In broadcasting, digital subchannels are a method of transmitting more than one independent program stream simultaneously from the same digital radio or television station on the same radio frequency channel. This is done by using data compression techniques to reduce the size of each individual program stream, and multiplexing to combine them into a single signal. The practice is sometimes called "multicasting".
The ATSC digital television standard used in the United States supports multiple program streams over-the-air, allowing television stations to transmit one or more subchannels over a single digital signal. A virtual channel numbering scheme distinguishes broadcast subchannels by appending the television channel number with a period digit (".xx"). Simultaneously, the suffix indicates that a television station offers additional programming streams. By convention, the suffix position ".1" is normally used to refer to the station's main digital channel and the ".0" position is reserved for analog channels. For example, most of the owned-and-operated stations/affiliates of Ion Television transmit six streams in the following format:
|16.1||720p||16:9||Main Ion Television programming|
|16.5||Home Shopping Network|
The most of any large broadcaster in the United States, Trinity Broadcasting Network stations transmit five channels (in standard definition) and its subchannel services Hillsong Channel, JUCE TV/Smile (two networks that technically operate as separate 24-hour services, but since June 2015, air portions of their respective schedules on a single subchannel over-the-air), TBN Enlace USA and TBN Salsa. More programming streams can be fit into a single channel space at the cost of broadcast quality. Among smaller stations, KAXT-CD in San Francisco is believed to have the most feeds of any individual over-the-air broadcaster, offering twelve video and several audio feeds (all transmitted in standard definition). WANN-CD in Atlanta, Georgia, with ten video and six audio feeds, comes at a close second. Several cable-to-air broadcasters, such as those in Willmar, Minnesota and Cortez, Colorado, have multiplexed more than five separate cable television channels into subchannels of one signal.
Operating in a sector traditionally lacking subchannels, digital cable television provider Music Choice packages its nearly 50 music channels (including Music Choice Play) as digital subchannels of one channel. This is possible as the only information sent over each channel are audio feeds and a still slide which rotates every 20 seconds, displaying an advertisement and information about the current playing song on the individual channel. The audio feed and rotating stills occupy significantly less bandwidth than video feeds, leaving space for more multiplexed content.
A broadcaster saves significant costs in power and bandwidth through multiplexing in comparison to the cost of operating additional analog television stations to accommodate the extra programming. In practice, operating extra stations is impossible due to the required channel and distance separations combined with the available number of channels.
Most ATSC tuners will automatically add a new digital subchannel to their internal channel map, once it is tuned to the station carrying the new channel. However, some of these will not delete the channel if the station removes it.
The Federal Communications Commission (FCC) considers all subchannels carried by a single station to have the same call letters for legal identification purposes. However, within the broadcast sales industry, to differentiate subchannels, the initial letter of a call sign changes per subchannel. As per Nielsen, digital stations identified with a "W" call letter will generally have their subchannels identified with an "E" (.2), "G" (.3), "H" (.4), "I" (.5) or "J" (.6). Digital stations identified with a "K" call-letter will generally have their subchannels identified with an "N" (.2), "O" (.3), "Q" (.4), "R" (.5) or "S" (.6). For example, if the call letters are WFRC and the station broadcasts on channel 10, then the 10.2 subchannel is identified as EFRC, 10.3 is GFRC, 10.4 is HFRC, 10.5 is IFRC and 10.6 is JFRC. If the call letters are KFRC and the station broadcasts on channel 10, then 10.2 is identified as NFRC, 10.3 is OFRC, 10.4 is QFRC, 10.5 is RFRC and 10.6 is SFRC.
Although digital television services in Canada use the same ATSC technology as the United States, none of the stations currently broadcasting a digital signal transmit any subchannel other than a possible HD service or a standard definition simulcast of the main channel. Unlike the FCC in the United States, the body that governs Canadian broadcasting licenses, the Canadian Radio-television and Telecommunications Commission (CRTC), requires stations to file license amendments in order to be considered for permission to carry digital subchannels (this differs from the Commission's rules for premium cable television services, which allow the addition of multiplex channels consistent with the service's license requirements without the need to amend the license). On August 17, 2012, the CRTC gave approval to Leamington, Ontario community station CFTV-TV to broadcast four local subchannels on its digital signal, making it the first station in Canada to launch original content on its multiplex channels.
Some Mexican TV stations use digital subchannels as they are used in the United States. The Sistema Público de Radiodifusión del Estado Mexicano, a public broadcaster, operates 26 multiplexed transmitters throughout Mexico carrying five to six public television services, while XHTRES-TDT carries Imagen Radio audio on a subchannel.
One notable experiment involving digital subchannels in Mexico was undertaken by TV Azteca, which used its three muxes in the Mexico City area to broadcast a service called Hi-TV, featuring several channels encoded in H.264 MPEG-4 encoding, which while available in the ATSC standard is not common on TV sets. This use of subchannels as pseudo-restricted signals within non-restricted channels was placed under investigation and litigation with authorities at COFETEL (the Federal Teleommunications Commission), involving a fine of 4,453,150 Mexican pesos. HiTV subchannels began broadcasting on an intermittent basis in 2013 and were almost completely deactivated in late 2014.
Televisa and TV Azteca use subchannels in rural areas in order to ensure national network service. As a result, since 2016, many areas that formerly had only one Azteca or Televisa network now have both from the same transmitter. Additionally, TV Azteca has two national services that are broadcast as subchannels in most areas, a+ and adn40.
In October 2016, the IFT put into effect new guidelines for the numbering of virtual channels. As a result, national networks use consistent numbers nationwide; SPR transmitters now use four or five major channel numbers (11, 14, 20, 22, and 45 in some areas). Prior to this, digital television stations usually used virtual channels corresponding to their former analog positions, still the case for certain local stations.
