Matt said at April 17th, 2007 at 12:14pm

Batten down the hatches, I can feel a storm a brewing…

I’ve commissioned lots of digital radio research in my time, most of which isn’t published, and it’s great to see Ofcom’s survey tallies with all of mine. Listeners, by and large, love their digital radio and think it’s great. Which is excellent news for the radio industry.

There is a small minority that would like higher audio quality, something that in itself is not a bad thing, it’s just something that economically is difficult to deliver on DAB Digital Radio, when the main thing that encourages people to get the platform is choice.

Just because super-high bitrates aren’t available on DAB it doesn’t mean that the radio industry doesn’t provide the option for those listeners who would like to hear their content at higher quality. The less bandwidth intensive platforms - satellite and online - provide that option for these listeners.

Martin Belam said at April 17th, 2007 at 1:04pm

I always get the impression that the DAB quality debate on radio is similar to the DOG debate on TV. The people who care about DOGs are extraodinarily vexed about them and disproportionately loud, whilst the majority of TV viewers simply don’t notice or care about them.

steve martin said at April 17th, 2007 at 1:12pm

Different delivery technologies make the audio sound different and it’s a subjective judgement and entirely personal matter to say whether the application of one technology is “better” or “worse” than another.

A DAB radio tells you in figures what to expect the quality to sound like so it is an easy target for criticism. It’s more difficult to criticise FM but it does certainly sound different. FM suffers from inherent noise, multipath distortion and pre-emphasis. Personally, I find that irritating, especially on the more breathy female Radio 4 voices whose gorgeous sibilants can arrive distorted if the reception isn’t perfect. That never happens on DAB (or longwave for that matter).

Of the 6% of people who describe DAB sound as poor we don’t know how many are complaining about the specific radio set they chose to buy or how many simply live somewhere yet to receive a strong signal. Let’s assume half of them have those problems and half don’t like bitrate compression… that’s still nearly 2 million people who would, it seems, appreciate hearing certain radio content at a higher bitrate and, for some content providers, that could well be a group big enough to take seriously.

This reflects my personal views at the time of writing and not those of my employer.

William T said at April 17th, 2007 at 9:23pm

James - what’s your general opinion of Ofcom’s current level of competency?

With the caveat I haven’t read all the 184 pages of the consultation, my concerns include:

- I think ditching AM is a bad idea, given the use of it by BBC local radio for opt-outs for live sport, which there’s no room for on DAB.

- They don’t seem terribly bothered about the fuss and worry they’ve created in the theatre industry by the possibility of selling off VHF frequencies currently used for radio mics.

- Freeview has become something of a free for all with people running competing subscription services, which require different standards of boxes, fighting over EPG placement and undercutting each other’s bitrates to get more channels in.

- Maybe it won’t be as marked a difference in 5 years time, but at the moment DAB radios are still significantly more expensive than analogue ones, have significantly shorter battery life, cost a fortune to get installed in cars and yet don’t support RDS or EON, use MPEG2 instead of AAC (yes I know - but it concerns me we’re encouraging lots of non-techie people to buy a ‘digital’ radio and as soon as most of them have they’ll have to go and buy another one).

@ Martin Belam: DOGs don’t bother me that much, and I certainly wouldn’t bombard newsgroups with complaints about them - however there are a hell of a lot of petty annoyances in modern day TV which combined made you despair at times:

- announcers talking over the end credits
- end credit promos - “Coming up next” captions whilst a programme is still going on
- squashing the credits into odd shapes or making them so small as to be unreadable
- the BBC producing such a small number of trails on such high rotation they bore people to death
- the BBC trailing the big programmes everyone knows about rather than the gems they don’t
- ITV deliberately fiddling with the audio for ads so that they appear louder than the programmes they interrupt
- tickers on news channels
- people presenting the weather in front of screens when it looks better in chromakey
- newsreaders standing up and walking around when they should just be sat down at a desk like they used…. I mean I could go on…

Matt T said at April 18th, 2007 at 6:56pm

I’m quite firmly stood in the position that DAB is going to inadaquate for the future. Yes, the results do show some conclusive results of the “average-joe” general public. However, it isn’t considering the change in attitudes of technology. Most people above 30 (you could say 25 possibly) don’t know about bitrates and codecs that effect sound quality. They only get you’re given.

