DAB Report

[Gordon]

I thought they had now been stopped from saying DAB is 'CD quality', which it was (almost) at the original bit rates, but not for long, as we know.

They do seem to have stopped using the "CD" bit but DRUK still harp on about "crystal clear sound".

You are right though that way back when bit rates were higher than now sound quality, as such, wasn't that bad. The failure back then was not so much sound quality itself as reception issues and there the claim "CD quality" was as much about freedom from hiss and interference etc as anything else. Once a sufficient level of signal strength is attained there is little in DAB to prevent the codec from giving its best - and we know that is not good enough now. Back then the coverage was not widespread and many areas had no or poor cover. Add that to the fact, that is now very obvious, that many early receivers had dreadful sensitivity, appalling in some instances, and they are probably still out there unless they are in skips somewhere.

Now signal strength is better as is coverage and receivers are certainly better BUT in the shops there is no guarantee that a DAB receiver has adequate performance. IF there had been a date set for DRSO then a guaranteed minimum performance would be forthcoming through a Tick scheme. Now that there is no date there is no Tick scheme and consumers are on their own again. Who asks for technical performance in a radio receiver nowadays?? Should they? Should retailers?

[Dave2002]

They do seem to have stopped using the "CD" bit but DRUK still harp on about "crystal clear sound".

You are right though that way back when bit rates were higher than now sound quality, as such, wasn't that bad. The failure back then was not so much sound quality itself as reception issues and there the claim "CD quality" was as much about freedom from hiss and interference etc as anything else. Once a sufficient level of signal strength is attained there is little in DAB to prevent the codec from giving its best - and we know that is not good enough now. Back then the coverage was not widespread and many areas had no or poor cover. Add that to the fact, that is now very obvious, that many early receivers had dreadful sensitivity, appalling in some instances, and they are probably still out there unless they are in skips somewhere.

Now signal strength is better as is coverage and receivers are certainly better BUT in the shops there is no guarantee that a DAB receiver has adequate performance. IF there had been a date set for DRSO then a guaranteed minimum performance would be forthcoming through a Tick scheme. Now that there is no date there is no Tick scheme and consumers are on their own again. Who asks for technical performance in a radio receiver nowadays?? Should they? Should retailers?

There was a claim by the BBC after the earlier R3 debacle over degrading the bit rate from 192 kbps to 160 kbps that their new (at the time) encoding equipment should have compensated for a lost of quality due to the bit rate reduction. At the time this definitely did not seem to be true, though a bit later some of the broadcasts at 160 kbps did sound acceptable enough. While I accept that better encoding may reduce problems, digital lossy compression generally does not give good results on all types of music until 256 kbps or above is reached, and some people claim to hear differences with any lossy compression scheme.

Quality factors (or negative factors) besides the basic "tone" quality include:

1. Hiss - FM and AM (mono only in the UK)
2. Dropouts - FM and also DAB - in some situations
3. Bubbling mud - DAB
4. Edginess to the sound - DAB in marginal areas, Sibilance on some FM sets.
5. Dropouts - Internet. Internet delivery is good - except when it isn't, and dropouts occur, which can be frequent.
6. Dynamic range issues - all of the above - depending on how dynamic range is handled.
R3 is one of the few channels which has a reasonable dynamic range, which some have considered to mean it is a "quiet" station - hence not loved
by advertisers - though they're not allowed on that channel anyway.
7. Frequency distortion - it is perhaps easy to improve the apparent sound of a channel by modifying the frequency characteristics
to make it sound "nicer", "smoother" etc., but not necessarily more realistic. Some channels certainly do this. AM has a restricted frequency range.
FM is restricted compared with DAB, but many people won't notice.
8. Interference from other stations - FM - also AM.
9. Fading - AM
10. Volume - related to Dynamic Range. Often a problem with mixed speech and music channels.
This can also be a major problem with film
soundtracks, though most radio channels don't do that. However TV channels do
and that can be an additional source of annoyance for TV viewers - sound effects too loud, too much bass, can't hear the speech etc.

I threw in AM at a late stage, as it is still used by some.

