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<hr />
<div>{{See also|Digital terrestrial television}}<br />
{{pp-move-indef}}<br />
{{Refimprove|date=May 2010}}<br />
{{Table Digital video broadcast standards}}<br />
'''Digital television''' ('''DTV''') is the transmission of television signals, including the sound channel, using [[Digital signal|digital]] encoding, in contrast to the earlier television technology, [[analog television]], in which the video and audio are carried by [[analog signal]]s. It is an innovative advance that represents the first significant evolution in television technology since [[color television]] in the 1950s.<ref>Kruger, L. G. (2001). Digital Television: An Overview. Hauppauge, New York: Nova Publishers.</ref> Digital TV transmits in a new image format called [[high definition television|HDTV]] (high definition television), with greater resolution than analog TV, in a wide screen [[aspect ratio]] similar to recent movies in contrast to the narrower screen of analog TV. It makes more economical use of scarce [[radio spectrum]] space; it can transmit multiple channels, up to 7, in the same [[Bandwidth (signal processing)|bandwidth]] occupied by a single channel of analog television,<ref>{{cite web | url=http://www.disabled-world.com/artman/publish/digital-hdtv.shtml|title=HDTV Set Top Boxes and Digital TV Broadcast Information|accessdate=28 June 2014}} - dead link</ref> and provides many new features that analog television cannot. A [[digital television transition|transition]] from analog to digital broadcasting began around 2006 in some countries, and many industrial countries have now completed the changeover, while other countries are in various stages of adaptation. Different digital television broadcasting standards have been adopted in different parts of the world; below are the more widely used standards:<br />
* Digital Video Broadcasting ([[Digital Video Broadcasting|DVB]]) uses coded orthogonal frequency-division multiplexing ([[OFDM]]) modulation and supports hierarchical transmission. This standard has been adopted in Europe, Africa, Asia, Australia, total about 60 countries.<br />
* Advanced Television System Committee ([[ATSC]]) uses eight-level vestigial sideband ([[8VSB]]) for terrestrial broadcasting. This standard has been adopted by 6 countries: United States, Canada, Mexico, South Korea, Dominican Republic and Honduras.<br />
* Integrated Services Digital Broadcasting ([[ISDB]]) is a system designed to provide good reception to fixed receivers and also portable or mobile receivers. It utilizes [[OFDM]] and two-dimensional interleaving. It supports hierarchical transmission of up to three layers and uses [[MPEG-2 video]] and [[Advanced Audio Coding]]. This standard has been adopted in Japan and the Philippines. [[ISDB-T International]] is an adaptation of this standard using [[H.264/MPEG-4 AVC]] that been adopted in most of South America and is also being embraced by Portuguese-speaking African countries.<br />
* Digital Terrestrial Multimedia Broadcasting ([[DTMB]]) adopts time-domain synchronous (TDS) OFDM technology with a pseudo-random signal frame to serve as the guard interval (GI) of the OFDM block and the training symbol. The DTMB standard has been adopted in the People's Republic of China, including Hong Kong and Macau.<ref>Ong, C. Y., Song, J., Pan, C., & Li, Y.(2010, May). Technology and Standards of Digital Television Terrestrial Multimedia Broadcasting [Topics in Wireless Communications], Communications Magazine, IEEE , 48(5),119-127</ref><br />
* Digital Multimedia Broadcasting ([[Digital Multimedia Broadcasting|DMB]]) is a digital [[radio transmission]] [[technology]] developed in [[South Korea]]<ref>{{cite web|url=http://www.zdnet.co.kr/ArticleView.asp?artice_id=00000039146251 |title=Korea's Terrestrial DMB: Germany to begin broadcast this May |publisher=ZDNet Korea |date= |accessdate=2010-06-17}}</ref><ref>{{cite web |url=http://www.textually.org/picturephoning/archives/cat_dmb.htm |title=picturephoning.com: DMB |publisher=Textually.org |date= |accessdate=2010-06-17 |deadurl=yes |archiveurl=https://web.archive.org/web/20100809051720/http://www.textually.org/picturephoning/archives/cat_dmb.htm |archivedate=2010-08-09 |df= }}</ref><ref>{{cite web |url=http://www.reportworld.co.kr/cbqna/cb_answer_view.html?no=40590 |title=South Korea : Social Media 답변 내용 : 악어새 - 리포트월드 |publisher=Reportworld.co.kr |date= |accessdate=2010-06-17 |deadurl=yes |archiveurl=https://web.archive.org/web/20090817143122/http://www.reportworld.co.kr/cbqna/cb_answer_view.html?no=40590 |archivedate=2009-08-17 |df= }}</ref> as part of the national [[information technology|IT]] project for sending multimedia such as [[TV]], [[radio]] and [[datacasting]] to [[mobile device]]s such as mobile phones, laptops and GPS navigation systems.<br />
