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DVB-T

DVB-T, short for Digital Video Broadcasting – Terrestrial, is the DVB European-based consortium standard for the broadcast transmission of digital terrestrial television that was first published in 1997[1] and first broadcast in Singapore in February, 1998.[2][3][4][5][6][7][8] This system transmits compressed digital audio, digital video and other data in an MPEG transport stream, using coded orthogonal frequency-division multiplexing (COFDM or OFDM) modulation. It is also the format widely used worldwide (including North America) for Electronic News Gathering for transmission of video and audio from a mobile newsgathering vehicle to a central receive point. It is also used in the US by Amateur television operators.

The logo of DVB-T

Basics

Rather than carrying one data carrier on a single radio frequency (RF) channel, COFDM works by splitting the digital data stream into a large number of slower digital streams, each of which digitally modulates a set of closely spaced adjacent sub-carrier frequencies. In the case of DVB-T, there are two choices for the number of carriers known as 2K-mode or 8K-mode. These are actually 1,705 or 6,817 sub-carriers that are approximately 4 kHz or 1 kHz apart.

DVB-T offers three different modulation schemes (QPSK, 16QAM, 64QAM).

DVB-T has been adopted or proposed for digital television broadcasting by many countries (see map), using mainly VHF 7 MHz and UHF 8 MHz channels whereas Taiwan, Colombia, Panama and Trinidad and Tobago use 6 MHz channels. Examples include the UK's Freeview.

The DVB-T Standard is published as EN 300 744, Framing structure, channel coding and modulation for digital terrestrial television. This is available from the ETSI website, as is ETSI TS 101 154, Specification for the use of Video and Audio Coding in Broadcasting Applications based on the MPEG-2 Transport Stream, which gives details of the DVB use of source coding methods for MPEG-2 and, more recently, H.264/MPEG-4 AVC as well as audio encoding systems. Many countries that have adopted DVB-T have published standards for their implementation. These include the D-book in the UK, the Italian DGTVi,[9] the ETSI E-Book and the Nordic countries and Ireland NorDig.

DVB-T has been further developed into newer standards such as DVB-H (Handheld), which was a commercial failure and is no longer in operation, and DVB-T2, which was initially finalised in August 2011.

DVB-T as a digital transmission delivers data in a series of discrete blocks at the symbol rate. DVB-T is a COFDM transmission technique which includes the use of a Guard Interval. It allows the receiver to cope with strong multipath situations. Within a geographical area, DVB-T also allows single-frequency network (SFN) operation, where two or more transmitters carrying the same data operate on the same frequency. In such cases the signals from each transmitter in the SFN needs to be accurately time-aligned, which is done by sync information in the stream and timing at each transmitter referenced to GPS.

The length of the Guard Interval can be chosen. It is a trade-off between data rate and SFN capability. The longer the guard interval the larger is the potential SFN area without creating intersymbol interference (ISI). It is possible to operate SFNs which do not fulfill the guard interval condition if the self-interference is properly planned and monitored.

Technical description of a DVB-T transmitter

 
Scheme of a DVB-T transmission system

With reference to the figure, a short description of the signal processing blocks follows.

  • Source coding and MPEG-2 multiplexing (MUX): Compressed video, compressed audio, and data streams are multiplexed into MPEG program streams (MPEG-PSs). One or more MPEG-PSs are joined together into an MPEG transport stream (MPEG-TS); this is the basic digital stream which is being transmitted and received by TV sets or home Set Top Boxes (STB). Allowed bit rates for the transported data depend on a number of coding and modulation parameters: it can range from about 5 to about 32 Mbit/s (see the bottom figure for a complete listing).
  • Splitter: Two different MPEG-TSs can be transmitted at the same time, using a technique called Hierarchical Transmission. It may be used to transmit, for example a standard definition SDTV signal and a high definition HDTV signal on the same carrier. Generally, the SDTV signal is more robust than the HDTV one. At the receiver, depending on the quality of the received signal, the STB may be able to decode the HDTV stream or, if signal strength lacks, it can switch to the SDTV one (in this way, all receivers that are in proximity of the transmission site can lock the HDTV signal, whereas all the other ones, even the farthest, may still be able to receive and decode an SDTV signal).
  • MUX adaptation and energy dispersal: The MPEG-TS is identified as a sequence of data packets, of fixed length (188 bytes). With a technique called energy dispersal, the byte sequence is decorrelated.
  • External encoder: A first level of error correction is applied to the transmitted data, using a non-binary block code, a Reed–Solomon RS (204, 188) code, allowing the correction of up to a maximum of 8 wrong bytes for each 188-byte packet.
  • External interleaver: Convolutional interleaving is used to rearrange the transmitted data sequence, in such a way that it becomes more rugged to long sequences of errors.
  • Internal encoder: A second level of error correction is given by a punctured convolutional code, which is often denoted in STBs menus as FEC (Forward error correction). There are five valid coding rates: 1/2, 2/3, 3/4, 5/6, and 7/8.
  • Internal interleaver: Data sequence is rearranged again, aiming to reduce the influence of burst errors. This time, a block interleaving technique is adopted, with a pseudo-random assignment scheme (this is really done by two separate interleaving processes, one operating on bits and another one operating on groups of bits).
  • Mapper: The digital bit sequence is mapped into a base band modulated sequence of complex symbols. There are three valid modulation schemes: QPSK, 16-QAM, 64-QAM.
  • Frame adaptation: the complex symbols are grouped in blocks of constant length (1512, 3024, or 6048 symbols per block). A frame is generated, 68 blocks long, and a superframe is built by 4 frames.
  • Pilot and TPS signals: In order to simplify the reception of the signal being transmitted on the terrestrial radio channel, additional signals are inserted in each block. Pilot signals are used during the synchronization and equalization phase, while TPS signals (Transmission Parameters Signalling) send the parameters of the transmitted signal and to unequivocally identify the transmission cell. The receiver must be able to synchronize, equalize, and decode the signal to gain access to the information held by the TPS pilots. Thus, the receiver must know this information beforehand, and the TPS data is only used in special cases, such as changes in the parameters, resynchronizations, etc.
 