[Gordon]

Boarders may like to know that the final version of the Digital Radio Action Plan has just been published together with some of its reports:

https://www.gov.uk/government/publications/digital-radio-action-plan

https://www.gov.uk/government/collections/digital-radio-action-plan-and-associated-documents

[johnb]

Well, if I can't repair my old Tivoli Pal (AM/FM only) I will probably replace it with the same model (without DAB) - mainly because of the battery duration between charges and because the delayed FM switch off. It is advertised at 16 hrs which might be a little optimistic, but it is certainly in the range of 12-16 hrs.

[Gordon]

Well, if I can't repair my old Tivoli Pal (AM/FM only) I will probably replace it with the same model (without DAB) - mainly because of the battery duration between charges and because the delayed FM switch off. It is advertised at 16 hrs which might be a little optimistic, but it is certainly in the range of 12-16 hrs.

I can't say I'd blame you!! But those PAL devices aren't half expensive!! Power consumption has been one of the issues with digital radios; the DSP chip set and a display accounts for most of the excess over a simple FM only receiver. Looking here:

http://tivoliaudio.co.uk/media/userguides/ownersmanual_PALiPALCE1009.pdf

and here:

http://www.tad-audiovertrieb.de/service/Manual_Tivoli_Audio_Model_PAL_Plus.pdf

we see the battery specs [as follows] as 1200 mAh for the PAL and 2200 mAh for DAB, almost double. Current is specfied as 500 mA and 1000 mA respectively. These are very high currents for a simple FM radio - so I supect they use a DSP module, and there is no display to consume power, essential with DAB. The chip set will consume a given more or less constant current and the rest will be the power amp, hence the talk of less battery life at high volumes. High impedance headphones will improve matters. At 1200 mAh a battery will last 10 hours at 120 mA, 12 hours at 100 mA etc.. That battery size is compariable to 4 AA rechargeable cells.

We assume that the power consumption of the PLA+ is quoted for DAB operation and that for FM is the same as the ordinary PAL device, about half, judging from the current ratings. So expect about half the battery life, other things being equal [but they are not because the PAL+ has almost twice [11/6 = 1.82] the battery capacity as the PAL].


Specifications:
Model: Portable Audio Laboratory (PAL)™
Type: Portable, weather resistant AM/FM radio
Driver: 1 x 2.5" treated, magnetically shielded, full range driver
Power: 12VDC nominal - 15VDC maximum, 500mA
Battery Pack: Model MA-1, NiMH, 7.2V, 1200mAh
Battery Current: 500mA
AC Adaptor: Model PAL-PS:
UL: 120V-60Hz, 18W, 12VDC, 500mA, 6VA
CE: 230V-50Hz, 15W, 12VDC, 500mA, 6VA


Specifications:
Model: PAL+ [the one with DAB in it]
Type: Portable DAB/DAB+/DMB/FM radio
Driver: 2.5" full range, video shielded
Receiveing Bands: FM: 87.5-108.0MHz (receiving range may vary by region)
DAB (Band III)/DAB+/DMB: 174-240MHz
Power: 12VDC nominal – 15VDC maximum, 1000mA
Battery Pack: NiMH 7.2V 2200mA
Battery Current: 1000mA
Power Supply: PALP-PS-CE : 12VDC 1A 230V 50Hz

Rather than quote specific hours per battery charge in these manuals they now hedge their bets:

Battery Playback Time: There are many variables such as volume level and program material that determine the amount of playback time you will get from a fully charged battery. For instance, playing the PAL at a low volume level will usually yield a longer playback time than at a high volume. As you use your PAL you will develop a good idea of what to expect under various conditions. There is no harm operating your PAL continuously from the external adapter.

[johnb]

Thanks for the interesting information.

I am a little puzzled though. According to the PAL AM/FM spec the battery capacity is 1200mAh and the current is 500mA. This seems to imply that the running time when powered by battery is ~2.5 hours whereas my old PAL lasts much, much longer - difficult to estimate but it is probably greater than 10 hours. Perhaps the 500mA is the maximum current supplied by the battery.