The IFT enforces minimum bitrates for digital television channels, and as such it is not possible for a station to broadcast two HD feeds in MPEG-2 encoding. Most HD feeds are provided in 1080i with all subchannels in 480i standard definition.
Australian digital subchannels are currently divided between high definition (HD), standard definition (SD) and radio subchannels (the latter type is only carried by the stations of non-commercial networks SBS Television and ABC Television). Due to technical reasons, each network is currently only permitted one HD sub channel. All networks use their HD subchannel to provide a simulcast of their primary channel.
Inclusive of their primary standard definition channels (ignoring HD):
Community television stations in Melbourne (C31) and Adelaide (44 Adelaide) also broadcast digital signals, however they typically only broadcast a single SD subchannel which simulcasts that station's primary channel.
There have been a number of issues surrounding the introduction of digital subchannels in Australia. The first subchannels launched by the ABC – ABC Kids and Fly TV – closed after less than two years in operation in 2003 as a reaction to budget cuts by the conservative Howard Government under Communications Minister Alston and low viewership (partly due to the limited distribution of set-top boxes); and commercial broadcasters could not legally air a digital subchannel other than a single high-definition service until 2009.
As most digital services in Europe rely on more complex methods of multiplexing, where a large number of digital channels by many different broadcasters can be broadcast on one single frequency, the concept of a subchannel is instead applied to the variety of channels that are produced by a single company. This can vary widely depending on the country: for example, ITV currently has four of its digital channels (ITV, ITV2, ITV3 and ITV4) broadcasting on one multiplexed service, while two others (ITV2 +1 and CITV) are each broadcast on another, separate multiplex.
As the amount of data which can be carried on one digital television channel at one time is limited, the addition of multiple channels of programming as digital subchannels comes at the expense of having less available bandwidth for other purposes, such as the ability to transmit high definition content. A station carrying multiple subchannels will normally limit itself to one high-definition channel (or in some cases, two HD channels), with any additional channels being carried in standard definition. Because of the tradeoffs, stations owned by CBS Corporation through its CBS Television Stations subsidiary (which include owned-and-operated stations of CBS and The CW, and some independent stations) generally opted not to carry digital subchannels and transmitted only a 1080i high definition main feed; this changed in 2013 with the addition of dedicated local news channels on CBS O&Os in New York City and Philadelphia (the company later announced the creation of Decades, a multicast network part-owned by CBS which now airs on all CBS-owned stations).
It is possible for stations to carry more than two subchannel feeds in HD, at least nominally. Actual picture quality may be comparable to DVD video. Some examples of stations broadcasting in this format are:
|Callsign||Market/city of license||Description|
|KBMT||Beaumont, Texas||In addition to broadcasting ABC programming on its main channel in 720p, KBMT transmits NBC programming on its second subchannel and Cozi TV on its third subchannel (all three channels are broadcast in 16:9 widescreen, although the DT3 subchannel is presented in 480i); the station also offers Me-TV programming in 480i 4:3 SD on its fourth subchannel.|
|KXII||Sherman, Texas||KXII carries Fox programming in HD on its third subchannel and MyNetworkTV programming in SD on its second subchannel, in addition to carrying CBS programming in HD on its main channel.|
|KTEN||Ada, Oklahoma||In addition to carrying NBC programming in HD on its main channel in 1080i, KTEN carries CW programming in 720p HD on its second subchannel and ABC programming in 720p HD on its third subchannel.|
|WGXA||Macon, Georgia||WGXA began carrying ABC programming on its second digital subchannel on January 1, 2010, after WPGA-TV disaffiliated from the network in a compensation and program content dispute; WGXA transmits its Fox-affiliated main channel and its ABC subchannel in 720p (the native HD resolution format for both networks). The station's main channel is branded as "Fox 24" and maps via PSIP as 24.1, while the ABC subchannel brands as "ABC 16," in reference to the station's physical digital channel 16 (but maps its PSIP virtual channel as 24.2). A standard definition feed of Comet was launched on its third subchannel in October 2015.|
|WKBN-TV||Youngstown, Ohio||WKBN carries a simulcast of Fox-affiliated sister station WYFX-LD on its second digital subchannel in order to make its programming available to the entire market (WYFX is licensed as a low-power station), in addition to transmitting CBS programming on its main channel. Both subchannels transmit in 720p HD (in the case of the main channel, this differs from CBS's preferred 1080i HD format). Comparatively, its sister station, ABC affiliate WYTV transmits both its MyNetworkTV-affiliated second subchannel and its Bounce TV-affiliated third subchannel in standard definition (since ABC and MyNetworkTV both transmit in 720p, the 33.2 subchannel could be reconfigured to high definition in a manner that creates limited issues in regards to bandwidth for the 33.3 subchannel). In 2017, WKBN sold its spectrum for $34 million as part of the FCC's spectrum reallocation program and will move its broadcasting to WYTV's frequency, limiting more bandwidth to both stations.|
|WTHI-TV||Terre Haute, Indiana||In addition to airing its main CBS program feed in 1080i, WTHI transmits Fox programming in 720p HD on its second subchannel and CW+ programming in 720p HD on its third subchannel, in addition to a standard definition 480i widescreen Ion Television feed on its fourth subchannel.|
|WTRF-TV||Wheeling, West Virginia||In addition to carrying CBS programming in 1080i on its main channel, WTRF-TV carries ABC programming in 720p on its third subchannel. Until the network moved to a subchannel of NBC affiliate WTOV-TV in September 2014, WTRF carried Fox programming in 720p on its second subchannel, which remains affiliated with MyNetworkTV.|