<br />
== History ==<br />
<br />
Digital TV's roots have been tied very closely to the availability of inexpensive, high performance computers. It wasn't until the 1990s that digital TV became a real possibility.<ref name="benton">{{cite web |url= http://www.benton.org/initiatives/obligations/charting_the_digital_broadcasting_future/sec1 |title= The Origins and Future Prospects of Digital Television |publisher= [[Benton Foundation]] }}</ref><br />
<br />
In the mid-1980s, as Japanese consumer electronics firms forged ahead with the development of [[HDTV]] technology, and as the [[Multiple sub-Nyquist sampling encoding|MUSE]] analog format was proposed by Japan's public broadcaster [[NHK]] as a worldwide standard, Japanese advancements were seen as pacesetters that threatened to eclipse U.S. electronics companies. Until June 1990, the Japanese MUSE standard—based on an analog system—was the front-runner among the more than 23 different technical concepts under consideration. Then, an American company, [[General Instrument]], demonstrated the feasibility of a digital television signal. This breakthrough was of such significance that the FCC was persuaded to delay its decision on an ATV standard until a digitally based standard could be developed.<br />
<br />
In March 1990, when it became clear that a digital standard was feasible, the FCC made a number of critical decisions. First, the Commission declared that the new ATV standard must be more than an enhanced [[analog signal]], but be able to provide a genuine HDTV signal with at least twice the resolution of existing television images. Then, to ensure that viewers who did not wish to buy a new digital television set could continue to receive conventional television broadcasts, it dictated that the new ATV standard must be capable of being "[[simulcast]]" on different channels. The new ATV standard also allowed the new DTV signal to be based on entirely new design principles. Although incompatible with the existing NTSC standard, the new DTV standard would be able to incorporate many improvements.<ref name="benton" /><br />
<br />
The final standard adopted by the FCC did not require a single standard for scanning formats, aspect ratios, or lines of resolution. This outcome resulted from a dispute between the consumer electronics industry (joined by some broadcasters) and the computer industry (joined by the film industry and some public interest groups) over which of the two scanning processes—interlaced or progressive—is superior. Interlaced scanning, which is used in televisions worldwide, scans even-numbered lines first, then odd-numbered ones. Progressive scanning, which is the format used in computers, scans lines in sequences, from top to bottom. The computer industry argued that progressive scanning is superior because it does not "flicker" in the manner of interlaced scanning. It also argued that progressive scanning enables easier connections with the Internet, and is more cheaply converted to interlaced formats than vice versa. The film industry also supported progressive scanning because it offers a more efficient means of converting filmed programming into digital formats. For their part, the consumer electronics industry and broadcasters argued that interlaced scanning was the only technology that could transmit the highest quality pictures then (and currently) feasible, i.e., 1,080 lines per picture and 1,920 pixels per line. Broadcasters also favored interlaced scanning because their vast archive of interlaced programming is not readily compatible with a progressive format.<ref name="benton" /><br />
<br />
=== Inaugural launches ===<br />