Spectrum of a DVB-T signal in 8k mode (note the flat-top characteristics)
  • OFDM modulation: The sequence of blocks is modulated according to the OFDM technique, using 1705 or 6817 carriers (2k or 8k mode, respectively). Increasing the number of carriers does not modify the payload bit rate, which remains constant.
  • Guard interval insertion: to decrease receiver complexity, every OFDM block is extended, copying in front of it its own end (cyclic prefix). The width of such guard interval can be 1/32, 1/16, 1/8, or 1/4 that of the original block length. Cyclic prefix is required to operate single frequency networks, where there may exist an ineliminable interference coming from several sites transmitting the same program on the same carrier frequency.
  • DAC and front-end: The digital signal is transformed into an analogue signal, with a digital-to-analog converter (DAC), and then modulated to radio frequency (VHF, UHF) by the RF front end. The occupied bandwidth is designed to accommodate each single DVB-T signal into 5, 6, 7, or 8 MHz wide channels. The base band sample rate provided at the DAC input depends on the channel bandwidth: it is   samples/s, where   is the channel bandwidth expressed in Hz.
Available bit rates (Mbit/s) for a DVB-T system in 8 MHz channels
Modulation Coding rate Guard interval
1/4 1/8 1/16 1/32
QPSK 1/2 4.976 5.529 5.855 6.032
2/3 6.635 7.373 7.806 8.043
3/4 7.465 8.294 8.782 9.048
5/6 8.294 9.216 9.758 10.053
7/8 8.709 9.676 10.246 10.556
16-QAM 1/2 9.953 11.059 11.709 12.064
2/3 13.271 14.745 15.612 16.086
3/4 14.929 16.588 17.564 18.096
5/6 16.588 18.431 19.516 20.107
7/8 17.418 19.353 20.491 21.112
64-QAM 1/2 14.929 16.588 17.564 18.096
2/3 19.906 22.118 23.419 24.128
3/4 22.394 24.882 26.346 27.144
5/6 24.882 27.647 29.273 30.160
7/8 26.126 29.029 30.737 31.668

Technical description of the receiver

The receiving STB adopts techniques which are dual to those ones used in the transmission.

  • Front-end and ADC: the analogue RF signal is converted to base-band and transformed into a digital signal, using an analogue-to-digital converter (ADC).
  • Time and frequency synchronization: the digital base band signal is searched to identify the beginning of frames and blocks. Any problems with the frequency of the components of the signal are corrected, too. The property that the guard interval at the end of the symbol is placed also at the beginning is exploited to find the beginning of a new OFDM symbol. On the other hand, continual pilots (whose value and position is determined in the standard and thus known by the receiver) determine the frequency offset suffered by the signal. This frequency offset might have been caused by Doppler effect, inaccuracies in either the transmitter or receiver clock, and so on. Generally, synchronization is done in two steps, either before or after the FFT, in such way to resolve both coarse and fine frequency/timing errors. Pre-FFT steps involve the use of sliding correlation on the received time signal, whereas Post-FFT steps use correlation between the frequency signal and the pilot carriers sequence.
  • Guard interval disposal: the cyclic prefix is removed.
  • OFDM demodulation: this is achieved with an FFT.
  • Frequency equalization: the pilot signals are used to estimate the Channel Transfer Function (CTF) every three subcarriers. The CTF is derived in the remaining subcarriers via interpolation. The CTF is then used to equalize the received data in each subcarrier, generally using a Zero-Forcing method (multiplication by CTF inverse). The CTF is also used to weigh the reliability of the demapped data when they are provided to the Viterbi decoder.
  • Demapping: since there are Gray-encoded QAM constellations, demapping is done in a "soft" way using nonlinear laws that demap each bit in the received symbol to a more or less reliable fuzzy value between -1 and +1.
  • Internal deinterleaving
  • Internal decoding: uses the Viterbi algorithm, with a traceback length larger than that generally used for the basic 1/2 rate code, due to the presence of punctured ("erased") bits.
  • External deinterleaving
  • External decoding
  • MUX adaptation
  • MPEG-2 demultiplexing and source decoding

Countries and territories using DVB-T or DVB-T2

 
Digital terrestrial television systems worldwide. Countries using DVB-T or DVB-T2 are shown in blue.[10]

Americas

Europe

Oceania

Asia

Africa

DTT switch-off

While many countries have expected a shift to digital terrestrial television, a few have moved in the opposite direction following unsuccessful trials.