|WUVG-DT||Atlanta, Georgia||WUVG, which operates as a Univision owned-and-operated station, carries UniMás in 1080i HD on its second subchannel due to a lack of a sister full-power station, and both GetTV and Escape in 480i on their respective third and fourth subchannels in addition to carrying Univision programming on its main channel in 1080i HD.|
|WATM-TV||Johnstown, Pennsylvania||In addition to carrying ABC programming in 720p on its first subchannel, WATM-TV transmits Fox programming of its sister station, WWCP-TV, in 720p on its second subchannel. This enables the WWCP-TV signal to reach the State College area. WATM-TV further transmits This TV and Antenna TV programming in 480i on its third and fourth subchannels, respectively.|
|WKTV||Utica, New York||In addition to carrying NBC programming in 1080i on its first subchannel, WKTV transmits CBS programming on its second subchannel and The CW on its third subchannel, both in 720p HD (in the case of WKTV-DT2, this differs from CBS's preferred 1080i HD format). The station also offers MeTV programming in 480i 4:3 SD on its fourth subchannel.|
|WTVG||Toledo, Ohio||In addition to carrying ABC programming in 720p on its first subchannel, WTVG-TV transmits The CW programming in 720p on its second subchannel. This allows Toledo, Findlay, and surrounding areas to receive CW programming over-the-air; in the past CW and WB programming was exclusive to local cable viewers through Buckeye CableSystem via their cable-only Toledo 5 channel, requiring antenna viewers to pull in WKBD-TV/Detroit from the north for CW programming. WTVG-TV further transmits WeatherNation TV in 480i on its third subchannel.|
|WGEM-TV||Quincy, Illinois||The station broadcasts four subchannels in total, all in HD: the main subchannel in 1080i, and three additional subchannels in 720p.|
Outside the United States – especially in Europe – high-definition feeds are rarer, and most countries only provide a single high-definition service for each broadcaster. For example, in France, there are only five HD services: one each for TF1, France 2, Canal+, M6 and Arte; in the United Kingdom, four HD services are currently transmitted over terrestrial frequencies: BBC One HD, BBC Two HD, ITV HD and Channel 4 HD (S4C Clirlun is broadcast in Wales instead of Channel 4 HD).
In the United States, digital subchannels have been used to provide programming from multiple major networks on a single television station. This has become prevalent since the late 2000s in smaller markets that have as few as one or two commercial stations, which during the era of analog television, would not have been able to carry the complete programming lineups of all four major commercial networks (CBS, NBC, ABC and Fox) because of the station's own local and syndicated programming commitments, and overlapping network programs that would be tough to schedule outside of regular timeslots. A prime example is the Wheeling, West Virginia/Steubenville, Ohio market, which for decades was home to only two stations (CBS affiliate WTRF-TV and NBC affiliate WTOV-TV; the cable-only WBWO also served the market as a WB and now as a CW affiliate) and had to mostly rely on stations in Pittsburgh (and to a lesser extent Columbus and Youngstown, Ohio) to view programming from other networks. However, the advent of digital television allowed WTRF to launch two digital channels (one as a primary Fox/secondary MyNetworkTV affiliate, the other affiliated with ABC) while still carrying CBS programming in full on its main signal (WTOV later took the Fox affiliation for its second subchannel in September 2014).
Upon their launches in September 2006, The CW and MyNetworkTV were among the first conventional networks to actively utilize subchannel-only affiliations in markets where a standalone station is not available to affiliate with; this is particularly true of The CW's small-market feed, The CW Plus, which originally consisted mostly of cable-only affiliations (by way of inheriting the model and much of the affiliate body of predecessor The WB 100+ Station Group). Since its launch, affiliates of other major networks have taken over the operations of cable-only CW Plus affiliates (or even outright replacing WB 100+ cable channels at the launch of The CW) and began transmitting the service over subchannels to reach viewers who do not subscribe to a pay television service. Some Spanish language networks (such as MundoFox, Estrella TV and Mexicanal) have also been carried on digital subchannels, either as subchannel-exclusive services or to provide programming to markets where a main channel affiliation may not be available. Other stations have launched subchannels with an independent station format on their DT2 signals (such as WTTV in Indianapolis, Indiana – a market with enough commercial stations able to support affiliations with all six networks and a standalone independent, although the seventh (WTTK) instead acts as a WTTV satellite – which converted its 4.2 subchannel as an independent station in January 2015 as a result of owner Tribune Media selling the local rights to the CW affiliation that was to move from its main feed on 4.1 to WISH-TV, whose CBS affiliation was assumed by WTTV).
Digital subchannels are also used to relay stations beyond their traditional signal coverage areas to reach an entire market. In the Upper Peninsula of Michigan and northern Minnesota, many of these stations are on duplicate frequencies to cover a large market area. This is used to duplicate network service for stations that are part of duopolies, where transmitters scattered through a large geographical area allow multiple networks and channels to be carried. The most prominent example is the Granite Broadcasting Corporation's virtual quadropoly in Duluth, Minnesota, which consists of two separate full-power stations, NBC affiliate KBJR-TV and CBS affiliate KDLH, which combined carry three subchannels (two affiliated with major networks – CW Plus affiliate "Northland CW 2" on KDLH and MyNetworkTV affiliate "My9" on KBJR – and the third, a local weather subchannel on KBJR). While KDLH carries the CW subchannel on their DT2 feed and KBJR carries the MyNetworkTV subchannel on its DT2 feed on their primary signals, all five channels are carried on satellite station KRII in Chisholm, providing the Iron Range region (located north of Duluth) programming from networks that were previously unavailable over-the-air. In the Traverse City-Cheboygan market in Upper Michigan, NBC affiliate WPBN/WTOM also simulcasts sister station WGTU/WGTQ, providing that station's ABC programming to the entire market; CBS affiliate WWTV/WWUP carries its Fox-affiliated sister WFQX/WFUP on their DT2 subchannel to expand their coverage area further north into the eastern portion of the Upper Peninsula.