Yes the PAL is bl**dy expensive but it is one of the few battery powered portable radios I have heard which is acceptable for music and I am nervous about buying a cheaper portable and then being dissatisfied. (Of course the audio quality isn't anywhere near the same as my audio system but is fine for when I am pottering around.)

[Dave2002]

Boarders may like to know that the final version of the Digital Radio Action Plan has just been published together with some of its reports:

https://www.gov.uk/government/publications/digital-radio-action-plan

https://www.gov.uk/government/collec...ated-documents

I am "puzzled" by this

Of technology:
to support a wide range of technologies used to deliver digital
radio, including DAB, internet and Digital TV

from the early section on CONSUMER CHOICE. What part of "Internet and Digital TV are not radio - as most of us know it to be" - do these people not understand?

Internet now uses some similar technology in places, but basically is not a wireless radio service. Digital TV uses different spectrum from DAB, though the modulation and coding methods are similar. However, most TV sets which receive radio stations do not normally do so via DAB, but rather via Freeview or Freesat.

As far as the infrastructure to provide radio services goes, behind the scenes this could be digital (indeed almost certainly largely is), but it is also capable of feeding FM transmitters.

[Gordon]

Thanks for the interesting information.

I am a little puzzled though. According to the PAL AM/FM spec the battery capacity is 1200mAh and the current is 500mA. This seems to imply that the running time when powered by battery is ~2.5 hours whereas my old PAL lasts much, much longer - difficult to estimate but it is probably greater than 10 hours. Perhaps the 500mA is the maximum current supplied by the battery.

It is confusing. I think the 500 mA rating is the max current required when the volume is up to max for a period of time, whether from battery or PSU but even so it seems high. The spec doesn't say what the power rating of the amp is and what the speaker impedance might be, very possibly higher than 8 Ohms.

The power rail is only 7.2 Volts [the battery] so the absolute maximum [unachievable] audio output rms voltage is 3.6 x 0.7 = 2.5 volts [unless there is some jiggery-pokery going on with voltage multiplication to get a higher rail for the output stage - unlikely]. At 8 Ohms that would be a current of 2.5/8 Amps = ~300mAmps. I suspect the speaker is higher impedance than 8 Ohms which reduces the current.

Your experience suggests that the total average current at the volume level you use is nearer 100mA or less with an output voltage much less than 2.5 volts. That implies that the chip set used consumes quite a bit less than 100 mA as does the output stage. If we share the current equally and let the output consume 50 mA, then at around 1 volt rms we have an implied impedance of 1/0.050 = 20 Ohms which is more likely. That being so then the 300 mA absolute maximum above becomes more like 2.5/20 = 125mA. Add the 50 mA chip set current and you get 175 mA MAX.

Why then 500 mA?? Perhaps it's the PSU rating to get the battery charged in a good time from flat and allow more sound out. Note that with the PSU engaged the power DC rail voltage is nominally 12 at 500 mA; regulation will increase towards 15 with reduced current. The swing is now nominally 4.2 v rms which will induce a current of 4.2/8 = 525 mA in an 8 Ohm load without counting the electronics. A 20 Ohm load will need only 210 mA but the rail voltage will go up to 15 so perhaps it would be 5/20 = 250 mA.

[Gordon]

I am "puzzled" by this, from the early section on CONSUMER CHOICE. What part of "Internet and Digital TV are not radio - as most of us know it to be" - do these people not understand?

Internet now uses some similar technology in places, but basically is not a wireless radio service. Digital TV uses different spectrum from DAB, though the modulation and coding methods are similar. However, most TV sets which receive radio stations do not normally do so via DAB, but rather via Freeview or Freesat.

Somewhere among the documents/reports published there should be some from the Consumer Expert Group [CEG]. The CEG suugested several things that were ignored: one was that the threshold for DSO was too low at 50%, another was that this should not apply to the sum of all digital listening, only "radio" as it is commonly known. Whilst internet and DTV/Sat listening is possible, and it is a regular choice for some consumers, it was not at the time widespread and even now DAB dominates but, clearly, most people still consume their radio by FM/AM on portables not HiFi.

