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Digital terrestrial television - Wikipedia, the free encyclopedia

Digital terrestrial television

From Wikipedia, the free encyclopedia

Digital Terrestrial Television (DTTV or DTT) is an implementation of digital technology to provide a greater number of channels and/or better quality of picture and sound using aerial broadcasts to a conventional antenna (or aerial) instead of a satellite dish or cable connection. The technology used is ATSC in North America, ISDB-T in Japan, DVB-T in Europe and Australia, and DMB-T/H in China (including Hong Kong); the rest of the world remaining mostly undecided. ISDB-T is very similar to DVB-T and can share front-end receiver and demodulator components.

DTT broadcasting systems by country.
DTT broadcasting systems by country.

Contents

[edit] Transmission

DTTV is transmitted on radio frequencies through the airwaves that are similar to standard analog television, with the primary difference being the use of multiplex transmitters to allow reception of multiple channels on a single frequency range (such as a UHF or VHF channel).

The amount of data that can be transmitted (and therefore the number of channels) is directly affected by the modulation method of the channel. The modulation method in DVB-T is COFDM with either 64 or 16 state Quadrature Amplitude Modulation (QAM). In general a 64QAM channel is capable of transmitting a greater bitrate, but is more susceptible to interference. 16 and 64QAM constellations can be combined in a single multiplex, providing a controllable degradation for more important programme streams. This is called hierarchical modulation.

New developments in compression have resulted in the MPEG-4/AVC standard which will enable two high definition services to be coded into a 24 Mbit/s European terrestrial transmission channel.

The DVB-T standard is not used for terrestrial digital television in North America. Instead, the ATSC standard calls for 8VSB modulation, which has similar characteristics to the vestigial sideband modulation used for analogue television. This provides considerably more immunity to interference, but is not immune - as DVB-T is - to multipath distortion and also does not provide for single-frequency network operation (which is in any case not relevant in the United States).

Both systems use the MPEG-2 transport stream and video codec; they differ significantly in how related services (such as multichannel audio, captions, and program guides) are encoded.

[edit] Advantages

  • Digital reception tends to be better overall, particularly with a weaker signal. With a good signal there is little perceptable difference, in fact analogue can be better.
  • It is easier to obtain the optimum digital picture than the optimum analogue picture.
  • Many more channels can fit on the digital transmission.
  • Interactice (red button) services can be provided.

[edit] Disadvantages

  • New equipment (set top box) is required.
  • An upgraded antenna installation may be required.
  • Analog requires lower signal strength to get a watchable picture. By extension, digital does not degrade as gracefully as analog.
  • Switching channels is slower because of the time delays in decoding digital signals.

[edit] Reception

DTTV is received via a digital set-top box, or integrated receiving device, that decodes the signal received via a standard aerial antenna. However, due to frequency planning issues, an aerial with a different group (usually a wideband) may be required if the DTTV multiplexes lie outside the bandwidth of the originally installed aerial. This is quite common in the UK, see external links.

[edit] DTT Around the world

Main article: List of digital television deployments by country

[edit] Europe

The United Kingdom (1998), Sweden (1999) and Spain (2000) were the first to launch DTT with platforms heavily reliant on pay television. All platforms experienced many starter problems, in particular the British and Spanish platforms which failed financially. Nevertheless, Boxer, the Swedish pay platform which started in 2004, proved to be very successful.

DTT in the United Kingdom was launched in November 1998 as a primarily subscription service branded as ONdigital, a joint venture between Granada Television and Carlton Communications, with only a few channels being available free to air. ONdigital soon ran into financial difficulties with subscriber numbers below expectations, and in order to attempt to reverse their fortunes, it was decided that the ITV and ONdigital brands should align, and the service was rebranded ITV Digital in 2001. Despite an expensive advertising campaign, ITV Digital struggled to attract sufficient new subscribers and in 2002 closed the service. After commercial failure of the Pay TV proposition it was relaunched as the free-to-air Freeview platform in 2002. Top Up TV, a lite pay DTT service, became available in 2004. Of all countries, the UK DTT has currently the highest penetration rate, in mid 2007 there were over 8 million subscribers. UK covers Northern Ireland DTT.