[[DirecTV]] in the U.S. launched the first commercial digital [[satellite television|satellite]] platform in May 1994, using the [[Digital Satellite System]] (DSS) standard.<ref>{{cite web|url=http://www.fundinguniverse.com/company-histories/u-s-satellite-broadcasting-company-inc-history/|title=History of U.S. Satellite Broadcasting Company, Inc. – FundingUniverse|website=www.fundinguniverse.com|accessdate=9 August 2018}}</ref><ref>{{cite web|url=https://eu.indystar.com/story/money/2015/09/04/business-insider-digital-satellite-tv-indy-roots/71611606/|title=Business Insider: Digital satellite TV has Indy roots|publisher=|accessdate=9 August 2018}}</ref> [[Digital cable]] broadcasts were tested and launched in the U.S. in 1996 by [[Tele-Communications Inc.|TCI]] and [[Time Warner]].<ref>{{cite web|url=http://money.cnn.com/1997/12/17/technology/nextlevel/|title=NextLevel signs cable deal - Dec. 17, 1997|website=money.cnn.com|accessdate=9 August 2018}}</ref><ref>{{cite web|url=http://money.cnn.com/1996/08/15/companies/tci_pkg/|title=TCI faces big challenges - Aug. 15, 1996|website=money.cnn.com|accessdate=9 August 2018}}</ref> The first [[digital terrestrial]] platform was launched in November 1998 as [[ONdigital]] in the United Kingdom, using the [[DVB-T]] standard.<ref>{{cite web|url=http://www.onhistory.co.uk/timeline/1998/11/10/canal-technologies-and-worlds-first-digital-terres|title=CANAL+ TECHNOLOGIES and the world's first digital terrestrial television service in the United Kingdom|publisher=|accessdate=9 August 2018}}</ref><br />
<br />
== Technical information ==<br />
<br />
=== Formats and bandwidth ===<br />
[[File:Digital & Analog TV screen quality comparison-1.jpg|thumbnail|right|Comparison of image quality between [[ISDB-T]] (1080i broadcast, top) and [[NTSC]] (480i transmission, bottom)]]<br />
Digital television supports many different picture formats defined by the [[broadcast television system]]s which are a combination of size and [[aspect ratio (image)|aspect ratio]] (width to height ratio).<br />
<br />
With [[digital terrestrial television]] (DTT) broadcasting, the range of formats can be broadly divided into two categories: [[high definition television]] (HDTV) for the transmission of [[high-definition video]] and [[standard-definition television]] (SDTV). These terms by themselves are not very precise, and many subtle intermediate cases exist.<br />
<br />
One of several different HDTV formats that can be transmitted over DTV is: 1280&nbsp;×&nbsp;720 [[pixel]]s in [[progressive scan]] mode (abbreviated ''[[720p]]'') or 1920&nbsp;×&nbsp;1080 pixels in [[interlaced video]] mode (''[[1080i]]''). Each of these uses a [[16:9]] aspect ratio. HDTV cannot be transmitted over analog [[television channel]]s because of [[channel capacity]] issues.<br />
<br />
SDTV, by comparison, may use one of several different formats taking the form of various aspect ratios depending on the technology used in the country of broadcast. In terms of rectangular pixels, [[NTSC]] countries can deliver a 640&nbsp;×&nbsp;480 resolution in 4:3 and 854&nbsp;×&nbsp;480 in [[16:9]], while [[PAL]] can give 768&nbsp;×&nbsp;576 in [[4:3]] and 1024&nbsp;×&nbsp;576 in [[16:9]]. However, broadcasters may choose to reduce these resolutions to reduce [[bit rate]] (e.g., many DVB-T channels in the United Kingdom use a horizontal resolution of 544 or 704 pixels per line).<ref>[http://dtt.me.uk Latest snapshots - Freeview/DTT bitrates] (Mendip transmitter, UK)</ref><br />
<br />
Each [[commercial broadcasting]] [[terrestrial television]] DTV channel in North America is permitted to be broadcast at a bit rate up to 19 [[megabit]]s per second. However, the broadcaster does not need to use this entire bandwidth for just one broadcast channel. Instead the broadcast can use the channel to include [[PSIP]] and can also subdivide across several video [[subchannel]]s (a.k.a. feeds) of varying quality and compression rates, including non-video [[datacasting]] services that allow one-way high-bit-rate streaming of data to computers like [[National Datacast]].<br />
<br />
A broadcaster may opt to use a standard-definition (SDTV) digital signal instead of an [[HDTV]] signal, because current convention allows the bandwidth of a DTV channel (or "[[multiplex (TV)|multiplex]]") to be subdivided into multiple [[digital subchannel]]s, (similar to what most FM [[radio station]]s offer with [[HD Radio]]), providing multiple feeds of entirely different [[television program]]ming on the same channel. This ability to provide either a single HDTV feed or multiple lower-resolution feeds is often referred to as distributing one's "[[bit budget]]" or [[multicasting]]. This can sometimes be arranged automatically, using a [[statistical multiplexer]] (or "stat-mux"). With some implementations, image resolution may be less directly limited by bandwidth; for example in [[DVB-T]], broadcasters can choose from several different modulation schemes, giving them the option to reduce the transmission [[bit rate]] and make reception easier for more distant or mobile viewers.<br />
