| Digital
Audio Broadcasting |
Definition
Digital audio broadcasting, DAB, is the most fundamental advancement in radio
technology since that introduction of FM stereo radio. It gives listeners interference
- free reception of CD quality sound, easy to use radios, and the potential for
wider listening choice through many additional stations and services. DAB
is a reliable multi service digital broadcasting system for reception by mobile,
portable and fixed receivers with a simple, non-directional antenna. It can be
operated at any frequency from 30 MHz to 36Hz for mobile reception (higher for
fixed reception) and may be used on terrestrial, satellite, hybrid (satellite
with complementary terrestrial) and cable broadcast networks. DAB
system is a rugged, high spectrum and power efficient sound and data broadcasting
system. It uses advanced digital audio compression techniques (MPEG 1 Audio layer
II and MPEG 2 Audio Layer II) to achieve a spectrum efficiency equivalent to or
higher than that of conventional FM radio.
The efficiency of use of spectrum
is increased by a special feature called Single. Frequency Network (SFN). A broadcast
network can be extended virtually without limit a operating all transmitters on
the same radio frequency. EVOLUTION
OF DAB DAB has been under development since
1981 of the Institute Fur Rundfunktechnik (IRT) and since 1987 as part of a European
Research Project (EUREKA-147). " In 1987
the Eureka-147 consoritium was founded. It's aim was to develop and define the
digital broadcast system, which later became known as DAB.
" In 1988
the first equipment was assembled for mobile demonstration at the Geneva WARC
conference.
" By 1990, a small number of test receivers was manufactured.
They has a size of 120 dm3
" In 1992, the frequencies of the L and S
- band were allocated to DAB on a world wide basis.
" From mid 1993 the
third generation receivers, widely used for test purposes had a size of about
25 dm3, were developed.
" The fourth generation JESSI DAB based test
receivers had a size of about 3 dm3. 1995 the
first consumer - type DAB receivers, developed for use in pilot projects, were
presented at the IFA in Berlin.
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