Digital audio broadcast (DAB)

Digital audio broadcast (DAB):

DAB Project is an industry-led consortium of over 300 companies

 The DAB Project was launched on 10th September, 1993

 In 1995 it was basically finished and became operational

 There are several sub-standards of the DAB standard

o DAB-S (Satellite) – using QPSK – 40 Mb/s

o DAB-T (Terrestrial) – using QAM – 50 Mb/s

o DAB-C (Cable) – using OFDM – 24 Mb/s

 These three sub-standards basically differ only in the specifications to the physical representation, modulation, transmission and reception of the signal.

 The DAB stream consists of a series of fixed length packets which make up a Transport Stream (TS). The packets support ‘streams’ or ‘data sections’.

 Streams carry higher layer packets derived from an MPEG stream & Data sections are blocks of data carrying signaling and control data.

 DAB is actually a support mechanism for MPEG.& One MPEG stream needing higher instantaneous data can ‘steal’ capacity from another with spare capacity.