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<div class="moz-cite-prefix">Don't forget that on VHF the effective
antenna height is a factor, for example, I once logged a 1 watt
RSL on a car radio around ten miles away (from their Wimbledon
Hill site) (on about 87 meg)! And similarly, four miles to a
walkman from 1 watt in Orpington (I was listening on the roof of a
tower block). Unfortunately, this also means hollows = signal
loss, something difficult to deal with if on limited power/antenna
height. <br>
<br>
Which leads on to the subject which has had most research in
recent times: protection ratios. For all practical purposes,
service areas are interference limited. Protection ratios are
effected by all sorts of variables, see Rec. ITU-R BS.412-9.
(There's an interesting section on synchronised motor way
services, as per Channel Travel Radio). There is a school of
thought that we simply jack up all the RF levels and just keep the
protection ratios intact, I believe this has been done in some
metro areas already?<br>
<br>
We no longer have the option of 9 x 2.2 MHz slots everywhere, but
if you want to avoid those annoying neighbours you will still need
your own ball park. If the DAB move is off, there is a case for
making room for more CR in the National sub bands, which are
populated by less contentious relays. <br>
<br>
Regards, Tony Bailey<br>
<br>
On 30/09/14 10:06, Alan Coote wrote:<br>
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<p class="MsoNormal"><a moz-do-not-send="true"
name="_MailEndCompose"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">It’s
amazing that 54dBuV/m at 10m has been maintained for so
long when it has little resemblance to the vast majority
of setups. When projected to antennas at a more normal 1.5
– 2.5 metres above ground level, the field strength needs
to be significantly greater.<o:p></o:p></span></a></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">The
other very significant practical issue is that the field
strength required to cover dense urban, urban and open
country is different. Greater power helps in towns and
cities due to the losses (refractions, reflections and
absorptions) which affect the wanted signal. <o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">This
is very apparent in lower power stations (like community
radio) as the fringes of coverage are often in areas which
the station wishes to reach. <o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">If
we accepted that 25W does not always = 5km, I wonder
therefore if Ofcom should take this more into account when
licensing stations? An additional benefit would be that
spectrum is better managed and (ref’ to Ian’s original post)
more groups would end up getting licensed. <o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<div>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Kind
Regards</span><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Alan<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><a moz-do-not-send="true"
href="http://www.letstalkbusinessonline.com/"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif"">Hear
Alan Every Week on Let’s Talk Business The UK’s Premier
Radio Programme For Current and Future Entrepreneurs -
Now Broadcast To 4.3 Million People </span></a><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> <o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Email
- </span><a moz-do-not-send="true"
href="mailto:alan.coote@5digital.co.uk"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif"">alan.coote@5digital.co.uk</span></a><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Phone
- 0800 949 6655<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Mobile
- 07801 518858<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Twitter
- </span><a moz-do-not-send="true"
href="http://www.twitter.com/TheAlanCoote"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif"">@TheAlanCoote</span></a><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p></o:p></span></p>
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<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><img
id="Picture_x0020_1"
src="cid:part6.09040305.09080000@pilgrimsound.co.uk"
alt="cid:image001.gif@01CE03CD.223AC920" border="0"
height="71" width="200"><o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">The
Media Production, Broadcasting and Training Company<o:p></o:p></span></p>
</div>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<div>
<div style="border:none;border-top:solid #B5C4DF
1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif""
lang="EN-US">From:</span></b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif""
lang="EN-US"> <a class="moz-txt-link-abbreviated" href="mailto:cma-l-bounces@mailman.commedia.org.uk">cma-l-bounces@mailman.commedia.org.uk</a>
[<a class="moz-txt-link-freetext" href="mailto:cma-l-bounces@mailman.commedia.org.uk">mailto:cma-l-bounces@mailman.commedia.org.uk</a>] <b>On
Behalf Of </b>Two Lochs Radio<br>
<b>Sent:</b> 29 September 2014 18:17<br>
<b>To:</b> ROBERT TYLER; The Community Media Association
Discussion List; <a class="moz-txt-link-abbreviated" href="mailto:ravensound@pilgrimsound.co.uk">ravensound@pilgrimsound.co.uk</a><br>
<b>Subject:</b> Re: [cma-l] Extending Community Radio on
FM<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Calibri","sans-serif"">Bob</span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Calibri","sans-serif"">You're
right about the original signal specs being based on the
assumption of outdoor aerials, but receivers were much
less sensitive at the time, and by happy chance the
improvements in receiver sensitivity have approximately
counteracted the move to indoor whip aerials, so the
planning based on the same 54dBuv/m signal level at 10m
height still gives a useful guide as to the required
