HOME

TheInfoList



OR:

In broadcasting, digital subchannels are a method of transmitting more than one independent program stream simultaneously from the same digital radio or
television Television, sometimes shortened to TV, is a telecommunication Media (communication), medium for transmitting moving images and sound. The term can refer to a television set, or the medium of Transmission (telecommunications), television tra ...
station Station may refer to: Agriculture * Station (Australian agriculture), a large Australian landholding used for livestock production * Station (New Zealand agriculture), a large New Zealand farm used for grazing by sheep and cattle ** Cattle statio ...
on the same
radio frequency Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around to around . This is roughly between the uppe ...
channel. This is done by using
data compression In information theory, data compression, source coding, or bit-rate reduction is the process of encoding information using fewer bits than the original representation. Any particular compression is either lossy or lossless. Lossless compressi ...
techniques to reduce the size of each individual program stream, and
multiplexing In telecommunications and computer networking, multiplexing (sometimes contracted to muxing) is a method by which multiple analog or digital signals are combined into one signal over a shared medium. The aim is to share a scarce resource - a ...
to combine them into a single signal. The practice is sometimes called "
multicasting In computer networking, multicast is group communication where data transmission is addressed to a group of destination computers simultaneously. Multicast can be one-to-many or many-to-many distribution. Multicast should not be confused with ...
".


ATSC television


United States

The ATSC digital television standard used in the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., federal district, five ma ...
supports multiple program streams over-the-air, allowing
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 and audio content via radio waves directly from a transmitter on the ear ...
s to transmit one or more subchannels over a single digital signal. A
virtual channel In most telecommunications organizations, a virtual channel is a method of remapping the ''program number'' as used in H.222 Program Association Tables and Program Mapping Tables to a channel number that can be entered via digits on a receiver' ...
numbering scheme distinguishes broadcast subchannels by appending the
television channel A television channel is a terrestrial frequency or virtual number over which a television station or television network is distributed. For example, in North America, "channel 2" refers to the terrestrial or cable band of 54 to 60 MHz, wit ...
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 Trinity Broadcasting Network transmit five streams in the following format: The most of any large broadcaster in the United States,
Ion Television Ion Television is an American broadcast television network owned by the Katz Broadcasting subsidiary of the E. W. Scripps Company. The network first began broadcasting on August 31, 1998, as Pax TV, focusing primarily on family-oriented ent ...
stations transmit nine channels (in standard definition) and the Katz Broadcasting subchannel services Court TV, Ion Mystery, Bounce TV, Laff,
Grit Grit, Grits, or Gritty may refer to: Food * Grit (grain), bran, chaff, mill-dust or coarse oatmeal * Grits, a corn-based food common in the Southern United States Minerals * Grit, winter pavement-treatment minerals deployed in grit bins * ...
, TrueReal, Defy TV, and Newsy. 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 San Francisco (; Spanish language, Spanish for "Francis of Assisi, Saint Francis"), officially the City and County of San Francisco, is the commercial, financial, and cultural center of Northern California. The city proper is the List of Ca ...
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 Atlanta ( ) is the capital and most populous city of the U.S. state of Georgia. It is the seat of Fulton County, the most populous county in Georgia, but its territory falls in both Fulton and DeKalb counties. With a population of 498,71 ...
, with ten video and ten audio feeds, comes at a close second. Several cable-to-air broadcasters, such as those in
Willmar, Minnesota Willmar is a city in, and the county seat of, Kandiyohi County, Minnesota, United States. The population was 21,015 at the 2020 census. History Agricultural expansion and the establishment of Willmar as a division point on the Great Northern ...
and Cortez, Colorado, have multiplexed more than five separate
cable television Cable television is a system of delivering television programming to consumers via radio frequency (RF) signals transmitted through coaxial cables, or in more recent systems, light pulses through fibre-optic cables. This contrasts with bro ...
channels into subchannels of one signal. Operating in a sector traditionally lacking subchannels,
digital cable television Digital cable is the distribution of cable television using digital data and video compression. The technology was first developed by General Instrument. By 2000, most cable companies offered digital features, eventually replacing their previo ...
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. Mobile DTV is also carried on ATSC stations, but as a separate service, according to the ATSC-M/H standard. The
Federal Communications Commission The Federal Communications Commission (FCC) is an independent agency of the United States federal government that regulates communications by radio, television, wire, satellite, and cable across the United States. The FCC maintains jurisd ...
(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.


