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Sounding Off: Is DAB A Disaster?

Hugh Robjohns
Published August 2009
By Hugh Robjohns

The UK Government's recently published Digital Britain report makes fascinating reading (). The part of the report that most interested — and then concerned — me is the part about "changing the radio licensing regime to enable digital coverage to be extended.” Chapter 3b spells out the detail — and the timeline: full transition of current national FM services to digital, the FM spectrum to be reallocated to ultra‑local community services, and the cessation of all AM radio services, all within six years. Pretty bold thinking, but apparently without full assessment of the impact to all parties — something the report openly admits!

Hugh Robjohns

The publication states that 32 percent of adults live in "DAB‑enabled” households, which is plausible, if surprising — but what I find rather less acceptable is the claim that "consumer satisfaction is high”. They didn't ask me or anyone I know, and most of us certainly wouldn't have given that answer! DAB is a clever combination of technologies developed as a very high‑quality radio delivery system. Sadly, those who govern and manage the airwaves value quantity over quality, even though there is growing evidence that such a policy isn't commercially viable. The sound quality of current DAB services is — both subjectively and technically — inferior to that achievable with FM, varying from just about acceptable to utterly atrocious, depending on the bit‑rate allocated to each service. DAB was conceived to use bit‑rates at least twice as high as those often employed now. Squeezing double or treble the number of programmes and services into the available multiplex bandwidth quickly destroyed the notion of audio quality, despite the marketing hype. Forcing the current national FM licence holders to move exclusively into the DAB spectrum isn't likely to make things any easier for anyone, either. The DAB transmission network will require considerable expansion, at immense cost, to match the coverage currently achieved with the national FM services. That investment will have to be repaid by the licence holders over a relatively short time‑span, and inevitably at a rate considerably higher than the FM transmission service costs. I'm not convinced the licence fee and advertising markets can bear that strain.

There's not even a guarantee that DAB will remain the national radio platform. The report acknowledges the advantages of DAB+ (similar to DAB but using AAC+ instead of layer II audio coding) and DMB‑A (Digital Multimedia Broadcasting‑Audio), and even states that all new digital receivers sold in the UK should have the capability of receiving and decoding all three formats. That makes it inevitable that there will be pressure to roll out services in one or both of these alternative formats too, at even more cost and rendering the existing nine million DAB receivers obsolete in the process.

But perhaps the most disappointing aspect of embracing the digital world is how non‑green it will be. I have a portable, battery‑operated, FM radio in my bathroom, powered by a pair of AA batteries that I last changed over a year ago. I also have a similarly sized battery‑operated DAB radio that drains six AA batteries in just over a week's similar usage. Although DAB transmitters are more energy efficient than their FM equivalents, considerably more are required to achieve the same geographical coverage. In addition, DAB receivers (of which there will be a very great many, of course) are enormously less efficient than their FM predecessors. Mains powered radios in bathrooms aren't a good idea, and neither are mountains of dead batteries! The eco‑warriors should be jumping up and down about this policy.

These plans are bad from an environmental point of view and potentially bad from a quality point of view, and the only arguable benefit is in offering the possibility of a lot of naff local radio stations — but only if pirate radio stations are policed far more effectively than they have been. What the plans do offer is a way for the Government to generate income from hundreds of new local FM radio licences, but it would be very brave to try to set up a local community radio station in the current economic climate, and I don't see it getting much easier in the next six years, either. There is an e‑petition about this at: http://petitions.number10.gov.uk/AM-FM-Radio/.

About The Author

Hugh Robjohns is Technical Editor of SOS and joined the company in 1997 after escaping from the BBC with some of his sanity intact. He continues to deliver occasional specialist training to the BBC, particularly in areas related to surround sound and digital audio.

Published August 2009