Government and protagonists of DAB want the numbers and so bundle all forms of listening. People like yourself and many boarders here are among the savvy minority who are interested in and aware of technology alternatives but the bulk of the radio public clearly are not [or don't care] and that explains the heavy publicity that DAB/DSO proponents engage in, without much success.

As far as the infrastructure to provide radio services goes, behind the scenes this could be digital (indeed almost certainly largely is), but it is also capable of feeding FM transmitters.

It is all digital, even the FM network which has been distributed digitally to the national network of transmitters since the 1970s using a variant of NICAM. Even the dreaded Optimod is a digital device.

One of the reasons for wanting rid of FM is to save costs which include potential re-investment in aging FM equipment. There are certainly problems with sourcing devices for aging AM transmitters. I don't know what life span is left in the NICAM chains, making more might be a problem[BBC design many years old and the designers are long retired] in which case why not use the DTV or DAB feeds off air and rebroadcast that?

[Nevalti]

..... allow an ex-BBC sound balancer and active audio professional to stick his oar in. Firstly, FM, if you can forbear not to use things like Optimod processing, is to all intents and purposes transparent - the stereo multiplex system is a very clever piece of engineering, and still well fit for purpose - not perfect, but better than the DAB system.

Lossy compression should be in the bin by now, but if we have to have it, there are far better algorithms than those in DAB, and trying to claim equivalence to uncompressed for anything less than 320kB/s is fraudulent. Far too much emphasis is placed on the Orwellian "digital good - analogue bad" argument, which is simplistic and wrong. And as for that sub-Barry White glove puppet...!

The plain fact is that DAB is a dead horse, but that too much economic and political capital has been put into it for the juggernaut to be stopped. ..........

Ah, the voice of experience, discernment, wisdom, clarity and honesty. We don't hear enough of those.

Sadly, such voices are ignored in the interests of making money out of us tax and licence fee payers. Despite us paying for EVERYTHING, even for the halfwits promoting this awful system, we are completely helpless. We are to be forced to buy DAB radios or just get on with our lives without portable and mobile radios. Soon, we will no longer be able to walk from room to room with a different radio on in each room - because all DAB radios process the signal at different speeds which would result in cacophony as well as irritating DAB sound.

Despite the FACT that ALL audio professionals understand very clearly just how bad DAB is, we are still subjected to the 'DAB good' propaganda. Those responsible for this rubbish should be locked in a room with a DAB radio for a week. That will change their minds!

Thank goodness we have internet radio and a few acceptable quality stations from the BBC, Linn etc. Maybe the internet will be the future source of high quality mobile radio. Perhaps DAB will disappear as an historic failure - from which many people nevertheless made their fortunes out of us mugs.

For clarity, I am perfectly happy with digital sources such as CDs - although it took about ten years before they sounded acceptable. I have little doubt that DAB+ has the potential to produce satisfactory sound but where is the commitment to go ahead with DAB+? If the government and the BBC made a commitment to introduce DAB+ I suspect that DAB radio sales would take off rapidly. I also have no doubt whatsoever that MP2 based DAB has zero potential to produce acceptable sound and most people are very well aware of that. I simply do not understand why anyone prefers DAB to FM (given equally good signals) except, maybe, for the spoken word in noisy environments.

The real problem is that 'Britain' thought they were leading the world with digital radio when DAB was introduced. The rest of the world very rapidly rejected the MP2 based British system because they all realised what rubbish it was. We now need to do the same. Tolerating DAB quietly simply delays the inevitable day when we will change to DAB+ or whatever they may want to call it.

[Gordon]

Ah, the voice of experience, discernment, wisdom, clarity and honesty. We don't hear enough of those.

Amen to that but I would take issue with Retroman on one thing he stated:

"FM, if you can forbear not to use things like Optimod processing, is to all intents and purposes transparent - the stereo multiplex system is a very clever piece of engineering, and still well fit for purpose - not perfect, but better than the DAB system. "

Agreed about Optimod, but it does have its uses if used correctly.