In the Republic of Ireland IT's TV was the sole applicant for a digital terrestrial television license under the provisions of the Irish Broadcasting Act 2001 which also established Telífís na Gaeilge, now TG4. It proposed a triple play deployment with Broadband, TV and Digital Radio services. However following financial difficulties with other DTT deployments, most particularly in the neighbouring UK and in Spain and Portugal, Its TV failed to get its license conditions varied or to get a time extension and its license was eventually withdrawn for non performance. Under subsequent legislation in May 2007, RTÉ and the separate broadcasting (BCI soon BAI) and spectrum regulators (ComReg) were mandated to invite applications during 2008 under the Broadcasting (Amendment) Act 2007 and the regulators which ComReg have issued to the BCI and which they BCI advertised and opened with submissions closing on May 2nd 2008. RTÉ Networks is required to broadcast in digital under the new Act and will receive an automatic license through the RTÉ Authority (soon the Broadcasting Authority of Ireland in its place) and will upgrade part of its network over a 5 year period. 1 Mux (group of channel radiowave space) will be public service with 98% Analogue Switchover (ASO) coverage required for Digital Aerial TV (DTT). The BAI 3 will will have a 90% coverage requirement at ASO. Following ASO 1 addition PSB mux and 1 or more commercial muxes will be made available for DTT, mobile television and other services.

The BCI (soon BAI received 3 conditional applications for 3 muxes which were presented in public on May 12th 2008 in Dublin, (conditional on all 3 muxes) and will decide on the winning consortium around July 21st 2008.[1]

A Houses of the Oireachtas Channel and Irish Film Channel Commissions will also be established under the Broadcasting Act 2008 as new public service broadcasters. The Broadcasting Authority of Ireland will replace the Broadcasting Complaints Commission, the Broadcasting Commission of Ireland and the RTÉ Authority and include Awards and Advisory Committees. [2].

The winning bidder will launch in 2009 according to all 3 submissions received.[3]

Portugal is expected to launch its DTT service in 2009 also with the public service broadcaster PTP providing FTA services in partnership with commercial broadcasters. Anacom regulates this area.

In Spain most multiplexes closed after the failure of Quiero TV, the country's original pay DTT platform. DTT was relaunched on 30 November 2005, with approximately 30 free-to-air national and autonomous region TV and radio services.

In Sweden, DTT was launched in 1999 solely as a paid service. Today (2007) there are 38 channels in 5 MUXs. 11 of those are free-to-air channels from a number of different networks. Switch-off of the analogue TV service started in September 2005 and finished on 15 October 2007.

Finland launched DTT in 2001, and terminated analogue transmissions nationwide as the third country in the world on 1 September 2007. Finland has successfully launched a mixture of pay and free-to-air DTT services.

Germany launched a free-to-air platform region-by-region, starting in Berlin in November 2002. The analogue broadcasts are planned to cease soon after digital transmissions are started. Berlin became completely digital on 4 August 2003.

France's TNT (Télévision Numérique Terrestre) offers 18 free and 11 pay channels. A 70% DTT penetration rate is expected by March 2007. Free-to-view satellite services offering the same DTT offer are also expected to be readied by the end of 2006.

Luxembourg launched DTT services in April 2006. The national service launched in June 2006. On 1 September 2006, Luxembourg became the first European country to transition completely to DTT.

The EU recommended in December 2005 that its Member States cease all analogue television transmissions by the year 2012. Some EU member states decided to complete the transition as early as 2007 (e.g. Finland), nevertheless two member states (unspecified in the announcement) have expressed concerns that they would not be able to switch due to technical limitations.

[edit] North and South America

In the United States by no later than February 17, 2009, all U.S. television broadcasts will be exclusively digital, under the Digital Television and Public Safety Act of 2005.[1] Furthermore, starting March 1, 2007, new television sets that receive signals over-the-air, including pocket sized portable televisions, must include ATSC digital tuners for digital broadcasts.[2] Currently, most U.S. broadcasters are transmitting in both analog and digital formats; a few are digital-only. Most U.S. stations are not permitted to shut down their analog transmissions prior to February 16, 2009, unless doing so is required in order to complete work on a station's permanent digital facilities.[3] In 2008, the FCC will finish auctioning channels 52–59 (the lower half of the 700 MHz band) for other communications services[4], completing the reallocation of broadcast channels 52–69 that began in the late 1990s.