In many cases, these "new" channels are existing secondary channels that were carried by a low-power or Class A station or by a cable television channel. Often, the owner of a full-power television station acquires or already owns a low-power secondary station in the same market to carry another network. The use of a digital subchannel on a full-power television station as a replacement for low-power station greatly increases the available coverage area for its programming.
Because of interference issues that stations transmitting on the low VHF band (channels 2 to 6) often experience, some stations broadcasting on these frequencies are relayed on the subchannels of stations that are less prone to interference. An example of this is CBS affiliate WRGB in Albany, New York. While WRGB broadcasts its main digital on VHF channel 6 in high definition, CW-affiliated sister station WCWN relays a standard-definition subchannel feed of WRGB over its digital channel 45.
Networks dedicated to sports programming have been launched specifically for use on digital subchannels. Until 2010, CBS affiliates often subdivided four temporary subchannels in order to show all of the early round games of the NCAA Men's Basketball Tournament in addition to those broadcast on the main digital channel (this was superseded as a result of a new television agreement with the NCAA that took effect in 2011, which gave cable networks TBS, TNT and TruTV partial rights to the tournament). Most of the major professional sports leagues, however, have strict prohibitions against using subchannels for carrying multiple game broadcasts and only allow one game to be aired in a market at one time (outside of Los Angeles, where if the Rams and Chargers play at the same time, Fox is allowed to broadcast the second game on MyNetworkTV affiliate KCOP-TV, or CBS on independent KCAL-TV, depending on the game's carrier that specific week); all four of the major sports leagues (the NFL, the NBA, Major League Baseball and the NHL) have out-of-market sports packages that require a pay television subscription and generate significant revenue for the leagues.
Most sports programming on digital subchannel broadcasters has been relegated to low-budget content such as amateur athletics, extreme sports, and hunting and fishing programming geared toward outdoorsmen, though minor league baseball, American Hockey League hockey and other minor league sports may also be seen. Prominent team sports programming on digital subchannels is rare; the general trend for sports programming tends to eschew the free-to-air model that digital subchannels use, and the cost of rights fees for most sports requires that they air on channels that air on cable and satellite television services and thus can recuperate costs through retransmission consent. Channels such as Sportsman Channel (and the now-defunct Universal Sports) that began as digital subchannel networks now operate as cable and satellite-exclusive services. There are nonetheless a few multicast channels that have broadcast familiar sports programs: Bounce TV, for instance, carried college football from historically black colleges and universities until 2013.
In January 2016, Sinclair Broadcast Group launched a 24-hour feed of its American Sports Network sports syndication service on subchannels of ten stations owned and/or operated by the group; the ASN multicast network was subsequently replaced by Stadium in August 2017, following the formation of a multi-platform network venture with the Chicago White Sox's Silver Chalice unit and 120 Sports.
Although not to the same level as in the late 2000s due to the population of entertainment-based multicast services, many local stations have used or currently use subchannels to carry continuous news or local weather content; in particular, there have been at least four networks that have been created to serve this audience: NBC Weather Plus (a service exclusive to NBC stations that operated from 2004 to 2008), The AccuWeather Channel, WeatherNation TV (which also maintains limited exclusive distribution on pay television services) and TouchVision. Locally programmed news subchannels (such as News 9 Now / News on 6 Now on KWTV in Oklahoma City and KOTV in Tulsa, Oklahoma or NewsChannel 5+ on WTVF in Nashville, Tennessee) often carry rebroadcasts and simulcasts of local news programs seen on the station's main feed, in some cases displaying a ticker with news headlines and weather forecasts to provide updated information.
Subchannels also allow stations to air news programs without fully pre-empting normally scheduled programing on the station's main feed. During significant breaking news or severe weather events, for instance, a station may choose to air extended news coverage on either its main channel or a subchannel and air network programming on the other. Thus, the station can accommodate viewers wanting to watch either regular programming or news coverage. Some sports leagues, most notably the NFL, have strict rules against their game broadcasts airing on a subchannel.
Since the late 2000s, entertainment-based specialty networks (also known as "diginets") have been created specifically for subchannels, most commonly those dedicated to airing reruns of classic television series (such as Me-TV, the Retro Television Network, Cozi TV and Antenna TV) and movies (such as This TV, GetTV and Movies!). Some networks (such as the African-American focused Bounce TV, the female-targeted Escape and the male-targeted Grit) feature programming aimed at specific demographics. With few exceptions (such as Bounce TV and the now-defunct Live Well Network), diginets typically do not offer first-run original programming, relying on acquired content from programming distributors (most popularly, television series from the 1980s and earlier) to fill their schedules. Some stations (such as K38IZ-D in Phoenix, Arizona) carry locally programmed channels offering classic television shows and music videos on their digital subchannels. With MTV's shift away from music videos since the 1990s, subchannel networks focusing entirely on music videos have also been attempted (such as ZUUS Country, Heartland, Tr3s and TheCoolTV), however many have either been unable to gain national coverage or have lost significant market share due to various issues (for example, LIN Media, the Sinclair Broadcast Group and the Journal Broadcast Group terminated or opted against renewing deals with TheCoolTV between 2011 and 2013; Journal, in particular, cited TheCoolTV parent Cool Music Network, LLC's failure to pay licensing fees behind its removal of the network in a lawsuit filed against the company in 2011).
