View source for Astronomy:DVB-S2

{{short description|Digital satellite television standard}}
{{Table Digital video broadcast standards}}

[[Image:KNCone TV Station DVBS2 PLUS pci card front 0595 by HDTVTotalDOTcom.jpg|right|thumbnail|upright=0.8|DVB-S2 PCI tuner card]]
'''Digital Video Broadcasting - Satellite - Second Generation''' ('''DVB-S2''') is a [[Engineering:Digital television|digital television]] broadcast standard that has been designed as a successor for the popular [[Astronomy:DVB-S|DVB-S]] system. It was developed in 2003 by the [[Digital Video Broadcasting]] Project, an international industry consortium, and ratified by ETSI (EN 302307) in March 2005. The standard is based on, and improves upon DVB-S and the [[Engineering:Electronic news-gathering|electronic news-gathering]] (or Digital Satellite News Gathering) system, used by mobile units for sending sounds and images from remote locations worldwide back to their home television stations.

DVB-S2 is designed for broadcast services including [[Engineering:Standard-definition television|standard]] and [[Engineering:High-definition television|HDTV]], interactive services including Internet access, and (professional) data content distribution. The development of DVB-S2 coincided with the introduction of HDTV and H.264 (MPEG-4 AVC) [[Video codec|video codec]]s.

Two new key features that were added compared to the DVB-S standard are:
* A powerful [[Forward error correction|coding]] scheme based on a modern [[Low-density parity-check code|LDPC code]]. For low encoding complexity, the LDPC codes chosen have a special structure, also known as Irregular Repeat-Accumulate codes. 
* VCM (Variable Coding and Modulation) and ACM (Adaptive Coding and Modulation) modes, which allow optimizing bandwidth utilization by dynamically changing transmission parameters.

Other features include enhanced [[Engineering:Modulation|modulation]] schemes up to [[Engineering:Amplitude and phase-shift keying|32APSK]], additional [[Code rate|code rate]]s, and the introduction of a generic transport mechanism for IP packet data including [[MPEG-4]] audio–video streams, while supporting backward compatibility with existing MPEG-2 TS based transmission.

DVB-S2 achieves [[Spectral efficiency#Comparison table|significantly better performance]] than its predecessors – mainly allowing for an increase of available bitrate over the same satellite transponder bandwidth. The measured DVB-S2 performance gain over DVB-S is around 30% at the same satellite transponder bandwidth and emitted signal power. When the contribution of improvements in video compression is added, an (MPEG-4 AVC) [[Engineering:HDTV|HDTV]] service can now be delivered in the same bandwidth that supported an early DVB-S based MPEG-2 SDTV service only a decade before.

In March 2014, [[Astronomy:DVB-S2X|DVB-S2X]] specification has been published by DVB Project as an optional extension adding further improvements.<ref>{{cite news|title=DVB-S2X specification receives approval from DVB Steering board| url=http://www.dvb.org/resources/public/pressreleases/dvb_pr241_steering_board_approves_dvb-s2x.pdf| newspaper=DVB Project| archive-url=https://web.archive.org/web/20140407071914/http://www.dvb.org/resources/public/pressreleases/dvb_pr241_steering_board_approves_dvb-s2x.pdf| archive-date=7 April 2014| url-status=dead}}</ref>

