Web and Radio Broadcasting

Valerie Thomson

The World Digital Audio Broadcasting committee recently established standards for transmitting data over the air. And now , products based on those digital audio broadcasting (DAB) standards are starting to emerge. DAB enables the transmission of program-associated data and information services such as traffic and weather updates. Its most compelling use, however, could be Web datacasting. Trials of DAB datacasting have been completed in The Netherlands, Finland, and Germany. Commercial services are already running in Sweden and the U.K.

DAB inserts MPEG Layer 2 compressed multimedia data into the audio stream. A new Multimedia Object Transfer (MOT) protocol controls broadcasting of data objects. These objects can include HTML documents, bit-map graphics , MPEG audio and video files, and also zipped executables. According to the German DAB-Platform group, Java applets may soon be part of the MOT data type list as well.

Because of its data transfer rates of up to 1.2 Mbps, many European Internet users might eventually consider DAB Web datacasting as an alternative to Internet access via phone lines. A DAB receiver plug-in PC card, developed by German manufacturer TechniSat (Daun, Germany), is slated to be on the market by June of 1998. In addition, developers such as Roke Manor Research (Romsey, U.K.) have already launched a Windows 95-based DAB receiver software development kit.

While audio features will drive the mass market for DAB in the near term, manufacturers and service providers say that multimedia and data services will eventually be even more important. In contrast to GSM, for example, DAB was designed with data services in mind and is backed by media-savvy broadcasters; GSM data wa s introduced and developed primarily by telcos who are just now beginning to build up the know-how and strategic alliances required to offer useful and compelling multimedia services.

Interactive DAB services are the subject of a number of ongoing trials. As with digital video broadcasting (DVB), which enables broadcast of data in addition to digital TV, European developers are working to commercialize a viable back channel for interactivity.

One possibility may be the GSM cellular phone network. For example, in the pan-European Multimedia Environment for Mobiles (MEMO) project, conducted by more than 20 research and telecommunication industry participants, DAB forms the broadband channel with data rates of up to 1.8 Mbps for downloading. The back channel runs over GSM at 9.6 Kbps, which is sufficient for users' interactions.

Experts say that projects like MEMO have initiated a new generation of integrated DAB and GSM chips. Expect first prototypes from manufacturers Bosch and Hitachi to be available for testing next year.

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A Little DAB'll Do Ya

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First DAB receiver cards for your PC will be available next year.