Canada

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 The Canadian Radio-television and Telecommunications Commission (CRTC; french: Conseil de la radiodiffusion et des télécommunications canadiennes, links=) is a public organization in Canada with mandate as a regulatory agency for broadcasti ...
(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 Leamington ( ) is a municipality in Essex County, Ontario, Canada. With a population of 27,595 in the Canada 2016 Census, it forms the second largest urban centre in Windsor-Essex County after Windsor, Ontario. It includes Point Pelee National ...
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.


Mexico

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 TV Azteca, S.A.B. de C.V. is a Mexican multimedia conglomerate owned by Grupo Salinas. It is the second-largest mass media company in Mexico after Televisa. It primarily competes with Televisa as well as some local operators. It owns two nation ...
, 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.


DVB television


Australia

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). Each network currently has at least one HD sub channel. All networks use their HD subchannel to provide a simulcast of their primary channel or their multichannels. Inclusive of their primary standard definition channels (ignoring HD): * SBS Television offers three unique SD subchannels ( SBS Food, NITV and SBS WorldWatch) and a HD simulcast of its primary channel ( SBS HD); as well as it’s SBS Viceland and SBS World Movies channels with no SD simulcasts. * ABC Television offers three unique SD subchannels ( ABC TV Plus/ ABC Kids, ABC Me, and
ABC News ABC News is the journalism, news division of the American broadcast network American Broadcasting Company, ABC. Its flagship program is the daily evening newscast ''ABC World News Tonight, ABC World News Tonight with David Muir''; other progra ...
) and a HD simulcast of its primary channel ( ABC HD). * The Seven Network offers three unique SD subchannels ( 7two,
7mate 7mate is an Australian free-to-air digital television multichannel, which was launched by the Seven Network on 25 September 2010. The channel contains sport and regular programs aimed primarily to a male audience, with programming drawn from a ...
and 7flix), a datacasting channel (
Racing.com Racing.com (stylised as RACING.COM) is an Australian free-to-air standard-definition digital television channel, owned and operated by the Seven Network and Racing Victoria. The channel broadcasts live Victorian and South Australian horse racing ...
) and a HD simulcast of its primary channel ( 7HD) as well as it’s 7two and 7mate channels. (
7mate HD 7mate is an Australian free-to-air digital television multichannel, which was launched by the Seven Network on 25 September 2010. The channel contains sport and regular programs aimed primarily to a male audience, with programming drawn from a c ...
, 7two HD). * The Nine Network offers four unique SD subchannels ( 9Go!, 9Rush, 9Gem and 9Life), a datacasting channel ( Extra) and a HD simulcast of its primary channel ( 9HD) as well as a HD simulcast of its 9Gem channel. * Network 10 offers two unique SD subchannels ( 10 Peach, and
10 Shake 10 Shake is an Australian free-to-air digital television multichannel owned by Network 10. It launched on 27 September 2020 at 6am. The channel includes a mix of shows for people aged forty and under. It broadcasts programming for children fro ...
), two datacasting channels ( TVSN and Gecko TV) and a HD simulcast of its primary channel ( 10 HD) as well as their 10 Bold channel with no SD simulcast. Community television stations in
Melbourne Melbourne ( ; Boonwurrung/ Woiwurrung: ''Narrm'' or ''Naarm'') is the capital and most populous city of the Australian state of Victoria, and the second-most populous city in both Australia and Oceania. Its name generally refers to a me ...
( C31) and
Adelaide Adelaide ( ) is the list of Australian capital cities, capital city of South Australia, the state's largest city and the list of cities in Australia by population, fifth-most populous city in Australia. "Adelaide" may refer to either Greater A ...
( C44) 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 Conservatism is a cultural, social, and political philosophy that seeks to promote and to preserve traditional institutions, practices, and values. The central tenets of conservatism may vary in relation to the culture and civilization in ...
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.