Although the revenue potential is limited, many broadcasters have found subchannel-only networks to be a means of generating extra advertising revenue, as they are easily marketable to a given demographic (although they do not enjoy the same retransmission consent revenue stream from cable providers as other networks do). There have been a few notable holdouts as late as 2014 such as the Meredith Corporation (only a few of its stations have subchannels, and some of these primarily carry only local news or weather services, or in the case of WGGB-TV/Springfield, Massachusetts, allows a Fox subchannel affiliate to operate in a market with limited full-power signals traditionally beholden in the past to the Hartford, Connecticut market to the south for CBS, Fox, WB and UPN affiliates besides WGGB's ABC programming and WWLP's NBC affiliation) and the Nexstar Broadcasting Group (which previously used subchannels for the sole purposes of simulcasting co-owned/managed sister stations to reach an entire market or to carry programming from major networks in smaller markets, and often eliminated subchannels affiliated with multicast services following station acquisitions). Nexstar has since added multicast services such as Bounce TV and WeatherNation TV on some of its stations. Unlike the major broadcast networks, diginets carried by local stations not associated with the five major networks or MyNetworkTV are often carried on higher cable channel placements (usually within the digital cable tiers) not readily found by most subscribers. Satellite and IPTV providers generally do not carry multicast networks unless the local station also secondarily carries a major network on that subchannel.
Most diginets reach affiliation agreements with a limited number of station owners prior to launch, before expanding their national coverage through additional deals made after their debut (by comparison, Fox, The CW, MyNetworkTV and to a lesser extent, The WB and UPN, had initial station coverage reaching 60%+ of all U.S. television households through affiliation deals that were largely made before their launches, in order to have wide distribution in at least the top 100 markets). Since the majority of multicast networks are carried on major network affiliates, some full-power stations are recitant about further compressing bitrate space to fit more than one subchannel at the expense of the picture quality of their high-definition main feed. As well, in markets with fewer than six stations, available subchannel space is tighter and some multicast networks may not be able to gain affiliations especially if one of the stations uses a subchannel for the primary purpose of carrying programming from a major network (which are also often transmitted in HD, limiting bitrate space). Some networks remedy this in certain markets by affiliating with low-power stations that do not carry a major network. As of 2014, only 12 primarily subchannel-only networks reach at least 50% of all U.S. markets (with MeTV, which is available in 91% of the country — a national reach comparable to the six major commercial networks and PBS — being the largest).
Diginets with wider national coverage and decent viewership are more likely to attract major advertisers, although most rely on smaller-scale advertisers such as national law firms, mortgage providers and direct response advertisers. Multicast networks often make barter deals to secure affiliations in which advertising inventory is split between the network and the station, however some networks enter into subchannel leasing deals (often if they are unable to secure sufficient cable distribution), in which the network handles the sale of advertising inventory and pays its affiliates a monthly licensing fee to carry its programming.
Many PBS member stations around the United States broadcast their main channel in high definition and up to three standard definition subchannels; however, a few reconfigure their digital channels depending on daypart, carrying four standard definition channels during the daytime, reducing them to one HD and one SD channel at night due to technical limitations at the station's level that may prevent it from carrying PBS programming in HD full-time and maintain multiple full-time subchannels like other member stations. PBS stations often carry additional national channels such as PBS HD (PBS Satellite Service), PBS Kids, World, and Create. In the Washington, D.C. area, MHz Networks is available as ten subchannels transmitted by two stations, with their virtual channels mapped uniformally, making them appear as if they are transmitted by one station.
In some U.S. states, statewide educational, cultural or public affairs services are carried on a digital subchannel of a PBS member station or network (such as the Minnesota Channel, Wisconsin Channel or New York State broadcaster ThinkBright TV). The use of subchannels has also allowed educational television broadcasters to sell off former secondary PBS analogue stations to commercial broadcasters (such as WNEQ in Buffalo, which its sister station WNED-TV sold in 1999 to LIN TV (now owned by Media General) to become WNLO, now a CW affiliate), as the additional educational content these separate stations once provided can now be carried by multiple subchannels of a single parent station. Subchannels also allow some educational stations to devote an entire channel to telecourses, which are recorded by instructors and students for later use, allowing the station's main channel to air a generalized schedule in the morning and overnight hours.
A digital subchannel can be used to restore service from a station that has been knocked off the air due to an antenna tower collapse; the affected signal would be made available in standard-definition, or even in compressed high definition, on a subchannel of another local station, most often a competitor. ABC affiliate KATV in Little Rock, Arkansas was forced to follow this path in 2008, moving its digital signal to a subchannel of MyNetworkTV affiliate KWBF (now KARZ-TV) after a tower collapse knocked its main signal offline. The virtual channel numbering scheme allows an existing licensed broadcaster to keep its displayed channel number unchanged (in the case of KATV, PSIP channel 7) even if the signal is carried physically as a subchannel of another local station.
During the Station Fire in 2009, NBC owned-and-operated station KNBC in Los Angeles temporarily replaced programming from NBC Plus and Universal Sports on its subchannels with standard-definition feeds of its two Spanish language sister stations – independent station KWHY-TV (now a MundoFox affiliate, since sold to the Mueriello Group) and Telemundo owned-and-operated station KVEA – as an emergency measure in the event that the transmitters of those stations were destroyed or disabled as the fire reached Mount Wilson, where the transmitter facilities of most Los Angeles area stations are based.
In rare cases, digital television broadcasters have included a service known as DTV radio, in which the audio of a commonly owned broadcast radio station is simulcast over a subchannel (for instance, KPJK in San Mateo, California broadcasts former FM sister KCSM on its DT3 signal). WANN-CD in Atlanta offers six radio stations owned by iHeartMedia, in addition to ten television channels.
