Television station

A television station is a set of equipment managed by a business, organisation or other entity, such as an amateur television (ATV)
operator, that transmits video content via radio waves directly from a transmitter on the earth's surface to a receiver on earth. Most
often the term refers to a station which broadcasts structured content to an audience or it refers to the organization that operates the
station. A terrestrial television transmission can occur via analog television signals or, more recently, via digital television signals.
Television stations are differentiated from cable television or other video providers in that their content is broadcast via terrestrial
radio waves. A group of television stations with common ownership or affiliation are known as a TV network and an individual
station within the network is referred to asO&O or affiliate, respectively.

Because television station signals use the electromagnetic spectrum, which in the past has been a common, scarce resource,
governments often claim authority to regulate them. Broadcast television systems standards vary around the world. Television
stations broadcasting over an analog system were typically limited to one television channel, but digital television enables
broadcasting via subchannels as well. Television stations usually require a broadcast license from a government agency which sets
the requirements and limitations on the station. In the United States, for example, a television license defines the broadcast range, or
geographic area, that the station is limited to, allocates the broadcast frequency of the radio spectrum for that station's transmissions,
sets limits on what types of television programs can be programmed for broadcast and requires a station to broadcast a minimum
amount of certain programs types, such aspublic affairs messages.

Another form a television station may take is non-commercial educational (NCE) and considered public broadcasting. To avoid
concentration of media ownership of television stations, government regulations in most countries 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 as mere 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
television news.

Contents
1 Transmission
2 Program production
3 See also
4 References

Transmission
To broadcast its programs, a television station requires operators to operate equipment, a transmitter or radio antenna, which is often
located at the highest point available in the transmission area, such as on a summit, the top of a high skyscraper, or on a tall radio
tower. To get a signal from the master control room to the transmitter, a studio/transmitter link (STL) is used. The link can be either
by radio or T1/E1. A transmitter/studio link (TSL) may also send telemetry back to the station, but this may be embedded in
subcarriers of the main broadcast. Stations which retransmit or simulcast another may simply pick-up that station over-the-air, or via
STL or satellite. The license usually specifies which other station is it allowed to carry
.

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 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. Cerro de Punta, Puerto Rico's
Despite this, in the U.S., the Federal Communications Commission (FCC) is taking highest peak, and its TV
transmission towers
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 are 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
Most television stations are commercial broadcasting enterprises which are structured in a variety of ways to generate revenue from
television commercials. They may be an independent station or part of a broadcasting network, or some other structure. They can
produce some or all of their programs or buy some broadcast syndication programming for or all of it from other stations or
independent production companies.

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 (ENG) operations are based, receivingremote broadcasts via remote pickup unit or satellite TV. Outside broadcasting
vans, production trucks, or SUVs with electronic field production (EFP) equipment are sent out with reporters, who may also bring
back news stories on video tape rather than sending them backlive.

To keep pace with technology United States television stations have been replacing operators with broadcast automation systems to
increase profits in recent years.

Some stations (known asrepeaters or translators) only simulcast another, usually the programmes seen on its owner's flagship station,
and have no television studio or production facilities of their own. This is common in developing countries. Low-power stations
typically also fall into this category worldwide.

Most stations which are notsimulcast produce their own station identifications. TV stations may also advertise on or provide weather
(or news) services to localradio stations, particularly co-ownedsister stations. This may be a barter in some cases.

See also
Class A television service
Digital television transition
Fernsehsender Paul Nipkow: the world's first regular television service[1]
Low-power broadcasting
Must carry
Pay television
Significantly viewed out of market TV stations in the United States
Terrestrial television
List of European television stations
List of North American broadcast station classes
References
1. "22.3.1935: Erstes Fernsehprogramm der W
elt" (http://www.kalenderblatt.de/index.php?what=thmanu&lang=de&ma
nu_id=1737&sdt=20090322&maca=de-podcast_kalenderblatt-1086-xml-mrss) . Deutsche Welle. Retrieved 27 July
2015.

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