Europe

As most digital services in
Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a subcontinent of Eurasia and it is located enti ...
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 ( ITV1, ITV2, ITV3 and ITV4) broadcasting on one multiplexed service, while two others ( ITV2 +1 and
CITV CITV (short for Children's ITV, also known as the CITV Channel) is a British free-to-air children's television channel owned by ITV plc. It broadcasts content from the CITV archive and acquisitions, every day from 6 am to 9 pm which ...
) are each broadcast on another, separate multiplex.


ISDB television

In Japan and
Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
, ISDB (similar to the DVB format) is used, and was specifically designed with physical RF segments that could be split to use for different subchannels. In Brazil, a digital subchannel is only allowed to the public and educational stations.


Tradeoffs

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 High definition or HD may refer to: Visual technologies *HD DVD, discontinued optical disc format *HD Photo, former name for the JPEG XR image file format *HDV, format for recording high-definition video onto magnetic tape * HiDef, 24 frames-pe ...
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 The second incarnation of CBS Corporation (the first being a short-lived rename of the Westinghouse Electric Corporation) was an American multinational media conglomerate with interests primarily in commercial broadcasting, publishing, an ...
through its CBS Television Stations subsidiary (which include owned-and-operated stations of CBS and
The CW ''The'' () is a grammatical article in English, denoting persons or things that are already or about to be mentioned, under discussion, implied or otherwise presumed familiar to listeners, readers, or speakers. It is the definite article in ...
, 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 New York, often called New York City or NYC, is the most populous city in the United States. With a 2020 population of 8,804,190 distributed over , New York City is also the most densely populated major city in the U ...
and
Philadelphia Philadelphia, often called Philly, is the largest city in the Commonwealth of Pennsylvania, the sixth-largest city in the U.S., the second-largest city in both the Northeast megalopolis and Mid-Atlantic regions after New York City. Sinc ...
(the company later announced the creation of Decades, a multicast network part-owned by CBS which aired on all CBS and CW owned-and-operated stations from 2015 to 2018). 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: 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 France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans. Its metropolitan ar ...
, there are only five HD services: one each for
TF1 TF1 (; standing for ''Télévision Française 1'') is a French commercial television network owned by TF1 Group, controlled by the Bouygues conglomerate. TF1's average market share of 24% makes it the most popular domestic network. TF1 is par ...
, France 2, Canal+, M6 and
Arte Arte (; (), sometimes stylized in lowercase or uppercase in its logo) is a European public service channel dedicated to culture. It is made up of three separate companies: the Strasbourg-based European Economic Interest Grouping ARTE, pl ...
; in the
United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the European mainland, continental mainland. It comprises England, Scotlan ...
, four HD services are currently transmitted over terrestrial frequencies: BBC One HD,
BBC Two HD BBC Two is a British free-to-air public broadcast television network owned and operated by the BBC. It covers a wide range of subject matter, with a remit "to broadcast programmes of depth and substance" in contrast to the more mainstream ...
, ITV HD and
Channel 4 HD Channel 4 is a British free-to-air public broadcast television network operated by the state-owned Channel Four Television Corporation. It began its transmission on 2 November 1982 and was established to provide a fourth television service i ...
(
S4C Clirlun S4C (, ''Sianel Pedwar Cymru'', meaning ''Channel Four Wales'') is a Welsh language free-to-air public broadcast television channel. Launched on 1 November 1982, it was the first television channel to be aimed specifically at a Welsh-speaki ...
is broadcast in Wales instead of Channel 4 HD).


