Television channel
From Freepedia
The term television channel generally refers to either a television station or its cable/satellite counterpart (both outlined below). Sometimes, it is confused with the term television network, which (when properly utilized) describes a group of geographically distributed television stations that share affiliation/ownership and some or all of their programming with one another. (While not technically accurate, the term "network" also has come to describe some nationwide cable/satellite channels; this is an arbitrary, inconsequential distinction, and varies from company to company.)
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 to further areas.
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. In other countries such as the United Kingdom, 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, individual stations usually have no call signs or other individual traits known to the general public, and are therefore largely nonexistent in the public mind.
Because some regions have had difficulty picking up over-the-air signals (particularly in mountainous areas), direct-to-home satellite and cable television has been introduced. Television channels specifically built to run on cable or satellite blur the line between TV station and TV network. That fact led some early cable channels to call themselves superstations.
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 Los Angeles. Satellite and cable have created changes. Broadcast stations in an area can sign up to be carried on cable (called "must-carry" in the U.S.), but content providers like TLC can too. They are not licensed to run broadcast equipment like a station, and they don't regularly provide content to licensed broadcasters either. Furthermore, a distributor like TNT may begin producing its own programming, and shows presented exclusively on cable/satellite by one distributor may be syndicated to broadcast stations.
A person viewing by cable or satellite might not know what kind of organization is responsible for the program, especially if it is syndicated, so what seems to be a station or a network may be neither.
For lists by country and language, see lists of television channels.