The analog switch-off will render all non-digital televisions unable to receive most over-the-air television channels obsolete; however, low-power television stations and cable TV systems are not required to convert to digital until 2011 or later. Beginning January 1, 2008, consumers may request coupons to help cover most of the cost of these converters by calling a toll free number or via a website.[5]

In Venezuela, tests are being performed with full deployment to start 2008-2009. DTT will coexist with analog standard television for some time, until full deployment of the system on a nationwide level is accomplished.

In Brazil, they chose a modified version of the Japanese ISDB-T standard, called SBTVD.

Cuba has announced recently that in the current year could leave defined the norm to use. According to official sources of the MIC (Ministry of Computer science and Telecommunications) the Caribbean island would be decided between European format DVB or the DSM used by China. At the moment, Cuban specialists make tests in both formats but "analogical blackout" is far away.

Uruguay has chosen the European DVB.T standard.

[edit] Asia

[edit] Japan

Japanese Ministry of Internal Affairs and Communications and Dpa (The Association for Promotion of Digital Broadcasting-Japan) jointly set the specification and announced the guide line of "simplified DTT tuner" with price under 5,000 Japanese yen on December 25, 2007. MIAC officially solicit manufactures to put it on the market by end of March 2010 (end of fiscal year 2009). MIAC is estimating 14 million, at maximum, set of traditional non-digital TV remains and needs the "simplified DTT tuner" to be adapted even after complete transition to DTT after July 2011, and is aiming to avoid disposal of large number of useless TV sets without such a tuner at one time.

December 20, 2007, Japan Electronics and Information Technology Industries Association set the rule (of copy control) for DTT broadcasting allows consumers up to 10 time of dubbing of entire TV program with video and audio into DVD recorder and etc. by naming "Dubbing 10"(ja:ダビング10) (actually up to 9 times of copy then 1 time or last time of move) and is supposed to start the broadcasting with "Dubbing 10" at about 4:00 a.m. on June 2, 2008, but postponed, that settled after long talks with Japanese Society for Rights of Authors, Composers and Publishers. The manufacture for DVD recorder and associated DTT recorder will make unit conforming "Dubbing 10" rule and some manufacture shall release the down loading subprogram to up date recorder's internal software for existing user.

April 3, 2008, Dpa (The Association for Promotion of Digital Broadcasting-Japan) announced that total 32.71 million of DTT (ISDB-T) receiving TV sets (except 1seg receiver) are installed in Japan as of end of March 2008. Dpa also announced the guide line documentation to manufacture who make the DTT receive, recod and replay unit to operate with Personal computer on April 8, 2008 . This add-on unit operates on USB or PCI BUS, and started to sell on reservation basis from late April and put on retail store in mid. May 2008.

May 8, 2008, Ministry of Internal Affairs and Communications announced that 43.7% of home have DTT (ISDB-T) receiving TV and/or Tuner with DVD recorder by end of March 2008, which was 27.8% in one year before, and expecting 100% by April 2011.

[edit] Analogue to digital transition

The broadcasting of digital terrestrial transmissions has led to many countries planning to phase out existing analogue broadcasts. This table shows the launches of DTT and the closing down of analogue television in several countries.

