A DAB hand at clarity
The beauty of digital radio is its crystal-clear reception. But its path to establishing itself as the dominant audio broadcasting technology has been plagued by interference.
The UK has been at the forefront of pushing development of the Digital Audio Broadcasting (DAB) technical standard, which offers major advantages over existing analogue transmissions (see panel, right). However, despite its undisputed superiority, DAB remained a niche technology mainly limited to expensive hi-fi tuners until economically priced products finally began appearing earlier this year.
This was greeted with huge relief by the radio industry, including the BBC, which since the mid-1990s has invested heavily in upgrading transmitters and launching dedicated stations based on DAB.
Quentin Howard, chief executive of Digital One - holder of the UK's only national commercial digital radio licence - says it became clear two years ago that something had to be done if DAB was to be saved from the technological scrapheap. 'The roll-out of stations by the broadcasters was proceeding at a good pace, so was the roll-out of transmitters,' he says.
What was missing was the promised delivery of affordable DAB-based consumer electronics products from the likes of Sony and JVC. 'We trusted them. They said, 'You provide the programmes and the stations and we'll make the receivers,'' says Howard. 'But they didn't. Whatever we did, the electronics manufacturers just weren't delivering.'
The non-appearance of low-cost DAB radios set alarm bells ringing among broadcasters, who realised that the entire project could founder unless enough people had access to the necessary electronics. According to Howard, the problem lay back down the line in the R&D departments of the world's big electronics manufacturers. 'We realised that DAB silicon was very expensive,' he says. 'People just weren't confident of recovering their R&D costs.'
A DAB sub-system was adding up to $100 (£64) to the cost of a digital radio receiver, a price that only high-end niche products would bear, and far too high for the mass audience broadcasters such as Digital One need to reach. 'We needed to create some competition in the silicon marketplace and take cost off the silicon itself,' says Howard.
Digital One decided to take matters into its own hands. It linked up with Imagination Technologies, a Hertfordshire high-tech electronics specialist, to develop a DAB sub-system that could achieve its ends. The result was Chorus, an advanced DAB chip cheap enough to allow receivers to be manufactured for retail below the magic £100 mark. 'We wanted an off-the-shelf DAB module that a Chinese manufacturer could easily plug into its own production line,' says Howard.
Nine months on, Howard claims Chorus has had the desired effect. 'From a broadcaster's point of view it was job done,' he says. 'We identified a blockage in the system and unblocked it.'
There is some evidence to support Howard's view in the appearance of more DAB chips, notably from US electronics giant Texas Instruments.
The budget radios produced using the cheaper silicon have proved popular with consumers. The first batch of the Pure Evoke-1, a £99 DAB radio powered by the Chorus microprocessor, sold out when it was launched earlier this year. At least five other manufacturers have said they will launch budget DAB products in time for Christmas.
However, there are few in the DAB community who would argue that the technology has overcome all the hurdles it faces.
A significant amount of radio listening is done in the car, but the automotive industry - never one to leap before it looks - has been vague about plans to fit digital radio systems as standard. Howard admits: 'The automotive industry has put up every objection under the sun.'
But he claims as consumers grow used to enjoying the benefits of DAB at home they will demand the same in their car. 'One of the manufacturers will break ranks and then the others will follow,' he says.
Another problem arises from the use by the US of a different standard to DAB for its terrestrial digital radio broadcasting. Most of the world, including Canada, is basing its plans for digital radio on Eureka-147, the European DAB specification. The US has gone its own way with an alternative system, originally called In-Band On-Channel and recently renamed High Definition (HD) radio.
The fact that the world's most important consumer market is pursuing a different standard is yet another headache for the electronics industry. Neighbouring Canada's adoption of DAB makes matters more complicated still. Vehicles are produced for the North American market as a whole, and manufacturers face having to build support for several digital standards into their car radios. And just for good measure, terrestrial standards such as DAB and HD are not the only ones active in the digital radio market. Satellite digital radio systems are already broadcasting in the US and are scheduled to begin in Europe within the next few years.
Mandy Green, spokeswoman for the Digital Radio Development Board - the UK body set up to promote the technology - claims neither the US divergence nor the appearance of satellite should hinder DAB. She says the Americans actually had little choice in the matter, because the bandwidth used by the European standard is allocated for use by the military and the emergency services in the US. 'It would have been nice if the US had been with us on Eureka-147, but I don't believe it is a major problem,' she says.
As for satellite, DAB's supporters believe the two can happily exist alongside each other fulfilling different needs. 'We believe there is room for at least two transmission standards in any European country,' says Green.
However, although the digital radio community is sounding more upbeat than it was 18 months ago, some analysts claim the technology's intrinsic benefits will never quite be enough to convince millions of people to abandon their well-worn analogue receiver.
The government eventually wants to switch off the analogue radio frequencies but, as with analogue television, this will not happen for years. If DAB can offer more thanbetter reception and some extra stations it could achieve the momentum it needs.
Because DAB multiplexes have more bandwidth than is needed for audio transmission alone there is an opportunity to stream different types of data alongside the radio broadcast. This could be text, high-quality pictures or diagrams. Some researchers even hope to stream video clips and web pages alongside DAB transmissions, bringing a host of new interactive services that will make radio more than something you listen to.
Paul Smith, director of the radio devices unit at Roke Manor Research, the UK-based Siemens subsidiary, claims such research has the potential to transform DAB. 'Many people see DAB as a means to deliver data products, and it is ideally suited to that task,' he says. 'If you can provide a return delivery channel - a way of sending information back as well as receiving it - there is an enormous amount you could do.'
Smith says DAB is at a make-or-break point on all fronts - the cost of the technology, the additional functions it can perform and even the size of the hardware. He points out that a DAB receiver has been demonstrated that is half the size of a mobile phone. 'DAB has taken a lot longer than people imagined to develop as a technology, but I suspect its time is finally here,' he says.
Sidebar: A step up from analog
Digital broadcasting systems such as DAB avoid the problems of multipath interference suffered by analogue broadcasts.
Multipath problems occur when radio signals bounce off buildings, hills and other obstacles between the transmitter and receiver. By digitising the data and compressing it into highly efficient packets, the broadcast can be sent reliably even in areas prone to interference. The sound quality is also much better, and is comparable to a CD.
At the heart of digital broadcasting is the multiplex, a digitised bundle of signals that can be carried together on the same frequency. Because not all the bandwidth available in each multiplex is necessarily needed for the audio signal, broadcasters can send other types of data. This can already include text, and static images and even video clips are likely to appear on special screens built into future digital radios.