5DVB standards

DVB is set of standards covering not only video/audio compressing but all functions relating to digital video delivery to end users or other providers. Such DVB system has to multiplex all input streams (video, audio, data signals) into one final transport stream and send it via given transmission medium in a proper form. As was already mentioned, MPEG-2 systems layer (part 1) defines how various elementary streams representing one or multiple programmes are multiplexed together. The elementary streams can carry video, audio, data, and other information. This multiplexing process creates a single (multi-programme transport) data stream that can be stored or transmitted via a physical medium.

In general, the MPEG-2 systems layer performs multiplexing, packetization, timing and synchronization, conditional access.

Fig. 6 shows a block diagram illustrating all main operations that have to be done at a DVB transmitter side to broadcast a digital content to users [5]. At first all programmes have to be encoded and multiplexed along with information such as time stamps, tables and other supporting data (e.g. teletext). The resulting transport stream is equipped by error protecting codes and modulated to a carrier. At a last phase the signal is amplified and sent via the transmission medium.

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Fig. 6 - Block diagram of DVB transmitter

DVB standards [6] cover broadcasting TV via cable (DVB-C, DVB-C2), satellite (DVB-S, DVB-S2, DVB-S2X, DVB-SH) and terrestrial transmissions (DVB-T, DVB-T2, DVB-H), return channel (DVB-RCS/RCT/RCC), microwave broadcasting (DVB-MC/MS), transmission of high speed data services (DVB-Data). They also define service information (DVB-SI), common scrambling algorithm (DVB-CSA), common interface (DVB-CI), network independent protocols, java-based multimedia home platform (DVB-MHP) as well as a subtitling, measurement, multiplexing, 3D-TV, IPTV, source coding, etc.

Next subsections deal with actual DVB standards defining methods and algorithms at data link and physical layer of the communication model for TV broadcasting to fixed and mobile end user devices. They use the same multiplexing process to produce DVB transport stream but differ in a way how this stream is adjusted for broadcasting via given medium.