Information about Tv Network

A television network is a distribution for television content whereby a central operation provides programming for many television stations. Until the mid-1980s, television programming in most countries of the world was dominated by a small number of broadcast networks. Many early television networks (e.g. the BBC, NBC or CBS) evolved from earlier radio networks. It may be confused with a television channel.

Within the industry, a tiering is sometimes created among groups of networks based on whether their programming is simultaneously originated from a central point, and whether the network master control has the technical and administrative capability to take over the programming of their affiliates in real-time when it deems this necessary—the most common example being breaking national news events.

In countries where most networks broadcast identical, centrally originated content from all their stations and where most individual transmitters therefore operate only as large "repeater stations", the terms television network, television channel and television station have become interchangeable in everyday language, with only professionals in TV-related occupations continuing to make a difference between them, if one was ever made. This applies to the United Kingdom, Australia, Japan, South Korea and most other countries outside Northern America.

However, in North America in particular, many television channels available via cable and satellite television are branded as "networks" but are not truly networks in the sense defined above, as they are singular operations – they have no affiliates or component stations. Such channels are more precisely referred to by terms such as "specialty channels" (Canada) or "cable networks" (U.S.), although the latter term is somewhat of a misnomer (however, it may be judged otherwise because cable channels are networked across the country by various cable and satellite systems).

In the U.S., television networks are simply identified as "networks" (such as ABC, CBS or NBC), while the local stations are identified by the station's call sign and city of license. In Europe and much of Asia, Africa and South America, television networks are often more or less numbered (for example, Britain's BBC One, BBC Two, ITV1, Channel 4 and five etc, or the Netherlands' Nederland 1, Nederland 2, Nederland 3. In Australia, television networks are identified by the channel number in the capital cities (such as Seven, Nine or Ten).

History

NBC set up the first permanent coast-to-coast radio network in the United States by 1928, using dedicated telephone line technology. But the signal from an electronic television system, containing much more information than a radio signal, required a broadband transmission medium. Transmission by a nationwide series of radio relay towers would be possible but extremely expensive.

Researchers at the AT&T subsidiary Bell Telephone Laboratories patented coaxial cable in 1929, primarily as a telephone improvement device. Its high capacity (transmitting 240 telephone calls simultaneously) also made it ideal for long-distance television transmission, where it could handle a frequency band of 1 megahertz.^[1] German television first demonstrated such an application in 1936 by relaying televised telephone calls from Berlin to Leipzig, 180 km (112 miles) away, by cable.^[2] The network was later extended to television viewing offices in Nuremberg and Munich.

AT&T laid the first L-carrier coaxial cable between New York and Philadelphia, with automatic signal booster stations every 10 miles (16 km), and in 1937 they experimented with transmitting televised motion pictures over the line.^[3] Bell Labs gave demonstrations of the New York-Philadelphia television link in 1940-1941. AT&T used the coaxial link to transmit the Republican national convention in June 1940 from Philadelphia to New York City, where it was televised to a few hundred receivers over the NBC station.^[4]

NBC had earlier demonstrated an inter-city television broadcast on February 1, 1940, from its station in New York City to another in Schenectady, New York by General Electric relay antennas, and began transmitting some programs on an irregular basis to Philadelphia and Schenectady in 1941. Wartime priorities suspended the manufacture of television and radio equipment for civilian use from April 1, 1942 to October 1, 1945, temporarily shutting down expansion of television networking. However, in 1944 a short film, "Patrolling the Ether", was broadcast simultaneously over three stations as an experiment.

AT&T made its first postwar addition in February 1946, with the completion of a 225-mile (362 km) cable between New York City and Washington, D.C., although a blurry demonstration broadcast showed that it would not be in regular use for several months. NBC launched what it called "the world's first regularly operating television network" on June 27, 1947, serving New York, Philadelphia, Schenectady and Washington.^[5] Baltimore and Boston were added to the NBC television network in late 1947. In the 1950s the networks stretched coast to coast, carried on the new microwave radio relay network of AT&T Long Lines.

FCC regulations in the United States restricted the number of television stations that could be owned by any one network, company or individual. This led to a system where most local television stations were independently owned, but received programming from the network through a franchising contract, except in a few big cities that had network owned-and-operated stations. In the early days of television, when there were often only one or two stations broadcasting in an area, the stations were usually affiliated with several networks and were able to choose which programs to air. Eventually, as more stations were licensed, it became common for each station to be affiliated with only one network and carry all of the "prime time" network programs.

Another FCC regulation, the Prime Time Access Rule, restricted the number of hours of network programming that could be broadcast on the local affiliate stations. This was done to encourage the development of locally produced programs and to give local residents access to broadcast time. More often, the result included a substantial amount of syndicated programming, usually consisting of old movies, independently produced and syndicated shows, and reruns of network programs. Occasionally, these shows were presented by a local host, especially in programs that showed cartoons and short comedies intended for children. See List of local children's television series (United States).

References

See also

• List of television networks by country
• Television system