fbpx
Wikipedia

Digital subchannel

January 12, 2023

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".

ATSC television

United States

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 Trinity Broadcasting Network transmit five streams in the following format:

The most of any large broadcaster in the United States, Ion Television stations transmit nine channels (in standard definition) and the Katz Broadcasting subchannel services Court TV, Ion Mystery, Bounce TV, Laff, Grit, TrueReal, Defy TV, and Scripps News. 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 ten audio feeds, comes at a close second. Several cable-to-air[clarification needed] 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.[citation needed]

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 (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.[citation needed]

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 (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.[1]

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, 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):

  • Network 10 offers two unique SD subchannels (10 Peach, and 10 Shake), 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 (C31) and Adelaide (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 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 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) are each broadcast on another, separate multiplex.

ISDB television

In Japan and Brazil, 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.[2][3]

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 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.[citation needed] 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 aired on all CBS and CW owned-and-operated stations from 2015 to 2018).[4]

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. Until a later multiplexer upgrade, both subchannels transmitted in 720p HD (the main signal now transmits CBS's preferred 1080i HD format). Comparatively, its sister station, ABC affiliate WYTV transmitted 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 merged their programming onto WYTV's, requiring the removal of the 33.3 signal in order to manage the high definition needs of three 720p channels and one in 1080i (two former WKBN and WYTV subchannels moved onto WYFX-LD's spectrum).[5]
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,[6] 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 720p 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 720p 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 WKTV previously carried NBC programming in 1080i on its first subchannel, 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). All three networks are currently transmitting in 720p. The station also offers MeTV programming in 480i 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 – respectively affiliated with Fox, The CW and MeTV – in 720p.
WDTN Dayton, Ohio Through channel-sharing agreements with WBDT (Springfield, Ohio) and WKOI (Richmond, Indiana), WDTN's spectrum transmits two 1080i signals: NBC (channel 2) and The CW (channel 26). WDTN's spectrum also carries Ion Mystery, Bounce, and Ion in 480i. Through the use of PSIP, these channels appear to the viewer to be three different channels: 2 (NBC), 26 (The CW) and 43 (Ion)

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.[citation needed] 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).[7]

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 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).[6]

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 – 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).[8][9]

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.

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 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 station 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 (via Mission Broadcasting & Vaughan Media), and Gray Television (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 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.

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. 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.

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 reruns 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) 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.[10] Some stations (such as K14RK-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 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).[11] 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 four major networks, The CW, and MyNetworkTV are often carried on higher cable channel placements (usually within the digital cable tiers) not readily found by most subscribers.[11] 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).[11]

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,[11] 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.[10][12]

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.[13] 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, Stadium, & TBD), in addition to others such as the game show-themed Buzzr, which Sinclair rated as the most popular channel on Stirr.[14]

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, 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, PBS Wisconsin's 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 Nexstar Media Group) 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.

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 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 (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 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.

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):

HDTV channels Subchannels
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.

For a frame rate of 30p or 60i, uncompressed DTV channels have the following data rates in megapixels per second:

60 Hz 50 Hz
  • 640×480i60/p30 (NTSC SDTV): 9.216
  • 704×480i60/p30 (ATSC wide SDTV): 10.1376
  • 720×480i60/p30 (NTSC DVD): 10.368
  • 1280×720p30: 27.648
  • 1280×720p60: 55.296
  • 1920×1080i60/p30: 62.208

 

  • 704×576i50/p25 (PAL SDTV): 10.1376
  • 720×576i50/p25 (PAL DVD): 10.368
  • 1280×720p25: 23.04
  • 1280×720p50: 46.08
  • 1920×1080i50/p25: 51.84

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 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. 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 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 beyond FCC limits.

AM broadcasting 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 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.[15] 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.[16] 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(.)"[17] A proposed FCC rule would require stations that wish to multiplex their digital AM signals to request and receive permission to do so.[17]

