Digital terrestrial television
Information about Digital terrestrial television
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.
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.
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 ONdigtital 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, British DTT has currently the highest penetration rate. 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. It proposed its proposition around triple play such as broadband, TV and digital radio services. However, following difficulties in financial markets aroud DTT, most particularly in the neighbouring UK, Spain and Portugal around similar models it failed to get license conditions varied nor get extra time and its license was withdrawn. Under new legislation in May 2007, RTÉ and the broadcasting and spectrum regulators are mandated to each invite licenees during 2008 under the Broadcasting (Amendment) Act 2007 and are expected to invite licensee applications in January and June 2008 respectively. RTÉ is required to broadcast in digital under the new Act and will receive its license through the RTÉ Authority and upgrade its network over a 2 year period.
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 will finish 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.
In the United States by no later than February 17, 2009, all U.S. television broadcasts will be exclusively digital, by order of the Federal Communications Commission, with legislation setting this deadline signed into law in early 2006.[1] Furthermore, starting March 1, 2007, new television sets that receive signals over-the-air, including pocket sized portable televisions, must include digital or HDTV tuners for digital broadcasts.[2] Currently, most U.S. broadcasters are beaming their signals in both analog and digital formats; a few are digital-only. Citing the bandwidth efficiency of digital TV, after the analog switch-off the FCC will auction off channels 52–59 (the lower half of the 700 MHz band) for other communications traffic[3], completing the reallocation of broadcast channels 52–69 that began in the late 1990s. The analog switch-off ruling, which so far has met little opposition from consumers or manufacturers, would render all non-digital televisions dark and obsolete within 2 years. The FCC has determined that an external tuning device can simply be added to non-digital televisions to lengthen their useful lifespan. (However, as of March 2007, external tuning devices are not widely available, are relatively expensive, and require bulky AC power supplies.) Currently, even the earliest televisions continue to work with present broadcast standards. This mandate was designed to help provide a painless transition to the new standards.
In Venezuela there are already being performed the test phases for implementing the protocol, which is foreseen to start usage between 2008-2009. It will coexist with analog standard television for some time, until fully deployment of the system on a nationwide level is accomplished.
Debt, AIDS, Trade in Africa (or DATA) is a multinational non-government organization founded in January 2002 in London by U2's Bono along with Bobby Shriver and activists from the Jubilee 2000 Drop
..... Click the link for more information.
Quadrature amplitude modulation (QAM) is a modulation scheme which conveys data by changing (modulating) the amplitude of two carrier waves.
..... Click the link for more information.
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.
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.DTT Around the world
Main article: List of digital television deployments by countryThe 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 ONdigtital 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, British DTT has currently the highest penetration rate. 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. It proposed its proposition around triple play such as broadband, TV and digital radio services. However, following difficulties in financial markets aroud DTT, most particularly in the neighbouring UK, Spain and Portugal around similar models it failed to get license conditions varied nor get extra time and its license was withdrawn. Under new legislation in May 2007, RTÉ and the broadcasting and spectrum regulators are mandated to each invite licenees during 2008 under the Broadcasting (Amendment) Act 2007 and are expected to invite licensee applications in January and June 2008 respectively. RTÉ is required to broadcast in digital under the new Act and will receive its license through the RTÉ Authority and upgrade its network over a 2 year period.
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 will finish 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.
In the United States by no later than February 17, 2009, all U.S. television broadcasts will be exclusively digital, by order of the Federal Communications Commission, with legislation setting this deadline signed into law in early 2006.[1] Furthermore, starting March 1, 2007, new television sets that receive signals over-the-air, including pocket sized portable televisions, must include digital or HDTV tuners for digital broadcasts.[2] Currently, most U.S. broadcasters are beaming their signals in both analog and digital formats; a few are digital-only. Citing the bandwidth efficiency of digital TV, after the analog switch-off the FCC will auction off channels 52–59 (the lower half of the 700 MHz band) for other communications traffic[3], completing the reallocation of broadcast channels 52–69 that began in the late 1990s. The analog switch-off ruling, which so far has met little opposition from consumers or manufacturers, would render all non-digital televisions dark and obsolete within 2 years. The FCC has determined that an external tuning device can simply be added to non-digital televisions to lengthen their useful lifespan. (However, as of March 2007, external tuning devices are not widely available, are relatively expensive, and require bulky AC power supplies.) Currently, even the earliest televisions continue to work with present broadcast standards. This mandate was designed to help provide a painless transition to the new standards.
