Although the BBC has been the biggest investor in DAB, and the UK the most enthusiastic adopter (alongside the Scandinavian countries), it is the single most widely used digital radio platform worldwide. Second would be satellite radio – eg Sirius, XM (now defunct) and Worldspace (now defunct); third would be HD Radio (In-Band-On-Channel), which broadcasts digital signals on existing FM frequencies; and fourth would be Digital Radio Mondiale (DRM), which is mostly used for low bitrate, long distance shortwave service replacement.

Here are the countries using (and intending to use) our DAB system as the platform for digital radio services:
http://www.worlddab.org/country_information.

The criticism I’ve heard about the audio fidelity is more because of spectrum allocation and overcrowding of signals, rather than the capacity of the platform itself (data compression, rather than audio compression). That is, that DAB sounds much worse than CD (fair) rather than worse than FM (not fair).

Generally speaking, it’s better than streaming audio up to about 128k. The fact that some broadcasters are putting out music programmes in mono on DAB is simply because they’re bandwidth greedy and should be slapped. It’s not the platform.

There are two reasonable negative comparisons with FM. The first is more about reception with respect to line of sight to transmitter. If you lose a DAB signal, the music goes away completely. If you lose FM signal, it just goes fuzzy. But where your coverage is good, your signal is fine. Things are better in places that use Band III VHF rather than the much higher frequency L-band for broadcasting. Higher frequencies are more directional, and so obstacles can become a problem.

The second is that DAB doesn’t need the brutal processing that FM radio does, but broadcasters still use it. FM radio is compressed to hell – the dynamic range and the frequency range squashed within an inch of its life. Digital broadcasts don’t require the same level of processing (arguably, nor do FM broadcasts, but that’s where we are), but the reason broadcasters still use it is partly because they believe people think that this is what radio is supposed to sound like, but mostly because of The Loudness War, which is even worse in radio than it is in CD mastering.

In effect, the complaint is that DAB sounds as bad as FM.

I would like to see all existing terrestrial over-the-air broadcasts (AM, FM & DAB) shift to internet streaming, given a good compression algorithm like AAC+, and given free, ubiquitous wifi.

In the meantime, I’d like to see an opening up of the spectrum for legal, unlicenced micro-broadcasting on the FM band. It works just fine in New Zealand where there’s no pirate radio – because it’s perfectly legal to broadcast to a small geographic area on a particular bit of the FM dial.

But given the investment in the broadcast technology, the commitment across all political parties and OfCom to a managed digital ’switchover’, the incredible market penetration and frequent upgrade habits of consumers in the mobile marketplace, a diversity of existing services and the advantages of free, over the air public and private broadcasting, the fact that the DAB chips are so cheap and plentiful, the (potential) audio fidelity despite the bad reputation, and just how easy it would be to do this, it’s difficult to see a downside.

Had this been done even 5 years ago, DAB would be utterly embedded by now. The one thing holding up its development has been that people didn’t want to buy expensive dedicated receivers – but they’ll spend more than double that without blinking on a handset that would be perfectly capable of doing the same job.

The short version is that Internet Radio is not the same as broadcast radio, even if the same noises come out – just like YouTube and iPlayer are not the same thing as digital TV. I’m talking here about a dedicated tuner and receiver – a DAB chip – built into the device, for the over-the-air reception of broadcast programming.

The long version, incidentally, is the subject of a 40,000 word dissertation that I wrote 5 years ago, but which I won’t inflict on you here.

Andrew

PS. I hope you don’t mind – I’ll probably be copying the 30 days idea on my own blog soon :-)