== Main features ==
* Direct input of one or more MPEG-2 Transport Streams (TS). MPEG-TS is supported using a compatibility mode.
* The native stream format for DVB-S2 is called [[Generic Stream Encapsulation|Generic Stream]] (GS), and can be used to efficiently carry IP-based data, including MPEG-4 AVC/H.264 services.
* [[Backward compatibility]] to DVB-S, intended for [[End user|end user]]s, and DVB-DSNG, used for [[Engineering:Backhaul (telecommunications)|backhaul]]s and [[Engineering:Electronic news gathering|electronic news gathering]].
* Variable coding and modulation (VCM) to optimize bandwidth utilization based on the priority of the input data; e.g., SDTV could be delivered using a more robust setting than the corresponding HDTV service.
* [[Engineering:Link adaptation|Adaptive coding and modulation]] (ACM) to allow flexibly adapting transmission parameters to the reception conditions of terminals, e.g., switching to a lower code rate during fading.
* Four [[Engineering:Modulation|modulation]] modes:
** QPSK and [[Phase-shift keying|8PSK]] are proposed for broadcast applications, and can be used in non-linear transponders driven near to saturation.
** [[Engineering:Amplitude and phase-shift keying|16APSK]] and  [[Engineering:Amplitude and phase-shift keying|32APSK]] are used mainly for professional, semi-linear applications, but can also be used for broadcasting though they require a higher level of available [[Engineering:Carrier-to-noise ratio|C/N]] and an adoption of advanced pre-distortion methods in the uplink station in order to minimize the effect of transponder nonlinearity.
* Improved [[Raised-cosine filter|rolloff]]: α = 0.20 and α = 0.25 in addition to the roll-off of DVB-S α = 0.35.
* Improved [[Forward error correction|coding]]: a modern large LDPC code is concatenated with an outer [[BCH code]] to achieve quasi-error-free (QEF) reception conditions on an [[Additive white Gaussian noise|AWGN]] channel. The outer code is introduced to avoid [[Error floor|error floor]]s at low bit-error rates. A single [[Forward error correction|forward error correction]]  or FEC frame may have either 64,800 bits (normal) or 16,200 bits (short). If VCM or ACM is used, the broadcast can be a combination of normal and short frames.
* Several [[Code rate|code rate]]s for flexible configuration of transmission parameters: 1/4, 1/3, 2/5, 1/2, 3/5, 2/3, 3/4, 4/5, 5/6, 6/7, 8/9, and 9/10. Code rates 1/4, 1/3, and 2/5 have been introduced for exceptionally poor reception conditions in combination with QPSK modulation. Encoding values 8/9 and 9/10 behave poorly under marginal link conditions (where the signal level is below the noise level). However, with targeted [[Engineering:Spot beam|spot]] [[Astronomy:Ku band|Ku]] or [[Astronomy:Ka band|Ka band]] downlinks these code rates may be recommended to prevent out-of-region viewing for copyright or cultural reasons.
* Optional input stream synchronization to provide a constant end-to-end delay.

Depending on code rate and modulation, the system can operate at a [[Engineering:Carrier-to-noise ratio|C/N]] between −2.4&nbsp;[[Physics:Decibel|dB]] (QPSK, 1/4) and 16&nbsp;dB (32APSK, 9/10) with a quasi-error free goal of a 10<sup>−7</sup> TS packet error rate. Distance to the Shannon limit ranges from 0.7&nbsp;dB to 1.2&nbsp;dB.

Modes and features of DVB-S2 in comparison to DVB-S:
{| class="wikitable" style="font-size: 100%; text-align: center;"
|-
!
! DVB-S
! DVB-S2
|-
| Input interface
| Single transport stream (TS)
| Multiple transport stream and [[Generic Stream Encapsulation|generic stream encapsulation]] (GSE)
|-
| Modes
| Constant coding & [[Engineering:Modulation|modulation]]
| Variable coding & modulation and [[Adaptive coding|adaptive coding]] & modulation
|-
| [[Forward error correction|FEC]]
| [[Reed–Solomon error correction|Reed–Solomon]] (RS) 1/2, 2/3, 3/4, 5/6, 7/8
| LDPC + [[BCH code|BCH]] 1/4, 1/3, 2/5, 1/2, 3/5, 2/3, 3/4, 4/5, 5/6, 6/7, 8/9, 9/10
|-
| [[Engineering:Modulation|Modulation]]
| Single-carrier QPSK
| QPSK, 8PSK, 16APSK, 32APSK
|-
| [[Forward error correction#Interleaving|Interleaving]]
| Bit-interleaving
| Bit-interleaving
|-
| [[Pilot signal|Pilots]]
| Pilot symbols
| Pilot symbols
|}

