from Alexandra Palace in London on November 2, 1936. The outbreak of the Second World War caused the service to be suspended. TV transmissions only resumed from Alexandra Palace in 1946.
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 Crown 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 with the technological capability has developed at least one television channel.
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 determined by the Cathode Ray Tube (CRT) manufacturing technology of the time -- today's CRT technology allows the manufacture of wider tubes. However, due to the negative heavy metal health effects associated with disposal of CRTs in landfills and the space-saving attributes of flat screen technologies that lack the aspect ratio limitations of CRTs, CRTs are becoming obsolete.
The switch-over to DTV systems coincides with a change in picture format from a aspect 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 movies, which range from 1.85:1 to 2.35:1. The 16:9 format was first introduced for "widescreen" video and DVDs. The current technical implementation of 16:9 uses the same pixel raster as 4:3 video, in a full screen anamorphic format.
There is no technical reason for this aspect ratio change to be coupled with the introduction of DTV, but it has been decided to synchronize these changes for marketing reasons.
Aspect Ratio Incompatibility
A wide image on a conventional screen can be shown:
- with "letterbox" black stripes at the top and bottom
- with the extreme left and right of the image falling off (or in "pan and scan", parts selected by an operator)
- with the image horizontally compressed
- with black parts at the left and right
- with the top and bottom of the image falling off
- with the image horizontally expanded
Horizontal expansion has advantages in situations in which several people are watching the same set; 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.)
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.
Color television became available on December 30, 1953, backed by the CBS network. The government approved the color broadcast system proposed by CBS, but when RCA came up with a 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.
Starting in the 1990s, modern television sets diverged into three different trends:
- standalone TV sets;
- integrated systems with DVD players and/or VHS VCR built into the TV set itself (mostly for small size TV 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 who prefer components which 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).
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 or Y Pr Pb. 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.
- S-Video- two separate channels, one carrying brightness, the other carrying color. Also referred to as Y/C video. Provides most of the benefit of component video, with slightly less color fidelity. Use started in the 1980s for S-VHS, Hi-8 and early DVD players to relay high quality video. Audio is not carried on this cable.
- Composite video- The most common form of connecting external devices, putting all the video information into one stream. Most televisions provide this option with a yellow RCA cable. Audio is not carried on this cable.
- Coaxial or RF (coaxial cable)- All audio channels and picture components are transmitted through one wire and modulated on a radio frequency. Most TVs manufactured during the past 15-20 years accept coaxial connection, and the video is typically "tuned" on channel 3 or 4.
AdvertisingFrom the earliest days of the medium, television has been used as a vehicle for advertising. Since their inception in the USA in the late 1940s, TV commercialss have become far and away the most effective, most pervasive, and most popular method of selling products of all sorts. US advertising rates are determined primarily by Nielsen Ratings
In the US, television networks produce prime-time programs for their affiliate stations to air from 8pm-11pm Monday-Saturday and 7pm-11pm on Sunday. (7pm and 10pm, 6pm and 10pm respectively in the Central and Mountain time zones). Most stations have their own programming off the prime time. The FOX Network does not produce programming for the last hour of prime time; as a result, many FOX affiliates air a local news program at that time. 2 newer broadcasting networks, The WB and UPN, also do not provide the same amount of network programming as so-called traditional networks.
- The Tube/Boob Tube
- The Goggle Box
- The Cyclops
- List of 'years in television'
- Lists of television channels
- List of television programs
- List of television commercials
- List of television personalities
- List of television series
- Animation and Animated series
- Nielsen Ratings
- Home appliances
- Reality television
- Television network
- Voyager Golden Record
- Wasteland Speech
- "Television History"
- Early Television Foundation and Museum
- Television History site from France
- TV Dawn
- British TV History Links
- UK Television Programmes
TV as social pathogen, opiate, mass mind control, etc
- Jerry Mander Four Arguments for the Elimination of Television
- Marie Winn The Plug-in Drug
- Neil Postman Amusing Ourselves to Death
- Terence McKenna Food of the Gods
- Joyce Nelson The Perfect Machine
Alternate use of the term: Television (band)