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<DIV><FONT size=2 face=Calibri>Hi Glynn</FONT></DIV>
<DIV><FONT size=2 face=Calibri></FONT> </DIV>
<DIV><FONT size=2 face=Calibri>That's a nice map for browsing, but as far as
mapping all transmitters to allow assessment of potential interference, it
surely isn't the way to go. As you'll be well aware you need much more than a
simple mapping of potential co-channels - you have to take into account
image channels and the directional power templates of antennas at the very
least, even before thinking about the intervening terrain. You also have
to take into account transmissions in neighbouring countries of
course.</FONT></DIV>
<DIV><FONT size=2 face=Calibri></FONT> </DIV>
<DIV><FONT size=2 face=Calibri>I think all that can be done far more effectively
in tabular form than on a map.</FONT></DIV>
<DIV><FONT size=2 face=Calibri></FONT> </DIV>
<DIV><FONT size=2 face=Calibri>Of course, the elephant in this particular
room is not in any case what frequencies are or aren't occupied, but
what parameters Ofcom applies in assessing their potential for mutual
interference - eg should a 99% confidence level or a 90% confidence level be
used, should second adjacent channel be regarded as safe or not? Those are
what make all the difference to the assumed potential for interference
between transmitters. Similarly, is potential interference acceptable for 0.1%
or 1% of the time or location? All these parameters are really what set the
technical bar as to whether or not there are channels available. Then
of course there are strategic and political issues, agrements for the BBC to
have priority use of certain sub-bands etc.</FONT></DIV>
<DIV><FONT size=2 face=Calibri></FONT> </DIV>
<DIV><FONT size=2 face=Calibri>One thing that could be considered for releasing
more community radio frequencies is for Ofcom to reuse channels more
closely on the basis of a mutual agreement between stations that they will
not complain about the remote possibility of mutual interference less than say
1% of the time in 10% of their fringe. We have transmitters on the same
frequencies just a few miles apart, but terrain-limited with no significant
mutual interference in locations of interest, because we were able to agree not
to complain about our transmitters interfering with each other! A similar thing
happens on 96.6 between Nevis Radio (Fort William) and MFR
(Aviemore) in the Laggan area half way between them. I suspect many groups
would be willing to accept a service that might be subject to a little marginal
interference in some limited locations rather thna no licence at
all.</FONT></DIV>
<DIV><FONT size=2 face=Calibri></FONT> </DIV>
<DIV><FONT size=2 face=Calibri>As for suggestions on the map, which is
nonetheless nice to have, could I suggest you add in the Scottish not-for-profit
stations that operate as non-profit community stations, but for historical
reasons have commercial licences (Cuillin FM, Two Lochs Radio, Lochbroom FM,
Argyll FM, Oban FM, Isles FM). That would give a more representative picture of
community radio cover in the northwest of the UK, which otherwise looks a bit
empty on the map! There are also community op-outs from MFR in the
north-east.</FONT></DIV>
<DIV><FONT size=2 face=Calibri></FONT> </DIV>
<DIV><FONT size=2 face=Calibri>Also for adding the Northern Ireland stations
there is a batch convertor for Irish grid references here <A
href="http://www.osi.ie/calculators/batch.asp?alias=/services/gps-services/co-ordinate-converter">http://www.osi.ie/calculators/batch.asp?alias=/services/gps-services/co-ordinate-converter</A></FONT></DIV>
<DIV><FONT size=2 face=Calibri></FONT> </DIV>
<DIV><FONT size=2 face=Calibri>Alex</FONT></DIV>
<DIV><FONT size=2 face=Calibri></FONT> </DIV>
<DIV><FONT size=2 face=Calibri></FONT> </DIV>
<DIV>----- Original Message ----- </DIV>
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style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px">
<DIV
style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: black"><B>From:</B>
<A title=info@a-bc.co.uk href="mailto:info@a-bc.co.uk">Associated Broadcast
Consultants</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=cma-l@mailman.commedia.org.uk
href="mailto:cma-l@mailman.commedia.org.uk">The Community Media Association
Discussion List</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Wednesday, September 24, 2014 2:54
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [cma-l] Community Radio on
AM</DIV>
<DIV><BR></DIV>
<DIV dir=ltr>Further to Ian's update below - we recently mapped the Ofcom data
for FM CR's onto an interactive Google Map that you can browse, zoom
etc. If you click on any site if gives the essential information.
<DIV><BR></DIV>
<DIV><A
href="http://a-bc.co.uk/community-radio-station-map/">http://a-bc.co.uk/community-radio-station-map/</A></DIV>
<DIV><BR></DIV>
<DIV>If there is interest we might do a similar map for all UK transmitters
(nearly 2000 of them) that you can filter by frequency - thus to get an
insight into co-channel interference for any station/location/frequency you
wish. Or other variations if people have suggestions.</DIV>
<DIV><BR></DIV>
<DIV>Regards, Glyn</DIV>
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