== Use cases ==
Envisaged scenarios for DVB-S2 by the standard document are:

* Broadcasting television services in SDTV or HDTV. Optionally, this transmission may be backwards compatible with DVB-S, but does not benefit from the 30% extra bandwidth.
* Interactive services including Internet access. Data generated by the user may be sent by cable (copper/fibre optic), mobile wireless, or satellite uplink ([[Astronomy:DVB-RCS|DVB-RCS]]).
* Professional applications, where data must be multiplexed in real time and then broadcast in the VHF/UHF band (e.g., digital TV contribution, satellite news gathering). These transmissions are not intended for the average viewer.
* Large-scale data content distribution. These include point-to-point and multicast services, as well as transmission to head-ends for (re-)distribution over other media.

== Improvements over DVB-S ==
DVB-S2 is 30% more efficient than [[Astronomy:DVB-SH|DVB-S]]. It allows a wider range of applications combining DVB-S features (for household tasks), and DVB-DSNG (for professional tasks). DVB-S2 can adapt codification to maximize satellites resources value. It is compatible with last generation.

The main disadvantage, there are many millions of devices deployed using DVB-S over the world which has to be upgraded.

The next table compares both standards.
{| class="wikitable" style="text-align:center;"
! Satellite EIRP (dBW)
| colspan="2" |51
| colspan="2" |53.7
|-
!System
|DVB-S
|DVB-S2
|DVB-S
|DVB-S2
|-
!Modulation and codification
|QPSK 2/3
|QPSK 3/4
|QPSK 7/8
|8PSK 2/3
|-
!Speed per token
|27.5 (a = 0.35)
|30.9 (a = 0.25)
|27.5 (a = 0.35)
|29.7 (a = 0.25)
|-
!C/N, 27.5&nbsp;MHz (dB)
|5.1
|5.1
|7.8
|7.8
|-
!Bitrate (Mbit/s)
|33.8
|46 (+36%)
|44.4
|58.8 (+32%)
|-
!№ channels SDTV
|7 MPEG-2, 15 AVC
|10 MPEG-2, 21 AVC
|10 MPEG-2, 20 AVC
|13 MPEG-2, 27 AVC
|-
!№ channels HDTV
|1–2 MPEG-2, 3–4 AVC
|2 MPEG-2, 5 AVC
|2 MPEG-2, 5 AVC
|3 MPEG-2, 6 AVC
|}

== The DVB-S to DVB-S2 upgrade process ==
The conversion process from DVB-S to DVB-S2 is being accelerated, due to the rapid increase of [[Engineering:HDTV|HDTV]] and introduction  of 3D-HDTV. The main factor slowing down this process is the need to replace or upgrade set-top boxes, or acquire TVs with DVB-S2 integrated tuners, which makes the transition slower for established operators.

