Introduction to DAB/DAB+/DMB
|The world of digital broadcasting is not static - it demands flexibility and adaptability to meet the demands of the ever more rapid digital development, spectrum efficiency, new applications and device features. WorldDMB is at the forefront of these changes with its ever growing family of standards based on DAB (Digital Audio Broadcasting). Our members work together to shape the future of digital radio and mobile TV around the world and create the standards of future developments.
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WorldDMB's three most well-known standards are the original digital radio standard DAB, the recently developed additional radio standard DAB+ and the multimedia/video standard DMB. Over 500 million people around the world can now receive over 1400 different DAB/DAB+/DMB services. Commercial DAB receivers have been on the market since summer 1998. There are now over 340 different DAB receivers commercially available. There are also over 20 different DMB receivers in the market, which of course can also receive DAB services. DAB+ receivers have also recently entered the market and with the quick take up of the standard throughout the world the number is expected to increase in the next year.
The Eureka 147 consortium was part of EUREKA - an intergovernmental initiative supporting European innovation starting in 1985. A technical body under the name of Eureka 147 Consortium initiated the original DAB (Digital Audio Broadcasting) System. This project developed a new digital transmission system which received ITU recognition as a world standard - the only one to meet its stringent requirements. The Eureka 147 DAB System is seen as the future of radio.
The European funded DAB project turned out to be the 147th project of the technical body of which represents many technical projects that have been pursued throughout the years. Thus, the DAB project was adequately named Eureka 147 and to subsidise the project a consortium of members was created.
When the original DAB (Digital Audio Broadcasting) was first developed in the late 1980s, it was based on MPEG Audio Layer II coding, which was then state of the art and is still a commonly used coding technology in radio nowadays.
Since then, MPEG Audio Layer III, better known as MP3 has conquered the market of digital music players and radio streams. Even though still the most successful technology on the market, MP3 has already been overtaken in efficiency and performance by MPEG-4 (AAC). This development called for an additional audio coding system in DAB which would allow for more efficiency at lower bitrates - hence the birth of DAB+.
Another important innovation was the addition of video/multimedia capabilities to Digital Audio Broadcasting, allowing DAB to become a digital mobile television platform DMB (Digital Multimedia Broadcasting) as well as a multimedia digital radio platform.
Both for DMB and DAB+ the technical basis remains to be DAB. In other words, the physical layer is still the same, just new applications, new transport protocols and a second error control coding layer was added. All three technologies can therefore be used alongside each other on one multiplex and basically use the same infrastructure, so there is a whole range of possible multiplex scenarios.
WorldDMB recommends that DAB (ETSI 300 401) or DAB+ (ETSI TS 102 563) should be used for radio-centric services and that DMB (ETSI TS 102 428) should be used for services which include a video component.