  • Switzerland : Swiss public broadcaster SRG terminated DTT network on 3 June 2019. A regional station from the Geneva area has kept broadcasting. A DVB-T2 antenna was later activated in the east of the country to relay Swiss TV to Austrian cable operators. A similar broadcast is planned to cover Grand Geneva.
  • Turkey terminated DTT network on 1 June 2017.

See also

Notes

  1. ^ "ETSI EN 300 744 – Digital Video Broadcasting (DVB); Framing structure, channel coding and modulation for digital terrestrial television" (PDF). European Telecommunications Standards Institute. October 2015. p. 66. (PDF) from the original on 26 March 2016.
  2. ^ "DATAONE LIMITED RESPONSE TO CONSULTATION PAPER ON DATACASTING" (PDF). Infocomm Media Development Authority, Singapore. (PDF) from the original on 5 February 2020.
  3. ^ "TELEVISION BROADCAST FOR SINGAPORE – March 3, 1998" (PDF). 8 October 1999. (PDF) from the original on 8 October 1999. Retrieved 5 February 2020.
  4. ^ "Advent Television launches the world's first digital terrestrial service in Singapore" (PDF). 8 October 1999. (PDF) from the original on 8 October 1999. Retrieved 5 February 2020.
  5. ^ "The Future is in Digital Broadcasting and that future is with Advent Television". 11 April 2001. from the original on 11 April 2001. Retrieved 5 February 2020.
  6. ^ "Press Release – April 27, 1998" (PDF). 4 June 2000. (PDF) from the original on 4 June 2000. Retrieved 5 February 2020.
  7. ^ "S'pore testing digital TV format". The Business Times. 5 March 1998. p. 4.
  8. ^ "SBA plans to launch digital TV after trying out systems". The Straits Times. 9 March 1998. p. 30.
  9. ^ (in Italian). Archived from the original on 2008-04-19. Retrieved 2008-07-30.{{cite web}}: CS1 maint: unfit URL (link)
  10. ^ DVB.org 20 March 2011 at the Wayback Machine, Official information taken from the DVB website
  11. ^ . Archived from the original on 1 September 2013. Retrieved 26 June 2016.
  12. ^ . El Espectador (in Spanish). 28 August 2008. Archived from the original on 13 April 2019. Retrieved 28 August 2008.
  13. ^ "TV Digital no ha llegado a toda Colombia y la CNTV ya piensa en modificar la norma". Evaluamos (in Spanish). 21 July 2011.
  14. ^ . DVB.org. 19 May 2009. Archived from the original on 3 September 2013. Retrieved 26 June 2016.
  15. ^ "KTV Ltd". Retrieved 26 June 2016.
  16. ^ "Plan for the introduction of terrestrial digital television broadcasting (DVB-T) in the Republic of Bulgaria" (in Bulgarian). Ministry of Transport, Information Technology and Communications of Bulgaria. Retrieved 17 December 2012.
  17. ^ . NURTS (TV tower operator). Archived from the original on 1 December 2012. Retrieved 17 December 2012.
  18. ^ (in Icelandic). fjarskiptahandbokin.is. Archived from the original on 31 August 2009. Retrieved 27 October 2009.
  19. ^ "Russia adopts DVB-T2". Advanced-Television.com. 29 September 2011.
  20. ^ (in Serbian). Archived from the original on 16 April 2012. Retrieved 22 March 2012.
  21. ^ "Switzerland to switch off DTT on June 3, 2019". 6 December 2018.
  22. ^ . Oqaab.af. 31 March 2015. Archived from the original on 23 March 2016. Retrieved 26 June 2016.
  23. ^ a b c d e f g h Hawkes, Rebecca (19 May 2014). "Samart eyes Middle East market for digital TV-enabled smartphone". Rapid TV News. Retrieved 26 June 2016.
  24. ^ "Digital TV services to be introduced in Bangladesh by 2014". Asia-Pacific Broadcasting Union. 5 June 2012.
  25. ^ "PERSYARATAN TEKNIS ALAT DAN PERANGKAT PENERIMA TELEVISI SIARAN DIGITAL BERBASIS STANDAR DIGITAL VIDEO BROADCASTING TERRESTRIAL – SECOND GENERATION" (PDF). KomInfo.go.id. Ministry of Communication and Information Technology (Indonesia). (PDF) from the original on 31 March 2014. Retrieved 1 April 2017.
  26. ^ (PDF). KomInfo.go.id. Ministry of Communication and Information Technology (Indonesia). Archived from the original (PDF) on 27 June 2017. Retrieved 19 February 2012.
  27. ^ Hawkes, Rebecca (26 February 2014). "Kuwait TV opts for Harris DVB-T2 technology". Rapid TV News. Retrieved 11 April 2014.
  28. ^ . DVB.org. 7 November 2014. Archived from the original on 19 April 2016. Retrieved 7 April 2016.
  29. ^ "北朝鮮で4局が地上デジタル放送を実施中、ASUS ZenFone Go TVで確認". blogofmobile.com (in Japanese). 8 September 2019. Retrieved 24 June 2020.
  30. ^ Williams, Martyn (17 March 2013). "Report: DPRK testing digital TV". North Korea Tech – 노스코리아테크. from the original on 23 September 2019. Retrieved 25 September 2019.
  31. ^ . DVB.org. 11 December 2013. Archived from the original on 26 September 2019. Retrieved 12 April 2014.
  32. ^ . DVB.org. 4 February 2014. Archived from the original on 29 December 2016. Retrieved 7 April 2016.
  33. ^ Mochiko, Thabiso (26 November 2010). "BusinessDay – State U-turn on Nyanda's digital-TV signal plan". BusinessDay.co.za. BDFM Publishers. from the original on 30 November 2010. Retrieved 26 November 2010.
  34. ^ Etherington-Smith, James (3 January 2011). "DVB-T2 chosen as digital TV standard". MyBroadband.co.za. Retrieved 3 January 2011.

