Turning off the FM signal

[Resurrection Man]

Just came across this article from 2006 which seems rather prophetic in hindsight. http://www.hi-fiworld.co.uk/tuners/7...-/192-dab.html

and this one on compression http://www.hi-fiworld.co.uk/tuners/7...mpression.html

[Ferretfancy]

Whenever I visit a good audio dealer I'm always told that there isn't yet any serious cause for alarm, and that my FM tuner will be in use for a few years yet. I gave up listening to DAB on my Evoke radio in the kitchen and switched over to FM because the DAB quality was so bad. If I'm forced to abandon FM on my living room audio, I'll probably use Freeview.

[Bryn]

I had missed Steve's articles in Hi-Fi World. For a short period a few years back he contributed on the old BBC Radio 3 boards for a while, specifically regarding his campaign against the UK implementation of DAB. He was always particularly angry about the way Radio 3 kept 192kbps when all the other BBC radio channels got reduced to 128kbps and worse, (back around Christmas 2001 it was).

[jayne lee wilson]

Whenever I visit a good audio dealer I'm always told that there isn't yet any serious cause for alarm, and that my FM tuner will be in use for a few years yet. I gave up listening to DAB on my Evoke radio in the kitchen and switched over to FM because the DAB quality was so bad. If I'm forced to abandon FM on my living room audio, I'll probably use Freeview.

But freeview R3 is still limited to 192kbps mp2, only differing from DAB in not being reduced regularly to the awful 160. Only the main BBCTV channels get 256.

It may seem a challenge but do try to get the 320 kbps AAC webstream via R3 homepage or iTunes. It really is vastly superior. Check your broadband deal, if it's the lowest cost one with a given provider they may limit speeds (and thus continuity) during peak evening hours. Usually only a few quid to upgrade it.

I'd all but given up on R3 concerts via DAB and FM before the AAC, latterly "HD", came along...

[David-G]

One of the reasons that I generally rely on FM for hi-fi listening to Radio 3 is that I find it so hard to listen to the 320 kbps aac stream without it cutting out. I get short dropouts - they are not too bad - but after about 10 minutes, the stream just dies. I have tried everything that I can think of, to no effect. The only way that I can listen reasonably continuously is to use my old xp laptop in place of my Vista one. But this is a bother, so I only do this occasionally.

[Resurrection Man]

Listening again to the interview with Ford Ennals shows how poorly briefed the presenter was and allowed several statements to go unchallenged. I've penned a brief feedback article to World At One. Who knows. Maybe they might do a more in-depth piece and have someone across the table from Ford Ennals to challenge him !

[Gordon]

Hate to point out the obvious, but DAB Radio is "MP2" of course (MPEG1 LAYER 2) and the BBC R&D document originally recommended 256 kbps for high-quality stereo (224 acceptable),

Can you supply a reference to that report please?

[jayne lee wilson]

Can you supply a reference to that report please?

Ha, I only wish I could! Once the scandal of DAB's problems drew complaints from a wider audience, R4 listeners to Feedback etc., it became "mysteriously" impossible to locate online...

[Bryn]

Ha, I only wish I could! Once the scandal of DAB's problems drew complaints from a wider audience, R4 listeners to Feedback etc., it became "mysteriously" impossible to locate online...

I bet Steve Green has a copy of it on file. I used to have his email address, but that was several computers ago. He used to go under the noms de guerre "DAB sounds worse [later, far worse] than FM" and "digitalradiotech". However, he seems to have gone to ground these days.

[Gordon]

Ha, I only wish I could! Once the scandal of DAB's problems drew complaints from a wider audience, R4 listeners to Feedback etc., it became "mysteriously" impossible to locate online...

That's odd. Looking through the list of R&D reports there are no gaps as would happen if a report had been withdrawn, unless it was the last of a given year. The era would be the early 90s - about when the BBC was deciding on a service- and the authors would include either David Meares or perhaps Neil Gilchrist. I was sure I had a copy of the thing somewhere from when it was first published but I can't find it. In those days coders were not very good and so I could believe that 256 Kbit/sec was what they needed. Those results are way out of date now.

Yes Steve Green does seem to have disappeared. Pity, he was entertaining in his rants but people got tired of hearing the same old thing.

[Resurrection Man]

Can you supply a reference to that report please?

Gordon..you can download it from here https://dl.dropbox.com/u/106644512/B...B%20WHP061.pdf

It was referenced in the Wiki article on DAB.

[Resurrection Man]

Ha, I only wish I could! Once the scandal of DAB's problems drew complaints from a wider audience, R4 listeners to Feedback etc., it became "mysteriously" impossible to locate online...