<br />
=== Receiving digital signal ===<br />
There are several different ways to receive digital television. One of the oldest means of receiving DTV (and TV in general) is from terrestrial transmitters using an [[Television antenna|antenna]] (known as an ''aerial'' in some countries). This way is known as [[Digital terrestrial television]] (DTT). With DTT, viewers are limited to channels that have a terrestrial transmitter in range of their antenna.<br />
<br />
Other ways have been devised to receive digital television. Among the most familiar to people are [[digital cable]] and [[digital satellite]]. In some countries where transmissions of TV signals are normally achieved by [[microwaves]], digital [[MMDS]] is used. Other standards, such as [[Digital multimedia broadcasting]] (DMB) and [[DVB-H]], have been devised to allow handheld devices such as [[mobile phones]] to receive TV signals. Another way is [[IPTV]], that is receiving TV via Internet Protocol, relying on [[digital subscriber line]] (DSL) or optical cable line. Finally, an alternative way is to receive digital TV signals via the open Internet ([[Internet television]]), whether from a central streaming service or a P2P (peer-to-peer) system.<br />
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Some signals carry [[encryption]] and specify use conditions (such as "may not be recorded" or "may not be viewed on displays larger than 1 m in diagonal measure") backed up with the force of law under the World Intellectual Property Organization Copyright Treaty ([[WIPO Copyright Treaty]]) and national [[legislation]] implementing it, such as the U.S. [[Digital Millennium Copyright Act]]. Access to encrypted channels can be controlled by a removable [[smart card]], for example via the Common Interface ([[DVB-CI]]) standard for Europe and via [[Point Of Deployment]] (POD) for IS or named differently [[CableCard]].<br />
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=== Protection parameters for terrestrial DTV broadcasting ===<br />
<br />
Digital television signals must not interfere with each other, and they must also coexist with analog television until it is phased out.<br />
The following table gives allowable signal-to-noise and signal-to-interference ratios for various interference scenarios. This table is a crucial regulatory tool for controlling the placement and power levels of stations. Digital TV is more tolerant of interference than analog TV, and this is the reason a smaller range of channels can carry an all-digital set of television stations.{{Citation needed|reason=As far as I know, it's the data compression possible with digital that makes higher channel density possible.|date=September 2011}}<br />
<br />
{| class="wikitable"<br />
|-<br />
! System Parameters<br /><small>(protection ratios)</small><br />
! Canada [13]<br />
! USA [5]<br />
! EBU [9, 12]<br /><small>ITU-mode M3</small><br />
! Japan & Brazil [36, 37]<ref>ISDB-T (6&nbsp;MHz, 64QAM, R=2/3), Analog TV (M/NTSC).<br /></ref><br />
|-<br />
! C/N for AWGN Channel<br />
| +19.5&nbsp;dB<br />(16.5&nbsp;dB<ref name="protection_parameters_table_note_a">The Canadian parameter, C/(N+I) of noise plus co-channel DTV interface should be 16.5 dB.<br /></ref>)<br />
| +15.19&nbsp;dB<br />
| +19.3&nbsp;dB<br />
| +19.2&nbsp;dB<br />
|-<br />
! Co-Channel DTV into Analog TV<br />
| +33.8&nbsp;dB<br />
| +34.44&nbsp;dB<br />
| +34 ~ 37&nbsp;dB<br />
| +38&nbsp;dB<br />
|-<br />
! Co-Channel Analog TV into DTV<br />
| +7.2&nbsp;dB<br />
| +1.81&nbsp;dB<br />
| +4&nbsp;dB<br />
| +4&nbsp;dB<br />
|-<br />
! Co-Channel DTV into DTV<br />
| +19.5&nbsp;dB<br />(16.5&nbsp;dB<ref name="protection_parameters_table_note_a" />)<br />
| +15.27&nbsp;dB<br />
| +19&nbsp;dB<br />
| +19&nbsp;dB<br />
|-<br />
! Lower Adjacent Channel DTV into Analog TV<br />
| −16&nbsp;dB<br />
| −17.43&nbsp;dB<br />
