DAB is dead
DAB in 2009
It's rather a bold statement to say that DAB is dead - but that would be the case if the commercially funded broadcasters could have their way.
DAB was crippled from the outset by its poor coverage and very poor audio quality. Technically a now rather outdated standard was chosen for DAB in the UK which meant that to obtain reasonable sound quality - on a par with good FM broadcasting - a fairly high bit bate of at least 192kbps would be needed. However due to bandwidth limitations (i.e not enough radio frequencies allocated to DAB by the government) the bit rates had to be severely reduced by the broadcasters, including the BBC, in order that the required number of stations could be transmitted. This caused audio quality to be much worse than the hi-fi quality potentially available with a good VHF/FM stereo signal.
This severe reduction in bit rate resulted in a severely reduced audio quality. This certainly had the ability to hinder the take-up of DAB by the general listening public.
Back in the eighties, when listeners were encouraged to swap from AM broadcasting, which was the most popular method of listening from the 1920's to the 1970's, to listening on FM, there was the carrot that FM radio had vastly superior sound quality compared to AM. There is no such advantage when swapping from FM to DAB - in fact DAB can actually sound worse than FM!
Other limiting factors include the fact that most people have more than one AM/FM radio - often a significant number: A radio in the kitchen, bedroom, bathroom, lounge, car plus hi-fi tuner etc - maybe half a dozen or more. This must certainly count as a factor against wider DAB adoption since DAB sets that can cost around £40 to £50 each.
The major handicap, however, is coverage. DAB coverage generally not as wide or effective as FM radio coverage, so it can often be the case that were FM radio reception was perfectly fine on the kitchen radio - DAB reception is non existent. So, you buy a nice new DAB radio - and it doesn't work!
Not only is DAB coverage often more restricted due to fewer and/or less powerful DAB transmitters and the fact that the higher radio frequencies used for DAB get attenuated (reduced in strength) more readily than the lower frequencies used for analogue radio. Also there is the additional problem in the way that the DAB system works:
When radio signals are weak FM reception simply gets progressively noisier until it gradually disappears, whereas with DAB reception when signals get to a certain weakness simply stops working altogether, it does not gradually get worse in the way that a weak AM or FM signal would - the reception just falls off a metaphorical cliff. DAB reception is particularly poor inside buildings due to the fact that the signals are more easily screened and therefore blocked by the structure.
More DAB transmitters would help, but with the uncertainty of the format and current economic woes, commercial broadcasters are not willing to invest in additional equipment and transmission sites. DAB is very expensive to transmit - and unsustainable when commercial broadcasters are making no money, or even having their cash swallowed up in the DAB money-pit.
Another problem for DAB is that there are so many alternative sources for radio reception. AM and FM analogue broadcasting is the obvious choice and which many listeners are perfectly satisfactory, plus there is the availability of many radio stations via digital terrestrial television - "Freeview"; digital satellite television - "Freesat"; cable and via internet streams - although the latter methods are not portable and remain quite an inconvenient method of listening to the radio.
A ten quid AM and FM 'tranny' does very nicely in the bathroom thank you!
To overcome the previously mentioned poor DAB sound quality and new system has been devised called DAB+
DAB+ uses much more efficient 'codecs' (the digital encoding algorithms) than standard DAB and therefore can offer substantially better sound quality with lower bit rates and therefore smaller bandwidth. Listeners complaining of the current poor audio quality from standard DAB radio have been hoping that this new DAB+ system would be adopted by broadcasters in the UK.
However there are two problems.
1/ All the current - old technology - DAB radios would become obsolete and only fit for land fill because they would not be able to receive the new DAB+ standard and cannot be upgraded by firmware or hardware modification, so listeners would have to buy yet more new equipment.
2/ DAB+ has missed the boat as far as the radio industry is concerned. Since commercial broadcasters have been unable to make money out of DAB radio, therefore there is no spare cash for further investment, and the change from the current technology to DAB+ risks alienating all those who have already bought DAB receivers.
DAB+ will never be adopted in the UK.
The uncertainty of DAB adoption caused the commercial broadcasters to, understandably, reduce investment in the system. In 2008 the then GCap Media company (now part of Global Radio) realised that they would not produce any profit from DAB radio. In 2008 Fru Hazlett, GCap's Chief Executive said that if GCap could switch off DAB today - they would.
The failure of DAB was thrown into sharp focus at that point. Channel Four television and their "4 Digital" arm had recently spent a huge sum of money winning the second national DAB licence from Ofcom to operate a variety of new digital radio stations on the Digital 2 network. However the statement from Hazlett ensured that Digital 2 would never come to fruition and Channel 4 closed their embryonic digital radio operation down very quickly. Even the current Digital One DAB network only has four stations being transmitted on its network - three of which can be heard on analogue radio already. Not much of an incentive there for listeners to invest in a new DAB radio.