Current direct-to-home broadcasters using DVB-S2 are:
{{col-begin}}{{col-2}}
;{{wipe|Australia}}
* VAST fully replaced the previous DVB-S Aurora service from December 2013.  The extra capacity has allowed a Network Ten affiliate to be added along with five HD, seven SD multi-channels and limited advertisement targeting for viewers in DVB-T black-spot areas on Optus C1/D3 156E).
* [[Company:Foxtel|Foxtel]] use this for their four HD downlinks on [[Engineering:Optus D3|Optus D3]] @ 156E.
;{{wipe|Germany}}, Austria and {{wipe|Switzerland}}
* ARD and ZDF.
* [[Company:HD+|HD+]].
* Servus TV.
* Sky.
* SRG SSR.
;Hungary
* Hello HD (also uses DVB-S for some SD and HD channels).
* Magyar Telekom.
* UPC Direct; also operates in Slovakia and the [[Place:Czech Republic|Czech Republic]].
;{{wipe|India}}
* [[Company:Sun Direct|Sun Direct]] is the first broadcaster in India commenced transmission of HD Channels on DVB-S2 way back in 2007.
* Airtel Digital TV.
* [[Company:Videocon d2h|Videocon d2h]].
* Dish TV for all its HD/SD channel transmissions via AsiaSat 5 and DVB-S is being used for transmissions via [[Engineering:NSS-6|NSS-6]]..
* [[Company:Tata Sky|Tata Sky]] for its HD channel transmissions via [[Engineering:INSAT-4A|INSAT-4A]].
;Bangladesh
* Maasranga Television for its SD/HD channel transmissions via APSTAR-7.
* GaanBangla, NexusTV as well as most other channels
;[[Religion:Iran|Iran]]
* IRIB on Badr5 26°E and on Intelsat 902 62°E and on Eutelsat W3A 7°E.
* Gem Group on YahSat 1A 52.5°E.
;[[Place:Turkey|Turkey]]
* Digiturk on Türksat 4A/5B/6A 42°E.
* D-Smart on Türksat 4A 42°E.
* Star Digital on Türksat 4A/5B/6A 42°E.
* TRT (HDTV feed only) on Turksat 4A/5B/6A 42°E.
* DTVH (HD feed only) on Turksat 3A 42°E.
;{{wipe|United Kingdom}} and Ireland
* [[Engineering:Sky Q|Sky Q]]
* BBC (for all its HD channels, which are part of the Sky and Freesat services).
* ITV; Central West and Meridian South variants of ITV HD only <small>({{as of|2013|01|17|lc=on|df=us}})</small>.
* STV (STV HD channel).
* [[Company:Saorsat|Saorsat]] (only available in Ireland).
{{col-2}}
;Romania
* Dolce operated by Romtelecom (now Telekom Romania), only for HD channels. For SD channels is using DVB-S. Backward compatibility, if subscribed to HD package. Service can only be accessed with proprietary Set-top-boxes. NDS Encrypted. Card paired with set top box. If You have a HD receiver from them, you are able to receive two HD channelsin basic package. Needs special antena for HD. 
* Focus Sat operated by UPC Romania, only for HD .SD remains in DVB-S ( except fashion TV SD). Can be used with a DVB-S receiver for SD channels, or DVB-S2 for SD and HD. May be used also with a CAM and a TV with built in DVB-S (for SD channels)or DVB-S2 (Both SD and HD) tuner and common interface slot. HD channels are offered on separate package, therefore aside a HD terminal (TV or STB), you need to pay this package. CONNAX CAS 7 Encryption. Card not paired with receiver.
* Orange TV operated by Orange Romania, only in DVB-S2 both SD and HD. Viaccess Encrypted. Only available with proprietary set top boxes. Card paired with set top box. Set top boxes are only HD, these channels are available from the cheapest package.
* Digi TV, operated by RCS & RDS (since March 2014). Until March 2014, only DVB-S, SD. Nagravision 3 Encrypted. Although it is said that the card and receiver are paired, some subscribers stated that the service can also be accessed with a TV with built in DVB-S/S2 tuner and common interface by using a CAM. However, Until March 2014, only SD channels were available. Needs special subscribing for HD. DVB-S is used in SD reception while DVB-S2 is used both for SD and HD.
;Other countries
* Astro in Malaysia (currently only for HD channels; uses DVB-S for backwards compatibility with SD channels).
* Bell Satellite TV in {{wipe|Canada}} (experimentally).
* Canal+ in {{wipe|Spain}}.
* CanalDigitaal in the Netherlands (HD channels only + some SD channels on Astra 3 23.5°E).
* CanalSat in {{wipe|France}}.
* [[Engineering:Cignal|Cignal]] in {{wipe|Philippines}}.
* [[Company:Claro TV|Claro TV]] Satelital in Guatemala, Honduras, El Salvador, Nicaragua and Dominican Republic.
* Cosmote TV in Greece.
* Dialog TV in Sri Lanka for HD channels and some SD channels; other SD channels use DVB-S.
* Digital+ in {{wipe|Spain}} (currently only for HD channels and only on Astra).
* [[Company:DirecTV|DirecTV]] in the US using H.264/MPEG-4 AVC codec for local and some national HDTV channels (newer satellites).
* [[Company:Dish Network|Dish Network]] in the US (new channels).
* DStv in {{wipe|South Africa}} for HD channels; SD channels use DVB-S.
* ENTV in Algeria since July 17th 2021.
* [[Company:GVT TV|GVT TV]] in {{wipe|Brazil}}. (Available to current customers of the GVT ADSL and telephony services).
* HRT in Croatia (from December 1).
* meo in Portugal.
* nc+ in {{wipe|Poland}}.
* [[Company:MTS (network provider)|MTS]] and Platform HD in {{wipe|Russia}}.
* Sky Direct in {{wipe|Philippines}}.
* Sky HD in Italy.
* Skylife in {{wipe|South Korea}}.
* SKY PerfecTV! in {{wipe|Japan}}.
* Sky Network Television in [[Earth:New Zealand|New Zealand]] upgraded all its transponders on Optus D1 @ 160E to DVB-S2 in March 2019. This was previously only used for their HD channels.
* TopTV in {{wipe|South Africa}} (services launched May 1, 2010).
* Viasat in {{wipe|Ukraine}}.
* Vivacom in Bulgaria.
* VTC in Vietnam.
* Satellite BG in Bulgaria.
{{col-end}}