FM is a vast improvement on AM for sure but at the cost of a very siginificant increase in RF bandwidth per audio channel. In theory the bandwidth of an FM carrier signal is infinite. As to the Zenith/GE FM stereo system being "clever", it's a bodge!!

To get stereo into the same spectrum plan and to be received on existing mono receivers [ie backward compatibility] significant compromises were necessary, one major one being a massive increase in the RF C/N needed by the receivers to deliver low noise sound as one would expect for "HiFi". Over the almost 50 years since the UK adopted FM stereo front end performance has improved but the differential between mono and stereo still remains. Because of the pilot tone at 19 kHz and the use of a double sideband sub-carrier at 38kHz FM bandwidth cannot exceed much beyond the 15 kHz specified. The bandwidth of the stereo baseband is now 53 kHz instead of 15 [ignore RDS which raises it to 60 kHz] and this is now has to fit the same RF channel as for mono; something has to give and it's S/N performance, according to a cube law, because the modulation indices have to be reduced considerably. At the top of this band at 53 kHz the index is 75/53 ~ 1.4 whereas it was 5 for mono; the noise/bandwidth trade advantage that is the feature of FM has been given away and at 53 kHz FM is barely better than AM. And now the 53 kHz signals beget RF components [carrier +53] that only the first pair of sidebands fit the RF channel - ie just like AM - and all the others get lost. This FM stereo system relies on there being little HF in the L-R difference channel - but that is how stereo gets carried!!!

For high amplitude high frequency signals FM has poor distortion performance, made worse by the use of Pre-emphasis - which is there to deal with some of the noise problem. In the presence of multipath echoes, which are very prevalent when listening without a decent external aerial, FM distortion is severe. Listening on a kitchen portable won't necessarily expose that because of the distortion already produced in the class D audio amplifier and tinny 2" speaker.

FM CAN approach "transparency" provided that the equipment involved is capable of rendering its potential [ie NOT portables], an external aerial is used to provide that, AND that the modulation envelope is carefully managed to avoid over-modulation and spectrum starvation. It is fortunate that in the case of R3 its characteristic audio profile is occasionally demanding BUT for loud passages with lots of HF things get interesting. Most pop music stations hold the audio right on the modulation envelope, using a combination of audio DR compression and the Optimod.

Sadly, such voices are ignored in the interests of making money out of us tax and licence fee payers. Despite us paying for EVERYTHING, even for the halfwits promoting this awful system, we are completely helpless. We are to be forced to buy DAB radios or just get on with our lives without portable and mobile radios. Soon, we will no longer be able to walk from room to room with a different radio on in each room - because all DAB radios process the signal at different speeds which would result in cacophony as well as irritating DAB sound.

Quite so. Another thing the CEG complained about way back but were ignored. The radio manufacturing industry [for it is they who are responsible for this not the broadcasters] refused to address this issue by standardisng the demodulator/coder delay.

Despite the FACT that ALL audio professionals understand very clearly just how bad DAB is, we are still subjected to the 'DAB good' propaganda. Those responsible for this rubbish should be locked in a room with a DAB radio for a week. That will change their minds!

That is NOT a fact and ALL do not agree. Many professionals I know believe that DAB is good enough sound quality for the mass of the population, listening as they do predominantly on kitchen portables, not on expensive HiFi. DAB was not, is not and never will be an audiophile system. Perhaps if they had chosen to send one single audio signal coded in PCM in the same channel bandwidth as DAB uses we'd be more or less transmitting CD - but commercial and spectrum efficiency arguments won the day. When the proponents of DAB claim "high" sound quality, they do not necessarily mean what you mean. That may be reprehensible but they are NOT lying, they do believe that the sound produced for the average listener is good enough, it just isn't good enough for you. As for locking these people in a room as you suggest - they'd love it!!

Thank goodness we have internet radio and a few acceptable quality stations from the BBC, Linn etc. Maybe the internet will be the future source of high quality mobile radio. Perhaps DAB will disappear as an historic failure - from which many people nevertheless made their fortunes out of us mugs.

Well there is a satisfactory source for you that avoids DAB. Perhaps the internet will eventualy replace broadcasting. My guess FWIW is that DAB/DSO will not happen before 2020 because the listening criteria won't be satisfied. So you can relax and ignore it. But something may have to be done with the aging FM infrastructure by then.

