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An Engineer in Wonderland – DAB nightmare

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I use my DAB radio every day.

And I just bought another one, for my workshop.

So I must be a fan. 

Or at least not a detractor.

And when it first came in, I was extremely pleased because it promised to be the first digital technology since CD that was actually better than its analogue competitors and not just marketing bollocks.

That was in the good old days when 250kbit/s data rates were on the cards.

Things got a little shaky when just under 200kbit/s was offered which, on the MP2 codecs used by DAB, meant audio quality was just a little bit worse than FM.

Not a problem for me, as my radio dial has atrophied in the Radio 4 position.

But a poor show for music lovers.

Now DAB has degraded to just another minimum-acceptable-quality medium where channel-count is all that matters.

Disappointing, but quality is not the thing that is most distressing me about DAB at the moment.

My problem is that, and you can probably guess the next bit, the Government want to switch all national broadcast radio over to DAB by 2015 – as introduced in the Digital Britain report.

In 2015, the Government is expecting me to discard all the FM radios that I use in my house – I use 4 of these regularly, even with the new DAB receiver – and replace them with something that will be several tens of pounds per unit, and will need to be plugged in, frequently recharged, or often fed with batteries.

Now, I hope DAB radios will come down to a few quid, but with the 2015 deadline looming and a captive audience, will set makers have any reason to drop prices?

And will power consumption ever be low enough for a DAC bathroom radio to run for months on two AA alkalines?

Plus, the MP2 codec required by DAB is pathetic compared with even MP3 compression, let alone AAC. For the record, Digital Britain leaves all options open on the coding scheme

So only an idiot would mandate the MP2 codec for 2015 as AAC offers something like 4 times the quality – or more likely four times the number of channels.

Sadly, if all DAB channels were switched to a newer codec a large number of existing DAB radios could not cope – neither of mine could.

The minor good news at this point is that if your DAB radio has a USB socket, it is likely to be upgradeable.

If the switchover has to happen, a useful compromise would be to leave existing DAB stations with MP2 coding for a long time, and make the channels moving over from FM go direct to a more bandwidth-efficient scheme.

Check out http://www.savefm.org/ for more information, or http://www.digitalradiotech.co.uk/ if you want a proper tirade.

‘Alice’

Respond below, or to alice@electronicsweekly.com

(Picture – Alexandra Palace mast by Redvers under Creative Commons Attribution Licence)

Tags: acceptable quality, alkalines, captive audience, power consumption, radio 4

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11 Comments

  1. September 14, 2009 10:12

    Hi Mike. Don’t worry – your comment was not supressed. We do moderate comments so it wouldn’t go directly live on Saturday. Thank you for your very intersting points – a welcome addition to the debate!
    As for FM surviving switch-off, I hope you are right. It would be an exaggeration to say ‘politcal suicide’, but a lot of people would be inconvenienced, so I think politcians might hold that decision.

  2. Mike Thomson
    September 13, 2009 22:07

    Hi, there!
    I posted a comment a couple of days ago, but there’s no sign of it as a response to the original article. I hope it hasn’t been suppressed because it disputes the commonly held view that DAB is worse than FM?
    I don’t believe for a moment that FM really will be switched off in 2015, but I am convinced that the dynamic range compression applied to Radio 3 broadcasts on FM is much less palatable to a musician than any limitations of the mp2 codec.
    Regards,
    Mike

  3. Mike Thomson
    September 12, 2009 12:05

    The audio range compression applied by the BBC to their Radio 3 broadcasts on FM, but not on DAB, completely undermines the claim that DAB sounds worse than FM – on Radio 3 at least. We might be oblivious to the compromised stereo separation, the high frequency roll-off due to the pilot tone, and the background hiss to which FM stereo is subject, but it cannot be right to apply 6 to 8 dB of compression (see the Radio 3 samples on http://www.digitalradiotech.co.uk/index.htm) when musicians work so hard to implement a dynamic range in the first place – quite aside from the fact that instruments such as the piano exhibit very different overtones when played loudly compared with being played softly. These subtleties are greatly diminished when you compress the dynamic range. I would therefore argue that FM’s audio range compression is much less desirable than the outdated Codec’s digital compression on Radio 3 via DAB.

  4. 'Alice'
    September 11, 2009 13:51

    Thanks for another bunch of reasons why a 100% switchover to DAB is bonkers.
    There must be some powerful lobbying going on.
    Anyone know from where?

  5. Trevor Gill
    August 26, 2009 13:17

    There’s another BIG issue with analogue switch off. I’ve just bought a new car. For the last 18 months, while thinking about it, I’ve been asking car dealers about DAB. Ony of my shortlist cars was a BMW 1xx. DAB is not even an option yet at any price. When I test drove a Toyota Prius (brand new model this month), I was glad to see a button on the dash labelled “DAB”, but my hopes were dashed when I discovered it was only available as an after-fit option. The price? £450. Rolls on floor laughing. How can we turn off FM if you still can’t get DAB in a new car. The dealers say you wouldn’t want it anyway, as the coverage is awful. A chance to try would be a fine thing.

  6. August 03, 2009 09:19

    I thought I would enjoy the BBC Proms on the TV over the weekend and listen on Radio 3 as I have a much better sound system via the tuner. This has worked really well in the past. Here I had the opposite problem to the DAB radio scenario. Our TV, via cable, is now digital and the high quality radio output is analogue. Besides having different presenters, the picture was seconds behind the sound (talk about bad lip sync!) and the program was completely unwatchable.
    I wonder if the DAB radio and digital TV are synched and how soon the BBC will stop the “pips” which are obviously late on DAB.
    Naturally, we live in one of those many suburban postcodes where there is no DAB radio or freeview TV coverage.

  7. J Childs
    July 31, 2009 22:22

    It’s an old story….. when there is something can be improved, often something else suffers. If money is involved money ALWAYS wins.
    i.e. No free lunch!

  8. John Kettle
    July 24, 2009 16:16

    I have just read your item on DAB Radio on “ElectronicsWeekly.com” and it echoes my sentiments. However, you do not mention the biggest problem as far as I am concerned, at least where I live, which is poor signal strength. I can be listening to a DAB broadcast in the evening satisfactorily, but when the radio is turned on the following morning the reception “warbles” so much it is impossible to listen to.

  9. Mark Alan Thomas
    July 24, 2009 12:19

    I’m very angry about this.
    By profession, I trained as an analogue designer, and now build HiFi for fun to retain my practical and design skills. Also, I love music.
    I was already annoyed about the degradation in quality of the formats forced on us, over standard CD quality….even worse, new CDs recorded in download quality, (Little Boots etc, great music, sounds awful)!
    So having been pre-conditioned, we are expected to just accept this course compressed sound.
    One last rant…..where’s the bandwidth logic, why can I receive speech based content at 192k stereo, and pure music stations (Kerrang! for example) only in 56k mono….explain that!
    Mark Thomas
    Solihull.

  10. robert gillatt
    July 23, 2009 16:57

    You have almost said it all Alice. The unthinkable waste of millions of perfectly sound FM radios needs hammering home and with what are we going to replace our Hi-Fi quality top-end tuners?

  11. John Scrivens
    July 23, 2009 12:56

    You failed to mention all the annoying silences that occur just when someone is saying something interesting or important. Or when a piece of music peaks.
    You also failed to mention that you can’t set your clock to DAB radio, or walk from one room to another with continuity of sound.
    If DAB were a child, I expect social services would be having a few stern words with the parents.

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