A method of sending television, radio, and mobile phone data over long distances by using digital encoding to modulate a continuous beam of charged electromagnetic particles (typically radio waves, but also microwaves, electricity through wires, and visible light via fibre-optic cables). Digital signals consist of binary information which is symbolic and therefore arbitrarily related to its source; however, in the case of picture and sound information it is analogue signals that are being digitized so the indexicality of the information is preserved. Digital signals encode information in discrete bursts, unlike continuous analogue signals, and their modulations are expressed in abrupt changes (steps) rather than smoothe transitions (slopes). The main advantages of digital over analogue signals are that they can be compressed and that noise can be identified and removed. Digital transmission systems use a variety of methods: pulseband systems, such as those used for broadcast digital television, use digitized analogue waveforms while baseband systems, such as those used on the internet, send information in discrete bundles or ‘packets’. Digital television transmission allows for multiplexing, whereby multiple channels are bundled together and sent simultaneously in a single stream of data. See also MPEG2; transmitter.
http://www.bbc.co.uk/rd/pubs/papers/pdffiles/DTV150399rpm.pdf Digital broadcasting
Subjects: Media Studies.