For clarity, I am perfectly happy with digital sources such as CDs - although it took about ten years before they sounded acceptable. I have little doubt that DAB+ has the potential to produce satisfactory sound but where is the commitment to go ahead with DAB+? If the government and the BBC made a commitment to introduce DAB+ I suspect that DAB radio sales would take off rapidly.

I don't agree with that. Even if DAB+ were introduced the basic proposition to consumers is the same - they are not audiphiles and do not necessarily rate high audio quality especially since most of them listen on portables.

I also have no doubt whatsoever that MP2 based DAB has zero potential to produce acceptable sound and most people are very well aware of that. I simply do not understand why anyone prefers DAB to FM (given equally good signals) except, maybe, for the spoken word in noisy environments.

The BBC would be prepared to move to DAB+ if the rest of the industry would too. The people who have resisted it most are the radio manufacturers who did not want [they claimed] to pay additional patent royalties on the technology. MP2 royalties, which were modest, died a couple of years ago. AAC royalties are more expensive. Main problem is managing a transition for which additional spectrum might be needed. Will DAB+ solve the problem anyway - there'll be another, even better system soon? Yes DAB+ should have been introduced years ago, water under the bridge, we are where we are. DAB is moribund not because of the technical quality issues of a tiny minority but because the public are not taken with the proposition of extra channels, there are enough radio services on FM already.

The real problem is that 'Britain' thought they were leading the world with digital radio when DAB was introduced. The rest of the world very rapidly rejected the MP2 based British system because they all realised what rubbish it was. We now need to do the same. Tolerating DAB quietly simply delays the inevitable day when we will change to DAB+ or whatever they may want to call it.

Just to be pedantic, DAB is NOT British!!! The UK may have been among the first to deploy it. It was developed as a European collaborative project and the BBC Research Department was involved. The patents were all pooled and the audio part was predominantly German, being a derivative of the IRT's MUSICAM.

[Bryn]

Would one of the voices "of experience, discernment, wisdom, clarity and honesty" like to comment on the relative dynamic ranges offered by Radio 3 FM and Radio 3 DAB at 192kbps mp2? Does DAB not leave FM standing where this criterion in concerned? Oh, and when it comes to stereo separation (where DAB is using discrete, rather than the dreadful intensity joint stereo) does not DAB also leave FM in the starting blocks again. It's what mp2 throws away that degrades its tonal qualities below what FM can offer, but at 192kbps discrete stereo it's surely a case of swings and roundabouts where DAB and FM comparisons are concerned. Neither, of course, compares with what Radio 3's HD Sound (nominally 320kbps AAC-LC) has the potential to offer.

[Gordon]

Would one of the voices "of experience, discernment, wisdom, clarity and honesty" like to comment on the relative dynamic ranges offered by Radio 3 FM and Radio 3 DAB at 192kbps mp2? Does DAB not leave FM standing where this criterion in concerned? Oh, and when it comes to stereo separation (where DAB is using discrete, rather than the dreadful intensity joint stereo) does not DAB also leave FM in the starting blocks again. It's what mp2 throws away that degrades its tonal qualities below what FM can offer, but at 192kbps discrete stereo it's surely a case of swings and roundabouts where DAB and FM comparisons are concerned. Neither, of course, compares with what Radio 3's HD Sound (nominally 320kbps AAC-LC) has the potential to offer.

Agreed Bryn, good points all. Given that the bandwidth of FM stereo is limited by its design to 15 kHz, or thereabouts, if MP2 is coded from a PCM source that was sampled at 44.1 kHz then, in theory, the bandwidth is around 22kHz; surely that is audibly better than 15 for those people that can hear like bats [not me I'm afraid, 16's my limit nowadays]? If the source PCM was 48 then even better.

Given also the relatively poor performance of MP2 compression, surely the best thing to do in a coder is to limit the audio bandwidth to say 15 so it is the same as FM [who's to complain if FM is good enough?], then you can blank out the sub-bands from 15 to 22 kHz [33% of the bandwidth] and use the bits saved there to help code the sub 15 kHz band better! Why wouldn't you? Anyone got any spectrum plots of audio from FM and DAB to compare?

