Television channel

This article is about television broadcast frequencies. For the infrastructure and issues relating to transmission, seeTelevision station.For the concept of a specific television service (known as a channel or station in some areas), seeTelevision network.

Anelectronic program guideshowing television listings inNew Orleansfor broadcast and cable channels.

Atelevision channel,orTV channel,is aterrestrial frequency or virtual numberover which a television station or television network is distributed. For example, inNorth America,channel 2refers to the terrestrial or cable band of 54 to 60MHz,withcarrierfrequenciesof 55.25 MHz forNTSCanalog video (VSB) and 59.75 MHz for analog audio (FM), or 55.31 MHz for digitalATSC(8VSB). Channels may be shared by many different television stations or cable-distributed channels depending on the location and service provider

Depending on the multinationalbandplanfor a given region,analog televisionchannels are typically 6, 7, or 8 MHz inbandwidth,and thereforetelevision channel frequenciesvary as well. Channelnumberingis also different.Digital terrestrial televisionchannels are the same as their analog predecessors forlegacyreasons, however throughmultiple xing,each physicalradio frequency(RF) channel can carry severaldigital subchannels.Onsatellites,eachtranspondernormally carries one channel, however multiplesmall, independent channelscan be on one transponder, with some loss ofbandwidthdue to the need forguard bandsbetween unrelatedtransmissions.ISDB,used inJapanandBrazil,has a similar segmented mode.

Preventing interference between terrestrial channels in the same area is accomplished by skipping at least one channel between two analog stations'frequency allocations.Where channel numbers are sequential, frequencies are notcontiguous,such as channel 6 to 7 skip fromVHFlow to high band, and channel 13 to 14 jump toUHF.On cable TV, it is possible to useadjacent channelsonly because they are all at the same power, something which could only be done terrestrially if the two stations were transmitted at the samepowerandheightfrom the samelocation.For DTT,selectivityis inherently better, therefore channels adjacent (either to analog or digital stations) can be used even in the samearea.

Other meanings

Commonly, the termtelevision channelis used to mean atelevision stationor itspay televisioncounterpart (both outlined below). Sometimes, especially outside the U.S. and in the context of pay television, it is used instead of the termtelevision network,which otherwise (in its technical use above) describes a group of geographically-distributed television stations that shareaffiliation/ownershipand some or all of their programming with one another. This terminology may be muddled somewhat in otherjurisdictions,for instanceEurope,where terrestrial channels are commonly mapped from physical channels to common numerical positions (i.e.BBC Onedoes not broadcast on any particularchannel 1but is nonethelessmapped to the1inputon most British television sets). On digital platforms, such (location) channels are usually arbitrary and changeable, due tovirtual channels.

Television station

Main articles:Television stationandDigital television transition

A television station is a type of terrestrial station thatbroadcastsbothaudioandvideototelevisionreceiversin a particular area. Traditionally, TV stations made their broadcasts by sending specially-encodedradiosignals over the air, calledterrestrial television.Individual television stations are usually grantedlicensesby agovernment agencyto use a particular section of theradio spectrum(achannel) through which they send their signals. Some stations useLPTVbroadcast translatorstoretransmitto further areas.

Many television stations are now in the process of converting from analog terrestrial (NTSC,PALorSECAM) broadcast, todigital terrestrial(ATSC broadcast,DVBorISDB).

Non-terrestrial television channels

Because some regions have had difficulty picking upterrestrial televisionsignals (particularly inmountainousareas), alternative means of distribution such as direct-to-home satellite and cable television have 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 themselvessuperstations.

Satellite and cable have created changes.Local programmingTV stations in an area cansign-upor evenbe requiredto be carried on cable, but content providers likeTLCcannot. They are not licensed to run broadcast equipment like a station, and they do not regularly provide content to licensed broadcasters either. Furthermore, a distributor likeTNTmay start producing its own programming, and shows presented exclusively on pay-TV by one distributor may besyndicatedto terrestrial stations. The cost of creating a nationwide channel has been reduced and there has been a huge increase in the number of such channels, with most catering to a small group.

From the definitions above, use of the termsnetworkorstationin reference to nationwide cable or satellite channels is technically inaccurate. However, this is an arbitrary, inconsequential distinction, and varies from company to company. Indeed, the termcable networkhas entered into common usage in the United States in reference to such channels, even with the existence ofdirect broadcast satellite.There is even some geographical separation amongnationalpay television channels in the U.S., be it programming (e.g., theBally Sportsgroup of regional sports channels, which share several programs), or simply regionalized advertising inserted by the local cable company.

Should a legal distinction be necessary between a (location) channel as defined above and a television channel in this sense, the termsprogramming service(e.g.) orprogramming undertaking(for instance,) may be used instead of the latter definition.

See also

• Barker channel
• Free-to-air
• Lists of television channels
• Pay television
• Streaming television
• Television channel frequencies

External links

• Media related toTelevision channelsat Wikimedia Commons
• What ever happened to Channel 1?