DAB+ and DAB – the differences, and its use in the UK
What does a DAB plus signal actually do, and can we see the UK changing over to DAB+ in the future?
By James Cridland
Posted 7 March 2016, 9.10pm est
- Want a less technical answer? Try What is DAB+ - also here on media.info
In the comments of a story on my old blog in 2010 about Hong Kong’s DAB ambitions, Scott posts:
James, I have learnt that in the UK, they are evolving into DAB+ from DAB while most of European countries are using DAB+. What are the major differences? Thanks!
Since Scott asked, here's a quick primer about DAB+, updated for 2016:
A DAB audio signal is encoded in MP2 (the ancestor to today’s MP3 format). A DAB+ audio signal is encoded in aacPlus (strictly, aacPlus HE v2). Your iPod uses AAC as standard; aacPlus uses a number of clever techniques to make it more efficient, so audio sounds better at lower bitrates. Roughly, 48kbps DAB+ sounds the same as a 128kbps DAB signal.
A DAB+ audio signal also includes slightly better error correction, which might mean a reduction in 'bubbling mud' or other problems in poor reception areas.
Apart from that, there are no differences. DAB+ and DAB use the same transmitters, same multiplexing equipment, and so on, and DAB and DAB+ signals can happily live on the same DAB multiplex. A DAB+ radio will also happily decode DAB signals as well (although a DAB radio won’t decode DAB+). Many DAB radios on sale today will cope with DAB+ automatically, or will prompt you with instructions on how to upgrade (which could be as easy as typing a code in, or downloading some new firmware).
Any radio with a Digital Radio tickmark will receive DAB+ without any problem. If buying a DAB radio, you should ensure it has the Digital Radio tickmark somewhere on the packaging: it ensures it'll sound as good as it can, and has other benefits in terms of performance.
DAB+ is now the standard way to launch new DAB services, and is in use in, among other places, Australia, Norway, Switzerland, Belgium, Germany, The Netherlands, and many more. The main benefit is that you can get many more channels onto a typical DAB multiplex.
In the UK, the new national multiplex contains a few DAB+ services, including Fun Kids, Magic Chilled, Union Jack and Jazz FM. Everything else on that multiplex, however, is standard DAB. DAB+ services are also available on some small-scale multiplexes, including London, Portsmouth and Manchester.
So, that done, let’s put a few facts straight:
The UK has no plans to move from DAB to DAB+
While DAB+ services are now appearing in the UK, there are no plans to switch the majority of radio broadcasting over to DAB+: not yet, anyway. There have been a lot of DAB sets sold in the UK. DAB sets are in over half of all households here, and generally we don’t replace radios as fast as any other entertainment equipment (like a TV, a set-top box, or a mobile phone). Given this, it’s unlikely that the UK will be switching to DAB+ any time soon, and there are no plans to make that complete change. That doesn't mean that individual stations won't make the switch, though.
DAB+ doesn’t automatically mean better audio
Some of the main proponents of DAB+ in this country want it because they think it’ll result in better-sounding audio, in comparison with DAB. It might not. Many DAB+ countries use 48kbps aacPlus, and the new services on the SDL multiplex are at 32kbps: they offer a good stereo signal, but they're still not a brilliantly clear sound. The main benefits to radio listeners from DAB+ will be additional choice, not enhanced sound quality. That said, DAB+ normally means stereo is available at bitrates formerly only used for mono.
DAB+ doesn’t always mean cheaper costs for broadcasters
Changing to DAB+ instead of DAB doesn’t make the transmitters any cheaper (and, actually, makes them slightly more expensive since there's a patent to pay to Fraunhofer). Broadcasters are charged for the bitrate they use, but most DAB multiplexes in the UK aren’t full. Multiplex owners will still want to cover their costs.
The UK is currently only using DAB+ where it's the only way to get onto a multiplex. If there's 128kbps spare, it may make more sense to launch an old-fashioned DAB service, since you're likely to be able to be received by many more listeners. However, as DAB+ sets become more popular, this won't always be the case.
DAB+ is the only sensible choice if you’re launching digital radio now
If you’re launching digital radio in a new market, it makes no sense to be looking at standard DAB. DAB+ is robust, reliable, and comparatively cheap, particularly if you consider the opportunities of launching over 20 channels on one multiplex. Receivers are cheap, power-efficient, and available now. The technology is tried and tested. Broadcast radio, free at the point of consumption, has significant benefits over internet radio.
There are lots of reasons to go with DAB+ for a new marketplace. For the UK, however, there are few benefits to move over to DAB+, and plenty of reasons not to do so yet.
Having just bought a new digital radio I am sad it won't be able to receive the new radio stations being rolled out as has been the new multiplex from John macleod
Most modern DAB radios can also handle DAB+, but it's not been advertised because until recently, there was no DAB+ stations to receive in this country.
A DAB+ audio signal is encoded in aacPlus (strictly, aacPlus HE v2).
Not quite true James. It's only HE AAC v2 used for bitrates below 64kbps AND when Parametric Stereo is required.
HE AAC v1 is used for mono services with bitrates below 64kbps.
For bitrates of 64kbps and above LE AAC is used (because HE AAC offers no improvement in sound quality at higher bitrates).
Another point I would make is that whilst it is true DAB+ benefits from Reed Solomon error correction on top of Equal Error Protection, the improvement in coverage is marginal. So marginal, that in the real world the sensitivity of the radio being used makes more of a difference to the vast majority of listeners.
Really impressed by the quality of Jazz FM on D2. The fidelity of sound just stands out from anything else on D1 or D2!
