25-01-2012, 04:31 PM
Digital Audio Broadcasting radio now and for the future
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Introduction
The Eureka 147 Digital Audio Broadcasting (DAB)
system is well known to readers of this journal:
there is already a wealth of literature which gives
information on the technical characteristics and the
performance of the system1.
Recently, some debate has started on the role that
DAB could play in the future information highway.
Analogue radio
In 1895, Guglielmo Marconi (1874 – 1937) conducted
his first experiments with wireless telegraphy
on his father’s estate in Italy. Now, a century
later, analogue AM and FM emission standards
have achieved technological and operational
maturity; every day, radio reaches about two
billion receivers worldwide, offering the listeners
a large diversity of speech and music programmes.
Frequency shortages
The frequency bands available for sound broadcasting
are either rapidly saturating or have
already become saturated. As a result, the reception
quality is suffering more and more from
mutual interference between transmissions. In
many countries, there are now very little or no
prospects of additional radio services being
provided by means of the existing analogue
technologies.
Difficulties with FM radio reception
FM radio services in VHF Band II were originally
planned in the 1950s and 60s for fixed reception
using a directional receiving antenna at a height
of 10 m above ground level. Those listeners who
have installed a good outdoor (or loft-mounted)
antenna are generally quite happy with the quality
of their FM reception.
