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<body class='hmmessage'><div dir='ltr'>I don't agree that ".....proper computerised tools are needed to do it properly" Glyn - sorry.<div>Computerised tools have got us into the farce that we are currently in.</div><div>Certainly we need proper planning - but after that we need practical onsite trials as you say with measurement and analysis.</div><div>This however is costly in terms of the equipment and manpower which Ofcom does not have available and is not going to get funded by HMG.</div><div>So Ofcom <b>could</b> do it but won't.<br>Lots of us <b>can</b> do it - but Ofcom doesn't accept that concept.<br><br><div><hr id="stopSpelling">From: tlr@gairloch.co.uk<br>To: info@a-bc.co.uk<br>Date: Wed, 24 Sep 2014 18:11:01 +0100<br>CC: cma-l@mailman.commedia.org.uk<br>Subject: Re: [cma-l] Community Radio on AM<br><br>
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<div><font size="2" face="Calibri">I understand the 'complex scientific' side of it,
but I still don't honestly see how the map helps give any insight other than in
the crudest measure of overall density of stations. </font></div>
<div><font size="2" face="Calibri"></font> </div>
<div><font size="2" face="Calibri">It shows the general density of stations and is a
nice tool for browsing stations and frequencies, but it gives no visual
representation whatever of frequencies or powers, so I don't honestly see how it
gives even the vaguest insight into the interference landscape for a
station.</font></div>
<div><font size="2" face="Calibri"></font> </div>
<div><font size="2" face="Calibri">It could maybe take useful steps in
that direction with some development. For example if one could select a
frequency or transmitter of interest and set a filter to show only stations of
that frequency, or of that frequency plus adjacent and/or image channels it
would start to give an idea of potential for interference. Combined with perhaps
a crude free space range indication using semi-transparent overlays based
on on powers and direction templayes it might beging to give a rough feel for
the interference landscape for a given station. But as it stands I don't see how
it does that in the slightest.</font></div>
<div><font size="2" face="Calibri"></font> </div>
<div><font size="2" face="Calibri">Not meaning to be picky, honest - I like it
for what it is, and it does give a feel for the geographic distribution of CR
stations, but it doesn't seem to me to offer any useful insight or even
vague feel for the interference landscape.</font></div>
<div><font size="2" face="Calibri"><br>Alex</font></div>
<blockquote style="BORDER-LEFT:#000000 2px solid;PADDING-LEFT:5px;PADDING-RIGHT:0px;MARGIN-LEFT:5px;MARGIN-RIGHT:0px;" dir="ltr">
<div style="FONT:10pt arial;">----- Original Message ----- </div>
<div style="FONT:10pt arial;BACKGROUND:#e4e4e4;"><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="tlr@gairloch.co.uk" href="mailto:tlr@gairloch.co.uk">Two Lochs Radio</a> </div>
<div style="FONT:10pt arial;"><b>Cc:</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 5:37
PM</div>
<div style="FONT:10pt arial;"><b>Subject:</b> Re: [cma-l] Community Radio on
AM</div>
<div><br></div>
<div dir="ltr">Absolutely right Alex - the frequency selective map would only be
for getting an "insight" or feel for the interference landscape - proper
computerised tools are needed to do it properly.
<div><br></div>
<div>It's complex and scientific, but this post below gives a pictorial,
non-technical insight into the "Protection Ratios" that Ofcom use, and are one
of the reasons they often say there are no frequencies available:-</div>
<div><br></div>
<div><a href="http://a-bc.co.uk/ofcom-fmvhf-protection-ratios-illustrated/" target="_blank">http://a-bc.co.uk/ofcom-fmvhf-protection-ratios-illustrated/</a><br></div>
<div><br></div>
<div><br></div>
<div>Glyn</div>
<div><br></div>
<div>-- <br>Glyn Roylance - Principal Consultant
<div><a href="http://www.a-bc.co.uk/" target="_blank">Associated Broadcast
Consultants</a></div></div>
<div class="ecxgmail_extra"><br>
<div class="ecxgmail_quote">On 24 September 2014 16:58, Two Lochs Radio <span dir="ltr"><<a href="mailto:tlr@gairloch.co.uk" target="_blank">tlr@gairloch.co.uk</a>></span> wrote:<br>
<blockquote style="BORDER-LEFT:rgb(204,204,204) 1px solid;MARGIN:0px 0px 0px 0.8ex;PADDING-LEFT:1ex;" class="ecxgmail_quote"><u></u>
<div>
<div><font face="Calibri">Hi Glynn</font></div>
<div><font face="Calibri"></font> </div>
<div><font 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 face="Calibri"></font> </div>
<div><font face="Calibri">I think all that can be done far more effectively in
tabular form than on a map.</font></div>
<div><font face="Calibri"></font> </div>
<div><font 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 face="Calibri"></font> </div>
<div><font 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 face="Calibri"></font> </div>
<div><font 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 face="Calibri"></font> </div>
<div><font 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" target="_blank">http://www.osi.ie/calculators/batch.asp?alias=/services/gps-services/co-ordinate-converter</a></font></div><span>
<div><font face="Calibri"></font> </div>
<div><font face="Calibri">Alex</font></div>
<div><font face="Calibri"></font> </div>
<div><font face="Calibri"></font> </div>
<div>----- Original Message ----- </div></span>
<blockquote style="BORDER-LEFT:rgb(0,0,0) 2px solid;PADDING-LEFT:5px;PADDING-RIGHT:0px;MARGIN-LEFT:5px;MARGIN-RIGHT:0px;">
<div style="FONT:10pt arial;BACKGROUND:rgb(228,228,228);"><b>From:</b>
<a title="info@a-bc.co.uk" href="mailto:info@a-bc.co.uk" target="_blank">Associated Broadcast Consultants</a> </div><span>
<div style="FONT:10pt arial;"><b>To:</b> <a title="cma-l@mailman.commedia.org.uk" href="mailto:cma-l@mailman.commedia.org.uk" target="_blank">The Community
Media Association Discussion List</a> </div></span>
<div style="FONT:10pt arial;"><b>Sent:</b> Wednesday, September 24, 2014
2:54 PM</div><span>
<div style="FONT:10pt arial;"><b>Subject:</b> Re: [cma-l] Community Radio
on AM</div>
<div><br></div></span><span>
<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/" target="_blank">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>
<div><br></div></div></span></blockquote></div></blockquote></div><br><br clear="all">
<div><br></div><br>
<div><a href="http://www.a-bc.co.uk/index.html" target="_blank"></a> </div></div></div></blockquote>
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