Non-broadcast content, subscription television channels or datacasting operations unrelated to the main television programming are also permitted by the digital television standards but are less-commonly used. USDTV was an over-the-air pay television service that used H.264 compression instead of standard MPEG-2. Mobile DTV now uses MPEG-4 compression, which like H.264 yields a much lower bitrate for the same video quality. For example, the Sezmi TV/DVR service uses broadcast digital subchannels (not in the clear) in selected cities to stream a limited number of "cable" channels to its subscribers for an additional fee to supplement its otherwise free digital video recorder (DVR) service allowing recordings of local broadcast channels and free and subscription internet content.
Digital television supports multiple digital subchannels if the 19.39 Mbit/s (megabits per second) bitstream is divided. Therefore, station managers and broadcast engineers could run any of the following scenarios using one 6 MHz channel (note that the actual bitrate moves up and down, due to usage of variable bitrate encoding):
|1× 1080i or 720p HDTV (19 Mbit/s)||No additional subchannels.|
|1× 1080i or 720p HDTV (15 Mbit/s)||+ 1||480p or 480i SD subchannel (~3.8 Mbit/s)|
|1× 1080i or 720p HDTV (11 Mbit/s)||+ 1||720p HDTV (8 Mbit/s) subchannel|
|1× 1080i or 720p HDTV (11 Mbit/s)||+ 2||480p or 480i SD subchannels (~3.8 Mbit/s each)|
|1× 720p HDTV channel (8 Mbit/s)||+ 3||480p or 480i SD subchannels (~3.8 Mbit/s each)|
|2× 720p HDTV channels (9.6 Mbit/s each)||No SD subchannels|
|2× 720p HDTV channels (7.8 Mbit/s each)||+ 1||480p or 480i SD subchannel (~3.8 Mbit/s)|
|No HDTV channels||+ 2||480p or 480i SD subchannels (~6 Mbit/s each)|
|No HDTV channels||+ 3||480p or 480i SD subchannels (~6 Mbit/s each)|
|No HDTV channels||+ 4||480p or 480i SD subchannels (~4.2 Mbit/s each)|
|No HDTV channels||+ 5||480p or 480i SD subchannels (~3.8 Mbit/s each)|
|No HDTV channels||+ 6||480p or 480i SD subchannels (~3.1 Mbit/s each)|
|No HDTV channels||+ 7||480p or 480i SD subchannels (~2.7 Mbit/s each)|
|No HDTV channels||+ 8||480p or 480i SD subchannels (~2.4 Mbit/s each)|
|No HDTV channels||+ 9||480p or 480i SD subchannels (~2.1 Mbit/s each)|
|No HDTV channels||+ 10||480p or 480i SD subchannels (~1.9 Mbit/s each)|
|No HDTV channels||+120||mono radio subchannels (~0.2 Mbit/s each)|
With improvements in MPEG encoding, and tighter VBR encoding, more subchannels can be combined. 1×720p + 4×480i is becoming more common.
|60 Hz||50 Hz|
Various forms of digital radio also allow for multiple program streams.
JUCE TV is a youth-oriented Christian television network owned and operated by the Trinity Broadcasting Network. The network is aimed at teenagers and young adults between the ages of 13 and 30 years, and features a format similar to MTV and MTVU, airing Christian music videos, and original content such as Christian-themed entertainment and lifestyle programming, along with some church services.
JUCE TV is carried over-the-air on digital subchannels of TBN owned-and-operated and affiliated stations nationwide, usually on the third subchannel (for example, if the local TBN station broadcasts on channel 17, then JUCE TV would be carried on digital subchannel 17.3). Since June 1, 2015, the network has shared subchannel space with sister network Smile of a Child TV over-the-air; however, JUCE TV continues to operate as a separate 24-hour channel on pay television providers as well as on select digital streaming platforms that offer TBN's six U.S. networks.The network is also currently available through various cable providers nationwide as well as across North and Central America on Glorystar through the Ku band Galaxy 19 satellite and on C-Band Galaxy 14 satellite. The network is also live-streamed on its and TBN's official website as well as on the TBN Mobile App for the iPad, iPhone and iPod Touch. JUCE TV and other TBN-owned networks are broadcast internationally free-to-air via satellites such as ABS1 to India and Middle East on Ku band, Intelsat 701 and DTH to Australia and New Zealand on Optus B3 and also to Europe, North Africa and the Middle East via Eutelsat (Hotbird 13°E) and Agila 2 satellite (both C-band and Ku band signal) in Asia and the Philippines. Some JCTV programming can also be seen on Grace TV in Canada and on Trinity Broadcasting Network Europe.KCSG
KCSG, virtual channel 8 (UHF digital channel 14), is a MeTV-owned-and-operated television station licensed to Cedar City, Utah, United States. Owned by Weigel Broadcasting, the station maintains studio facilities located on West 1600 South Street in St. George, and its transmitter is located on Cedar Mountain, southeast of Cedar City. The station has a network of about 15 broadcast translators that extend its over-the-air coverage throughout southwestern Utah. KCSG is also available on DirecTV, Dish Network, Galaxy 19, and cable systems throughout the geographically large Salt Lake City market.KCWH-LD
KCWH-LD, virtual and UHF digital channel 18, is a CW+-affiliated television station licensed to Lincoln, Nebraska, United States. Owned by Gray Television, it is a sister station to Lincoln CBS affiliate KOLN (channel 10) and its satellite KGIN (channel 11) in Grand Island, and NBC/MyNetworkTV/MeTV affiliate KSNB-TV (channel 4) in Superior. KCWH-LD's studios and transmitter are located at the KOLN studios on North 40th Street in Lincoln.
