Saturday, 16 March 2013

The Digital Fallacy

Labelling anything today as digital bestows an aura of enhanced quality which is quite unjustified. If we exclude my hobbyhorse - the declining quality of photography - and consider DAB (Digital Audio Broadcast) radio.
The government plans to phase out all national FM radio broadcasts and replace them with DAB services.  This is being sold to the public as an improvement and the arguments being used to support it are often fallacious.

Take this one:  reported in   the Daily Telegraph: July 2010
New research to be published later today claims to show broadcasting digitally is more energy efficient than analogue. It suggests that transmitting Classic FM nationally via DAB uses less than 7% of the electricity needed to transmit it via FM.
(Evidence from Sweden and Switzerland which takes into account the extra transmitters required indicate that the figure is more like 15%)

Now consider this submission to the OFCOM consultation 

"The consultation fails to consider another unfortunate characteristic DAB radios,their power consumption. My FM only radios work for around 100 hours on a set ofbatteries, but my DAB radios only work for about 6 hours.The environmental impact of additional battery usage must be considered as part of
the switch over plans.Additionally, the short battery life makes ‘portable’ DAB radios impractical without access to mains power. So in a rural area (eg. North Norfolk), where both DAB and FM coverage is poor, I can locate my FM radio on window ledges, tops of cupboards etc. which is not practical for DAB radios that need mains power most of the time"

The author is an ordinary radio listener with no interests in the broadcast industry.
He is a telecommunications professional, but not active in the radio industry.He is a Chartered Engineer and Fellow of the Institution of Engineering Technology(formally IEE). He holds a full UK amateur radio licence and specialises in using amateur radio’s digital modes.He lives in London but has a second home in North Norfolk so is familiar with broadcast radio reception issues in city and rural environments and while driving.

According to RAJAR (the body which measures radio audiences) the hours of radio listening per year is currently 1,040,000,000 hours.  
That's a lot of batteries.

Moving national radio stations to DAB will utilise the waveband spectrum more efficiently: more stations can be squeezed into a given waveband (12.7 times as many).As we have seen above, whilst this saves money for the broadcaster it will increase costs considerably the consumer.  With a DAB radio it will scan available stations and save them as presets. This would be a boon to us as each time we moor up we may be in a different catchment area for radio.  So I bought a portable radio but it was using a set of batteries every day: rechargeable were even worse - it was impossible to recharge them quickly enough. I calculated that my DAB machine was consuming batteries 17 times as fast as the FM portable (in which rechargeables last weeks)  The other problem I encountered is that the DAB signal is more susceptible to physical obstruction by hills and buildings. We know boaters who select their mooring spot by the TV signal strength available: we use other criteria and could not accept DAB to determine where we moor.

So what are the benefits to the consumer of DAB?
- More radio channels.  When DAB was introduced in 2006, residents in southern Norway experienced an increase from 6 channels to 21.
- Reduced interference from adjacent channels - crosstalk. 
-Enhanced features. DAB radios search for available stations and carry information such as song names etc.
- No hiss when the signal is weak (it just breaks up and disappears)
And the disadvantages?
 -No hiss when the signal is weak - it breaks up and disappears 
- DAB is meant to improve fidelity but that has not been the case to date.
A BBC R&D White paper in June 2003 states: 
A value of 256 kbit/s has been judged to provide a high quality stereo broadcast signal. However, a small reduction, to 224 kbit/s is often adequate, and in some cases it may be possible to accept a further reduction to 192 kbit/s, ..... At 192 kbit/s, it is relatively easy to hear imperfections in critical audio material.
In July 2006 when BBC reduced Radio 3 broadcasts from 192 to 160kbts the ensuing complaints by listeners forced them to return to the former level.  Radio 4, however, fares less well.  During the day, programmes are broadcast at 128kbts and in stereo, but in the evenings they are reduced to 80kbts and mono, whilst the same programmes on FM are still broadcast in stereo.
- Digital delay.  Because of the decoding and de-interlacing required within the receiver DAB programmes are heard 2-4 seconds later than FM ones.  This is confusing when you have an FM radio in one room and DAB in another as they are always out of step.  It can be even more annoying when listening to a live event.

So do we feel that programmes with a discernably poorer definition  and perhaps in mono with a digital delay and costing us 17 times as much to listen to is an improvement?


  1. With high speed Internet technology, the out-of-step part is inexcusable.

  2. Anonymous10:26 pm GMT

    I was given a DAB radio by Vikings, the office supplies people. I leave it on the kitchen table, plugged in to the mains. Whenever I light the gas cooker the crystal sparky thing cuts out the reception on the DAB radio but not on the FM.
    Just thought you would like to know.
    (I wrote 'crystal sparky thing' because I don't know how to spell Peezo, Pietcho, Pietzo or whatever it is.
    Martin the famous author.

  3. Dear Famous Author
    Welcome to the New Improved World of DAB1
    I think the technical term for this phrnomenum is

  4. Never heard of "Vikings" as a vendor, but the comment at first put me in mind of a new invasion of the UK by Norse sea marauders, this time not pillaging, but handing out dubious audio technology.


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