The commercial companies may plod along for the time being with DAB in its current form, and the BBC still offers its national radio services via its own national DAB network of transmitters. The BBC local radio stations are required to be carried on the commercially operated DAB multiplexes - where such a multiplex exists. However, we won't hold our breath for any major new DAB announcements just yet.
Perhaps the only bright spot is that the BBC did upgrade their own DAB encoders in an effort to make the most of the current DAB technology and improve sound quality. Some listeners did note an improvement in audio quality of some of the BBC radio stations being carried on DAB.
DAB COVERAGE MAPS
To Give You An Indication As To Whether You Are Within The DAB Reception Area
Interesting And Useful Link About DAB and VHF/FM Aerials:
DAB - A GENERAL OVERVIEW
Now that the long wave, medium wave and vhf/fm bands are effectively full up and can accommodate no further stations, DAB could be the ideal way to expand future domestic radio broadcasting.DAB is a system developed by the BBC and European broadcasters under the EUREKA 147 project and has been adopted by the EBU (European Broadcasting Union) as the future standard for digital audio broadcasting in Europe. DAB has been adopted by numerous other countries around the world too, with the notable exeption of the USA where the FCC is experimenting with a different digital broadcasting standard known as IBOC (In Band On Channel) which piggybacks a digital service alongside a current station on FM. IBOC has not proved to be a complete success as yet, however.
DAB, meanwhile, is transmitted in vhf band III (174 to 230 MHz), the band that the old 405 line black and white televison used to occupy in the UK from 1955 to 1982. Many areas can receive three multiplexes; the BBC National DAB Multiplex: the national commercial multiplex Digital One : and a Local Multiplex operated by a commercial operator. Some heavily populated areas can receive a additional regional multiplex. In my own area which has good radio reception, I can receive BBC, Digital One, a regional multiplex (MXR), a local multiplex (NOW), PLUS two other 'out of area' multiplexes (TWG-EMAP and CE Digital).
Each Multiplex can carry several radio stations, perhaps six or more depending on the data rates of each station. The lower the data rate of each service the more programme choice can be provided - but at lower audio quality. Typically 160 or 192 kbs is required for good audio quality and these rates are sometimes used by national music stations. 128 kbs is accepted as the minimum quality required for music reproduction, although the audio quality is really rather annoying when compared to FM or CD, and this is the rate used by most local music stations and is set by the commercial operator so that maximum revenue can be squeezed out of the multiplex from the greatest number of stations carried.
DAB is eminently portable, quicker and far easier to use than any other type of radio delivery system and offers very good sound quality, much better than AM and free of the hiss and crackles, pops and multipath distortion that could effect FM reception. Technically the sound quality is not as good as that which can be achieved with a standard analogue wideband FM band II vhf signal and when comparing a 128kbs stereo DAB station with a good analogue broadcast on FM via a high quality hi-fi tuner the DAB sound quality is VERY noticeable worse. However given the good bit rates (160kbs - 192kbs) offered by Classic FM, Virgin Radio and Radio Three the sound quality is a little better if being played through a hi-fi system, though subjectively still not equal to a good FM signal. I prefer FM every time over DAB.
HIGHEST QUALITY: If you are looking for the best radio quality then you need to consider radio via digital satellite - the SKY system - or via digital terrestrial television - i.e. Freeview.
DAB currently has one and has one major advantage over FM radio, that of significantly lower audio compression, such as the awful Optimod and Omnia systems so heavily used by most stations on FM. I use a Pure Evoke 2 for portable use, and this offers quite amazing audio from its built in ported hi-fi speakers on FM and the high bit-rate DAB stations. The Pure range of radios are really quite impressive despite the poorer sound quality offered by most DAB stations.
The lack of audio compression is, of course, purely at the broadcasters whim. As DAB is more widely adopted by the listening public there is a chance that audio compresion may gradually be introduced on some stations, which would be a shame for an audio broadcasting medium that can offer reasonable audio quality without the hiss and crackles of FM and AM.
DAB seems to me to be an ideal portable digital radio medium, but I think the system should be used to expand choice rather than to simply replace the existing AM and FM bands, and certainly 'squashing' (digitally compressing) too many stations into each DAB multiplex will have a very detrimental effect on sound quality due to lower bit-rates that would then have to be employed.