Well I've studied FM, DAB, and DAB+ subjectively with headphones many many times, and my conclusion is simple: the new DAB+ transmissions at 32kbps and 64kbps (especially) 32kbps is a serious compromise. Both bit rates offer a 'hollow' and morphed stereo image, not remotely High Fidelity at all, sorry but it is true. When the BBC pump a non-compressed sound image through the network (or at least very high bit-rate digital signal), it simply blows away MP2 DAB @128kbps, although Radio 3's DAB @192kbps is good.
Long live FM until further notice!
PS - I can only see the bit rates of the improved DAB+ codec being brought down to the lowest tolerable levels to squeeze in as many stations in as possible!? So much for 'progress'.
Dear Eric I cannot get dab plus to work on my new digital radio but you explain in great detail what it should do I am only too disappointed that digital 2 is not in Scotland to experience the full effects of digital broadcasting at its bear or maybe worst depending on stations listened to from John macleod
Hello John Macleod, DAB+ transmissions may be a bit 'thin on the ground' at the moment nationally? Here in Staffordshire I can pick up a few, but only at a dire 32Kbps stereo, which is truly pathetic. An earlier test transmission in 2014/2015 offered just 64Kbps stereo, and again this was below par in quality. They may sound great from a distance or in mono, but once you listen and study the sound with headphones, you may begin to hear all sort of compromises, in particular it's like sound with a 'tunnel effect', and an inherent 'hollowness', it is quite alien in nature. Not surprising as the data-saving algorithms are complex which subtract harmonic content that we humans cannot apparently hear (using Fourier Transform analysis?) at source, and then this is knitted togther later. In essence, the lower the Tx bit-rate, the bigger the compromise. Ideally all DAB+ ought to be transmitted at 96Kbps stereo AND higher to make listening a pleasure.
DAB+ at 128Kbps and higher? ... I won't be holding my breath in the mean time John.
Dear Eric thank you for your quick reply to my message to you,as you rightly say dab plus is thin on the ground and I appreciate you telling me what transmissions are like in Staffordshire it's all but a question of wait and see or hear what may transpire in Scotland and many other parts of the UK by the way does the premise of 75 percent of the population getting digital 2still hold true or has this changed yours sincerely from John macleod
I know no more than you concerning any criteria for further DAB/DAB+ transmissions. As you may understand now, I am a bit of a audiophile, and currently the MP2 DAB codec is truly a regressive step, without question in fact. It has failed, but they (BBC especially) continue to flog adverts for us to buy DAB radios almost around the clock. Losing FM (if ever) would honestly be a regressive step, as they would cram in as many DAB stations they could on to the same MultiPleX.
Dear Eric image heard and seen these adverts you speak of by the BBC,on another subject fm radio may well be switched off by 2020according to one or two sources in Inverness but if it does come off my only hope is that digital radio finally comes into its own in the way we hoped it could and would have from the outset but that's another matter for another time you sound as though your interest in the advancement of radio is diverse complex and highly knowledgeable all very much credit to you if you'll pardon any pun not intended with sincere good wishes to you from john macleod
I am not an audiophile and I am in middle age but the current DAB system to me sounds awful. I have listened to the new JazzFM Stereo output using DAB+ and often hear weird distortion particularly on vocals. The bit rates used are just too low. DAB is useless for quality and DAB+ if it is ever used in the UK would be used at the lowest bit rates possible. Money talks and if the multiplexes can squeeze more low quality audio in they will. Not impressed and have doubts about the future of broadcast radio.
Dear sir with media moguls as have done last week bought into a big radio company it doesn't look to good or in any way fortunate if the murdochs of this world continue to exist radio as it stands just now needs more of an injection that hurts those who listen to it because it's not being carried through in the way listeners of the platform would wish or hope for,yours sincerely from John macleod
Trevor Smith, If you crave for a high fidelity music experience, forget about DAB or DAB+... DAB is not an ideal platform for fireside listening!
Purchase an internet radio ''separate'' for your hifi or plug in a Revo Mondo set top device into the hifi auxilliary port. Tune in to online channels like Linn Jazz, a channel at 320kbps stereo (MP3) or catch Jazz on BBC Radio 3 at 320kbps AAC, giving audio reproduction akin to compact disc quality!
Due to financial cost, DAB+ will never, ever stream services at that calibre of sound!
Mainstream commercial channels on internet radio, generally use around 128kbps MP3 stereo, a sort of 160kbps stereo equivalent on the legacy DAB system.
Even at this lower data rate, sound quality is acoustically pleasing to most listeners!
You can escape from DAB at home, but more difficult to do that while in the car. Ongoing signal reliability for DAB+ on the road is currently far superior to reception offered on mobile broadband!
DAB is naff for inhouse entertainment!!
Willie what you say makes absolute sound sense to pardon any pun not intended and I would be first in the orderly queue to purchase one of the radio devices you mention in your message I think you understand implicitly everything about this spectrum of radio that others may never even touch the sides let alone allow their ears to appreciate the value of true enhancement of sound as it should be heard or am o lifted,if I state this case as knowing little and that you know more it is because you do,yours sincerely from John macleod
John, Thanks for the compliment!
To be honest, I am not an expert on radio, more of an enthusiast.
If the incumbent UK government defers a future announcement about a digital radio switch over date, the radio industry may require a rethink about DAB/DAB+ strategy!
Many thanks Willie, and also for further information relating to digital radio switchover which as an enthusiast which your good self is will one day look forward to it arriving, yours sincerely from John macleod
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