  • Official launch: The official launch date of digital terrestrial television in the country, not the start for trial broadcasts.
  • Start of closedown: The date for the first major closedown of analogue transmitters.
  • End of closedown: The date when analogue television is definitely closed down.
  • System: Transmission system, e. g. DVB-T, ATSC or ISDB-T.
  • Interactive: System used for interactive services, such as MHP and MHEG-5.
  • Compression: Video compression standard used. Most systems use MPEG-2, but the more efficient H.264/MPEG-4 AVC has become increasingly popular among networks launching later on. Some countries use both MPEG-2 and H.264, for example the UK which uses MPEG-2 for standard content but MPEG-4 for some HD broadcasts.
Country
 Official launch
 Start of
closedown
 End of
closedown
 System
 Interactive
 Compression
 References
Albania 2005-08 DVB-T [citation needed]
Andorra 2007-09-25 DVB-T MHP [6]
Australia 2001-01-01 The new government has also extended the starting date of digital-only transmission in metropolitan markets for a year from December 2008[7] 2013-12-31 DVB-T MPEG-2 [citation needed]
Austria 2006-10-26 2007-03-05[8] DVB-T MHP [citation needed]
Belgium 2002/2003 2008-12-31 (Flemish Community) 2011 (Francophone Community) DVB-T No MPEG-2 [citation needed]
Brazil 2007-12-03 — 2016-06-29 SBTVD H.264/MPEG-4 AVC [citation needed]
Canada 2011-08-31 ATSC MPEG-2 [9]
China 2007-2008 DMB-T/H [citation needed]
Croatia 2007 2010 DVB-T [citation needed]
Czech Republic 2004 2007-08 2010-10 DVB-T MHP MPEG-2 [citation needed]
Denmark 2006-03-31 2009-11-01 DVB-T MHP MPEG-2, H.264 [4]
Estonia 2006-12-15 2008-03-30 (Ruhnu island) 2012-02 (planned) DVB-T MPEG-4 H.264 [10][11]
Faroe Islands 2002-12 2002-12 DVB-T [citation needed]
Finland 2001-08-27 2007-09-01[12] 2007-09-01 DVB-T MHP (abandoned) MPEG-2 [13]
France 2005-03-31 2008-03 2011-11-30 DVB-T MPEG-2, H.264 [citation needed]
Germany 2002-11 2003-08 2008 (planned) DVB-T MPEG-2 [citation needed]
Greece 2006 DVB-T
Hong Kong 2007-12-31 2012 DMB-T/H MHEG-5 (TVB) MPEG-2, H.264 [14][15]
Ireland 1999-2002 attempt abandoned, 2006-2008 Trial, Early to mid 2009 public launch planned 2012 likely due to NI ASO 2012 & EC objective. DVB-T RCT abandoned MPEG-4 H.264 [16][17][18][19]
Italy 2004-01-01 2010-01-01 DVB-T MHP MPEG-2 [citation needed]
Japan 2003-12-01 2011-07-24 (planned) ISDB-T [20][21]
Lithuania 2006 DVB-T MPEG-4
Luxembourg 2006-04 2006-09-01 2008/2009 DVB-T [citation needed]
Malaysia 2006-09 (trials) 2015 DVB-T MHEG-5 H.264 [citation needed]
Mexico 2004-07-05[22] 2022-01-01 ATSC [23]
Morocco 2007-06-01 DVB-T [citation needed]
Netherlands 2003 2006-12-11 DVB-T [citation needed]
New Zealand April 2008 75% digital penetration or 2012, whichever comes first. 1 year after start DVB-T MHEG-5 H.264/MPEG-4 AVC [24][25]
Norway 2007-09 [26] 2008-03 2009-12 DVB-T H.264/MPEG-4 AVC [citation needed]
Philippines 2006-10 (trials)/ 2007 2015-12-31 (Announced by NTC) 2015-12-31 (Announced by NTC) DVB-T (testing) [citation needed]
Romania 2005-12-01 2012-12-31 (planned) DVB-T [citation needed]
Portugal 2008 2011 (planned by PT) DVB-T MPEG-4
Russia 2012 2017 DVB-T
Slovenia 2007 2010 2011 DVB-T H.264/MPEG-4 AVC [citation needed]
South Africa 2006-03 2008-11-01 2011-11-01 DVB-T H.264/MPEG-4 AVC [citation needed]
South Korea 2001 2012-12-31 2012-12-31 ATSC [citation needed]
Spain 2000-05 2008[27] 2010-04-03 DVB-T MHP MPEG-2 [citation needed]
Sweden 1999-04-01[28] 2005-09-19 2007-10-15 DVB-T MHP MPEG-2/H.264[29] [citation needed]
Switzerland 2001 2002-03 2009-10 DVB-T [citation needed]
Taiwan 2006-07 2008 2010 DVB-T [citation needed]
Turkey 2006-02 (trial services) DVB-T [citation needed]
United Kingdom 1998-11-15 2007 (Whitehaven) 2012 DVB-T MHEG-5 MPEG-2, H.264 [30]
United States 2003 2009-02-17 ATSC MPEG-2 [31]
Venezuela 2008 SBTVD H.264/MPEG-4 AVC [citation needed]
v • d • e
Wireless video and data distribution methods