Television applications


Commercial networks

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 Syndication may refer to: * Broadcast syndication, where individual stations buy programs outside the network system * Print syndication, where individual newspapers or magazines license news articles, columns, or comic strips * Web syndication, ...
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 Steubenville is a city in and the county seat of Jefferson County, Ohio, United States. Located along the Ohio River 33 miles west of Pittsburgh, it had a population of 18,161 at the 2020 United States Census, 2020 census. The city's name is deri ...
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 Pittsburgh ( ) is a city in the Commonwealth (U.S. state), Commonwealth of Pennsylvania, United States, and the county seat of Allegheny County, Pennsylvania, Allegheny County. It is the most populous city in both Allegheny County and Wester ...
(and to a lesser extent
Columbus Columbus is a Latinized version of the Italian surname "''Colombo''". It most commonly refers to: * Christopher Columbus (1451-1506), the Italian explorer * Columbus, Ohio, capital of the U.S. state of Ohio Columbus may also refer to: Places ...
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 Azteca America, Estrella TV and Telemundo) 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 Indiana () is a U.S. state in the Midwestern United States. It is the 38th-largest by area and the 17th-most populous of the 50 States. Its capital and largest city is Indianapolis. Indiana was admitted to the United States as the 19th ...
– 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 A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioiso ...
– 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 Michigan () is a U.S. state, state in the Great Lakes region, Great Lakes region of the Upper Midwest, upper Midwestern United States. With a population of nearly 10.12 million and an area of nearly , Michigan is the List of U.S. states and ...
and northern
Minnesota Minnesota () is a state in the upper midwestern region of the United States. It is the 12th largest U.S. state in area and the List of U.S. states and territories by population, 22nd most populous, with over 5.75 million residents. Minne ...
, 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 , settlement_type = City , nicknames = Twin Ports (with Superior), Zenith City , motto = , image_skyline = , image_caption = Clockwise from top: urban Duluth skyline; 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 Cable television is a system of delivering television programming to consumers via radio frequency (RF) signals transmitted through coaxial cables, or in more recent systems, light pulses through fibre-optic cables. This contrasts with bro ...
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 Very high frequency (VHF) is the ITU designation for the range of radio frequency electromagnetic waves (radio waves) from 30 to 300 megahertz (MHz), with corresponding wavelengths of ten meters to one meter. Frequencies immediately below 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 Albany ( ) is the capital of the U.S. state of New York, also the seat and largest city of Albany County. Albany is on the west bank of the Hudson River, about south of its confluence with the Mohawk River, and about north of New York Ci ...
. 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. Since the late 2010s, some station groups have started consolidating major network affiliations onto one signal if they own the non-licensing assets of those channels. Some of this was due to the 2016 United States wireless spectrum auction, but most have been due to companies who use
sidecar A sidecar is a one-wheeled device attached to the side of a motorcycle, scooter, or bicycle, making the whole a three-wheeled vehicle. A motorcycle with a sidecar is sometimes called a ''combination'', an ''outfit'', a ''rig'' or a ''hack''. ...
companies to create virtual duopolies via local marketing agreements when they are not legally able to own a duopoly outright. In the latter scenario, the station whose programming is on an LMA station is moved to a subchannel of a station that is owned outright by the ststion that own the non-licensed assets of other stations. Many companies such as Sinclair Broadcast Group (via Cunningham Broadcasting, Deerfield Media, & Howard Stirk Holdings),
Nexstar Media Group Nexstar Media Group, Inc. is an American publicly traded media company with headquarter offices in Irving, Texas; Midtown Manhattan; and Chicago, Illinois. The company is the largest television station owner in the United States, owning 197 tele ...
(via Mission Broadcasting & Vaughan Media), and
Gray Television Gray Television, Inc. is an American publicly traded television broadcasting company based in Atlanta, Georgia. Founded in 1946 by James Harrison Gray as Gray Communications Systems, the company owns or operates 180 stations across the United St ...
(via American Spirit Media & SagamoreHill Broadcasting) have been doing this, partially due to regulation pressure.


