Sunday, 19 June 2011

In praise of Digital Audio Broadcasting


Every once in a while, a revolutionary new technology comes along which is so much better than the technology it replaces that it immediately sweeps the old away and supplants it utterly. Digital Audio Broadcasting is a case in point - a technology which wholly eclipses the primitive and outdated Frequency Modulated VHF system.

Let's start with audio quality, which is, of course, what audio broadcasting is all about. Admittedly, when it has good reception, an antiquated FM radio has slightly better audio quality than DAB. But when it doesn't have good reception, the audio quality of FM degrades markedly. All radio systems suffer from time to time from poor reception and interference, of course, but DAB handles these in a far preferable manner: when DAB cannot provide an optimal listening experience, it cuts out entirely. After all, silence is golden, and who wants to listen, for example, to a weather forecast or a traffic report, or an important news story, with a degraded signal?

DAB values silence so highly, indeed, that it will use software glitches to sometimes introduce periods of silence into your listening even when reception is perfect - a truly wonderful innovation.

Then there is the matter of the time signal. For fifty years or so the BBC has broadcast the Greenwich time signal several times a day. FM radio, and its predecessors such as Long Wave, transmitted this signal virtually instantaneously, allowing people across the nation to set their watches to precisely the same time. Obviously, this meant that when you were late for an appointment, there was no excuse.

Fortunately DAB changes all that. DAB not only introduces a delay, critically it introduces an inconsistent delay. No two DAB radios will play the time signal at the same moment. No-one can say how much the time signal on a particular DAB set will be delayed. Consequently, everyone's watch is set to a slightly different time. No longer is anyone embarrassed to arrive late  for a meeting.

Again, FM receivers can typically pick up only a few stations, typically including local ones. For example, here in Scotland, FM provides only BBC Radios 1, 2, 3, 4, and 5, and BBC Radio Scotland. By contrast, on DAB, many stations are available. For example, BBC Radio Scotland is available everywhere in the United Kingdom except Scotland - clearly a better service.

But finally, in these eco-sensitive times, we must come to the issue of energy efficiency. While an old-fashioned FM radio will run for only a few months - rarely as much as a year - on one set of batteries, a DAB radio will run for many hours, sometimes even into days. The consequences of this innovation for energy consumption and for toxic waste are little short of revolutionary.
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