Digital Video Broadcasting - Satellite - Second Generation (DVB-S2) is adigital television broadcast standard that has been designed as a successor for the popularDVB-S system. It was developed in 2003 by theDigital Video Broadcasting Project, an international industry consortium, and ratified byETSI (EN 302307) in March 2005. The standard is based on, and improves upon DVB-S and theelectronic 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 includingstandard andHDTV,interactive services including Internet access, and (professional) data content distribution. The development of DVB-S2 coincided with the introduction of HDTV andH.264 (MPEG-4 AVC)video codecs.
Two new key features that were added compared to the DVB-S standard are:
A powerfulcoding scheme based on a modernLDPC 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 enhancedmodulation schemes up to32APSK, additionalcode rates, and the introduction of ageneric transport mechanism for IP packet data includingMPEG-4 audio–video streams, while supporting backward compatibility with existingMPEG-2 TS based transmission.
DVB-S2 achievessignificantly 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 invideo compression is added, an (MPEG-4 AVC)HDTV service can now be delivered in the same bandwidth that supported an early DVB-S based MPEG-2SDTV service only a decade before.
In March 2014,DVB-S2X specification has been published by DVB Project as an optional extension adding further improvements.[1]
Direct input of one or moreMPEG-2 Transport Streams (TS). MPEG-TS is supported using a compatibility mode.
The native stream format for DVB-S2 is calledGeneric Stream (GS), and can be used to efficiently carry IP-based data, including MPEG-4 AVC/H.264 services.
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.
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 duringfading.
QPSK and8PSK are proposed for broadcast applications, and can be used in non-linear transponders driven near to saturation.
16APSK and32APSK are used mainly for professional, semi-linear applications, but can also be used for broadcasting though they require a higher level of availableC/N and an adoption of advanced pre-distortion methods in the uplink station in order to minimize the effect of transponder nonlinearity.
Improvedrolloff: 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).
Severalcode rates 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 targetedspotKu orKa 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 aC/N between −2.4 dB (QPSK, 1/4) and 16 dB (32APSK, 9/10) with a quasi-error free goal of a 10−7 TS packet error rate. Distance to theShannon limit ranges from 0.7 dB to 1.2 dB.
Modes and features of DVB-S2 in comparison to DVB-S:
This section needs to beupdated. The reason given is: This section is stated as if DVB-S2 was not yet rolled out; it's been rolled out for more than a decade.. Please help update this article to reflect recent events or newly available information.(April 2023)
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 (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.
DVB-S2 is 30% more efficient thanDVB-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 conversion process from DVB-S to DVB-S2 is being accelerated, due to the rapid increase ofHDTV 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.
VAST fully replaced the previous DVB-S Aurora service from December 2013. The extra capacity has allowed aNetwork 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 onOptus C1/D3 156E).
Foxtel use this for their four HD downlinks onOptus D3 @ 156E.
Dolce operated byRomtelecom (nowTelekom 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 channels in basic package. Needs special antena for HD.
Focus Sat operated byUPC 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 byOrange 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 byRCS & 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 inMalaysia (currently only for HD channels; uses DVB-S for backwards compatibility with SD channels).