References

  • ETSI Standard: EN 300 744 V1.5.1, Digital Video Broadcasting (DVB); Framing structure, channel coding and modulation for digital terrestrial television, available at (This will open ETSI document search engine, to find the latest version of the document enter a search string; free registration is required to download PDF.)

External links

  • Website of the DVB Project
  • Official factsheet of DVB-T

short, digital, video, broadcasting, terrestrial, european, based, consortium, standard, broadcast, transmission, digital, terrestrial, television, that, first, published, 1997, first, broadcast, singapore, february, 1998, this, system, transmits, compressed, . DVB T short for Digital Video Broadcasting Terrestrial is the DVB European based consortium standard for the broadcast transmission of digital terrestrial television that was first published in 1997 1 and first broadcast in Singapore in February 1998 2 3 4 5 6 7 8 This system transmits compressed digital audio digital video and other data in an MPEG transport stream using coded orthogonal frequency division multiplexing COFDM or OFDM modulation It is also the format widely used worldwide including North America for Electronic News Gathering for transmission of video and audio from a mobile newsgathering vehicle to a central receive point It is also used in the US by Amateur television operators The logo of DVB T Contents 1 Basics 2 Technical description of a DVB T transmitter 3 Technical description of the receiver 4 Countries and territories using DVB T or DVB T2 4 1 Americas 4 2 Europe 4 3 Oceania 4 4 Asia 4 5 Africa 5 DTT switch off 6 See also 7 Notes 8 References 9 External linksBasics EditRather than carrying one data carrier on a single radio frequency RF channel COFDM works by splitting the digital data stream into a large number of slower digital streams each of which digitally modulates a set of closely spaced adjacent sub carrier frequencies In the case of DVB T there are two choices for the number of carriers known as 2K mode or 8K mode These are actually 1 705 or 6 817 sub carriers that are approximately 4 kHz or 1 kHz apart DVB T offers three different modulation schemes QPSK 16QAM 64QAM DVB T has been adopted or proposed for digital television broadcasting by many countries see map using mainly VHF 7 MHz and UHF 8 MHz channels whereas Taiwan Colombia Panama and Trinidad and Tobago use 6 MHz channels Examples include the UK s Freeview The DVB T Standard is published as EN 300 744 Framing structure channel coding and modulation for digital terrestrial television This is available from the ETSI website as is ETSI TS 101 154 Specification for the use of Video and Audio Coding in Broadcasting Applications based on the MPEG 2 Transport Stream which gives details of the DVB use of source coding methods for MPEG 2 and more recently H 264 MPEG 4 AVC as well as audio encoding systems Many countries that have adopted DVB T have published standards for their implementation These include the D book in the UK the Italian DGTVi 9 the ETSI E Book and the Nordic countries and Ireland NorDig DVB T has been further developed into newer standards such as DVB H Handheld which was a commercial failure and is no longer in operation and DVB T2 which was initially finalised in August 2011 DVB T as a digital transmission delivers data in a series of discrete blocks at the symbol rate DVB T is a COFDM transmission technique which includes the use of a Guard Interval It allows the receiver to cope with strong multipath situations Within a geographical area DVB T also allows single frequency network SFN operation where two or more transmitters carrying the same data operate on the same frequency In such cases the signals from each transmitter in the SFN needs to be accurately time aligned which is done by sync information in the stream and timing at each transmitter referenced to GPS The length of the Guard Interval can be chosen It is a trade off between data rate and SFN capability The longer the guard interval the larger is the potential SFN area without creating intersymbol interference ISI It is possible to operate SFNs which do not fulfill the guard interval condition if the self interference is properly planned and monitored Technical description of a DVB T transmitter Edit Scheme of a DVB T transmission system With reference to the figure a short description of the signal processing blocks follows Source coding and MPEG 2 multiplexing MUX Compressed video compressed audio and data streams are multiplexed into MPEG program streams MPEG PSs One or more MPEG PSs are joined together into an MPEG transport stream MPEG TS this is the basic digital stream which is being transmitted and received by TV sets or home Set Top Boxes STB Allowed bit rates for