However, the general public get to know more about MP3s, AACs, bitrates and such like in the future. I’m for one is fussy about audio quality. I won’t ever buy DAB in it’s current state.

Looking at digital technology, there are two important things….

- Efficiency and flexibility

At the moment, DAB doesn’t offer this. We’re seeing more stations being squashed into DAB. However resulting in lower bitrates and showing that quality is deteriorating under the old system of MP2.

We’ve seen Radio 4 listeners notice the change in bitrate (obviously lowered) and requesting to know why the BBC were doing it and demanding a change. Consumers will understand the importance in the long run.

If the majority of the commercial industry seeks that “music” radio is to progressively to become more dominant rather than the BBCs “personality” entertainment across the range; don’t we need higher bitrates to make music more enjoyable to listen to?

I can only tolerate noticeable artifacts in audio for so long now. I can see Internet Radio becoming far more popular if it’s accelerating the way it is. GCap has recently pumped up all their stations to 128kbps WMA which is very pleasurable to listen to. Online streaming will become more affordable, especially with AAC+ around now. Why not get DAB+ out asap? Ofcom could make a big mistake not slowly rolling it out now.

The simple fact is MP2 (MPEG-1 layer 2) is getting too old to battle newer codecs. This is a fine example of Ofcom’s reactive defense of DAB. I just hope more people cotton onto DRM taking advantage of AAC+

Kev said at April 18th, 2007 at 9:45pm

@ William T RE BBC Local Radio sports opt outs…

For BBC Local Radio stations with few opt outs they could quite easily broadcast two mono sports stream (the audio quality of these broadcasts on FM leaves a lot to be desired so 64kbps mono would be more than sufficient to carry such programming). Whether or not the local multiplex operators could support this dynamic reconfiguration is a different question. Here in Nottinghamshire you could continue with 103.8 and 95.1FM broadcasting Nottm Forest, 95.5FM and primary DAB broadcasting Notts County and 1584MW and DAB secondary “BBC Nottm -Stags” broadcasting Mansfield Town commentary. Admittedly this might be a bit more problematic for the likes of BBC Radio Lancashire that seem to have around half a dozen opt outs (then again, they would have three FM slots and four DAB slots to use once the Morecambe Bay multiplex is licensed).

@ William T RE RDS and EON missing from DAB car sets….

My DAB car radio (JV DB-711 ~ £100 + FM aerial splitter) has FM RDS and EON and even auto switches between the BBC FM and DAB national services, and local FMers - hey it even follows XFM Midlands round between the local multiplexes; The lack of TA when listening to DAB isn’t a massive disadvantage as I never seem to get Nottingham travel news anyway, but that from as far a field as Cambridgeshire and Sheffield instead. In my experience the only flaw the set has is the lack of an accessible AF switch - the switching between Kerrang! on 105.2 and the appalling rubbish sounding (64kbps mono) DAB equivalent every 20 seconds or so along the A50(T) is rather annoying.

With regards to people finding that DAB sounds better than FM as 77% of the respondents to the ICM survey indicate - FM /may/ sound better in an ideal world, but this isn’t an ideal world, for starters 30% of the UK’s population live in rented accommodation which in many cases prohibits the installation of external aerials, and in those cases it might be nigh on impossible to get the most out of FM, however when within DAB coverage areas the platform is is easily able to overcome those problems - as long as you have avoided the cheapest tat (how the radio I purchased at the local supermarket was unable to pickup a good signal from Now Nottingham around 3.5km from the transmitter I’ll never know) you just pull up the aerial, hit auto tune and it works - 18 stations with no static or other forms of interference - move it a few centimetres and you get 28 - practically no effort involved in this; over on FM that drops to 2 (Trent, BBC Nottm), maybe 5 (+Smooth, Faza, and Kemet) with a lot more faffing.