DAB

See also

References

  1. ^ "Decision CRTC 12-446". Canadian Radio-television and Telecommunications Commission. 17 August 2012.
  2. ^ "Folha de S.Paulo - Outro Canal - Daniel Castro: Governo proíbe novos canais de TV digital - 27/02/2009".
  3. ^ . Archived from the original on 2017-07-10.
  4. ^ "CBS Stations, Weigel Partner on Oldies Digi-Net Decades". Broadcasting & Cable. October 21, 2014. Retrieved November 11, 2014.
  5. ^ "Big money from FCC auction means end of some TV stations". post-gazette.com. Retrieved 15 March 2018.
  6. ^ a b Kevin Eck (July 11, 2014). "Sinclair Adds FOX Affiliation to Wheeling-Steubenville Station". TVSpy. Retrieved January 18, 2015.
  7. ^ "Freeview HD". Freeview. Retrieved January 18, 2015.
  8. ^ Malone, Michael (December 22, 2014). "Tribune Sells Indianapolis CW Affiliation to Media General". Broadcasting & Cable. Retrieved December 23, 2014.
  9. ^ Lindquist, David (December 23, 2014). "With new CW deal, WISH-8 won't be independent in 2015". Indianapolis Star. Retrieved December 31, 2014.
  10. ^ a b Guider, Elizabeth (June 18, 2014). "Classic TV Diginets Make The Old New Again". TVNewsCheck. Retrieved July 5, 2014.
  11. ^ a b c d Elizabeth Guider (June 17, 2014). "Diginets Building Themselves A Market". TVNewsCheck. Retrieved January 18, 2015.
  12. ^ Downey, Kevin (June 19, 2014). "Pay-For-Play Is Growing Diginet Strategy". TVNewsCheck. Retrieved July 5, 2014.
  13. ^ "Digital Subchannels Outperform Cable Competitors, Report Finds". 2 October 2017.
  14. ^ Bouma, Luke (July 17, 2019). "Sinclair's Free Stirr Streaming Service Plans to Add 12 New Channels & Hits 1 Million Downloads". Cord Cutters News. Retrieved July 17, 2019.
  15. ^ . Stop IBOC Now Coalition (2007). Retrieved from the Wayback Machine December 17, 2019.
  16. ^ Fybush, Scott (December 6, 2019). "HD2 arrives on AM radio". NorthEast Radio Watch. Retrieved December 6, 2019.
  17. ^ a b https://docs.fcc.gov/public/attachments/DOC-367361A1.pdf[bare URL PDF]
  • "How Digital Television Works". HowStuffWorks. 10 January 2001. Retrieved 2007-01-29.