Sports programming

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 The National Collegiate Athletic Association (NCAA) is a nonprofit organization that regulates student athletics among about 1,100 schools in the United States, Canada, and Puerto Rico. It also organizes the athletic programs of colleges and ...
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 National Football League (NFL) is a professional American football league that consists of 32 teams, divided equally between the American Football Conference (AFC) and the National Football Conference (NFC). The NFL is one of the major ...
, the NBA,
Major League Baseball Major League Baseball (MLB) is a professional baseball organization and the oldest major professional sports league in the world. MLB is composed of 30 total teams, divided equally between the National League (NL) and the American League (AL) ...
and the
NHL The National Hockey League (NHL; french: Ligue nationale de hockey—LNH, ) is a professional ice hockey league in North America comprising 32 teams—25 in the United States and 7 in Canada. It is considered to be the top ranked professional ...
) 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 The American Hockey League (AHL) is a professional ice hockey league based in the United States and Canada that serves as the primary developmental league for the National Hockey League (NHL). Since the 2010–11 season, every team in the le ...
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 Sportsman Channel is an American sports-oriented digital cable and satellite television network owned by the Outdoor Sportsman Group subsidiary of Kroenke Sports & Entertainment. The channel is dedicated to programming about outdoor sports, inclu ...
(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 Historically black colleges and universities (HBCUs) are institutions of higher education in the United States that were established before the Civil Rights Act of 1964 with the intention of primarily serving the African-American community. M ...
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 A stadium ( : stadiums or stadia) is a place or venue for (mostly) outdoor sports, concerts, or other events and consists of a field or stage either partly or completely surrounded by a tiered structure designed to allow spectators to stand o ...
in August 2017, following the formation of a multi-platform network venture with the Chicago White Sox's Silver Chalice unit and
120 Sports 120 Sports was an internet television service, operated as a joint venture between Time Inc., Silver Chalice, MLB Advanced Media, and the National Hockey League. The service produced and streamed sports news and highlight content catered towards di ...
.


Local and informational channels

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 TouchVision was an American digital broadcast and internet Video on demand television network that was owned by Think Televisual. The service provided rolling news coverage that was distributed to television, mobile and tablet platforms. TouchVisi ...
. Locally programmed news subchannels (such as News 9 Now / News on 6 Now on KWTV in
Oklahoma City Oklahoma City (), officially the City of Oklahoma City, and often shortened to OKC, is the capital and largest city of the U.S. state of Oklahoma. The county seat of Oklahoma County, it ranks 20th among United States cities in population, an ...
and KOTV in
Tulsa, Oklahoma Tulsa () is the second-largest city in the U.S. state, state of Oklahoma and List of United States cities by population, 47th-most populous city in the United States. The population was 413,066 as of the 2020 United States census, 2020 census. ...
or NewsChannel 5+ on WTVF in
Nashville Nashville is the capital city of the U.S. state of Tennessee and the seat of Davidson County. With a population of 689,447 at the 2020 U.S. census, Nashville is the most populous city in the state, 21st most-populous city in the U.S., and t ...
,
Tennessee Tennessee ( , ), officially the State of Tennessee, is a landlocked state in the Southeastern region of the United States. Tennessee is the 36th-largest by area and the 15th-most populous of the 50 states. It is bordered by Kentucky to ...
) 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 Breaking news, interchangeably termed late-breaking news and also known as a special report or special coverage or news flash, is a current issue that broadcasters feel warrants the interruption of scheduled programming or current news in orde ...
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.


