Digital audio broadcasting (DAB), also known as digital radio and high-definition radio,
is audio broadcasting in which analog audio is converted into a digital signal and
transmitted on an assigned channel in the AM or (more usually) FM frequency range.
DAB is said to offer compact disc (CD)- quality audio on the FM (frequency modulation)
broadcast band and to offer FM-quality audio on the AM (amplitude modulation) broadcast
band
DAB is suitable for new (data) services. The listener can set voice / music power ratio and
 choose his own dynamic range of the audio material. Along with the audio, additional
information can be transmitted, such as

programme / format information
song texts
traffic information
radio text
Digital radio is now being provided to the underdeveloped world. A satellite communications
company named WorldSpace is setting up a network of three satellites, including “AfriStar”,
 ”AsiaStar”, and “AmeriStar”, to provide digital audio information services to Africa, Asia,
 and Latin America. AfriStar and AsiaStar are in orbit, and AmeriStar is expected to join them
 soon.

Each satellite provides three transmission beams that can support 50 channels each, carrying news,
 music, entertainment, and education, and including a computer multimedia service. Local, region
al, and international broadcasters are working with WorldStar to provide services.

Low-cost DAB radio receivers are now available from various Japanese manufacturers, and
 WorldSpace has worked with Thomson Broadcast to introduce a village communications center
 known as a Telekiosk to bring communications services to rural areas. The Telekiosks are
self-contained and are available as fixed or mobile units.

The new Digital Radio system DAB (Digital Audio Broadcasting) is a highly innovative and
universal multimedia broadcast system that will replace the existing AM and FM audio broadcast
 services in many parts of the world in the immediate future. It is designed for excellent mobile
reception, is highly robust against multipath reception and allows the use of single frequency
networks (SFN) for high frequency efficiency.

In addition to several high-quality digital audio services, DAB is able to transmit programme
associated data and a host of other data services including travel and traffic information and
still and moving pictures. Dynamic multiplex management on the network side opens up new
 possibilities for flexible programming. Written in an accessible style, Digital Audio Broadcasting
 provides an excellent guide for developers in industry, planning engineers together with
broadcasters, network providers and service and content providers. For students and those
wishing to get to grips with the new concepts of digital broadcasting it will serve as a
comprehensive introduction to the field.