For most of its history, KCWH-LD, under the call sign K18CD, served as a translator for KSNB-TV, whose signal is weak in Lincoln. In 2018, Gray converted the station into a standalone CW affiliate, simulcast on the third digital subchannel of SonLife affiliate KNHL (channel 5) in Hastings (which is owned by Legacy Broadcasting, but is in the process of being acquired by Gray) and the second digital subchannel of Fox affiliate KIIT-CD (channel 11) in North Platte. NBC programming (via KSNB) remains available in Lincoln on KOLN's second digital subchannel.KFTU-DT
KFTU-DT, virtual channel 3 (UHF digital channel 36), is a UniMás owned-and-operated television station serving Tucson, Arizona, United States that is licensed to Douglas. The station is owned by the Univision Local Media subsidiary of Univision Communications, as part of a duopoly with Green Valley-licensed Univision owned-and-operated station KUVE-DT (channel 46). The two stations share studios on Forbes Boulevard in Tucson; KFTU's transmitter is located on Juniper Flats Road northwest of Bisbee.
KFTU-CD, virtual channel 34 (UHF digital channel 18), is a low-power Class A television station licensed to Tucson that rebroadcasts KFTU-DT to the city, as KFTU's coverage area falls well short of Tucson proper. KFTU-DT is also rebroadcast on KUVE's second digital subchannel in order to reach the entire market; this signal can be seen on UHF channel 34.2 (or virtual channel 46.2 via PSIP) from a transmitter atop Mount Bigelow. Likewise, KUVE is rebroadcast on KFTU's second digital subchannel. Master control and most internal operations for KFTU and KUVE are based at the studios of sister station KTVW-DT on 30th Street in southern Phoenix.
Similar to sister station KFPH-DT in Flagstaff, KFTU brands itself as UniMás 34, using the over-the-air channel of its Class A repeater in Tucson. On cable, the station is available on Cox Communications channel 60.KLDO-DT2
KLDO-DT2 is the LATV-affiliated commercial television station for the Laredo, Texas and Nuevo Laredo, Tamaulipas markets. It is the second digital subchannel of Univision affiliate KLDO owned by Entravision Communications. Over-the-air, KLDO-DT2 broadcasts a standard definition digital signal on UHF channel 19.2 from a transmitter at its studios in Laredo, Texas. The origins of KLDO-DT2 began in 2009 when KLDO-TV announced that it would launch a LATV affiliate on channel 19.2.KTES-LD
KTES-LD, virtual channel 40 (UHF digital channel 26), is a low-powered MeTV-affiliated television station licensed to Abilene, Texas, United States. Owned by the Sinclair Broadcast Group, it is a sister station to Sweetwater-licensed ABC affiliate KTXS-TV (channel 12). The two stations share studios on North Clack Street in Abilene and transmitter facilities near Trent, Texas. In addition to its own digital signal, the station is simulcast in standard definition on KTXS' third digital subchannel.KTIV
KTIV is an NBC-affiliated television station licensed to Sioux City, Iowa, United States. It broadcasts a high-definition digital signal on UHF channel 14 (or virtual channel 4 via PSIP) from a transmitter near Hinton, Iowa. Owned by Quincy Media, KTIV maintains studio facilities on Signal Hill Drive in Sioux City.
KTIV also carries The CW, which replaced The WB network in September 2006, on its 4.2 digital subchannel, and on June 6, 2013, the station launched a third digital subchannel on 4.3, identifying locally as MeTV Siouxland.KUNA-LP
KUNA-LP is a low-powered Telemundo-affiliated television station licensed to Indio, California, United States, serving Palm Springs and the Coachella Valley. It broadcasts an analog signal on UHF channel 15 from a transmitter in the Indio Hills.
Owned by the News-Press & Gazette Company, it is a sister station to Palm Springs-licensed ABC affiliate KESQ-TV (channel 42), Cathedral City-licensed Class A CBS affiliate KPSP-CD (channel 38), Class A Fox affiliate KDFX-CD (channel 33.2, licensed to both Indio and Palm Springs), and Palm Springs-licensed low-powered CW affiliate KCWQ-LD (channel 2). The five stations share studios on Dunham Way in Thousand Palms.
Due to its low-powered status, KUNA-LP does not broadcast a digital signal of its own, and there are no immediate plans to convert the station's signal to digital. However, the station is simulcast in high definition on KPSP's second digital subchannel (UHF channel 38.8 or virtual channel 15.1 via PSIP), and in standard definition on KESQ's eighth digital subchannel (UHF channel 42.8 or virtual channel 15.2 via PSIP). Both KPSP and KESQ transmit from Edom Hill northeast of Cathedral City and I-10.KUVE-DT
KUVE-DT, virtual channel 46 (UHF digital channel 34), is a Univision owned-and-operated television station serving Tucson, Arizona, United States that is licensed to Green Valley. The station is owned by the Univision Local Media subsidiary of Univision Communications, as part of a duopoly with Douglas-licensed UniMás owned-and-operated station KFTU-DT (channel 3). The two stations share studios on Forbes Boulevard in Tucson; KUVE's transmitter is located atop Mount Bigelow.
KUVE operates a low-power Class A translator station: KUVE-CD (virtual channel 42, UHF digital channel 36), licensed to Tucson; this station's transmitter is located atop the Tucson Mountains. KUVE-CD serves the northwest parts of the metropolitan area shielded from the primary station by Mount Lemmon. KUVE-DT is also rebroadcast on the second digital subchannel of KFTU-DT, whose transmitter is located on Juniper Flats Road northwest of Bisbee. Likewise, KFTU is rebroadcast on KUVE's second digital subchannel.