In Venezuela there are already being performed the test phases for implementing the protocol, which is foreseen to start usage between 2008-2009. It will coexist with analog standard television for some time, until fully deployment of the system on a nationwide level is accomplished.
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 | |||||
| Andorra | 2007-09-25 | DVB-T | MHP | [4] | |||
| Australia | 2001-01-01 | 2010 - 2012 (planned) | DVB-T | MPEG-2 | |||
| Austria | 2006-10-26 | 2007-03-05 [5] | DVB-T | MHP | |||
| Belgium | 2002/2003 | December 31 2008 (Flemish Community) | 2011 (Francophone Community) | DVB-T | No | MPEG-2 | |
| Brazil | 2007-12-03 | — | 2016-06-29 | ISDTV | H.264/MPEG-4 AVC | ||
| Canada | 2011-08-31 | ATSC | [6] | ||||
| China | 2007-2008 | DMB-T/H | |||||
| Croatia | 2007 | 2010 | DVB-T | ||||
| Czech Republic | 2004 | 2007-08 | 2010-10 | DVB-T | MHP | MPEG-2 | |
| Denmark | 2006-03-31 | 2009-11-01 | DVB-T | MHP | MPEG-2, H.264 | ||
| Estonia | 2006-12-15 | 2012-02 (planned) | DVB-T | H.264 | [7] | ||
| Faroe Islands | 2002-12 | 2002-12 | DVB-T | ||||
| Finland | 2001-08-27 | 2007-09-01[8] | 2007-09-01 | DVB-T | MHP (abandoned) | MPEG-2 | [9] |
| France | 2005-03-31 | 2008-03 | 2011-11-30 | DVB-T | MPEG-2, H.264 | ||
| Germany | 2002-11 | 2003-08 | 2008 (planned) | DVB-T | MPEG-2 | ||
| Hong Kong | 2007 | 2012 | DMB-T/H | MHEG-5 (TVB) | MEPG-2, H.264 | [10][11] | |
| Ireland | 1999 Trial 2006-2008 Trial | DVB-T | RCT abandoned | MPEG-2, H.264 | |||
| Italy | 2004-01-01 | 2010-01-01 | DVB-T | MHP | |||
| Japan | 2003-12-01 | 2011-07-24 (planned) | ISDB-T | ||||
| Luxembourg | 2006-04 | 2006-09-01 | 2008/2009 | DVB-T | |||
| Malaysia | 2006-09 (trials) | 2015 | (testing) | ||||
| Mexico | 2004-7-5 [1] | 2022-1-1 | ATSC | [12] | |||
| Morocco | 2007-06-01 | DVB-T | |||||
| Netherlands | 2003 | 2006-12-11 | DVB-T | ||||
| New Zealand | 2008-05 | 2013 to 2017 | DVB-T | ||||
| Norway | 2007-09 [13] | 2008-03 | 2009-12 | DVB-T | H.264/MPEG-4 AVC | ||
| Philippines | 2006-10 (trials)/ 2007 | 2010 (planned) | 2015 (planned) | DVB-T (testing) | |||
| Portugal | never | never | never | none | |||
| Romania | 2005-12-01 | 2012-12-31 (planned) | DVB-T | ||||
| Russia | 2012 | 2017 | DVB-T | ||||
| Slovenia | 2007-09 | 2010 | 2010 | DVB-T | H.264/MPEG-4 AVC | ||
| South Africa | 2006-03 | 2008-11-01 | 2011-11-01 | DVB-T | H.264/MPEG-4 | ||
| South Korea | 2001 | 31st December 2012 | 31st December 2012 | ATSC | |||
| Spain | 2000-05 | 2008[14] | 2010-04-03 | DVB-T | MHP | ||
| Sweden | 1999-04-01[15] | 2005-09-19 | 2007-10-15 | DVB-T | MHP | MPEG-2/H.264[16] | |
| Switzerland | 2001 | 2002-03 | 2009-10 | DVB-T | |||
| Taiwan | 2006-07 | 2008 | 2010 | DVB-T | |||
| Turkey | 2006-02 (trial services) | DVB-T | |||||
| United Kingdom | 1998-11-15 | 2007 (Whitehaven) | 2012 | DVB-T | MHEG-5 | MPEG-2, H.264 | [17] |
| United States | 2009-02-17 | ATSC | MPEG-2 |
See also
- DVB-T (Digital Video Broadcasting - Terrestrial)
- DVB (Digital Video Broadcasting)
- Digital television (DTV)
- List of digital television deployments by country
- 1seg
Notes
1. ^ Section 3002 of the Deficit Reduction Act of 2005, Pub. L. No. 109-171, 120 Stat. 4 (Feb. 8, 2006), amending the Communications Act of 1934, section 309(j)(14), codified at .