Away from home you are down at ground level and therefore suffer from a poorer signal strength - this is where DAB can really excel (provided there is a suitable local transmitter - something that can be added relatively simply (if expensively) compared with FM where there are supposedly no spare frequencies). For example if you were to compare the commercial national and regional FM services (Classic, Heart and Smooth) with the DAB equivalents, the FM variants suffer from large amounts of dead spots and areas where there is plenty of static; where as on DAB I have found just one area (outdoors) where the signal actually disappears (local FM also suffers from poor reception here). I will admit the BBC multiplex is problematic to receive, however they admits that parts of the city remain uncovered and that the local multiplex being on the adjacent channel has compounded that for areas within ~3km of the transmitter site (I wish they would just follow Digital One and add a local transmitter; I find it rather odd the only postcode in Nottingham I can find where there own postcode thinks you are very likely to receive BBC National DAB is the BBC’s own, where as Heart FM (who’s studios are right next door) get the more usual ‘fairly likely’ - are the BBC embarrassed about this, or is it just a coincidence?). I have seen numerous people say that DAB is useless on a hand-held device, however listening to Radio 1 (or static on 97.9 most of the time) in the city centre this lunch time reminded me how much I’ve come to be reliant on DAB’s excellent signal (alas the BBC have chosen to ignore my local transmitter so that wasn’t a valid alternative, hence why I was on FM in the first place).

I guess the DAB network is pretty much on par with the FM Radio 1 network in the early 1990s, hopefully in the years to come it will become cost effective to roll it out to be usable on hand-held device in more places than it is on FM (although Channel 4’s proposals to work with handset manufactures to improve aerial technology in hand-held may render this unnecessary in many areas if there work is successful).

Ofcom’s radio initiatives … said at April 23rd, 2007 at 12:34pm

[...] interesting reaction from the blogosphere: James Cridland on DAB sound quality [...]

Geoff Dixon said at May 11th, 2007 at 4:58pm

Are there any “DAB Radio” experts out there who can tell me how long cut the 2 arms of my (vertically mounted) Half-Wave Dipole to receive from the Morecambe Bay DAB Transmitter?

The Transmitter site mentions 3 different frequencies but I’m not clever enough to decide exactly which (transmission) I am receiving. The display (on the set itself) shows 225.648MHz for all the BBC channels but I also receive several on 222.064MHz and 227.360MHz. Can anyone tell me how many Centimeters each leg should be (as a compromise) and the distance between the rods? I would hate to cut too much off what was an FM aerial.

I hope you will understand my simplistic question ! Thanks !

David Robinson said at June 6th, 2007 at 9:34am

I read in the Guardian that James is “joining the BBC’s future media department as head of audio and music”.

I wonder James if you’ll be doing anything for the “vocal minority” (19%, or about 11 million people if you extrapolate, which seems unwise) who don’t think much of the sound quality on DAB?

“Matt” makes a good point in post 1, which is even more powerful for a “non commercial” broadcaster like the BBC: broadcasters should make higher quality versions available on the less bitrate starved platforms, because there is a minority (but still significant) audience for this.

Currently, the BBC do this in a very patchy manner. The bitrates are higher on satellite, but not that much higher - and the feed into the encoders isn’t clean so the advantage is lost.

Why not stop all the moaning from the “vocal minority” by guaranteeing and delivering a clean high quality feed on satellite for everyone that wants it?

I can see no downside to this, and only kudos for whoever makes this happen. Are you the man?

Cheers,
David.

James Cridland said at June 6th, 2007 at 9:56am

Geoff Dixon - 37.5 cm is an optimum wavelength for DAB.

Mark Woodrow said at October 8th, 2007 at 11:11am

I found this site which details a modified “Slim Jim” folded dipole antenna for DAB. Let you know how it works when I get around to building it.

http://www.hack247.co.uk/2006/06/06/diy-dab-radio-aerial-the-slim-jim/

As to audio quality, well what can I say? I’ve noticed that some receivers are a lot better than others; my original Pure Evoke-1 sounds pretty poor next to a handheld Mikomi DA-110E adn even a PSDAB2003. I guess a lot is down to post processing of the analogue signal once its recreated from the digital bitstream.

I’ve also noticed that some stations, on apparently the same (low) bitrate, sound truly awful, whereas others sound OK. This is at 64kbps mono. Different encoders perhaps?

I love my DAB radios. Yes, its telling that Classic FM, Radio 3 and Virgin are at higher bitrates, but I’m afraid that the “number of channels vs audio Quality” outcome was always pretty much a forgone conclusion.