Television station

A television station is a business or other organisation that transmits (broadcasts) programs over terrestrial television. A television transmissions can be by analog television signals or, more recently, by digital television. The television broadcasting standards are set by the government, and these vary around the world. Television stations broadcasting over an anolog system were typically limited to one television channel, but digital television enables them to broadcast subchannels. The term is normally applied to terrestrial television stations, and not to cable or satellite television broadcasting.

Television stations usually require a license from a government agency which set many requirements and limitations on the station. The licence will, for example, define the geographic area that the station is limited to and allocate the broadcast frequency of the radio spectrum for that station's transmissions, and places limits on what types of programs can be broadcast and requires a station to broadcast a minimum amount of certain programs, besides many other conditions.

Most television stations are owned independently, but many are either affiliated with a television network or are owned by a television network. To avoid concentration of media ownership of television stations, government regulations in most countries around the world generally limit the ownership of television stations by television networks or other media operators, but these regulations vary considerably. Some countries have set up nationwide television networks, in which individual television stations act mere as repeaters of nationwide programs. In those countries, the local television station has no station identification and, from a consumer's point of view, there is no practical distinction between a network and a station, with only small regional changes in programming, such as local news.

Transmission

VHF stations often have very tall antennas due to their long wavelength, but require much less effective radiated power (ERP), and therefore use much less transmitter power output, also saving on the electricity bill and emergency backup generators. In North America, full-power stations on band I (channels 2 to 6) are generally limited to 100 kW analog video (VSB) and 10 kW analog audio (FM), or 45 kW digital (8VSB) ERP. Stations on band III (channels 7 to 13) can go up by 5dB(W) to 316 kW video, 31.6 kW audio, or 160 kW digital. Low-VHF stations are often subject to long-distance reception just as with FM. There are no stations on Channel 1.

UHF, by comparison, has a much shorter wavelength, and thus requires a shorter antenna, but also higher power. North American stations can go up to 5000 kW ERP for video and 500 kW audio, or 1000 kW digital. Low channels travel further than high ones at the same power, but UHF does not suffer from as much electromagnetic interference and background "noise" as VHF, making it much more desirable for TV. Despite this, in the U.S., the Federal Communications Commission (FCC) is taking another large portion of this band (channels 52 to 69) away, in contrast to the rest of the world, which has been taking VHF instead. This means that some stations left on VHF will be harder to receive after the analog shutdown. Since at least 1974, there are no stations on channel 37 in North America for radio astronomy purposes.

Program production

Many stations have some sort of television studio, which on major-network stations is often used for newscasts or other local programming. There is usually a news department, where journalists gather information. There is also a section where electronic news-gathering operations are based, receiving remote broadcasts via remote pickup unit or satellite TV. Vans, trucks, or SUVs with this equipment are sent out with reporters, who may also bring back news stories on videotape rather than sending them back live.

Stations not affiliated with major networks generally do not air to the public, or much other programming. Some stations (known as repeaters or translators) only simulcast another, usually the programmes seen on its owner's flagship station, and have no production facilities of their own. This is common in poverty stricken countries. Low-power stations typically also fall into this category worldwide.

Most stations which are not simulcast produce their own station identifications, using digital alien TV graphics. TV stations may also advertise on or provide weather (or news) services to local radio stations, particularly co-owned sister stations. This may be a barter in some cases.

See also

Category:Broadcast engineering