[Bryn]

Agreed Bryn, good points all. Given that the bandwidth of FM stereo is limited by its design to 15 kHz, or thereabouts, if MP2 is coded from a PCM source that was sampled at 44.1 kHz then, in theory, the bandwidth is around 22kHz; surely that is audibly better than 15 for those people that can hear like bats [not me I'm afraid, 16's my limit nowadays]? If the source PCM was 48 then even better.

Given also the relatively poor performance of MP2 compression, surely the best thing to do in a coder is to limit the audio bandwidth to say 15 so it is the same as FM [who's to complain if FM is good enough?], then you can blank out the sub-bands from 15 to 22 kHz [33% of the bandwidth] and use the bits saved there to help code the sub 15 kHz band better! Why wouldn't you? Anyone got any spectrum plots of audio from FM and DAB to compare?

It's a few years now since I last checked, and they may have installed updated encoders since then, but when I last compared them, DAB effectively cut off at around 15kHz (and the frequency bands showed obvious steps down to the null level), so nothing really to choose re. frequency bandwidth. However, with mp2 allocating equal priority to all the (equally wide) frequency bands it processes, the all important mid-range which the human ear is most sensitive to gets relatively little data to use compared to similar bands encoded to aac, or indeed even mp3 (though I understand the latter is not a suitable codec for radio broadcast use due to its relative lack of data redundancy and other error correction considerations). This does mean that the extreme frequencies might well get a relatively better data deal from mp2, but at what audible cost?!

[I note that tomorrow night's Live in Concert is indeed to be a live broadcast. If I remember I will save the DAB mp2, the iPlayer HD Sound and FM (the latter at 44.1/24 to get the best I can of it). My Yagi lost its reflector in the recent storms (helped by years of perching by collared doves), but I am still getting a very good signal from Wrotham.]

[Nevalti]

Too many points to cover in full so I will try to be selective.

Agreed about Optimod, but it does have its uses if used correctly.

For musical enjoyment I generally find that FM has benign compression that actually helps in a noisy environment. Yes, it can get out of the envelope occasionally but that is better than constant DAB artifact and missing information irritation.

........This FM stereo system relies on there being little HF in the L-R difference channel - but that is how stereo gets carried!!!

How many UK DAB stations do you think there are in true stereo? You probably only need one hand to count them.

Listening on a kitchen portable won't necessarily expose that because of the distortion already produced in the class D audio amplifier and tinny 2" speaker.

That old chestnut again. 'DAB is good enough for a poor quality transistor radio' but is that really 'good enough'? No, it certainly is not. I listen on various hi-fi systems, car radio and headphones when on public transport or sometimes gardening etc, all of which reveal very clearly that it is not good enough. Even cheap portable headphones, as used daily by tens of thousands of us, reveal the shortcomings of DAB. I do have a (Sangian badge engineered to 'Roberts ecologic 1') DAB portable radio that I use in the bathroom but I never use it on DAB now because even through that tiny speaker the artifacts and the missing information are just too irritating.

Many professionals I know believe that DAB is good enough sound quality for the mass of the population, listening as they do predominantly on kitchen portables, not on expensive HiFi.

I think you have condemned yourself with your own words.

Even if DAB+ were introduced the basic proposition to consumers is the same - they are not audiphiles and do not necessarily rate high audio quality especially since most of them listen on portables.

You underestimate the general public. I believe that a truly significant proportion of the public are very well aware of the shortcomings of DAB - which is why they have not bought in to an inferior system.

The BBC would be prepared to move to DAB+ if the rest of the industry would too.

It is a government decision that needs to be made. The 'Interim Digital Report', a few years back, said that we were moving to DAB+, when the 'final' report came out, that had been reversed. The BBC cannot go it alone.

Just to be pedantic, DAB is NOT British!!!

I simply meant the British DAB system in use. Where else is it use and what countries intend to use 'our' system? The answer to that MUST tell us something.