| −5 ~ −11&nbsp;dB<ref name="protection_parameters_table_note_c">Depending on analog TV systems used.</ref><br />
| −6&nbsp;dB<br />
|-<br />
! Upper Adjacent Channel DTV into Analog TV<br />
| −12&nbsp;dB<br />
| −11.95&nbsp;dB<br />
| −1 ~ −10<ref name="protection_parameters_table_note_c" /><br />
| −5&nbsp;dB<br />
|-<br />
! Lower Adjacent Channel Analog TV into DTV<br />
| −48&nbsp;dB<br />
| −47.33&nbsp;dB<br />
| −34 ~ −37&nbsp;dB<ref name="protection_parameters_table_note_c" /><br />
| −35&nbsp;dB<br />
|-<br />
! Upper Adjacent Channel Analog TV into DTV<br />
| −49&nbsp;dB<br />
| −48.71&nbsp;dB<br />
| −38 ~ −36&nbsp;dB<ref name="protection_parameters_table_note_c" /><br />
| −37&nbsp;dB<br />
|-<br />
! Lower Adjacent Channel DTV into DTV<br />
| −27&nbsp;dB<br />
| −28&nbsp;dB<br />
| −30&nbsp;dB<br />
| −28&nbsp;dB<br />
|-<br />
! Upper Adjacent Channel DTV into DTV<br />
| −27&nbsp;dB<br />
| −26&nbsp;dB<br />
| −30&nbsp;dB<br />
| −29&nbsp;dB<br />
|}<br />
<br />
=== Interaction ===<br />
People can interact with a DTV system in various ways. One can, for example, browse the [[electronic program guide]]. Modern DTV systems sometimes use a return path providing feedback from the end user to the broadcaster. This is possible with a coaxial or fiber optic cable, a dialup modem, or Internet connection but is not possible with a standard antenna.<br />
<br />
Some of these systems support [[video on demand]] using a [[communication channel]] localized to a neighborhood rather than a city (terrestrial) or an even larger area (satellite).<br />
<br />
=== 1-segment broadcasting ===<br />
{{main article|1seg}}<br />
[[1seg]] (1-segment) is a special form of [[ISDB]]. Each channel is further divided into 13 segments. The 12 segments of them are allocated for [[HDTV]] and remaining segment, the 13th, is used for narrow-band receivers such as mobile television or [[cell phone]].<br />
<br />
== Timeline of transition ==<br />
{{Further information|Digital television transition}}<br />
<br />
== Comparison of analog vs digital ==<br />
{{See also|Analog television}}<br />
<br />
DTV has several advantages over analog TV, the most significant being that digital channels take up less bandwidth, and the bandwidth needs are continuously variable, at a corresponding reduction in image quality depending on the level of compression as well as the resolution of the transmitted image. This means that digital broadcasters can provide more digital channels in the same space, provide [[high-definition television]] service, or provide other non-television services such as multimedia or interactivity. DTV also permits special services such as multiplexing (more than one program on the same channel), electronic program guides and additional languages (spoken or subtitled). The sale of non-television services may provide an additional revenue source.<br />
<br />
Digital and analog signals react to interference differently. For example, common problems with analog television include [[Ghosting (television)|ghosting]] of images, noise from weak signals, and many other potential problems which degrade the quality of the image and sound, although the program material may still be watchable. With digital television, the audio and video must be synchronized digitally, so reception of the digital signal must be very nearly complete; otherwise, neither audio nor video will be usable. Short of this complete failure, "blocky" video is seen when the digital signal experiences interference.<br />
<br />
Analog TV began with monophonic sound, and later developed [[multichannel television sound]] with two independent audio signal channels. DTV allows up to 5 audio signal channels plus a [[sub-woofer]] bass channel, with broadcasts similar in quality to movie theaters and DVDs.<ref>{{cite web|url=https://www.pbs.org/opb/crashcourse/digital_v_analog/sound.html |title=Digital TV: A Cringley Crash Course&nbsp;— Digital Vs. Analog |publisher=Pbs.org |date= |accessdate=2014-01-13}}</ref><br />
<br />
=== Compression artifacts, picture quality monitoring, and allocated bandwidth ===<br />
DTV images have some picture defects that are not present on analog television or motion picture cinema, because of present-day limitations of bit rate and compression algorithms such as [[MPEG-2]]. This defect is sometimes referred to as "[[mosquito noise]]".<ref>{{cite web<br />