Specialty programming

Since the late 2000s, entertainment-based specialty networks (also known as diginets) have been created specifically for subchannels, most commonly those dedicated to airing
rerun A rerun or repeat is a rebroadcast of an episode of a radio or television program. There are two types of reruns – those that occur during a hiatus, and those that occur when a program is syndicated. Variations In the United Kingdom, the wor ...
s of classic television series (such as Me-TV, Retro TV, 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 Ion Mystery and the male-targeted
Grit Grit, Grits, or Gritty may refer to: Food * Grit (grain), bran, chaff, mill-dust or coarse oatmeal * Grits, a corn-based food common in the Southern United States Minerals * Grit, winter pavement-treatment minerals deployed in grit bins * ...
) feature programming aimed at specific demographics. With few exceptions (such as Localish), 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
K14RK-D K14RK-D, virtual channel 14 (UHF digital channel 14), is a low-powered television station licensed to Phoenix, Arizona, United States. The station is owned by Good News Broadcasting Network, Inc. Its transmitter is located on South Mountain. H ...
in
Phoenix, Arizona Phoenix ( ; nv, Hoozdo; es, Fénix or , yuf-x-wal, Banyà:nyuwá) is the capital and most populous city of the U.S. state of Arizona, with 1,608,139 residents as of 2020. It is the fifth-most populous city in the United States, and the o ...
) carry locally programmed channels offering classic television shows and
music video A music video is a video of variable duration, that integrates a music song or a music album with imagery that is produced for promotional or musical artistic purposes. Modern music videos are primarily made and used as a music marketing devi ...
s 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 The Country Network and Heartland), 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 WWLP (channel 22) is a television station in Springfield, Massachusetts, United States, affiliated with NBC and The CW Plus. Owned by Nexstar Media Group, the station has studios at Broadcast Center in the Sandy Hill section of Chicopee at the ...
'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 four major networks, The CW, and MyNetworkTV are often carried on higher cable channel placements (usually within the
digital cable Digital cable is the distribution of cable television using digital data and video compression. The technology was first developed by General Instrument. By 2000, most cable companies offered digital features, eventually replacing their previo ...
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 firm A law firm is a business entity formed by one or more lawyers to engage in the practice of law. The primary service rendered by a law firm is to advise clients (individuals or corporations) about their legal rights and responsibilities, and to ...
s, 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. By 2017, diginets were doing better in the ratings than some major cable networks, with MeTV being the 20th ranked broadcast network, and are also available in more homes than many cable networks. Streaming services that offer free linear channels such as Peacock, Pluto TV, and Stirr have also added diginets to their services, giving diginets who lack an over-the-air home in a specific market coverage. Sinclair Broadcast Group, which owns Stirr, has included its own four diginets on Stirr ( Charge!,
Comet A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or Coma (cometary), coma, and sometimes also a Comet ta ...
,
Stadium A stadium ( : stadiums or stadia) is a place or venue for (mostly) outdoor sports, concerts, or other events and consists of a field or stage either partly or completely surrounded by a tiered structure designed to allow spectators to stand o ...
, & TBD), in addition to others such as the
game show A game show is a genre of broadcast viewing entertainment (radio, television, internet, stage or other) where contestants compete for a reward. These programs can either be participatory or demonstrative and are typically directed by a host, ...
-themed
Buzzr Buzzr is an American digital terrestrial television, digital broadcast television network owned by Fremantle North America, a unit of the Fremantle (company), Fremantle subsidiary of RTL Group. The network serves as an outlet for the extensive li ...
, which Sinclair rated as the most popular channel on Stirr.