the transported data depend on a number of coding and modulation parameters it can range from about 5 to about 32 Mbit s see the bottom figure for a complete listing Splitter Two different MPEG TSs can be transmitted at the same time using a technique called Hierarchical Transmission It may be used to transmit for example a standard definition SDTV signal and a high definition HDTV signal on the same carrier Generally the SDTV signal is more robust than the HDTV one At the receiver depending on the quality of the received signal the STB may be able to decode the HDTV stream or if signal strength lacks it can switch to the SDTV one in this way all receivers that are in proximity of the transmission site can lock the HDTV signal whereas all the other ones even the farthest may still be able to receive and decode an SDTV signal MUX adaptation and energy dispersal The MPEG TS is identified as a sequence of data packets of fixed length 188 bytes With a technique called energy dispersal the byte sequence is decorrelated External encoder A first level of error correction is applied to the transmitted data using a non binary block code a Reed Solomon RS 204 188 code allowing the correction of up to a maximum of 8 wrong bytes for each 188 byte packet External interleaver Convolutional interleaving is used to rearrange the transmitted data sequence in such a way that it becomes more rugged to long sequences of errors Internal encoder A second level of error correction is given by a punctured convolutional code which is often denoted in STBs menus as FEC Forward error correction There are five valid coding rates 1 2 2 3 3 4 5 6 and 7 8 Internal interleaver Data sequence is rearranged again aiming to reduce the influence of burst errors This time a block interleaving technique is adopted with a pseudo random assignment scheme this is really done by two separate interleaving processes one operating on bits and another one operating on groups of bits Mapper The digital bit sequence is mapped into a base band modulated sequence of complex symbols There are three valid modulation schemes QPSK 16 QAM 64 QAM Frame adaptation the complex symbols are grouped in blocks of constant length 1512 3024 or 6048 symbols per block A frame is generated 68 blocks long and a superframe is built by 4 frames Pilot and TPS signals In order to simplify the reception of the signal being transmitted on the terrestrial radio channel additional signals are inserted in each block Pilot signals are used during the synchronization and equalization phase while TPS signals Transmission Parameters Signalling send the parameters of the transmitted signal and to unequivocally identify the transmission cell The receiver must be able to synchronize equalize and decode the signal to gain access to the information held by the TPS pilots Thus the receiver must know this information beforehand and the TPS data is only used in special cases such as changes in the parameters resynchronizations etc Spectrum of a DVB T signal in 8k mode note the flat top characteristics OFDM modulation The sequence of blocks is modulated according to the OFDM technique using 1705 or 6817 carriers 2k or 8k mode respectively Increasing the number of carriers does not modify the payload bit rate which remains constant Guard interval insertion to decrease receiver complexity every OFDM block is extended copying in front of it its own end cyclic prefix The width of such guard interval can be 1 32 1 16 1 8 or 1 4 that of the original block length Cyclic prefix is required to operate single frequency networks where there may exist an ineliminable interference coming from several sites transmitting the same program on the same carrier frequency DAC and front end The digital signal is transformed into an analogue signal with a digital to analog converter DAC and then modulated to radio frequency VHF UHF by the RF front end The occupied bandwidth is designed to accommodate each single DVB T signal into 5 6 7 or 8 MHz wide channels The base band sample rate provided at the DAC input depends on the channel bandwidth it is f s 8 7 B displaystyle f s frac 8 7 B samples s where B displaystyle B is the channel bandwidth expressed in Hz Available bit rates Mbit s for a DVB T system in 8 MHz channels Modulation Coding rate Guard interval1 4 1 8 1 16 1 32QPSK 1 2 4 976 5 529 5 855 6 0322 3 6 635 7 373 7 806 8 0433 4 7 465 8 294 8 782 9 0485 6 8 294 9 216 9 758 10 0537 8 8 709 9 676 10 246 10 55616 QAM 1 2 9 953 11 059 11 709 12 0642 3 13 271 14 745 15 612 16 0863 4 14 929 16 588 17 564 18 0965 6 16 588 18 431 19 516 20 1077 8 17 418 19 353 20 491 21 11264 QAM 1 2 14 929 16 588 17 564 18 0962 3 19 906 22 118 23 419 24 1283 4 22 394 24 882 26 346 27 1445 6 24 882 27 647 29 273 30 1607 8 26 126 29 029 