|author1=Le Dinh, Phuc-Tue |author2=Patry, Jacques | url=http://www.videsignline.com/howto/180207350<br />
| title=Video compression artifacts and MPEG noise reduction<br />
| work=Video Imaging DesignLine | date=February 24, 2006<br />
| accessdate=April 30, 2010 }}</ref><br />
<br />
Because of the way the human visual system works, defects in an image that are localized to particular features of the image or that come and go are more perceptible than defects that are uniform and constant. However, the DTV system is designed to take advantage of other limitations of the human visual system to help mask these flaws, e.g. by allowing more [[compression artifacts]] during fast motion where the eye cannot track and resolve them as easily and, conversely, minimizing artifacts in still backgrounds that may be closely examined in a scene (since time allows).<br />
<br />
Broadcast, cable, satellite, and Internet DTV operators control the picture quality of television signal encodes using sophisticated, neuroscience-based algorithms, such as the structural similarity ([[SSIM]]) video quality measurement tool, which was accorded each of its inventors a [[Primetime Emmy]] because of its global use. Another tool, called [[Visual Information Fidelity (VIF)]], is a top-performing algorithm at the core of the [[Netflix]] [[VMAF]] video quality monitoring system, which accounts for about 35% of all U.S. bandwidth consumption.<br />
<br />
=== Effects of poor reception ===<br />
Changes in signal reception from factors such as degrading antenna connections or changing weather conditions may gradually reduce the quality of analog TV. The nature of digital TV results in a perfectly decodable video initially, until the receiving equipment starts picking up interference that overpowers the desired signal or if the signal is too weak to decode. Some equipment will show a garbled picture with significant damage, while other devices may go directly from perfectly decodable video to no video at all or lock up. This phenomenon is known as the digital [[cliff effect]].<br />
<br />
[[Block error]] may occur when transmission is done with compressed images. A block error in a single frame often results in black boxes in several subsequent frames, making viewing difficult.<br />
<br />
For remote locations, distant channels that, as analog signals, were previously usable in a snowy and degraded state may, as digital signals, be perfectly decodable or may become completely unavailable. The use of higher frequencies will add to these problems, especially in cases where a clear line-of-sight from the receiving antenna to the transmitter is not available.<br />
<br />
=== Effect on old analog technology ===<br />
{{Update|section|date=February 2017}}<br />
Television sets with only analog tuners cannot decode digital transmissions. When analog broadcasting over the air ceases, users of sets with analog-only tuners may use other sources of programming (e.g. cable, recorded media) or may purchase set-top converter boxes to tune in the digital signals. In the United States, a [[Coupon-eligible converter box|government-sponsored coupon]] was available to offset the cost of an external converter box. Analog switch-off (of full-power stations) took place on December 11, 2006 in The Netherlands,<ref>{{cite web|url=http://www.ivir.nl/publications/sloot/switch-off.pdf |title=How Television went Digital in The Netherlands |accessdate=2013-02-04 |format=PDF |work=Open Society Foundations September 2011 }}</ref> June 12, 2009 in the United States for full-power stations, and later for Class-A Stations on September 1, 2016,<ref>{{cite web|url=http://www.dtv.gov/affected.html |title=The Digital TV Transition: Will You Be Affected? |accessdate=2009-11-02 |work=FCC }}</ref> July 24, 2011 in Japan,<ref>{{cite web|url=http://www.broadcastingcable.com/blog/BC_DC_Eggerton_on_Washington/15430-New_DTV_Hard_Date_July_24_2011_.php |title=New DTV Hard Date: July 24, 2011? |accessdate=2009-11-02 |work=B&C }}</ref> August 31, 2011 in Canada,<ref>{{cite web|url=http://www.ic.gc.ca/eic/site/smt-gst.nsf/vwapj/DTV_PLAN_Dec08-e.pdf/$file/DTV_PLAN_Dec08-e.pdf |title=DTV Post-Transition Allotment Plan |accessdate=2009-11-02 |format=PDF |work=Spectrum Management and Telecommunications }}</ref> February 13, 2012 in Arab states, May 1, 2012 in Germany, October 24, 2012 in the