When the BBC's digital broadcasting services launched in earnest a few years ago, they were promoted by an advertising campaign that claimed one of the benefits of the new technology was that listeners would be able to "see" radio. This was later played down in favour of more channels and electronic programme guides but the potential for DAB (digital audio broadcasting), the technology behind digital radio, to carry pictures as well as sound is now being adapted for the mobile market.
In trials held during the National Association of Broadcasters (NAB) Convention in Las Vegas, which ends today, NTL Broadcast and Tandberg Television, leading companies in TV and radio transmission and network distribution for cable, satellite and IP respectively, have been working with Microsoft to demonstrate real-time video streaming using DAB as the carrying medium. The demo aimed to show that video and audio can be transmitted to PCs, PDAs and mobile phones at rates of 120kbps.
The demonstration highlighted mobiles but DAB receivers with reasonably sized screens are in production and will appear this year. These will be able to handle HTML for web connection and video, as well as more flexible browsing of electronic programme guides.
Material for the NTL demonstration came from two sources: Capital Radio Group which includes Capital FM, Capital Gold London, XFM and Century 105 - and video from CNN International. The DAB sound and video signals were IP encapsulated and multiplexed using technology from RadioScape, which recently demonstrated non real-time video over DAB. The CNN video was encoded through hardware designed by Tandberg for use with Windows Media 9 and carried on the DVB (digital video broadcasting) platform, the core technology of digital TV transmission.
The DAB and DVB streams were uplinked from NTL's teleport in the UK, bounced off an Atlantic Ocean satellite and received by a dish at the convention centre in Las Vegas. The signals were then decoded to be retransmitted over DAB. The MPeg-encoded live audio could be heard on a Windows XP PC fitted with a RadioScape DAB card and handheld PDAs. Store and forward capability, which allows material to be received, saved and accessed later, was also demonstrated on Pocket PCs, as well as desktop units.
It is the audio and video content that is seen as crucial in attracting people to mobile "broadcasting". "The only problem with the business model is finding the people to produce mass market receivers and make watchable content," says Simon Mason, head of new product development at NTL Broadcast. "There is an increasing number of people on the move who are demanding news and information that is not tied to a broadcast schedule and the technology is available today to deliver it to them."
Mason believes that DAB is regarded as better able to deliver audio and video than either 3G or DVB. "3G is not a broad enough network for a lot of content and DVB is best suited to fixed receivers," he says.
There were once fears that DAB could become cheap TV. Now there are indications that it could be the technology that carries forward the mobile dream.