30 737 31 668Technical description of the receiver EditThe receiving STB adopts techniques which are dual to those ones used in the transmission Front end and ADC the analogue RF signal is converted to base band and transformed into a digital signal using an analogue to digital converter ADC Time and frequency synchronization the digital base band signal is searched to identify the beginning of frames and blocks Any problems with the frequency of the components of the signal are corrected too The property that the guard interval at the end of the symbol is placed also at the beginning is exploited to find the beginning of a new OFDM symbol On the other hand continual pilots whose value and position is determined in the standard and thus known by the receiver determine the frequency offset suffered by the signal This frequency offset might have been caused by Doppler effect inaccuracies in either the transmitter or receiver clock and so on Generally synchronization is done in two steps either before or after the FFT in such way to resolve both coarse and fine frequency timing errors Pre FFT steps involve the use of sliding correlation on the received time signal whereas Post FFT steps use correlation between the frequency signal and the pilot carriers sequence Guard interval disposal the cyclic prefix is removed OFDM demodulation this is achieved with an FFT Frequency equalization the pilot signals are used to estimate the Channel Transfer Function CTF every three subcarriers The CTF is derived in the remaining subcarriers via interpolation The CTF is then used to equalize the received data in each subcarrier generally using a Zero Forcing method multiplication by CTF inverse The CTF is also used to weigh the reliability of the demapped data when they are provided to the Viterbi decoder Demapping since there are Gray encoded QAM constellations demapping is done in a soft way using nonlinear laws that demap each bit in the received symbol to a more or less reliable fuzzy value between 1 and 1 Internal deinterleaving Internal decoding uses the Viterbi algorithm with a traceback length larger than that generally used for the basic 1 2 rate code due to the presence of punctured erased bits External deinterleaving External decoding MUX adaptation MPEG 2 demultiplexing and source decodingCountries and territories using DVB T or DVB T2 Edit Digital terrestrial television systems worldwide Countries using DVB T or DVB T2 are shown in blue 10 Americas Edit Bermuda decided on 10 July 2007 11 Colombia decided on 28 August 2008 12 Uses DVB T H 264 MPEG 4 for SD and HD since 2011 13 Greenland Nuuk TV French Guiana Panama decided on 12 May 2009 14 uses DVB T MPEG 2 for SD and DVB T H 264 MPEG 4 for HD transmissions Saint Pierre and Miquelon Falkland Islands In 2008 KTV Ltd implemented DVB T 64QAM 7 8 1 32 MPEG2 for both SD and HD transmissions citation needed 15 Europe Edit Albania uses MPEG 2 for SD and H 264 MPEG 4 AVC for HD transmissions Andorra Armenia Austria transition to DVB T2 Azerbaijan Belgium uses DVB T MPEG 2 and DVB T2 H 264 MPEG 4 AVC Belarus uses DVB T H 264 MPEG 4 AVC for SD and HD transmission and DVB T2 for pay SD and HD transmissions Bulgaria H 264 MPEG 4 AVC FEC 2 3 guard interval 1 4 64 QAM Official simulcast started in March 2013 full switch has been done on 30 September 2013 16 17 Croatia From 2020 the transmission is on DVB T2 H 265 HEVC with HD 1080p50 see Television in Croatia Czech Republic MPEG 2 DVB T2 HEVC H 265 started in 2017 Cyprus H 264 MPEG 4 AVC video Denmark uses H 264 AVC for SD and HD transmissions See DVB T in Denmark Estonia uses H 264 AVC video Faroe Islands Finland France uses H 264 AVC for free HD pay SD and pay HD transmissions See Digital terrestrial television France Germany partly still DVB T MPEG 2 SD only since 2016 transition to DVB T2 H 265 HEVC with HD 1080p50 see Television in Germany Georgia Greece Both providers Digea and ERT use H 264 MPEG 4 AVC Hungary branded MinDigTV uses H 264 MPEG 4 AVC video exclusively Iceland 18 Ireland uses H 264 MPEG 4 AVC for HD and SD transmissions see Saorview Italy uses MPEG 2 for SD H 264 MPEG 4 AVC for HD Transition to DVB T2 scheduled in 2022 Latvia uses H 264 MPEG 4 AVC Lithuania uses H 264 MPEG 4 AVC Luxembourg uses DVB T MPEG 2 for SD and H 264 MPEG 4 AVC for HD Macedonia DVB T in Macedonia Malta Moldova uses MPEG 2 H 264 AVC is being tested Montenegro Netherlands uses DVB T2 operated by Digitenne Norway uses H 264 MPEG 4 AVC for SD and HD transmissions Poland uses DVB T2 with HEVC except MUX3 belonging to state owned TVP which still is allowed to use H 264 AVC video for SD and HD transmissions until the end of 2023 see DVB T in Poland Portugal uses H 264 AVC video Romania DVB T was only used experimentally in two cities and is being