United Kingdom<ref>{{cite web|url=http://www.digitaluk.co.uk/__data/assets/pdf_file/0004/82057/24-10-12_DSO_completion.pdf |title=End of analogue TV era as switchover completes in the UK |accessdate=2012-12-21 |work=Digital UK }}</ref> and Ireland,<ref>{{cite web|url=http://www.saorview.ie/news/analogue-switch-off-has-finally-happened/|title=Analogue switch off has finally happened|accessdate=2012-12-21 |work=SAORVIEW}}</ref> October 31, 2012 in selected Indian cities,<ref name="india-switchover">{{cite web|url=http://www.digitalindiamib.com/digital_switch_over.html |title=Find out when digital switch over is coming to you |accessdate=2012-12-21 |work=Government of India Ministry of Information & Broadcasting }}</ref> and December 10, 2013 in Australia.<ref>{{cite web|url=http://www.digitalready.gov.au/|title=Australia's ready for digital TV |accessdate=2013-12-25 |work=Digital Ready AU }}</ref> Completion of analog switch-off is scheduled for December 31, 2017 in the whole of India,<ref name="india-switchover"/> December 2018 in Costa Rica and around 2020 for the Philippines.<br />
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=== Disappearance of TV-audio receivers ===<br />
Prior to the conversion to digital TV, analog television broadcast audio for TV channels on a separate FM [[carrier signal]] from the video signal. This FM audio signal could be heard using standard radios equipped with the appropriate tuning circuits.<br />
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However, after the [[digital television transition|transition of many countries to digital TV]], no portable radio manufacturer has yet developed an alternative method for portable radios to play just the audio signal of digital TV channels. ([[DTV radio]] is not the same thing.)<br />
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=== Environmental issues ===<br />
The adoption of a broadcast standard incompatible with existing analog receivers has created the problem of large numbers of analog receivers being discarded during [[digital television transition]]. One superintendent of public works was quoted in 2009 saying; "some of the studies I’ve read in the trade magazines say up to a quarter of American households could be throwing a TV out in the next two years following the regulation change".<ref>[http://www.tonawanda-news.com/local/local_story_027233552.html North Tonawanda: council discusses future TV disposal], Neale Gulley, Tonawanda News, January 27, 2009</ref> In 2009, an estimated 99 million analog TV receivers were sitting unused in homes in the US alone and, while some obsolete receivers are being retrofitted with converters, many more are simply dumped in [[landfill]]s where they represent a source of toxic metals such as [[lead]] as well as lesser amounts of materials such as [[barium]], [[cadmium]] and [[chromium]].<ref>[http://www.wltx.com/news/story.aspx?storyid=69896&catid=306 Old Toxic TVs Cause Problems], USA TODAY, January 27, 2009</ref><ref>[http://www.jsonline.com/news/wisconsin/38198929.html Unloading that old TV not quite so simple], Lee Bergquist, [[Milwaukee Journal-Sentinel]], January 23, 2009</ref><br />
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According to one campaign group, a [[cathode ray tube|CRT]] [[computer monitor]] or TV contains an average of {{convert|8|lb|kg}} of lead.<ref>[http://news.bbc.co.uk/1/hi/technology/7820229.stm Campaigners highlight 'toxic TVs'], Maggie Shiels, [[BBC News]], 9 January 2009</ref> According to another source, the lead in glass of a CRT varies from 1.08&nbsp;lb to 11.28&nbsp;lb, depending on screen size and type, but the lead is in the form of "stable and immobile" lead oxide mixed into the glass.<ref>{{cite web|title=Lead in Cathode Ray Tubes (CRTs) Information Sheet** |date=2001-11-30 |url=http://www.premierinc.com/quality-safety/tools-services/safety/topics/computers/downloads/k_3_lead_in_crts.pdf |format=PDF |page=1 |publisher=[[Electronic Industries Alliance]] |accessdate=2009-09-29 |deadurl=yes |archiveurl=https://web.archive.org/web/20110520124802/http://premierinc.com/quality-safety/tools-services/safety/topics/computers/downloads/k_3_lead_in_crts.pdf |archivedate=2011-05-20 |df= }}</ref> It is claimed that the lead can have long-term negative effects on the environment if dumped as landfill.