The down-side of DAB is that the listener will really only hear those stations that the authorities (the government and Ofcom) and the multiplex operators themselves deem that they want you, the listener, to hear. Since each block of frequencies (multiplex) is re-used over and over again the possibilities of DX-ing (distant reception) other services and stations is very limited since the chances are that a distant multiplex will be blocked by a more local one using the same frequecy block. It's not the same as AM or FM DX-ing whereby a listener can 'weedle out' a distant station from in-between two more local transmitters by careful tuning and adjustments. So we are in danger of becoming far too regulated and restricted in this respect. Where I am located I can listen to Alan Beswick on BBC GMR many many miles outside the service area of BBC GMR on FM by careful tuning and a strategically placed dipole aerial, I have no chance on DAB however, so that avenue of enjoyment would be cut off if FM did not exist.
The biggest problem, it seems to me, is the one of which radio stations and services your local multiplex operator allows you to hear. If they don't want station 'Y' carried on their multiplex for economic or competitive reasons then they don't have to carry it. The smaller radio stations may be priced off the local DAB multiplex simply because the multiplex operator can charge what it wants to allow a station on to its programme stream. If a particular radio station cannot justify the costs being charged by the local multiplex operator then it simply will not be carried and could be left 'ghettoised'.
This is very worrying and could lead to anti-competitive practices, since all the local multiplexes are owned by the very big radio groups/conglomorates, and with ownership rules and regulations being relaxed by Ofcom, these multiplex operators will inevitably merge and consolodate and be in an even stronger position to squeeze out the smaller stations from their DAB multiplex 'market'.
Since the BBC has only been allocated one single national multiplex and no local multiplex the authorities (Ofcom) have required the local commercial multiplex operators (i.e. Capital, GWR, EMAP etc) to carry the BBC local station in the area on their multiplex.
Here is the other rub. The government only allowed a very small portion of the band III v.h.f. spectrum to be allocated to DAB broadcasting, this limited number of frequency blocks means that many areas of the UK will have no band III local DAB multiplex. In consequence areas with no local commercial DAB multiplex available cannot be provided with coverage of BBC local radio on DAB in that area. The areas that will have no local DAB reception on band III include Oxfordshire, Cambridgeshire, Suffolk, Lincolnshire, Kent Coast, Somerset, North Devon, Derbyshire, Nottinghamshire, and Northern Ireland (which has to make do with one combined national / regional commercial DAB multiplex).
In 2005 OFCOM announced that additional frequencies in Band III v.h.f. may be made available to expand national commercial and BBC DAB coverage and to guarantee that every area would have its own LOCAL DAB multiplex. The expansion of local multiplexes to fill in uncovered 'white' areas commences in 2006 and may take several years to complete.
DAB could offer excellent expansion opportunities and reception quality and a good choice of new stations, but perhaps it should not be at the expense of current AM and FM bands just yet. DAB is still in its infancy we cannot tell how the authorities will treat the development of this new medium or, indeed, the future development of domestic radio in general.
There will be additional possibilities for expansion of DAB into local areas without current reception with the introduction of services in a new higher frequency bands. A new DAB band in the 1400 MHz region may be released in or after 2007 to allow more expansion of very localised DAB services. The trouble is that nearly all DAB radios sold to date do not include these new frequencies and will be unable to exploit the new services. This seems quite daft planning on the part of the UK government (hardly surprising then, I suppose) that all current DAB radios can receive all the frequency blocks in vhf band III (174 to 230 MHz) but that the government only chose to use a limited number of blocks in a very small portion of this band for DAB - hopefully this situation will soon change after 2005.
This is no doubt due the the fact that rather than institute good DAB planning, the government have auctioned off these more suitable frequencies to make a quick buck. But whenever did the government do anything sensible, practical, economical or popular with the common-sense thinking public? The usual government motto seems to be 'If a job is worth doing it's worth fudging and botching and making inefficient and almost unworkable'.
So at the moment we are left with a typically British compromised system.
The radio manufacturers have come up with some pleasing, interesting and quite good sounding portable designs. The broadcasters, particularly the BBC, have put some good stations on the multiplexes. Sound quality, however, is the biggest disappontment and cannot even match the heights of top-quality FM radio, let alone CD, due to DAB's currently restricted bit-rates. DAB is generally free from crackles, however. We can hear BBC Five Live and Talk Sport in higher quality than that available on AM and have the benefit of additional services such as BBC7 and BBC 6 Music and Oneword to name but a few.
We are, of course, waiting for the additional space allocated on band III to bring DAB to unserved localities. It is slightly worrisome that the commercial local multiplex operators (owned by big conglomerates) are in a position to dictate what we can and cannot hear and price some stations off DAB altogether. Let's hope that DAB is used to expand choice rather than simply a means for the government to close down the VHF/FM and Medium Wave and Long Wave bands so that they can sell those frequencies off to make yet more fast bucks to pay for the usual government follies.
I am extremely pleased with the PURE EVOKE-2 DAB radio, the additional stations are very welcome and the set is extremely easy to operate. Such a shame that the broadcasters have spoilt the potential sound quality!
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