January 12, 2023
digital, subchannel, this, article, needs, additional, citations, verification, please, help, improve, this, article, adding, citations, reliable, sources, unsourced, material, challenged, removed, find, sources, news, newspapers, books, scholar, jstor, august. This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Digital subchannel news newspapers books scholar JSTOR August 2017 Learn how and when to remove this template message 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 Contents 1 ATSC television 1 1 United States 1 2 Canada 1 3 Mexico 2 DVB television 2 1 Australia 2 2 Europe 3 ISDB television 4 Tradeoffs 5 Television applications 5 1 Commercial networks 5 2 Sports programming 5 3 Local and informational channels 5 4 Specialty programming 5 5 Educational programming 5 6 Temporary installations 5 7 Data radio and non public signals 6 Technical considerations 7 Digital radio 7 1 HD Radio 7 2 DAB 8 See also 9 ReferencesATSC television EditUnited States Edit 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 Trinity Broadcasting Network transmit five streams in the following format Channel Video Aspect Programming40 1 720p 16 9 Trinity Broadcasting Network40 2 TBN Inspire40 3 480i 4 3 Smile40 4 Enlace40 5 16 9 PositivThe most of any large broadcaster in the United States Ion Television stations transmit nine channels in standard definition and the Katz Broadcasting subchannel services Court TV Ion Mystery Bounce TV Laff Grit TrueReal Defy TV and Scripps News 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 ten audio feeds comes at a close second Several cable to air clarification needed 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 citation needed 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 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 citation needed Canada Edit 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 1 Mexico Edit Some Mexican TV stations use digital subchannels as they are used in the United States The Sistema Publico de Radiodifusion 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 DVB television EditAustralia Edit 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 and a HD simulcast of its primary channel ABC HD The Seven Network offers three unique SD subchannels 7two 7mate and 7flix a datacasting channel Racing com and a HD simulcast of its primary channel 7HD as well as it s 7two and 7mate channels 7mate HD 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 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 C31 and Adelaide 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 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 Edit 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 ITV1 ITV2 ITV3 and ITV4 broadcasting on one multiplexed service while two others ITV2 1 and CITV are each broadcast on another separate multiplex ISDB television EditThis section needs expansion You can help by adding to it April 2018 In Japan and Brazil 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 2 3 Tradeoffs EditAs 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 citation needed 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 amp Os in New York City and Philadelphia 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 4 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 DescriptionKBMT 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 Until a later multiplexer upgrade both subchannels transmitted in 720p HD the main signal now transmits CBS s preferred 1080i HD format Comparatively its sister station ABC affiliate WYTV transmitted 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 merged their programming onto WYTV s requiring the removal of the 33 3 signal in order to manage the high definition needs of three 720p channels and one in 1080i two former WKBN and WYTV subchannels moved onto WYFX LD s spectrum 5 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 6 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 UniMas in 720p 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 720p 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 WKTV previously carried NBC programming in 1080i on its first subchannel 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 All three networks are currently transmitting in 720p The station also offers MeTV programming in 480i 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 respectively affiliated with Fox The CW and MeTV in 720p WDTN Dayton Ohio Through channel sharing agreements with WBDT Springfield Ohio and WKOI Richmond Indiana WDTN s spectrum transmits two 1080i signals NBC channel 2 and The CW channel 26 WDTN s spectrum also carries Ion Mystery Bounce and Ion in 480i Through the use of PSIP these channels appear to the viewer to be three different channels 2 NBC 26 The CW and 43 Ion 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 citation needed 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 7 Television applications EditThe examples and perspective in this section deal primarily with the United States and do not represent a worldwide view of the subject You may improve this section discuss the issue on the talk page or create a new section as appropriate February 2015 Learn how and when to remove this template message Commercial networks Edit 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 6 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 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 8 9 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 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 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 station that own the non licensed assets of other stations Many companies such as Sinclair Broadcast Group via Cunningham Broadcasting Deerfield Media amp Howard Stirk Holdings Nexstar Media Group via Mission Broadcasting amp Vaughan Media and Gray Television via American Spirit Media amp SagamoreHill Broadcasting have been doing this partially due to regulation pressure Sports programming Edit 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 Local and informational channels Edit 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 Specialty programming Edit It has been suggested that this section be split out into another article titled Diginet Discuss September 2022 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 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 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 10 Some stations such as K14RK 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 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 11 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 four major networks The CW and MyNetworkTV are often carried on higher cable channel placements usually within the digital cable tiers not readily found by most subscribers 11 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 11 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 11 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 10 12 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 13 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 Stadium amp TBD in addition to others such as the game show themed Buzzr which Sinclair rated as the most popular channel on Stirr 14 Educational programming Edit 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 PBS Wisconsin s 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 Nexstar Media Group 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 Temporary installations Edit 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 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 Edit 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 Technical considerations EditDigital 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 HDTV channels Subchannels1 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 subchannel1 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 subchannels2 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 For a frame rate of 30p or 60i uncompressed DTV channels have the following data rates in megapixels per second 60 Hz 50 Hz640 480i60 p30 NTSC SDTV 9 216 704 480i60 p30 ATSC wide SDTV 10 1376 720 480i60 p30 NTSC DVD 10 368 1280 720p30 27 648 1280 720p60 55 296 1920 1080i60 p30 62 208 704 576i50 p25 PAL SDTV 10 1376 720 576i50 p25 PAL DVD 10 368 1280 720p25 23 04 1280 720p50 46 08 1920 1080i50 p25 51 84For 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 EditVarious forms of digital radio also allow for multiple program streams HD Radio Edit The primary distinguishing feature of HD Radio 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 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 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 beyond FCC limits AM broadcasting 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 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 15 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 16 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 17 A proposed FCC rule would require stations that wish to multiplex their digital AM signals to request and receive permission to do so 17 DAB Edit This section needs expansion You can help by adding to it April 2010 See also EditIn band on channel IBOC digital radio technology allowing digital subchannels on FM stations DAB and DVB international digital radio television standards in use in Europe Australia and New Zealand QAM tunerReferences Edit Decision CRTC 12 446 Canadian Radio television and Telecommunications Commission 17 August 2012 Folha de S Paulo Outro Canal Daniel Castro Governo proibe novos canais de TV digital 27 02 2009 MULTIPROGRAMACAO Archived from the original on 2017 07 10 CBS Stations Weigel Partner on Oldies Digi Net Decades Broadcasting amp Cable October 21 2014 Retrieved November 11 2014 Big money from FCC auction means end of some TV stations post gazette com Retrieved 15 March 2018 a b Kevin Eck July 11 2014 Sinclair Adds FOX Affiliation to Wheeling Steubenville Station TVSpy Retrieved January 18 2015 Freeview HD Freeview Retrieved January 18 2015 Malone Michael December 22 2014 Tribune Sells Indianapolis CW Affiliation to Media General Broadcasting amp Cable Retrieved December 23 2014 Lindquist David December 23 2014 With new CW deal WISH 8 won t be independent in 2015 Indianapolis Star Retrieved December 31 2014 a b Guider Elizabeth June 18 2014 Classic TV Diginets Make The Old New Again TVNewsCheck Retrieved July 5 2014 a b c d Elizabeth Guider June 17 2014 Diginets Building Themselves A Market TVNewsCheck Retrieved January 18 2015 Downey Kevin June 19 2014 Pay For Play Is Growing Diginet Strategy TVNewsCheck Retrieved July 5 2014 Digital Subchannels Outperform Cable Competitors Report Finds 2 October 2017 Bouma Luke July 17 2019 Sinclair s Free Stirr Streaming Service Plans to Add 12 New Channels amp Hits 1 Million Downloads Cord Cutters News Retrieved July 17 2019 Why you don t need or want HD AM radio Stop IBOC Now Coalition 2007 Retrieved from the Wayback Machine December 17 2019 Fybush Scott December 6 2019 HD2 arrives on AM radio NorthEast Radio Watch Retrieved December 6 2019 a b https docs fcc gov public attachments DOC 367361A1 pdf bare URL PDF How Digital Television Works HowStuffWorks 10 January 2001 Retrieved 2007 01 29 Retrieved from https en wikipedia org w index php title Digital subchannel amp oldid 1132861136, wikipedia, wiki, book, books, library,

article

, read, download, free, free download, mp3, video, mp4, 3gp, jpg, jpeg, gif, png, picture, music, song, movie, book, game, games.