<ref>{{cite journal |first=C.S. |last=Poon |title=Management of CRT glass from discarded computer monitors and TV sets |year=2008 |journal=Waste Management |volume=28 |pages=1499–1499 |url=http://ewasteguide.info/biblio/management-cr |doi=10.1016/j.wasman.2008.06.001 |quote=number of studies have demonstrated that the neck and funnel glasses of CRT are hazardous wastes, while the panel glass exhibits little toxicity. |accessdate=2009-09-29 |pmid=18571917 |issue=9}}</ref> However, the glass envelope can be recycled at suitably equipped facilities.<ref>[http://www.wcsh6.com/news/local/story.aspx?storyid=99680&catid=2 What To Do With Your Old TV's], Mike Webster, [[WCSH-TV]], January 28, 2009 - dead link</ref> Other portions of the receiver may be subject to disposal as [[hazardous material]].<br />
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Local restrictions on disposal of these materials vary widely; in some cases [[second-hand store]]s have refused to accept working color television receivers for resale due to the increasing costs of disposing of unsold TVs. Those [[thrift store]]s which are still accepting donated TVs have reported significant increases in good-condition working used television receivers abandoned by viewers who often expect them not to work after digital transition.<ref>[http://www.sun-sentinel.com/business/custom/consumer/sfl-flhlpvasquez0119sbjan19,0,4669489.column Many people throwing out perfectly good TVs over digital confusion], Daniel Vasquez, Sun-Sentinel, Florida, January 19, 2009</ref><br />
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In Michigan in 2009, one recycler estimated that as many as one household in four would dispose of or recycle a TV set in the following year.<ref>[http://detnews.com/apps/pbcs.dll/article?AID=/20090123/METRO/901230383 Trashing the tube: Digital conversion may spark glut of toxic waste], Jennifer Chambers, [[Detroit News]], January 23, 2009</ref> The digital television transition, migration to [[high-definition television]] receivers and the replacement of CRTs with flatscreens are all factors in the increasing number of discarded analog CRT-based television receivers.<br />
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== See also ==<br />
* [[Broadcast television systems]]<br />
* [[Text to Speech in Digital Television]]<br />
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== Notes and references ==<br />
{{Reflist}}<br />
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== Further reading ==<br />
* [[Jeffrey A. Hart|Hart, Jeffrey A.]], [http://inethub.olvi.net.ua/ftp/Library/SomeLibrary/Techno/Hart%20J.A.%20-%20Technology,%20Television%20and%20Competition%5Bc%5D%20The%20Politics%20of%20Digital%20TV%20%282004%29%28en%29.pdf ''Television, technology, and competition : HDTV and digital TV in the United States, Western Europe, and Japan''], New York : Cambridge University Press, 2004. {{ISBN|0-521-82624-1}}<br />
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== External links ==<br />
{{Commons category|Digital television}}<br />
*[http://cinemacommander.com Overview of Digital Television Development Worldwide] [[Proceedings of the IEEE]], VOL. 94, NO. 1, JANUARY 2006 ([[University of Texas at San Antonio]])<br />
* [http://www.dtv.gov/ The FCC's U.S. consumer-oriented DTV website]<br />
* [http://www.ricability-digitaltv.org.uk/ Digital TV Consumer test reports - UK Government-funded website to support Digital Switchover]<br />
* {{wikiHow|Set-up-a-DTV-Digital-Converter-Box-and-Antenna|Set up a DTV Digital Converter Box and Antenna}}<br />
* {{wikiHow|Scan-for-DTV-Channels-Using-a-Digital-TV-Converter-Box|Scan for DTV Channels Using a Digital TV Converter Box (and why this must be done 11 June 2009 in US)}}<br />
* {{wikiHow|Use-Your-Older-VCR%2C-TiVo%2C-or-DVR-With-a-DTV-Converter-Box|Use Your Older VCR, TiVo, or DVR With a DTV Converter Box}}<br />
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{{Digital television deployments}}<br />
{{Broadcasting}}<br />
{{Telecommunications}}<br />
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{{DEFAULTSORT:Digital Television}}<br />
[[Category:Digital television| ]]<br />
[[Category:History of television]]<br />
[[Category:Film and video technology]]<br />
[[Category:Television terminology]]<br />
[[Category:Digital technology|Television]]<br />
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