[edit] See also

[edit] Notes

  1. ^ Title III of the Deficit Reduction Act of 2005, Pub. L. No. 109-171, 120 Stat. 4 (February 8, 2006), codified at 47 U.S.C. § 309(j)(14).
  2. ^ FCC rule requires all new TVs to be digital. The Boston Globe (2007-02-26). Retrieved on 2007-04-24.
  3. ^ Federal Communications Commission (2007-12-22). Third Periodic DTV Review Report and Order. Retrieved on [[2008-02-09]]. FCC 07-228}}
  4. ^ FCC: Wireless Services: Lower 700 MHz. Federal Communications Commission (2004-10-28). Retrieved on 2007-05-09.
  5. ^ http://www.dtv2009.gov Digital Transition website Access date= 2007-12-31
  6. ^ , <http://www.tdt.ad/> 
  7. ^ Complete digital TV switch over by 2013, Sydney Morning Herald, 2007-12-18, <http://news.smh.com.au/complete-digital-tv-switch-over-by-2013/20071218-1hun.html>. Retrieved on 21 December 2007 
  8. ^ DVB-T: Zeitplan, DVB-T.at, <http://www.dvb-t.at/wann-wie-umstellen/zeitplan.html>. Retrieved on 3 July 2007 
  9. ^ Broadcasting Public Notice CRTC 2007-53 - Determinations regarding certain aspects of the regulatory framework for over-the-air television, Canadian Radio and Television Commission, May 17, 2007, <http://www.crtc.gc.ca/archive/ENG/Notices/2007/pb2007-53.htm> 
  10. ^ Launch of DTT services in Estonia, DigiTAG Web Letter, December 15, 2006, <http://www.digitag.org/WebLetters/2006/External-Dec2006.html> 
  11. ^ , <http://levira.ee/771est.html> 
  12. ^ Digi-tv esillä ympäri maata. Finnish Ministry of Communications. Retrieved on 2007-08-15.
  13. ^ Finland will switch over to all-digital television, Finnish Ministry of Transport and Communications, 2007-08-31, <http://www.digitv.fi/sivu.asp?path=9;1239;9758> 
  14. ^ OFTA(2007-06-04), Hong Kong Technical Standard for Digital Terrestrial Television Broadcasting, Hong Kong
  15. ^ (Chinese) 望月. "獨家專訪TVB 折解數碼廣播七大疑團 (Exclusive interview with TVB on digital broadcasting)", e-zone AVzone, 6/9/2007, pp. 4-5. 
  16. ^ What is Digital Television?, Department of Communications, Energy & Natural Resources, 2008-03-04, <http://www.dcmnr.gov.ie/Broadcasting/Digital+Television/> 
  17. ^ BCI DTT Licensing Policy 2008 (Revised Edition, Broadcasting Commission of Ireland (soon Broadcasting Authority of Ireland (in 2009), 2008-02-09, <http://www.bci.ie/documents/BCI_dtt_licensing_policy_08_revised_edition.pdf/> 
  18. ^ BCI DTT Licensing 2008 (, Broadcasting Commission of Ireland (soon Broadcasting Authority of Ireland (in 2009), 2008-05-27, <http://www.bci.ie/DTT/licensing.html/> 
  19. ^ BCI News Releases 2008 (, Broadcasting Commission of Ireland (soon Broadcasting Authority of Ireland (in 2009), 2008-03-06, <http://www.bci.ie/news_information/press172.html> 
  20. ^ Digital Broadcasting Experts Group (DiBEG) promote ISDB-T
  21. ^ ISDB-T, Application, Present and Future, PDF File
  22. ^ Documento sin título
  23. ^ , <http://www.cft.gob.mx/cofetel/radio_tv/periodo_tran_tdt.shtml> 
  24. ^ , <http://tvnz.co.nz/view/page/1382967> 
  25. ^ , <http://www.beehive.govt.nz/ViewDocument.aspx?DocumentID=31480> 
  26. ^ RiksTV - Når kommer det?, RiksTV.no, <http://rikstv.no/Nar-kommer-det/>. Retrieved on 4 July 2007 
  27. ^ Local channels
  28. ^ Nya tillstånd för digitala TV-sändningar, Swedish Radio and TV Authority, January 20, 2001, <http://www.rtvv.se/se/Press/Nyheter/000120/> 
  29. ^ As of June 2007, H.264 is only used for HDTV in the Mälaren Valley region.
  30. ^ What is Digital Switchover?. DAS TV (2007-07-01). Retrieved on 2007-08-13.
  31. ^ National Telecommunications & Information Administration

[edit] External links


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