Why DAB radio in the UK is broken, and how to fix it

24th Jan 2014 | 16:00

Why DAB radio in the UK is broken, and how to fix it

The sound quality of DAB radio is awful and the system needs a major overhaul

DAB radio in the UK is badly broken and needs fixing.

That's right, fixing, and not replacing with internet streaming. Here's why.

Firstly, let's be clear about one thing - the real challenge isn't coverage, even if that does need improving. That's a well understood issue and the solution is obvious enough.

Nope, the main problem is bandwidth.

Did you know, for instance, that many DAB radio stations in the UK are broadcast at just 64kbps mono using the MP2 codec? Do not adjust your screen that really is just 64kbps. That really is mono not stereo. That really is MP2 and not MP3.

To put that into context, MP2 is a less efficient codec than MP3, so that 64kbps figure is more like 48kbps in MP3. And that, TechRadar reader, is actually offensive.

Opinions vary on what makes for decent music quality in the MP3 codec. That's especially true if the context is in-car radio where background noise is prevalent.

But we'll come back to why in-car DAB matters so much and why it means streaming isn't a viable alternative for the foreseeable future.

300Di

The sound of music

"And remember, those are all MP2 bitrates. Even BBC Radio 3 is scraping the barrel for tolerable sound quality."

Anyway, the tolerable minimum for most people who remotely care about sound quality tends to be in the 128 to 192kbps range for the MP3 codec. In other words, far, far more than many current DAB stations.

Actual bitrates will vary depending on where you are in the country. But stations that broadcast at 64kbps - at least from some transmitters - include Absolute Radio 80s, Amazing Radio, BBC Radio 5 Live, Jazz FM, Rainbow Radio and many more.

All the rest broadcast at 80kbps to 128kbps with a single, solitary exception, namely BBC Radio 3 which is 160kbps to 190kbps. And remember, those are all MP2 bitrates. Even Radio 3 is scraping the barrel for tolerable sound quality.

Sadly, it hasn't always been this way. DAB bitrates in the UK have actually been falling. It's ironic really. While screen technology races into a bold new 4K ultra HD age, DAB radio is plumbing the depths and pushing the limits of audio awfulness.

How, then, have we found ourselves in this position? Wasn't DAB meant to enable both far superior sound quality and many more stations?

Bandwidth brainache

Like we said, the problem is bandwidth. The best way to think about DAB is as a single data stream carrying all available stations. And the single data stream has a fixed data rate.

For the sake of argument, imagine that data rate in 1Mbps. All your radio stations have to fit inside that 1Mbps budget. With, say, four stations, you have a healthy 256kbps per channel. Nice.

But every time you add a station, something somewhere has to give. Immediately, you realise DAB is fundamentally at conflict with itself. It's supposed to offer better quality and more stations, but the more it does the latter, the less it can deliver the former.

Early DAB adopters may even remember how good the technology was at launch. Some stations were broadcast at 256kbps back when it was essentially a test technology for the BBC. But as stations were added, bitrates fell off and quality went south.

Of course, you may argue that none of this matters. Simply use streaming data over the internet and dump DAB. Simple.

And that's actually not a bad idea for most people in a home or office context – anywhere you can have an internet connection delivered by a landline.

BMW i8

Music on the move

"DAB radio is supposed to offer better quality and more stations, but the more it does the latter, the less it can deliver the former."

But as soon as you are on the move, the streaming proposition breaks down. We tried streaming music over EE's 4G network from London to Bath via the M4 – one of the UK's major trunk roads. It just doesn't work.

OK, buffering technology helps a lot. But it's not really a solution for live broadcast. If you want to listen to the news when it's actually news, you need an essentially unbroken stream and certainly no major breaks in connectivity. The UK's 3G and 4G networks aren't even close to being able to delivering that.

Fundamentally, then, streaming over the internet is a woefully inefficient way to go about getting live audio into cars.

As for what is to be done, part of the answer is simple. Switch the UK to DAB+. That's the follow up to DAB that supports the AAC codec which is more efficient even than MP3.

Jump ship to DAB+

Most recent DAB radios either already support DAB+ or can with a firmware upgrade. Yes, it will be a bit painful for owners of older DAB radios that don't do DAB+. But the simple fact is we jumped too fast into DAB. The fundamental idea is sound, it's just the current implementation that sucks.

There are other issues to solve, of course, most of which are beyond our pay grade.

In an ideal world the spectrum available to DAB+ would be upped and the cost to access the network would be lowered, making it commercially viable for new entrants and commercial stations that amounted to more than a computer in a broom cupboard playing a pre-programmed playlist.

The first step in getting anything done is raising awareness. If you remotely care about having decent radio quality in your car, start by telling everyone you know about the awfulness of DAB.

Indeed, any day now the government is expected to announce plans to open bidding on a new DAB multiplex - essentially a second parallel DAB network. Maybe the second multiplex can be DAB+ allowing the two technologies to be run in parallel for a time.

If that sounds promising, as ever the danger is that the bigger the fee paid at auction, the more stations licence holders will need to cram in to make the whole enterprise a goer.

Anyway, it's galling to see DAB continue to be marketed as a cutting edge technology delivering crystal-clear digital sound. We need to pull the rug out from under that fallacy. If paying punters universally sneer at the notion that DAB is a high quality service – as they should do – the message will surely begin to get through.

Let's get those noses crinkling and the tide turning against DAB in its current form. And for goodness sake, if we do get a chance to change the system let's get it right next time.

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