LOL! And which is why I have squirrelled away copies of documents like the DRWG Interim Report that suggested 50% of DAB listening as a criterium for FM Switch Off. Not the much looser 'digital radio' which became enshrined once they realised that they were on to a loser if they just stuck with DAB. You can bet your bottom dollar that the other criterium (coverage comparable to the current BBC FM service) will also quietly get dropped.

[Simon]

What chance have we got of reversing this, though? Will the MPs really listen? I don't want to be negative, though, and will willingly email mine, as I too cannot see the logic of the change as currently proposed.

(Well, I can in one sense, but I don't think it will be of general public benefit, which is the bit I'm bothered about).

[jayne lee wilson]

That's odd. Looking through the list of R&D reports there are no gaps as would happen if a report had been withdrawn, unless it was the last of a given year. The era would be the early 90s - about when the BBC was deciding on a service- and the authors would include either David Meares or perhaps Neil Gilchrist. I was sure I had a copy of the thing somewhere from when it was first published but I can't find it. In those days coders were not very good and so I could believe that 256 Kbit/sec was what they needed. Those results are way out of date now.

Yes Steve Green does seem to have disappeared. Pity, he was entertaining in his rants but people got tired of hearing the same old thing.

The only thing worth trusting is - your ears. Ever tried listening to string counterpoint, eg. a Bruckner adagio at 192 kbps mp2? Horribly rough, obvious distortion
where the edges rub against each other. Simpler classical arrangements can survive, without such obvious distortions (though critical listening to a solo violin (with FM/AAC 320 for comparison) is, er, instructive), but bleached of realistic texture or sonority. Most of my DAB listening was done on an Arcam Alpha 10 or a friend's Technics DAB/FM model. Later designs may have tried to smooth out the sound by limiting the higher frequencies; my sharp-eared audiophile friend tried out the later AVI DAB tuner (he had a very good all AVI system) and found it "smoother but musically dead".

"How it Works" Section 5, "Source Coding", of the quoted report (many thanks, RM!) says it all... "At 192 kbps, it is relatively easy to hear imperfections in critical audio material". And that certainly hadn't changed by 2006...

"Improvements in coders"? - well - guffaw! During the 2006 Proms we had at least 3 different explanations from the BBC for why 160 kbps mp2 would now sound as good or better than previously-coded 192. EVERYONE'S EARS (well, those without THE ulterior motive) told them different and they switched off in droves. I remember presenter Jon Swain commenting on the old BBC messageboards how terrible 160 sounded. During those Proms and for 2 weeks afterwards a Radio 5-live Sports Extra ad. ran continuously, eating up those other 32 kbps. On Feedback after the end of those Proms Jenny Abramski's apology to music lovers for the debacle was read out... 192 (luxury, bloody luxury) ran continuously (apologetically) for a while, and then...back came the redcution. It was those insults to the ears and the intelligence, along with FM dynamic compression, that forced me away from R3 concerts until the advent of AAC in 2009. The money I spent on DAB and FM tuners (which media the BBC then trashed)! Well, I had it then...

If the 256kbps mp2 standard is now way out of date, why still use it for TV?

[Dave2002]

Jayne,

Doesn't HD TV on DVB-T and DVB-S use aac, amongst other possibilities? I think the reason that SD uses mp2 is because older devices are only mp2 compatible, whereas an end user device which can receive HD TV should be able to use newer codecs.

256 kbps is really not too bad in most codecs.

Re the somewhat earlier 192/160b kbps debacle, the poor sound quality in the 160 kbps stream was noticeable,, though content dependent. The BBC's explanation at the time about "new codecs" was audibly incorrect, though in fact later on I believe they did manage to get better quality out of their codecs - it's not totally impossible/implausible, but they didn't put up convincing arguments at the time.

Re Steve Green - maybe he used to rant on, but then so does Quentin Howard, who belongs to an industry group which is intent on ramming DAB down all our throats. Some of QH's reasoning is sound enough. I'm still not convinced that the industry intention is for vanilla DAB, even though this has been commented on. There's a lot of fudging going on, and after all Mr Joe Public doesn't really know the difference between DAB, DAB2, DAB+, and other digital formats, so as most more modern "DAB" sets should cope with many variants, which as noted may be more efficient, then it is indeed possible that what would eventually happen is that older DAB sets would become obsoleted. One argument - which may sadly be possibly true, is that those who were keen enough to have bought expensive DAB tuners in the early days (yep - I was one - and it is hardly ever switched on) - will have moved on to other digital systems - such as streaming aac or even (eventually) streaming losslesss formats. This does seem possible to me, though as has also been noted, there can be disruption to networked audio.

PS: some TV programmes use surround sound encoding I think.