Local Television Stations

A television station is a type of broadcast station that broadcasts both audio and video to television receivers in a particular area. Traditionally, TV stations made their broadcasts by sending specially-encoded radio signals over the air, called terrestrial television. Individual television stations are usually granted licenses by a government agency to use a particular section of the radio spectrum (a channel) through which they send their signals. Some stations use LPTV broadcast translators to retransmit or rebroadcast to further areas. Television stations are a form of television channel, but not all television channels are necessarily stations.

Many television stations are now in the process of converting from analogue (NTSC, PAL, or SECAM) to digital (ATSC, DVB, or ISDB). In some countries, this is being forced on consumers and stations, while in others it is entirely voluntary.

In countries such as the United States, television stations usually just have one transmitter (or, more recently, two transmitters if the station broadcasts a digital signal in addition to its standard analog signal); most of these stations should be independent or affiliated to a television network such as ABC, CBS, Fox, or NBC.

Outside the US, television stations are generally associated with a nationwide television network, through which they get all of, or at least significant amounts of, their programming. In those countries, the signals broadcast in different areas have no well-known call-signs or other individual traits known to the general public (although a network might have regional variations, possibly broadcast from several different transmitters) and therefore from a consumer's point of view, there is no practical distinction between a network and a station.

In the United States, each nationwide terrestrial broadcast network can have a few "O&Os" — stations that it owns and operates, usually in the larger broadcast markets, like New York or Chicago. They can only own a limited number of stations because of FCC regulations.

Source: Wikipedia.org