Welcome to DVBS and DVBS 2

Welcome to DVBS Written by Web Master Saturday, 12 June 2004

DVB-S is the original Digital Video Broadcasting forward error coding and modulation standard for satellite television and dates from 1995. It is used via satellites serving every continent of the world. DVB-S is used in both MCPC and SCPC modes for broadcast network feeds, as well as for direct broadcast satellite services like Sky TV (UK) via Astra in Europe, Dish Network in the U.S., and Bell ExpressVu in Canada. The transport stream delivered by DVB-S is mandated as MPEG-2. DVB-S2:

Digital Video Broadcasting - Satellite - Second Generation (DVB-S2) is an enhanced specification to replace the DVB-S standard, developed in 2003 and ratified by ETSI in March 2005. DVB-S2 will probably be used for all future new European digital satellite multiplexes, and satellite receivers will be equipped to decode both DVB-S and DVB-S2. Today the main use for this new standard is the distribution of HDTV, while the original standard was used mainly for SDTV services. The development of DVB-S2 coincided with the introduction of HDTV and H.264 (MPEG-4) video codecs.

The system allows transmission of one or more MPEG2 audio/video streams , using QPSK or MAPSK modulation with concatenating encoding.

DVB-S2 is based on the DVS-S standard which is used for satellite broadcasting, and the DVB-DSNG standard, which is used by mobile units for sending external footage back to the television station. Two new key features which were added to DVS-S are : Changing encoding parameters in real time (VCM, Variable Coding and Modulation) ACM (Adaptive Coding and Modulation) which optimizes the transmission parametres for various users.

The authors claim that the DVB-S2 performance gain over DVB-S is around 30%. When the contribution of improvements in the video compression are added, a (MPEG-4) HDTV service can now be delivered in the same capacity that supported an early DVB-S-MPEG-2 SDTV service, only a decade before. Main features: Source may be one or more MPEG-2 TS (MPEG-2 Transport Stream). Packet streams other than MPEG-2 TS are also valid (MPEG4/H.264). MPEG-2 TS (MPEG-2 Transport Stream) are supported using a compatibility mode, whereas the native stream format for DVB-S2 is the so-called Generic Stream (GS). Adaptative mode: this block is heavily dependent on the application that generates the data. This means Synchronizing data using ACM and cancellation of null packets from the Transport Stream. CRC-8 Encoding. Used by a DVB-S2 for error correction. Merging full stream and subdivisions in blocks for error correction encoding (DF,Data Fields). Backward compatibility to DVB-S (intended for end users) and DVB-DSNG (DVB-Digital Satellite News Gathering)(used for backhauls and ENG) adaptive coding and modulation to optimize the use of satellite transponders Quoted dvbs.info