These broadcasters have used DVB-S2 in their internal broadcast distribution networks, but may not have instituted DVB-S2 transmissions for consumers.

== Licensing ==
Sisvel, a Luxembourg-based company, administers the licenses for patents applying to this standard,<ref>{{Cite web|title=Sisvel {{!}} We protect ideas - DVB-S2 - Introduction|url=https://www.sisvel.com/licensing-programs/digital-video-display-technology/dvb-s2/introduction|access-date=2021-07-03|website=www.sisvel.com}}</ref> as well as other [[Social:Patent pool|patent pools]].

== References ==

<references />

=== Sources ===
* [http://www.etsi.org/deliver/etsi_en/302300_302399/302307/01.02.01_60/en_302307v010201p.pdf Digital Video Broadcasting (DVB); Second generation framing structure, channel coding and modulation systems for Broadcasting, Interactive Services, News Gathering and other broadband satellite applications (DVB-S2)], ETSI EN 302 307, V1.2.1, April 2009.
* [http://www.etsi.org/deliver/etsi_tr/102300_102399/102376/01.01.01_60/tr_102376v010101p.pdf Digital Video Broadcasting (DVB) User guidelines for the second generation system for Broadcasting, Interactive Services, News Gathering and other broadband satellite applications (DVB-S2)], ETSI TR 102 376, V1.1.1, February 2005.
<!--dead link: * [http://dvb.org/technology/fact_sheets/DVB-S2_Factsheet.pdf DVB-S2 Fact Sheet] -->
* [http://www.ebu.ch/en/technical/trev/trev_300-morello.pdf DVB-S2 &ndash; ready for lift off], article in the EBU technical review
<!--dead link: * [http://www.newtec.eu/fileadmin/user_upload/product_leaflets/ACM_application_sheet_R1_01.pdf White paper on bandwidth efficiency]-->

==External links==
<!--dead link: *[https://free.dvb.com/resources/public/factsheets/dvb-s2_factsheet.pdf Official factsheet of DVB-S2] -->
* [http://www.satellite-calculations.com/ Online Satellite Calculations]
* [https://snc.newtec.eu Newtec DVB-S2(x) Calculator]
* [http://linuxtv.org/wiki/index.php/STMicroelectronics_STV0900A_16APSK_32APSK 16APSK/32APSK STV0900A tests under Linux]
*[http://www.ee.caltech.edu/EE/Faculty/rjm/papers/Brest00.pdf IRA code paper]

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[[Category:Television transmission standards]]

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