From Wikipedia, the free encyclopedia.
DVB, short for Digital Video Broadcasting, is a suite of internationally accepted, open standards for digital television maintained by the DVB Project, an industry consortium with more than 300 members, and published by an Joined Technical Comittee (JTC) of European Telecommunications Standards Institute (ETSI), European Committee for Electrotechnical Standardization (CENELEC) and European Broadcasting Union (EBU). The standards can be obtained for free at the ETSI website after registration.
How the several DVB sub-standards interact is described in the DVB Cookbook (DVB-Cook).
Transmission
The core standards of DVB are DVB-S (satellite), DVB-C (cable) and DVB-T (terrestrial), which are all based upon MPEG-2 (DVB-MPEG) for audio and video coding as well as the transport stream and are capable of high definition television (HDTV) as well. Upcoming is DVB-X or DVB-M for mobile reception in cellilar phone frequency bands.
These flavors differ mainly in the frequency modulations used, which is a required due to different bands. The high frequency DVB-S uses QPSK, lower hertz DVB-C uses QAM (64-QAM in general) and DVB-T (in VHF and/or UHF band) uses the same or COFDM.
DVB-S and DVB-C were ratified in 1994. DVB-T was ratified in early 1997. The first commercial DVB-T broadcasts were performed by the United Kingdom's Digital Terrestrial Group (DTG) in late 1998 and in 2003 Berlin, Germany was the first area to completely stop broadcasting analog TV signals.
Interaction
Besides audio and video transmission, DVB also defines data connections (DVB-DATA) with return channels DVB-RC* for several mediums (DECT, GSM, PSTN/ISDN etc.) and protocolos (DVB-IPI: Internet Protocol, DVB-NPI: network protocol independent). This is for example used for interactive interfaces like Multimedia Home Platform (DVB-MHP) and Electronic Program Guides (EPG).
Legacy technologies like teletext (DVB-TXT) and VBI (DVB-VBI) are also supported to ease conversion. However for many applications more advanced alternatives like DVB-SUB for sub-titling are available. The features are described with Service Informations (DVB-SI).
Japan uses different formats in all areas (ISDB), which are however quite similar to their DVB counterparts.
In North America DVB-S is often used in signal compression and encoding of digital satellite communications alongside Hughes DSS. Unlike Motorola's DigiCipher 2 standard, DVB has a wider adoption in terms of the number of manufacturers of receivers. Cable operators either use DVB-C or OpenCable. Terrestrial HDTV broadcasts use ATSC digital encoding with 8VSB modulation instead of DVB-T.Interfaces and Encryption
DVB describes a lot of (network) interfaces, but most importantly the Common Interface (DVB-CI) for Conditional Access (DVB-CA) with the Common Scrambling Algorithm (DVB-CSA) required for (de-)scrambling pay TV.Adoption
In its origin Europe, in Australia, South Africa and India DVB is used throughout the areas it covers or is at least decided to be. This also holds true for cable and satellite in most Asian, African and many South American countries. Many of these have not yet selected a format for digital terrestrial broadcasts and a few (Argentina, South Korea and Taiwan) chose ATSC instead of DVB-T for now.