phased out The official terrestrial broadcasting standard in Romania is DVB T2 and implementations started in 2015 Russia uses DVB T2 H 264 AVC 19 Serbia uses DVB T2 H 264 AVC 20 Slovakia uses MPEG 2 for SD and H 264 MPEG 4 AVC for HD testing DVB T2 H 264 AVC Slovenia uses H 264 MPEG 4 AVC video since 2007 See DVB T in Slovenia Spain uses DVB T MPEG 2 for SD and DVB T H 264 MPEG 4 for HD transmissions Sweden uses MPEG 2 and H 264 MPEG 4 AVC for SD and DVB T2 with H 264 AVC for SD and HD transmissions See DVB T in Sweden Switzerland one regional DVB T station remaining Terrestrial national TV broadcasting restored using DVB T2 near Austria soon near France 21 Turkey Not officially rolled out Last known DVB T2 test broadcasting TRT 4K ended on 1 June 2017 UK uses DVB T MPEG 2 for SD and DVB T2 H 264 AVC for HD transmissions See DVB T in United Kingdom Ukraine uses DVB T2 H 264 AVC for all nationwide broadcasts Oceania Edit Australia mostly uses MPEG 2 for SD transmissions and H 264 AVC for HD transmissions refer to this list of digital television channels in Australia New Zealand uses MPEG 4 H 264 video see Freeview New Zealand Fiji Papua New Guinea Solomon Islands Vanuatu Kiribati Nauru Samoa Tonga Tuvalu Niue Asia Edit Afghanistan uses DVB T2 MPEG 4 launched April 2015 22 Bahrain in assessment 23 Bangladesh Announced 24 Bhutan uses DVB T2 India uses MPEG 2 for SD and MPEG 4 for HD transmissions Indonesia adopted DVB T2 H 264 AVC 25 on 2 February 2012 26 Iran uses DVB T MPEG 4 H 264 AAC SD 720x576i HD 1920x1080i since 2020 transition to DVB T2 H 265 HEVC with HD 1080p50 see Television in Iran Iraq started in Kurdistan region Iraq by MIX Media 31 December 2011 uses MPEG 4 Israel uses MPEG 4 H 264 video Jordan 23 Kuwait will use DVB T2 27 Kyrgyzstan DVB T2 28 Lebanon 23 Malaysia 7 DVB T channels across 2 transponders during trial final system uses DVB T2 nationwide 17 TV channels and 14 radio channels across 2 transponders in UHF analog shutdown on 31 Oct 2019 Uses H 264 video and AAC audio Mongolia uses DVB T2 Myanmar North Korea uses DVB T2 trial began on 2012 29 30 Oman in assessment 23 Palestine in assessment citation needed Qatar 31 Singapore 4 DVB T Channels on 1 January 2007 and 7 DVB T2 Channels on 13 December 2013 Saudi Arabia 23 Syria using DVB T MPEG 2 and MPEG 4 23 Taiwan uses DVB T MPEG 2 for SD and DVB T H 264 MPEG 4 for HD transmissions Tajikistan DVB T2 32 Thailand uses DVB T2 H 264 AVC with HE AAC codec for both SD and HD transmissions launched on April 1 2014 Vietnam United Arab Emirates 23 Uzbekistan Yemen 23 Africa Edit Algeria Benin Burundi Cameroon Cape Verde C A R Chad Comoros Experimental DTMB D R Congo Congo Djibouti Egypt Gabon Gambia Ghana Ivory Coast Kenya Will use DVB T2MPEG 4 Lesotho Madagascar use DVB T2 on paid network Malawi Mali Mauritania Mauritius Morocco Mozambique Namibia Niger Nigeria Rwanda is already using DVB T MPEG 4 and will soon migrate to DVB T2 Sao Tome and Principe Senegal Seychelles Sierra Leone South Africa will use DVB T2 after briefly considering ISDB T 33 34 Sudan Swaziland Tanzania Togo Tunisia experimental Uganda ZambiaDTT switch off EditWhile many countries have expected a shift to digital terrestrial television a few have moved in the opposite direction following unsuccessful trials Switzerland Swiss public broadcaster SRG terminated DTT network on 3 June 2019 A regional station from the Geneva area has kept broadcasting A DVB T2 antenna was later activated in the east of the country to relay Swiss TV to Austrian cable operators A similar broadcast is planned to cover Grand Geneva Turkey terminated DTT network on 1 June 2017 See also EditATSC Advanced Television Systems Committee North American Standard Digital Audio Broadcasting low bit rate video suitable for moving receivers Digital Video Broadcasting technical standards underpinning DVB T DTV channel protection ratios DVB over IP DVB T2 Digital terrestrial television DMB T Digital Multimedia Broadcast Terrestrial Interactive television ISDB Integrated Services Digital Broadcasting ISDB T International Multimedia Home Platform standard to deliver interactive TV applications over DVB OFDM system comparison table Personal video recorder Spectral efficiency comparison table TeletextNotes Edit ETSI EN 300 744 Digital Video Broadcasting DVB Framing structure channel coding and modulation for digital terrestrial television PDF European Telecommunications Standards Institute October 2015 p 66 Archived PDF from the original on 26 March 2016 DATAONE LIMITED RESPONSE TO CONSULTATION PAPER ON DATACASTING PDF Infocomm Media Development Authority Singapore Archived PDF from the original on 5 February 2020 TELEVISION BROADCAST FOR SINGAPORE March 3 1998 PDF 8 October 1999 Archived PDF from the original on 8 October 