2. ^ FCC rule requires all new TVs to be digital. The Boston Globe (2007-02-26). Retrieved on 2007-04-24.
3. ^ FCC: Wireless Services: Lower 700 MHz. Federal Communications Commission (2004-10-28). Retrieved on 2007-05-09.
4. ^ , <[2]
5. ^ DVB-T: Zeitplan, DVB-T.at, <[3] (retrieved on 2007-07-03)
6. ^ Broadcasting Public Notice CRTC 2007-53 - Determinations regarding certain aspects of the regulatory framework for over-the-air television, Canadian Radio and Television Comission, May 17, 2007, <[4]
7. ^ Launch of DTT services in Estonia, DigiTAG Web Letter, December 15, 2006, <[5]
8. ^ Digi-tv esillä ympäri maata. Finnish Ministry of Communications. Retrieved on 2007-08-15.
9. ^ Finland will switch over to all-digital television, Finnish Ministry of Transport and Communications, 2007-08-31, <[6]
10. ^ OFTA(2007-06-04), Hong Kong Technical Standard for Digital Terrestrial Television Broadcasting, Hong Kong
11. ^ (Finland will switch over to all-digital television) 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.e-zone%20AVzone&rft.pages=4-5&rft.date=6%2F9%2F2007">
12. ^ , <[7]
13. ^ RiksTV - Når kommer det?, RiksTV.no, <[8] (retrieved on 2007-07-04)
14. ^ Local channels
15. ^ Nya tillstånd för digitala TV-sändningar, Swedish Radio and TV Authority, January 20, 2001, <[9]
16. ^ As of June 2007, H.264 is only used for HDTV in the Mälaren Valley region.
17. ^ What is Digital Switchover?. DAS TV (2007-07-01). Retrieved on 2007-08-13.
2. ^ FCC rule requires all new TVs to be digital. The Boston Globe (2007-02-26). Retrieved on 2007-04-24.
3. ^ FCC: Wireless Services: Lower 700 MHz. Federal Communications Commission (2004-10-28). Retrieved on 2007-05-09.
4. ^ , <[2]
5. ^ DVB-T: Zeitplan, DVB-T.at, <[3] (retrieved on 2007-07-03)
6. ^ Broadcasting Public Notice CRTC 2007-53 - Determinations regarding certain aspects of the regulatory framework for over-the-air television, Canadian Radio and Television Comission, May 17, 2007, <[4]
7. ^ Launch of DTT services in Estonia, DigiTAG Web Letter, December 15, 2006, <[5]
8. ^ Digi-tv esillä ympäri maata. Finnish Ministry of Communications. Retrieved on 2007-08-15.
9. ^ Finland will switch over to all-digital television, Finnish Ministry of Transport and Communications, 2007-08-31, <[6]
10. ^ OFTA(2007-06-04), Hong Kong Technical Standard for Digital Terrestrial Television Broadcasting, Hong Kong
11. ^ (Finland will switch over to all-digital television) 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.e-zone%20AVzone&rft.pages=4-5&rft.date=6%2F9%2F2007">
12. ^ , <[7]
13. ^ RiksTV - Når kommer det?, RiksTV.no, <[8] (retrieved on 2007-07-04)
14. ^ Local channels
15. ^ Nya tillstånd för digitala TV-sändningar, Swedish Radio and TV Authority, January 20, 2001, <[9]
16. ^ As of June 2007, H.264 is only used for HDTV in the Mälaren Valley region.
17. ^ What is Digital Switchover?. DAS TV (2007-07-01). Retrieved on 2007-08-13.
