Editing DVB-S2 (section)

== Main features ==
* Direct input of one or more [[MPEG-TS|MPEG-2 Transport Stream]]s (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]]s, and DVB-DSNG, used for [[backhaul (telecommunications)|backhaul]]s and [[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.
* [[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 [[modulation]] modes:
** [[Quadrature phase-shift keying|QPSK]] and [[Phase-shift keying|8PSK]] are proposed for broadcast applications, and can be used in non-linear transponders driven near to saturation.
** [[Amplitude and phase-shift keying|16APSK]] and  [[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 [[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 (though DVB-S can still benefit from improved roll off without breaking compatibility with existing DVB-S receivers).
* Improved [[forward error correction|coding]]: a modern large [[LDPC code]] is [[concatenated code|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]]s at low [[bit-error rate]]s. A single [[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]]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 [[spot beam|spot]] [[Ku band|Ku]] or [[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 [[carrier-to-noise ratio|C/N]] between −2.4&nbsp;[[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]] & [[modulation]]
| [[Variable coding]] & modulation and [[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
|-
| [[Modulation]]
| Single-carrier [[QPSK]]
| [[QPSK]], [[8PSK]], [[16APSK]], [[32APSK]]
|-
| [[Forward error correction#Interleaving|Interleaving]]
| Bit-interleaving
| Bit-interleaving
|-
| [[Pilot signal|Pilots]]
| Pilot symbols
| Pilot symbols
|}