Educational 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 In its most general sense, the term "world" refers to the totality of entities, to the whole of reality or to everything that is. The nature of the world has been conceptualized differently in different fields. Some conceptions see the worl ...
, and
Create To create is to make a new person, place, thing, or phenomenon. The term and its variants may also refer to: * Creativity, phenomenon whereby something new and valuable is created Art, entertainment, and media * Create (TV network), an America ...
. In the Washington, D.C. area, MHz Networks is available as ten subchannels transmitted by two stations, with their
virtual channel In most telecommunications organizations, a virtual channel is a method of remapping the ''program number'' as used in H.222 Program Association Tables and Program Mapping Tables to a channel number that can be entered via digits on a receiver' ...
s 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, PBS Wisconsin's Wisconsin Channel, or
New York State New York, officially the State of New York, is a U.S. state, state in the Northeastern United States. It is often called New York State to distinguish it from its largest city, New York City. With a total area of , New York is the List of U.S. ...
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 LIN Media was an American holding company founded in 1994 that operated 43 television stations. All except one were affiliates of the six major U.S. television networks. One of the remaining stations was a low powered weather station in Ind ...
(now owned by
Nexstar Media Group Nexstar Media Group, Inc. is an American publicly traded media company with headquarter offices in Irving, Texas; Midtown Manhattan; and Chicago, Illinois. The company is the largest television station owner in the United States, owning 197 tele ...
) 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 A schedule or a timetable, as a basic time-management tool, consists of a list of times at which possible tasks, events, or actions are intended to take place, or of a sequence of events in the chronological order in which such things are ...
in the morning and overnight hours.


Temporary installations

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 ( The "Little Rock") , government_type = Council-manager , leader_title = Mayor , leader_name = Frank Scott Jr. , leader_party = D , leader_title2 = Council , leader_name2 ...
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 In most telecommunications organizations, a virtual channel is a method of remapping the ''program number'' as used in H.222 Program Association Tables and Program Mapping Tables to a channel number that can be entered via digits on a receiver' ...
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 Los Angeles ( ; es, Los Ángeles, link=no , ), often referred to by its initials L.A., is the largest city in the state of California and the second most populous city in the United States after New York City, as well as one of the wor ...
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 (since sold to the Meruelo 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.


Data, radio and non-public signals

In rare cases, digital television broadcasters have included a service known as DTV radio, in which the audio of a
commonly owned Common ownership refers to holding the assets of an organization, enterprise or community indivisibly rather than in the names of the individual members or groups of members as common property. Forms of common ownership exist in every economi ...
broadcast
radio station Radio broadcasting is transmission of audio (sound), sometimes with related metadata, by radio waves to radio receivers belonging to a public audience. In terrestrial radio broadcasting the radio waves are broadcast by a land-based radi ...
is simulcast over a subchannel (for instance, KPJK in
San Mateo, California San Mateo ( ; ) is a city in San Mateo County, California, on the San Francisco Peninsula. About 20 miles (32 km) south of San Francisco, the city borders Burlingame, California, Burlingame to the north, Hillsborough, California, Hillsboro ...
broadcasts former FM sister KCSM on its DT3 signal). WANN-CD in
Atlanta Atlanta ( ) is the capital and most populous city of the U.S. state of Georgia. It is the seat of Fulton County, the most populous county in Georgia, but its territory falls in both Fulton and DeKalb counties. With a population of 498,71 ...
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 Pay television, also known as subscription television, premium television or, when referring to an individual service, a premium channel, refers to Subscription business model, subscription-based television services, usually provided by multichan ...
service that used H.264 compression instead of standard
MPEG-2 MPEG-2 (a.k.a. H.222/H.262 as was defined by the ITU) is a standard for "the generic coding of moving pictures and associated audio information". It describes a combination of lossy video compression and lossy audio data compression methods, w ...
. Mobile DTV now uses
MPEG-4 MPEG-4 is a group of international standards for the compression of digital audio and visual data, multimedia systems, and file storage formats. It was originally introduced in late 1998 as a group of audio and video coding formats and related ...
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.


Technical considerations

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): With improvements in MPEG encoding, and tighter VBR encoding, more subchannels can be combined. 1×720p + 4×480i is becoming more common. For a
frame rate Frame rate (expressed in or FPS) is the frequency (rate) at which consecutive images ( frames) are captured or displayed. The term applies equally to film and video cameras, computer graphics, and motion capture systems. Frame rate may also ...
of 30 p or 60 i, uncompressed DTV channels have the following
data rate Data rate and data transfer rate can refer to several related and overlapping concepts in communications networks: Achieved rate * Bit rate, the number of bits that are conveyed or processed per unit of time ** Data signaling rate or gross bit rate ...
s in
megapixel In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a raster image, or the smallest point in an all points addressable display device. In most digital display devices, pixels are the ...
s per second: For ATSC, these must be compressed into 19.4Mbit/s total per physical 6 MHz RF channel over the air, and 38.8Mbit/s for cable.


