Analysis of the technical deficiencies of DAB digital radio transmission in the UK and the regulator Ofcom's disinterest in solving these problems, written by Grant Goddard in February 2011 for Grant Goddard: Radio Blog.

1. RUBBISH DAB RADIO
RECEPTION: WHY IS OFCOM
WORKING SO HARD NOT TO FIX
THE PROBLEM?
by
GRANT GODDARD
www.grantgoddard.co.uk
February 2011

2. “Ofcom’s primary concern in radio is to look after the interests of the listeners.”
Peter Davies, Ofcom, January 2007.
When something is broken, you have to fix it. Thinking about fixing it, planning to fix it, talking
about fixing it, convening meetings about fixing it – none of these will actually fix it. You just
have to fix it.
DAB radio reception has been broken since the broadcast platform was introduced in the
1990s. Transmitter powers are inadequate and there are insufficient transmitters, particularly
in urban areas. These issues have still not been fixed.
For most of the last decade, the radio industry and the regulator were in denial that DAB
reception was rubbish. Initially, it proved easy to blame the consumer. The advice to early DAB
adopters was that they should install a DAB aerial on their roof and attach it to their new DAB
radio because their home might be constructed of the wrong type of materials (bricks?). What?
All this just to listen to 'Radio 7' in the bath?
Eventually, sufficient people had bought DAB radios that they started to compare experiences.
People in the same street, the same family, the same house all found that they had similar
problems with DAB reception.
In 2004, a technical paper entitled ‘Indoor Reception Of DAB’ by Simon Mason of NTL
concluded that “a field strength of 71 dbμV/m is required in order to provide good indoor DAB
reception to handheld devices.” Mason found that, in London, “the worse [sic] reception areas
were, in every case, on the ground and first floors” of large buildings.
In 2006, at the TechCon conference, Ofcom’s Mark Thomas explained:
“The Radio Authority had no data of how [DAB] receivers performed, so it had to make
some very broad-brush assumptions. More recently, now that we have a lot of
receivers in the market and we can see how they behave, an industry group has been
working under Ofcom’s chairmanship for the last two years to look into the issue in
more detail and come up with some modus operandi for new transmitter sites.”
At the same conference, EMAP’s Grae Allen advocated:
“In the future, as I envisage it, we will see a need to put more and more [DAB
transmitter] sites inside the cities in areas where we actually need significant power
where people are living and working.”
Did any of these ‘fixes’ happen? Only in London, and only for one of the four DAB multiplexes
that serve the capital. Did Ofcom fix this? No. Did the radio industry pay for it? No. It was BT
that paid for new DAB transmitters in London to improve the reception of its new mobile
television service, Movio, which soon failed commercially. The DAB improvements were left in
place.
As Mark Thomas had explained, it was the regulator (the Radio Authority, now Ofcom) that
had set the technical criteria for DAB transmitters in the UK. So you might imagine that it would
naturally be the regulator that would take responsibility to fix inadequate DAB reception. You
would be wrong.
Rubbish DAB Radio Reception: Why Is Ofcom Working So Hard NOT To Fix The Problem? page 2
©2011 Grant Goddard

3. In 2010, Ofcom launched a consultation about the terms of its contract renewals for DAB
multiplex licences. You might think that this would be the ideal opportunity for Ofcom to insist
that licensees must improve the coverage of DAB transmitters so that consumers would
receive satisfactory reception. You would be wrong.
Ofcom indirectly acknowledged that the current quality of DAB reception was the result of
inadequate criteria having been implemented. It stated:
“Digital One’s [national DAB] network and all other existing DAB networks have been
planned to a signal strength of 58 dBμV/m. This is what we currently call ‘outdoor’, or
mobile, coverage.”
“A signal strength of 65 dBμV/m is what we currently call ‘indoor’, or portable,
coverage. The network of 30 additional transmitters that Digital One implemented in
order to facilitate the now-defunct BT Movio mobile television service were planned in
order to deliver coverage in certain areas at a much higher signal strength of 82
dBμV/m.”
Evidently, BT had understood that you cannot hope to persuade consumers to spend their
money on new equipment if they find that reception is not good enough to use it.
Unfortunately, nobody in the radio sector took the hint. So what did Ofcom decide to do about
this sorry state of affairs that has ruined so many listeners’ usage of DAB since 1999? Nothing
at all. It said:
“In general, the coverage which applicants for radio multiplex licences propose to
deliver has been seen as a commercial decision for the licensees, with neither Ofcom
nor its predecessor regulator the Radio Authority seeking to impose a minimum
coverage obligation that an applicant's proposals must meet …” [emphasis added]
This decision was made, despite Ofcom having already convened meetings of an “ad-hoc
working group” that had included the BBC, the government and the DAB multiplex licensees.
The outcome was:
“This group came to a provisional agreement that the field strengths currently used for
determining coverage are no longer appropriate given operators’ experience after
several years of operation. The group provisionally agreed that a revised set of
appropriate field strengths should be used from now on …”
This group’s new recommended signal strengths for adequate DAB reception were:
 58 dBμV/m for outdoor reception
 69 dBμV/m for indoor reception
 77 dBμV/m for indoor reception in dense urban areas.
Rubbish DAB Radio Reception: Why Is Ofcom Working So Hard NOT To Fix The Problem? page 3
©2011 Grant Goddard

4. Rubbish DAB Radio Reception: Why Is Ofcom Working So Hard NOT To Fix The Problem? page 4
©2011 Grant Goddard
So it would make perfect sense for Ofcom to insist upon these agreed new field strengths in
the new contracts for DAB multiplexes that will run for a further 12 years. But to Ofcom, it did
not. Ofcom simply said to multiplex owners: just carry on as if nothing is at all wrong with DAB
reception. In Ofcom’s words:
“We are not proposing to set any additional coverage obligations that Digital One must
meet as part of the [national DAB multiplex] licence renewal process” and “we will not
set any additional coverage obligations for local [DAB] radio multiplex licensees as
part of the process of licence renewal …”
Perhaps Ofcom should explain precisely how its policy on DAB reception quality is working “to
look after the interests of listeners.” The story to date seems to look like this:
 When DAB was introduced, the regulator got its technical sums wrong
 Poor quality reception dogged DAB from the beginning
 The regulator ignored the problem
 The radio industry knew this was a problem
 The regulator still ignored the problem
 Belatedly, the industry came up with better DAB technical parameters
 Implementing those new parameters would cost it lots of money
 Belatedly, the regulator acknowledged the problem
 The regulator refused to accept responsibility for having created the problem
 The regulator refused to take responsibility for fixing the problem
 The regulator said it was a “commercial decision for the licensees” to fix the problem
 The regulator renewed existing DAB multiplex licences to prolong the problem for a further
12 years.
Maybe Peter Davies’ earlier quote should be amended to:
“Ofcom’s primary concern in DAB radio is to stick two fingers up to all those radio
listeners who, since 1999, have spent money buying a DAB radio, taken it home, and
found that reception is too poor to use it.”
[First published by Grant Goddard: Radio Blog as 'Rubbish DAB Radio Reception: Why Is Ofcom Working Hard NOT
To Fix The Problem?', 15 February 2011.]
Grant Goddard is a media analyst / radio specialist / radio consultant with thirty years of
experience in the broadcasting industry, having held senior management and consultancy
roles within the commercial media sector in the United Kingdom, Europe and Asia. Details at
http://www.grantgoddard.co.uk