1999 Retrieved 5 February 2020 Advent Television launches the world s first digital terrestrial service in Singapore PDF 8 October 1999 Archived PDF from the original on 8 October 1999 Retrieved 5 February 2020 The Future is in Digital Broadcasting and that future is with Advent Television 11 April 2001 Archived from the original on 11 April 2001 Retrieved 5 February 2020 Press Release April 27 1998 PDF 4 June 2000 Archived PDF from the original on 4 June 2000 Retrieved 5 February 2020 S pore testing digital TV format The Business Times 5 March 1998 p 4 SBA plans to launch digital TV after trying out systems The Straits Times 9 March 1998 p 30 DGTVi Per la Televisione Digitale Terrestre in Italian Archived from the original on 2008 04 19 Retrieved 2008 07 30 a href Template Cite web html title Template Cite web cite web a CS1 maint unfit URL link DVB org Archived 20 March 2011 at the Wayback Machine Official information taken from the DVB website About DVB Archived from the original on 1 September 2013 Retrieved 26 June 2016 Colombia adopta el estandar europeo para la tv digital terrestre El Espectador in Spanish 28 August 2008 Archived from the original on 13 April 2019 Retrieved 28 August 2008 TV Digital no ha llegado a toda Colombia y la CNTV ya piensa en modificar la norma Evaluamos in Spanish 21 July 2011 Panama adopts DVB T DVB org 19 May 2009 Archived from the original on 3 September 2013 Retrieved 26 June 2016 KTV Ltd Retrieved 26 June 2016 Plan for the introduction of terrestrial digital television broadcasting DVB T in the Republic of Bulgaria in Bulgarian Ministry of Transport Information Technology and Communications of Bulgaria Retrieved 17 December 2012 Digital Television NURTS TV tower operator Archived from the original on 1 December 2012 Retrieved 17 December 2012 Digital Island in Icelandic fjarskiptahandbokin is Archived from the original on 31 August 2009 Retrieved 27 October 2009 Russia adopts DVB T2 Advanced Television com 29 September 2011 ETV trial DVB T2 network in Serbian Archived from the original on 16 April 2012 Retrieved 22 March 2012 Switzerland to switch off DTT on June 3 2019 6 December 2018 100 000 likes Oqaab reaches over 1 Mio TV Households Oqaab af 31 March 2015 Archived from the original on 23 March 2016 Retrieved 26 June 2016 a b c d e f g h Hawkes Rebecca 19 May 2014 Samart eyes Middle East market for digital TV enabled smartphone Rapid TV News Retrieved 26 June 2016 Digital TV services to be introduced in Bangladesh by 2014 Asia Pacific Broadcasting Union 5 June 2012 PERSYARATAN TEKNIS ALAT DAN PERANGKAT PENERIMA TELEVISI SIARAN DIGITAL BERBASIS STANDAR DIGITAL VIDEO BROADCASTING TERRESTRIAL SECOND GENERATION PDF KomInfo go id Ministry of Communication and Information Technology Indonesia Archived PDF from the original on 31 March 2014 Retrieved 1 April 2017 Standar Penyiaran Televisi Digital PDF KomInfo go id Ministry of Communication and Information Technology Indonesia Archived from the original PDF on 27 June 2017 Retrieved 19 February 2012 Hawkes Rebecca 26 February 2014 Kuwait TV opts for Harris DVB T2 technology Rapid TV News Retrieved 11 April 2014 Kyrgyztelecom launches DVB T2 amp DVB S2 DVB org 7 November 2014 Archived from the original on 19 April 2016 Retrieved 7 April 2016 北朝鮮で4局が地上デジタル放送を実施中 ASUS ZenFone Go TVで確認 blogofmobile com in Japanese 8 September 2019 Retrieved 24 June 2020 Williams Martyn 17 March 2013 Report DPRK testing digital TV North Korea Tech 노스코리아테크 Archived from the original on 23 September 2019 Retrieved 25 September 2019 Qatar Goes DVB T2 DVB org 11 December 2013 Archived from the original on 26 September 2019 Retrieved 12 April 2014 Tajikistan Confirms DVB T2 Adoption DVB org 4 February 2014 Archived from the original on 29 December 2016 Retrieved 7 April 2016 Mochiko Thabiso 26 November 2010 BusinessDay State U turn on Nyanda s digital TV signal plan BusinessDay co za BDFM Publishers Archived from the original on 30 November 2010 Retrieved 26 November 2010 Etherington Smith James 3 January 2011 DVB T2 chosen as digital TV standard MyBroadband co za Retrieved 3 January 2011 References EditETSI Standard EN 300 744 V1 5 1 Digital Video Broadcasting DVB Framing structure channel coding and modulation for digital terrestrial television available at ETSI Publications Download Area This will open ETSI document search engine to find the latest version of the document enter a search string free registration is required to download PDF External links Edit Wikimedia Commons has media related to DVB T Website of the DVB Project Official factsheet of DVB T DigiTAG website Retrieved from https en wikipedia org w index php title DVB T amp oldid 1147431257, wikipedia, wiki, book, books, library,

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