Digital radio

Various forms of digital radio also allow for multiple program streams.


HD Radio

The primary distinguishing feature of
HD Radio HD Radio (HDR) is a trademark for an in-band on-channel (IBOC) digital radio broadcast technology. It generally simulcasts an existing analog radio station in digital format with less noise and with additional text information. HD Radio is used ...
has been its ability to multiplex an FM radio signal. As HD Radio never achieved widespread popularity in the United States (unlike television, radio is not required to turn off its analog signals due to HD Radio being in-band on-channel and thus compatible with analog, plus the greater quantity and difficulty in signal conversion of radios compared to fixed-link television sets), its use has largely been to serve as a
legal fiction A legal fiction is a fact assumed or created by courts, which is then used in order to help reach a decision or to apply a legal rule. The concept is used almost exclusively in common law jurisdictions, particularly in England and Wales. Deve ...
. Since HD Radio was introduced in the United States in the late 2000s (decade), the FCC has allowed American broadcasters to use low-powered
translators Translation is the communication of the Meaning (linguistic), meaning of a #Source and target languages, source-language text by means of an Dynamic and formal equivalence, equivalent #Source and target languages, target-language text. The ...
to transmit HD Radio subchannels in analog FM. This has allowed broadcasters to increase the number of programming choices available in a given
media market A media market, broadcast market, media region, designated market area (DMA), television market area, or simply market is a region where the population can receive the same (or similar) television and radio station offerings, and may also in ...
beyond FCC limits.
AM broadcasting AM broadcasting is radio broadcasting using amplitude modulation (AM) transmissions. It was the first method developed for making audio radio transmissions, and is still used worldwide, primarily for medium wave (also known as "AM band") transm ...
generally lacks the bandwidth to multiplex; though in theory an AM station could transmit two separate channels using C-QUAM AM stereo, there is a limit to how far the two audio channels can be separated, and thus
crosstalk In electronics, crosstalk is any phenomenon by which a signal transmitted on one circuit or channel of a transmission system creates an undesired effect in another circuit or channel. Crosstalk is usually caused by undesired capacitive, in ...
is inevitable. HD Radio can be used on AM, but the bandwidth limits the digital signal to a single channel, which under FCC rules must match the analog signal. AM broadcasters have criticized the use of HD Radio on AM due to the increased adjacent-channel interference caused by the greater bandwidth it requires, with little benefit. WWFD has operated as a digital-only station with no analog signal under special dispensation since 2018; in December 2019, it began testing a multiplexed digital signal with two channels. No consumer radio receivers currently have the capability to receive AM multicast signals, and thus (as with FM HD Radio) WWFD's signals have been carried on FM translators (and the Internet) to ensure continued availability. The FCC, in October 2020, concluded from WWFD's experiments: "the record does not establish that an audio stream on an HD-2 subchannel is currently technically feasible(.)"https://docs.fcc.gov/public/attachments/DOC-367361A1.pdf A proposed FCC rule would require stations that wish to multiplex their digital AM signals to request and receive permission to do so.


DAB


See also

* In-band on-channel (IBOC), digital radio technology allowing digital subchannels on FM stations *
DAB DAB, dab, dabs, or dabbing may refer to: Dictionaries * ''Dictionary of American Biography'', published under the auspices of the American Council of Learned Societies * ''Dictionary of Australian Biography'', published since 1949 Places * Dąb, ...
and DVB, international digital radio-television standards in use in
Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a subcontinent of Eurasia and it is located enti ...
, Australia and
New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 List of islands of New Zealand, smaller islands. It is the ...
* QAM tuner


References

* {{DEFAULTSORT:Digital Subchannel ATSC Digital television High-definition television Television technology