External links
- TV Fool - Coverage maps and info for US broadcast television stations
- Share help, tips and advice as Cumbria leads the way to digital tv in the UK
- Complete list of UK DTT transmitters and any change of group (see Reception section of this page)
- digitalUK - Official Switchover Information
- DigiTAG
- The DVB Project
- Official DVB-H Information
- European Audiovisual Observatory
- Research about DTT
- Open DVB-T Implementation (BSD license) with source code for Matlab and GNU Octave
- DVB-T in the north of France
- Official TNT site
- Digital terrestrial television in Spain
- Digital Broadcasting Device Manager
- Worldwide overview of the digital terrestrial systems ATSC, DVB-T and ISDB-T
- TNT in France (French Digital TV)
- Latest Irish Waffle Here
- Finland needs another 48 small relays to fill in coverage holes ( July 2007)
- Mexican FCC
- A blog about DTT receivers
antenna is a transducer designed to transmit or receive radio waves which are a class of electromagnetic waves. In other words, antennas convert radio frequency electrical currents into electromagnetic waves and vice versa.
..... Click the link for more information.
..... Click the link for more information.
satellite dish is a type of parabolic antenna designed with the specific purpose of transmitting signals to and/or receiving from satellites. A satellite dish is a particular type of microwave antenna.
..... Click the link for more information.
..... Click the link for more information.
cable is one or more wires or optical fibers bound together, typically in a common protective jacket or sheath. The individual wires or fibers inside the jacket may be covered or insulated. Combination cables may contain both electrical wires and optical fibers.
..... Click the link for more information.
..... Click the link for more information.
ATSC Standards document a digital television format which will replace (in the United States) the analog NTSC television system[1] (NTSC is used mostly in North America and Japan). It was developed by the Advanced Television Systems Committee.
..... Click the link for more information.
..... Click the link for more information.
Integrated Services Digital Broadcasting (ISDB) is the digital television (DTV) and digital radio format that Japan has created to allow radio and television stations there to convert to digital.
..... Click the link for more information.
Introduction
ISDB is maintained by the Japanese organisation ARIB...... Click the link for more information.
DVB, short for Digital Video Broadcasting, is a suite of internationally accepted open standards for digital television. DVB standards are maintained by the DVB Project, an industry consortium with more than 270 members, and they are published by a
..... Click the link for more information.
..... Click the link for more information.
This article or section contains information about a scheduled or expected digital television transmission standard
It may contain tentative information; the content may change as the event approaches and more information becomes available.
..... Click the link for more information.
It may contain tentative information; the content may change as the event approaches and more information becomes available.
..... Click the link for more information.
Radio frequency, or RF, is a frequency or rate of oscillation within the range of about 3 Hz and 300 GHz. This range corresponds to frequency of alternating current electrical signals used to produce and detect radio waves.
..... Click the link for more information.
..... Click the link for more information.
Analog television (or analogue television) encodes television and transports the picture and sound information as an analog signal, that is, by varying the amplitude and/or frequencies of the broadcast signal.
..... Click the link for more information.
..... Click the link for more information.
In electronics, telecommunications and computer networks, multiplexing (short muxing) is a term used to refer to a process where multiple analog message signals or digital data streams are combined into one signal. The aim is to share an expensive resource.
..... Click the link for more information.
..... Click the link for more information.
Cycles per second: 300 MHz to 3 GHz
Wavelength: 1 m to 100 mm Ultra high frequency (UHF) designates a range (band) of electromagnetic waves whose frequency is between 300 MHz and 3 GHz, which is 300 MHz to 3,000 MHz.
..... Click the link for more information.
Wavelength: 1 m to 100 mm Ultra high frequency (UHF) designates a range (band) of electromagnetic waves whose frequency is between 300 MHz and 3 GHz, which is 300 MHz to 3,000 MHz.
..... Click the link for more information.
Very high frequency (VHF) is the radio frequency range from 30 MHz to 300 MHz. It is also known as the meter band or meter wave as the wavelengths range from ten to one meters.
..... Click the link for more information.
..... Click the link for more information.
- For other uses, see Data (disambiguation).
Debt, AIDS, Trade in Africa (or DATA) is a multinational non-government organization founded in January 2002 in London by U2's Bono along with Bobby Shriver and activists from the Jubilee 2000 Drop
..... Click the link for more information.
DVB-T stands for Digital Video Broadcasting - Terrestrial and it is the DVB European consortium standard for the broadcast transmission of digital terrestrial television.
..... Click the link for more information.
..... Click the link for more information.
