Analogue radio broadcasting began in the UK almost 90 years ago, and the last bastion of consumer analogue technology, is still claiming over 70% of radio listening. Television broadcasting will have gone over entirely to digital in 18 months, while TV recorders and receivers have already done so. The progress of digital radio, introduced to the UK in 1995, has been somewhat rocky for technical and financial reasons…
Benefits of DAB
As with digital TV, DAB has many advantages over the analogue system. The greatest of them is a much wider choice of broadcasting stations, offering a huge range of programmes, from classical music to cricket, from rap and hip hop to international news analysis, from vintage comedy to easy-listening music. These embrace every kind of listener: the retired colonel engrossed in the test match commentary; a young student with headphones on the top deck of a London bus; a middle-aged bricklayer slapping on the mortar to the rhythm of the pop music of his youth. Such diversity, such richness, and all at no charge to listen. Other benefits of DAB are instant push-button station selection thanks to automatic self-tuning; a clarity of reception streets ahead of FM and AM due to the absence of interference and mistuning effects; and the provision of station, programme and music information in a scrolling display, which can also show real time, signal strength and other technical data. More sophisticated DAB sets offer live-pause, ‘rewind’ and recording features. What selling opportunities there are here with such wide ranges of product and listener.
There are, however, some downsides to DAB reception. Its coverage is not as wide geographically as the established FM network, though that is being rapidly addressed. As with digital TV, results can suddenly drop out from perfect to nothing as the signal strength and quality decreases. The quality and fidelity of music via DAB is slightly inferior to that from perfect FM reception, but it’s only noticeable on delicate music in quiet surroundings and with high-class reproducing equipment, while it’s true that most radio listening now is the background to some other activity, and thus less crucial: certainly in a car the conditions and ambience preclude critical listening. Early DAB radios were somewhat power-hungry because of their large and complex data-processing circuits, but current models are much better in this respect, borrowing low-energy technology from mobile phones, laptop PCs and the like.
Digital radio transmissions take place in the Band III VHF spectrum, once used for black-and-white 405-line ITV broadcasting. Whole bunches of stations are carried in single bouquets rather like DTV multiplexes, and in all cases there’s a trade-off between bit-rate and sound quality. For serious music stations like BBC Radio Three and Classic FM the data rate is 192 or 160 kbps (kilobits/second) while other music stations use 128 kbps and mono speech transmissions go down to 80 and even 64 kbps.
An improved transmission mode, DAB+, has become available, offering greater programme capacity and better immunity to low signal levels and interference, but it’s incompatible with most of the 20 million existing receivers, so a changeover would be problematic, calling for duplication of broadcasts. This situation arises from the early adoption of digital radio in the UK. Many current receiver designs are dual-standard; the entire current product range of manufacturer Pure, for instance, can receive both DAB and DAB+ transmissions.
The government has proposed a closing-down date for analogue radio broadcasting of 2015, but this looks very unlikely – 2020 or later is more realistic. Even so, analogue radios should now be sold with a health (longevity) warning. Certainly DAB has added value to the radio sector of our industry, but the bottom-end price of the product range has been badly eroded by £25 jobs from China via the supermarkets. A good seller has been the Pure Highway in-car DAB receiver/convertor, which recodes the stereo signals to VHF-FM for reproduction by the existing car radio using a spare FM band-slot. But in-car reception is one of the factors in the slow take-up of DAB services, with many major roads poorly served coverage wise, and a time lag in the design of in-built car radios, relatively few of which incorporate DAB.