Editing DVB (section)

==Transmission==
DVB systems distribute data using a variety of approaches, including:
* [[Satellite television|Satellite]]: [[DVB-S]], [[DVB-DSNG]], [[DVB-S2]], [[DVB-S2X]] and [[DVB-SH]]
** [[DVB-SMATV]] for distribution via [[SMATV]]
* [[Cable television|Cable]]: [[DVB-C]], [[DVB-C2]]
* [[Digital terrestrial television|Terrestrial television]]: [[DVB-T]], [[DVB-T2]]
** Digital terrestrial television for [[handheld]]s: [[DVB-H]], [[DVB-SH]]
* [[Microwave]]: using [[Digital terrestrial television|DTT]] ([[DVB-MT]]), the [[MMDS]] ([[DVB-MC]]), and/or [[MVDS]] standards ([[DVB-MS]])

These standards define the [[physical layer]] and [[data link layer]] of the distribution system. Devices interact with the physical layer via a synchronous parallel interface (SPI), synchronous serial interface (SSI) or [[asynchronous serial interface]] (ASI). All data is transmitted in [[MPEG transport stream]]s with some additional constraints (DVB-MPEG). A standard for temporally-compressed distribution to mobile devices (DVB-H) was published in November 2004.

These distribution systems differ mainly in the [[modulation]] schemes used and error correcting codes used, due to the different technical constraints. DVB-S ([[Super high frequency|SHF]]) uses [[QPSK]], 8-PSK or 16-[[Quadrature amplitude modulation|QAM]]. DVB-S2 uses QPSK, 8-PSK, 16-APSK or 32-APSK, at the broadcasters decision. QPSK and 8-PSK are the only versions regularly used. DVB-C ([[Very high frequency|VHF]]/[[Ultra high frequency|UHF]]) uses [[Quadrature amplitude modulation|QAM]]: 16-QAM, 32-QAM, 64-QAM, 128-QAM or 256-QAM. Lastly, DVB-T (VHF/UHF) uses 16-QAM or 64-QAM (or QPSK) in combination with [[Orthogonal frequency-division multiplexing|(C)OFDM]] and can support [[hierarchical modulation]].

The DVB-T2 specification was approved by the DVB Steering Board in June 2008 and sent to ETSI for adoption as a formal standard. ETSI adopted the standard on 9 September 2009.<ref>{{cite web |url=http://webapp.etsi.org/workProgram/Report_Schedule.asp?WKI_ID=28396 |title=Work Programme: Details of 'DEN/JTC-DVB-228' Work Item Schedule |publisher=ETSI |access-date=2010-08-29}}</ref> The DVB-T2 standard gives more robust TV reception and increases the possible bit rate by over 30% for single transmitters (as in the UK) and will increase the maximum bit rate by over 50% in large [[single-frequency network]]s (as in Germany and [[Sweden]]).

DVB has established a 3D TV group (CM-3DTV) to identify "what kind of 3D-TV solution does the market want and need, and how can DVB play an active part in the creation of that solution?" The CM-3DTV group held a DVB 3D-TV Kick-off Workshop in Geneva on 25 January 2010, followed by the first CM-3DTV meeting the next day.<ref>{{cite web |url=http://www.dvb.org/news_events/news/dvb-3d-tv-workshop/index.xml |title=DVB - Digital Video Broadcasting - DVB 3D TV Kick-Off Workshop |access-date=2010-01-12 |url-status=dead |archive-url=https://web.archive.org/web/20100115043236/http://www.dvb.org/news_events/news/dvb-3d-tv-workshop/index.xml |archive-date=15 January 2010 |df=dmy-all }}</ref> DVB now defines a new standard for 3D video broadcast: [[DVB 3D-TV]].