KUVE is a semi-satellite of Phoenix-based KTVW-DT (channel 33). It broadcasts an identical schedule to KTVW, including their newscast, Noticias 33, although the stations maintain separate broadcast facilities. However, a three-hour overnight segment of locally-produced programming is seen on KUVE on Monday mornings, to comply with KUVE-CD's Class A license. Master control and most internal operations for KUVE and KFTU are based at KTVW's studios on 30th Street in southern Phoenix.KYCW-LD
KYCW-LD, virtual channel 25 (UHF digital channel 19), is a CW-affiliated television station licensed to Branson, Missouri, United States. Owned by Gray Television, it is a sister station to Springfield-licensed NBC affiliate KYTV (channel 3) and ABC affiliate KSPR-LD (channel 33). The three stations share studios on West Sunshine Street in Springfield; KYCW-LD's transmitter is located on Switchgrass Road, north of Fordland.
KYCW-LD's low-powered digital broadcasting radius does not reach the entire market. Therefore, KYCW-LD is simulcast in standard definition on KYTV's third digital subchannel (UHF channel 44.5, mapped to virtual channel 33.2 via PSIP) from a transmitter located in Fordland. KYCW-LD is also simulcast on the second digital subchannel of low-power stations KSPR-LD and K17DL-D. KYCW-LD uses the same transmitter and tower facilities as the defunct KGHZ (formerly KSPR until a February 2017 channel shuffle), which had their license turned into the FCC on May 31, 2017 as part of the FCC's 2016 spectrum auction, albeit at a lower power to meet KYCW-LD's license requirements.KZSJ
KZSJ (1120 AM) is a radio station broadcasting a World Ethnic format. Licensed to San Martin, California, United States, it serves the South Santa Clara County area. The station is currently owned by Bustos Media Holdings. Programming is produced by Quê Hương Media, which used to air on a digital subchannel of KAXT-CD.LAT TV
LAT TV was a Spanish-language television network emphasizing family-oriented and educational programming. It was owned by Latin America Broadcasting of Houston, Texas and launched in May 2006, initially on five low-power television stations in Texas and Arizona, four of which were in top-ten Hispanic markets. The network folded in May 2008.List of MyNetworkTV affiliates
The following is a list of affiliates of MyNetworkTV, a former network which is now defined as a programming service.List of television stations in the United States by call sign (initial letter K)
This is a list of full-power television stations in the United States having call signs beginning with the letter K. Low-power TV stations, those with designations such as KAGN-LP or K11XQ, have not been included in this list.
See also the list of TV stations beginning with W and the list of TV stations beginning with X.List of television stations in the United States by call sign (initial letter W)
This is a list of full-power television stations in the United States having call signs beginning with the letter W. Low-power TV stations, those with designations such as WAOH-LP or W16CE, have not been included in this list.
See also the list of TV stations beginning with K and the list of TV stations beginning with X.TVMT
TVMT is a full-time television channel available on Montana cable systems, along with the DT5 digital subchannel on the member stations of the Montana PBS state network; service commenced January 2007. TVMT covers both houses of the Montana State Legislature, as well as other hearings staged in the Montana State Capitol at Helena.
TVMT is available to 350,000 cable TV customers across Montana. 
The channel does not have edited content.
The service was first introduced in 2001 as a part-time service, offering only Legislature coverage on local Government-access television (GATV) cable channels in Montana.The Worship Network
The Worship Network, or Worship, is a broadcast television service that provides alternative Christian worship-themed programming 24 hours a day, seven days a week. The network is based in Nashville, Tennessee, in the United States, and is available in more than 50 countries. It is owned by Christian Network, Inc. (CNI).
The network was broadcast on a digital subchannel of ION Television's owned and operated stations placed after ION Life on a station's digital channel map, usually broadcasting on the -DT4 subchannel. However, ION dropped the network from its stations on January 31, 2010.WTLH
WTLH, virtual channel 49 (UHF digital channel 50), is a Heroes & Icons-affiliated television station licensed to Bainbridge, Georgia, United States, serving Southwest Georgia and the Big Bend of Florida (including Tallahassee). The station is owned by New Age Media, which also operates Tallahassee-licensed CW affiliate WTLF (channel 24, which WTLH simulcasts on its second digital subchannel) through a local marketing agreement (LMA) with owner MPS Media, LLC.
Both of the stations, in turn, are operated by the Sinclair Broadcast Group, owner of Tallahassee-licensed NBC affiliate WTWC-TV (channel 40), under a master service agreement. WTLH and WTLF share studios on Commerce Boulevard in Midway, Florida while WTWC maintains separate facilities on Deerlake South in unincorporated Leon County, Florida northwest of Bradfordville (with a Tallahassee postal address). WTLH's transmitter is located in unincorporated Thomas County, Georgia, southeast of Metcalf, along the Florida state line.WYTV-DT2
WYTV-DT2 is a digital subchannel of ABC affiliate WYTV for the Mahoning Valley of Northeastern Ohio and Northwestern Pennsylvania. owned by Vaughan Media, but operated through a shared services agreement (SSA) and a joint sales agreement (JSA) by Nexstar Media Group. It is affiliated with MyNetworkTV. It broadcasts in standard definition on 33.2 and is simulcast into high definition on WYFX-LD 19.2. In order to provide 720p HD distribution over-the-air, this subchannel is being simulcast over WYFX-LD2; however, that high-definition simulcast of My YTV is being aired over a low-powered signal and its broadcasting radius only covers the immediate Youngstown area (as WYTV-DT2 is currently in standard definition, and its high definition simulcast is on a low-power station, MyNetworkTV programming in HD is only available on cable and satellite outside the immediate Youngstown area). WYTV-DT2 can also be seen on Time Warner Cable digital channel 373. Syndicated programming on the sub channel includes Cops Reloaded, How I Met Your Mother, and The Middle among others.