Digital Audio Broadcasting - DAB - Digital Video and Audio Broadcasting Technology - page 459

26 Digital Audio Broadcasting DAB
Although DAB (Digital Audio Broadcasting) was introduced back in the
early days of the nineties, well before DVB, it is still relatively unknown to
the public in many countries and it is only in a few countries such as, e.g.
the UK that some measure of success of DAB in the market can be regis-
tered. This chapter deals with the principles of the digital sound radio stan-
dard DAB.
At first, however, let us consider the history of sound radio. The age of
the transmision of audio signals for broadcasting purposes began in the
year 1923 with medium-wave broadcasting (AM). In 1948, the first FM
transmitter was taken into operation, developed and manufactured by
Rohde&Schwarz. The first FM home receivers were also developed and
produced by Rohde&Schwarz. 1983 was the year when everyone took the
step from analog audio to digital audio with the introduction of the com-
pact disk, the audio CD. In 1991, digital audio signals intended for the
public at large were broadcast for the first time via satellite in Europe,
DSR (Digital Satellite Radio). This method, operating without compres-
sion, did not last long, however, and was little known in public. 1993 then,
ADR (Astra Digital Radio) started operation which is broadcast on subcar-
riers of the ASTRA satellite system on which analog TV programs are also
transmitted. The MUSICAM method, used up to the present for audio
compression in MPEG-1 and MPEG-2 layer II and is also used in DAB or,
to put it more precisely, was developed for DAB as part of the DAB pro-
ject, was laid down in 1989. Digital Audio Broadcasting, DAB, was devel-
oped at the beginning of the nineties and used the then revolutionary new
techniques of MPEG-1 and MPEG-2 audio and the COFDM (Coded Or-
thogonal Frequency Division Multiplex) modulation method. In the mid-
nineties then the DVB-S, DVB-C and DVB-T standards for digital televi-
sion were finalized and thus the age of digital television had also begun.
Since 2001, there is a further digital sound radio standard DRM (Digital
Radio Mondiale), intended for digital short- and medium wave use, which
is also based on COFDM but uses MPEG-4 AAC audio coding.
The first DAB pilot test was carried out in 1991 in Munich. Germany
currently has a DAB coverage of about 80%, mainly in Band III. There are
also L-Band transmitters for local programs. As ever, DAB is almost un-