Orthogonal Frequency-Division Multiplexing (OFDM) — essentially identical to Coded OFDM (COFDM) — is a digital multi-carrier modulation scheme, which uses a large number of closely-spaced orthogonal sub-carriers.
..... Click the link for more information.
..... Click the link for more information.
“QAM
Quadrature amplitude modulation (QAM) is a modulation scheme which conveys data by changing (modulating) the amplitude of two carrier waves.
..... Click the link for more information.
Link adaptation, or adaptive modulation and coding (AMC), is a term used in wireless communications to denote the matching of the modulation, coding and other signal and protocol parameters to the conditions on the radio link (e.g.
..... Click the link for more information.
..... Click the link for more information.
ATSC Standards document a digital television format which will replace (in the United States) the analog NTSC television system[1] (NTSC is used mostly in North America and Japan). It was developed by the Advanced Television Systems Committee.
..... Click the link for more information.
..... Click the link for more information.
8VSB is the 8-level vestigial sideband modulation method adopted for terrestrial broadcast of the ATSC digital television standard in the United States, Canada, and other countries.
..... Click the link for more information.
Throughput
In the 6 MHz (megahertz) channel used for broadcast ATSC, 8VSB carries 19...... Click the link for more information.
sideband is a band of frequencies higher than or lower than the carrier frequency, containing power as a result of the modulation process. The sidebands consist of all the Fourier components of the modulated signal except the carrier. All forms of modulation produce sidebands.
..... Click the link for more information.
..... Click the link for more information.
MPEG-2 is a standard for "the generic coding of moving pictures and associated audio information".[1] It describes a combination of lossy video compression and lossy audio compression (audio data compression) methods which permit storage and transmission of movies using
..... Click the link for more information.
..... Click the link for more information.
Transport stream (TS, TP, or MPEG-TS) is a communications protocol for audio, video, and data which is specified in MPEG-2 Part 1, Systems (ISO/IEC standard 13818-1 [1] ).
..... Click the link for more information.
..... Click the link for more information.
A video codec is a device or software that enables video compression and or decompression for digital video. The compression usually employs lossy data compression. Historically, video was stored as an analog signal on magnetic tape.
..... Click the link for more information.
..... Click the link for more information.
A set-top box (STB) or set-top unit (STU) is a device that connects to a television and an external source of signal, turning the signal into content which is then displayed on the television screen.
..... Click the link for more information.
..... Click the link for more information.
antenna is a transducer designed to transmit or receive radio waves which are a class of electromagnetic waves. In other words, antennas convert radio frequency electrical currents into electromagnetic waves and vice versa.
..... Click the link for more information.
..... Click the link for more information.
The transition to digital television is a process that follows different paces around the world. Although digital satellite television is now commonplace and will soon render analogue satellite broadcasts obsolete, the switch to digital cable and terrestrial has taken longer.
..... Click the link for more information.
..... Click the link for more information.
Pay television or Premium Television refers to subscription-based television services, usually provided by both analogue and digital cable and satellite, but also increasingly by digital terrestrial methods.
..... Click the link for more information.
..... Click the link for more information.
Digital terrestrial television in the United Kingdom (which is also available on the Isle of Man and will one day be available on the Channel Islands) is made up of over fifty primarily free-to-air television channels (including all the national analogue stations) and over twenty
..... Click the link for more information.
..... Click the link for more information.
Granada Television
Based in Manchester
Broadcast area North (1956-1968)
North West England (1968-present)
Launched May 3, 1956
A Granada TV logo from 1992
Closed Lost on-air identity October 27,2002.
..... Click the link for more information.
Based in Manchester
Broadcast area North (1956-1968)
North West England (1968-present)
Launched May 3, 1956
A Granada TV logo from 1992
Closed Lost on-air identity October 27,2002.
..... Click the link for more information.
Carlton Communications Limited (formerly Carlton Communications plc) is a former British media company, which was founded by Michael Green and listed on the London Stock Exchange from 1983 until 2 February 2004, when it merged with Granada plc to form ITV plc.
..... Click the link for more information.
..... Click the link for more information.
This article is copied from an article on Wikipedia.org - the free encyclopedia created and edited by online user community. The text was not checked or edited by anyone on our staff. Although the vast majority of the wikipedia encyclopedia articles provide accurate and timely information please do not assume the accuracy of any particular article. This article is distributed under the terms of GNU Free Documentation License.