Modes and features of latest DVB-x2 system standards in comparison:
{| class="wikitable" style="text-align:center;"
|-
!
!DVB-S2
!DVB-T2
!DVB-C2
|-
|[[Input device|Input]] [[Interface (computing)|interface]]
|Multiple [[transport stream]] and [[generic stream encapsulation]] (GSE)
|Multiple transport stream and generic stream encapsulation (GSE)
|Multiple transport stream and generic stream encapsulation (GSE)
|-
|Modes
|[[Variable coding]] & modulation and [[adaptive coding]] & modulation
|Variable coding & modulation<ref name="DVB BlueBook A122, page 18">{{cite web|url=http://www.dvb.org/technology/standards/A122_DVB-T2_Spec.pdf|title=Digital Video Broadcasting (DVB); Frame structure channel coding and modulation for a second generation digital terrestrial television broadcasting system (DVB-T2)|publisher=DVB consortium|date=February 2011}}</ref>
|Variable coding & modulation and adaptive coding & modulation
|-
|[[Forward error correction|FEC]]
|[[LDPC]] + [[BCH code|BCH]] 1/4, 1/3, 2/5, 1/2, 3/5, 2/3, 3/4, 4/5, 5/6, 8/9, 9/10
|LDPC + BCH 1/2, 3/5, 2/3, 3/4, 4/5, 5/6
|LDPC + BCH 1/2, 2/3, 3/4, 4/5, 5/6, 8/9, 9/10<ref name="DVB BlueBook A138, page 29">{{cite web|url=http://www.telcogroup.ru/files/materials-pdf/DVB_standards/DVB-C/a138_DVB-C2.pdf|title=Digital Video Broadcasting (DVB); Frame structure channel coding and modulation for a second generation digital transmission system for cable systems (DVB-C2)|publisher=DVB consortium|date=2010-05-07}}</ref>
|-
|[[Modulation]]
|Single carrier, [[phase-shift keying|PSK]] or [[Amplitude and phase-shift keying|APSK]], multiple streams
|[[Orthogonal frequency-division multiplexing|OFDM]]
|absolute OFDM<ref name="DVB BlueBook A147, page 31, New concept of absolute OFDM">{{cite web|url=http://digitus.itk.ppke.hu/~takacsgy/a147_DVB-C2_Imp-Guide%5B1%5D.pdf|title=Digital Video Broadcasting (DVB); Implementation Guidelines for a second generation digital cable transmission system (DVB-C2)|publisher=DVB consortium|date=2010-11-19}}</ref>
|-
|Modulation schemes
|QPSK, 8-PSK, 16-APSK, 32-APSK
|QPSK, 16-[[QAM]], 64-QAM, 256-QAM
|16- to 4096-QAM
|-
|[[Guard interval]]
|Not applicable
|1/4, 19/256, 1/8, 19/128, 1/16, 1/32, 1/128
|1/64 or 1/128
|-
|Fourier transform size
|Not applicable
|1k, 2k, 4k, 8k, 16k, 32k [[Discrete Fourier transform|DFT]]
|4k [[Fast Fourier transform|Inverse FFT]]<ref name="DVB-C2 The second generation transmission technology for broadband cable, page 5, OFDM generator">{{cite web|url=http://www.ict-redesign.eu/fileadmin/documents/0904_DVB-C2_Cable_Show_Washington_Jaeger_rev2.pdf|title=DVB-C2 The second generation transmission technology for broadband cable|publisher=Dirk Jaeger, Philipp Hasse, Joerg Robert, Institut fuer Nachrichtentechnik at Technische Universitaet Braunschweig|date=2009-04-08|access-date=24 January 2013|archive-url=https://web.archive.org/web/20120402083731/http://www.ict-redesign.eu/fileadmin/documents/0904_DVB-C2_Cable_Show_Washington_Jaeger_rev2.pdf|archive-date=2 April 2012|url-status=dead}}</ref>
|-
|[[Interleaving (bitmaps)|Interleaving]]
|Bit-Interleaving
|Bit- time- and frequency-interleaving
|Bit- time- and frequency-interleaving
|-
|[[Pilot signal|Pilots]]
|Pilot symbols
| Scattered and continual pilots
| Scattered and continual pilots
|}