Sound Digital tests: See how hi-tech your digital radio is

Tests for the UK's forthcoming second national DAB digital radio multiplex are giving listeners the chance to see how hi-tech their DAB radios are.

Since the end of last week, Sound Digital has been testing a DAB+ service called "Sound Waves+" alongside the existing "Sound Waves" test station, enabling listeners to see if their radio can handle the newer DAB+ standard. The tests are currently taking place on VHF Block 11A ahead of the commercial launch of the new Sound Digital multiplex - also known as SDL National or Digital 2.

In a twist, the DAB+ service is using the newer HE-AAC v2 audio codec, which means some DAB+ radios will offer the station in mono, while others will enable the listener to hear stereo sound, depending on whether or not they have the relevant chip for HE-AAC v2. DAB+ radios with a mono speaker can be checked for their compatibility with HE-AAC v2 by plugging in head or earphones and checking if you can hear the waves breaking from one side to the other as they hit the coastline. Other stereo effects include a distant ambulance siren and a train speeding past in the background.

On Twitter, you've been telling a516digital about your reception reports, and the HE-AAC matter has gained some interest. The test transmissions aren't yet available from all future Sound Digital transmitter sites, and while some users have emailed in to say they're getting a clear sound on Sound Waves+, others have compared it to a poor quality internet stream.

The Sound Waves+ DAB+ test is for many UK listeners the first chance of trying out DAB+, the newer standard of terrestrial digital radio, already adopted as standard in other countries, including Australia, the Netherlands, Norway and Germany. Until now, there has only been a handful of DAB+ tests: notably Fun Kids DAB+ in NW Wales in late 2014 and the current broadcast of two DAB+ services on the Portsmouth trial multiplex.

Is your radio compatible with DAB+?
One major difference between original DAB and DAB+ is the absence of the "bubbling mud" phenomenon in weak signal areas: the Sound Waves+ service will generally fall silent if you move into a weak signal area (or play with the telescopic antenna).

In a nutshell:
  • Sound Digital is testing on VHF Block 11A. Not available in all areas. Further transmitters to be activated. You may see labels containing the term "3G" before the tests go live.
  • There are two services: Sound Waves and Sound Waves+.  Sound Waves+ is a DAB+ only station, and is allocated 32kbps of bandwidth. Radios with short displays (up to 8 characters) will display the services as Waves and Waves+.
  • The tests feature the sound of waves lapping onto the coast, with occasional noises from nearby roads and railway lines.
  • The DAB+ test will test the capabilities of your DAB radio - non-DAB+ compatible radios may display the name but not decode the service. DAB+ compatible radios (which should display the official DAB+ logo, shown above) may offer the sound in mono or stereo, depending on the chipset used in the radio. Of those DAB+ radios, there are differences in how the service is decoded, leading to large variations in sound quality reports.  
  • From 29th February, you'll be able to hear a number of new and existing stations on the multiplex.

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  1. 32kbps HE-AAC v2? No wonder some listeners have said it sounds like a bad internet stream, because at that bit rate and codec it certainly will! I assumed the plan was to halve bit rates from the current 128kbps MP2 to 64kbps AAC, but it seems I wasn't cynical enough. The DAB equivalent of pile em high, sell em cheap.

    1. It won't necessarily sound bad - I'd have to say it sounds quite good for that bitrate. It seems there's big differences between receivers accounting for the massive variations in opinion.

    2. yes quantity not quality.

    3. I'm not interested in sounds quite good "for that bit rate", it's the absolute sound quality that matters. My benchmarks for that are FM radio, and CD.

    4. It's a nice audio soundtrack of waves lapping at the seaside, with odd background noises. On the basis of the material being transmitted, using equipment with the right chipsets to decode it properly, it is clearer, sharper than material broadcast using original DAB at 64kbps or 80kbps. That's why it's very good for that bitrate. **Readers need to be aware that there are great discrepancies between devices, including those that will only process it as a mono service. **

      It is certainly suitable for a service such as BBC World Service or BBC Radio 4 Extra - speech led with odd pieces of music or stereo sound effects in dramas... providing the issues with the rendering of the audio on different devices can be overcome. It would not be suitable for a music led station.

      To be blunt, Sound Digital is driven by business needs - a lower cost, lower coverage network to reach the biggest populated areas with the fewest transmitters, and DAB+ allows stations to get enhanced coverage on digital radio without the cost: Jazz FM, one of the DAB+ stations on Sound Digital couldn't afford its previous carriage on D1 - now it can broadcast a stereo signal on SDL using less bandwidth, costing it less.

      In effect the choice is the likes of Jazz FM using low bitrate DAB+ or no Jazz FM at all on DAB. There's no 'forcing stations to use certain bitrates and meeting minimum coverage requirements' - they would go internet only. You would be left with a handful of mainstream pop music stations, and if they refused to shoulder the cost (fewer stations carrying the cost of a multiplex), DAB would be back to the situation it was in during 2009, whilst over on FM the same commercial groups would be pleading to reduce local and specialist music commitments even further, so you'd just end up with a few stations cherrypicking the most commercially viable sectors (i.e all sounding like Heart and Capital).

      So while the DAB+ test doesn't meet your audio requirements, for the majority who evidently don't mind (otherwise DAB listening wouldn't keep going up), it means more choice.

    5. That would be fine if Sound Digital were just an extra service with no other impact. But it's existence will be used as yet another excuse to say how well DAB is doing, how large "digital radio takeup" is, and that we should switch FM off. Despite the fact that Sound Digital doesn't remotely meet FM audio quality.

  2. There's also the Biggles+1 DAB+ test stream on Test Beds.

  3. The Dab+ transmission here in West Essex has become distorted this afternoon I was hoping that the technical staff would have picked this up by now the other transmission is ok just the Dab+ Sound Waves that was fine yesterday on all my Dab+ radio's let's hope that it is sorted out soon as it is a poor advert for Dab+ atm


    1. Indeed, and earlier today, I had a tweet about the very same issue. As you will now see, the above information has been updated. During the test phase, all sorts of strange things (strange from our point of view) are likely to happen.

  4. Transmission on Dab+ Sound Waves now sorted nice to know that some important people rad this,
    New line up for this Multiples from Feb 29th

    Virgin Radio
    Share Radio
    Mellow Magic
    Magic Chilled (new)
    Absolute 80s
    heat radio
    Planet Rock
    Sunrise Radio
    Awesome Radio
    Premier Christian Radio
    Premier Praise!
    Panjab Radio
    Fun Kids
    Jazz FM

    1. The station was also published on a516digital on the same morning, but with the DAB+ stations highlighted

  5. I have just tried the DAB+ on my DAB unit in my new Citreon C1 and it does sound very good for 32kbps..the standard DAB Waves sounds mono

  6. Lost contact with all my wildlife tracking transmitters thanks to this pointless new DAB service. Thank you very much Ofcom.

  7. Only the Mono service of Sound Waves test is active nothing on the Stereo Dab+ version from my Multiplex.


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