DIGITAL RADIO -- The Eureka 147 DAB System

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DIGITAL RADIO -- The Eureka 147 DAB System
THE THIRD AGE OF BROADCASTING The First Age of
Radio Broadcasting - the era of AM-1910. The
Second age - FM services -1950. The 'Third Age of
broadcasting DAB (Digital Audio
Broadcasting)-1995
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An outline of the Eureka 143 system
Hi-fi and more services are always the targets of
radio broadcast. The solution to increasing the
capacity and versatility of sound broadcast is
digital.

• THE UNIQUE BENEFITS OF DAB
• High-quality digital audio.
• Rugged, reliable delivery
• Efficient use of the limited radio frequency
  spectrum available
• Flexibility and choice
• System features
• Added-value system features

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TECHNICAL OVERVIEW OF THE EUREKA 147 SYSTEM

• Eureka 147 DAB is a reliable, multi-service,
  digital radio broadcasting system, designed
  specifically for robust reception by mobile,
  portable, and fixed receivers, using simple
  non-directional antennas.
• The Eureka 147 System comprises three main
  elements. These are
• MUSICAM Audio Coding
• Transmission Coding Multiplexing
• COFDM Modulation

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DAB signal generation
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DAB reception
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MUSICAM Audio Coding
Masking Pattern Universal Sub-band Integrated
Coding And Multiplexing. the system codes only
audio signal components that the ear will hear,
and discards any audio information that,
according to the psychoacoustical model, the ear
will not perceive
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TRANSMISSION CODING MULTIPLEXING

• The frame-based DAB multiplex comprises three
  distinct elements
• The Synchronisation Channel
• The Fast Information Channel (FIC)
• The Main Service Channel (MSC)

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COFDM MODULATION
Coded Orthogonal Frequency Division Multiplexing
(COFDM). COFDM uses many carriers -- up to 1536,
spaced at 1 kHz separation for DAB -- with each
carrier independently modulated using
differential QPSK(quadrature phase shift
keying). Affords some protection against
multipath echoes RefAlard M. and Lassalle R.,
1987, "Principles of modulation and channel
coding for digital broadcasting for mobile
receivers.".EBU Technical Review No. 224 pp.
168-190.
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ROLL OUT OF DAB IN THE UNITED KINGDOM
In the United Kingdom, 12.5 MHz of Band III
spectrum from 217.5 - 230 MHz has been allocated
to DAB This will accommodate seven multiplexes
each of which can carry six high-quality stereo
services or a greater number of mono ones, plus
data. The guard interval provides the DAB system
with immunity to long delay echoes. There is
little difference between another transmitter
transmitting exactly the same signal and an echo.
It is possible to provide a wide area broadcast
using a number of transmitters, all broadcasting
the same signal.--single frequency network.