signal for robust coverage.</span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<div>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Calibri","sans-serif"">When
the BBC VHF service first began they worked to a
definition of 60dBuv/m needed for good service in
mono (later 66dBuV/m for stereo), and 48dBuV/m (later
54dBuV/m for stereo) as the 'nominal limit of
satisfactory reception'. Ofcom still uses
this, summarizing it like this:</span><o:p></o:p></p>
</div>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Calibri","sans-serif""><img
id="_x0000_i1025"
src="cid:part7.06080502.01070905@pilgrimsound.co.uk"
border="0" height="245" width="402"></span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Calibri","sans-serif"">I
would be cautious about assuming much better selectivity
or sensitivity on modern FM receivers - there are plenty
of shower, bedside clock-radio and other cheapy FM radios
that tell a different tale!</span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Calibri","sans-serif"">I
was interested in your reference to "the Home Service
Bedford transmitter". What was that? I understood the VHF
Home Service for the southeast began in 1955 on much the
same site as today - Wrotham in Kent (there was 120kW at
Wrotham, Norwich and Sutton Coldfield to start with). Bow
Brickhill which now serves Bedford on VHF wasn't set up
until the 1980s as I recall, and was mainly as a result of
the need to cover the burgeoning Milton Keynes.</span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Calibri","sans-serif"">It's
not correct that in 1955 it was thought there would be
only two services on VHF - the Third programme was already
9 years old and went onto VHF simultaneously with the Home
Service and the Light Programme. </span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Calibri","sans-serif"">When
the BBC first planned it all for three services the band
was one-third its present size (88.0-94.6 MHz), and as for
us having more space between stations than any other
country in Europe - a quick look at a transmitter map of
Northern Europe both historically and today would show
that not to be true. Southern Europe (okay, Italy really)
is another story of course!</span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Calibri","sans-serif"">Alex</span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<blockquote style="border:none;border-left:solid black
1.5pt;padding:0cm 0cm 0cm
4.0pt;margin-left:3.75pt;margin-top:5.0pt;margin-right:0cm;margin-bottom:5.0pt">
<div>
<p class="MsoNormal"><span
style="font-size:10.0pt;font-family:"Arial","sans-serif"">-----
Original Message ----- <o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal" style="background:#E4E4E4"><b><span
style="font-size:10.0pt;font-family:"Arial","sans-serif"">From:</span></b><span
style="font-size:10.0pt;font-family:"Arial","sans-serif"">
<a moz-do-not-send="true"
href="mailto:bobtyler@btinternet.com"
title="bobtyler@btinternet.com">ROBERT TYLER</a> <o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><b><span
style="font-size:10.0pt;font-family:"Arial","sans-serif"">To:</span></b><span
style="font-size:10.0pt;font-family:"Arial","sans-serif"">
<a moz-do-not-send="true"
href="mailto:cma-l@mailman.commedia.org.uk"
title="cma-l@mailman.commedia.org.uk">The Community
Media Association Discussion List</a> ; <a
moz-do-not-send="true"
href="mailto:ravensound@pilgrimsound.co.uk"
title="ravensound@pilgrimsound.co.uk">ravensound@pilgrimsound.co.uk</a>
<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><b><span
style="font-size:10.0pt;font-family:"Arial","sans-serif"">Sent:</span></b><span
style="font-size:10.0pt;font-family:"Arial","sans-serif"">
Sunday, September 28, 2014 8:09 PM<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><b><span
style="font-size:10.0pt;font-family:"Arial","sans-serif"">Subject:</span></b><span
style="font-size:10.0pt;font-family:"Arial","sans-serif"">
Re: [cma-l] Extending Community Radio on FM<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<div>
<p class="MsoNormal" style="background:white"><span
style="font-family:"Tahoma","sans-serif";color:black">Tony<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal" style="background:white"><span
style="font-family:"Tahoma","sans-serif";color:black">It
is my understanding that the British specification for
the FM (then VHF) band was established before the
Second World War. At the time it was considered that
only the two BBC services would be on VHF. I believe
that the specifications laid down are still current
and are based on roof top aerials, as it was
considered that to receive VHF such an aerial would be
required. <o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal" style="background:white"><span
style="font-family:"Tahoma","sans-serif";color:black">Also
for some reason, we in the UK also decided to employ
extra separation/guarding, in order to prevent ANY
possibility of the Home Service Bedford transmitter
interfering with the Home Service Dover transmitter or
Crewe Relay. In other words, we have more space
between services than any other country in Europe. In
many respects we have the perfect VHF/FM transmitter
network.<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal" style="background:white"><span
style="font-family:"Tahoma","sans-serif";color:black">Of
course then, it was not expected that the reception of
radio would extend to telescopic aerials or tiny coil
antenna, thereby making the roof top aerial redundant.
Nor even then, was the prospect of commercial or
community radio in the future mix. As a side issue, a
few commercial stations and many community radio
station are in allocated BBC spectrum at the behest of
Dear Old Aunty. <o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal" style="background:white"><span
style="font-family:"Tahoma","sans-serif";color:black">The
mystery of so called �expertise� in planning the
VHF/FM spectrum has remained in the hand of the
regulators. I do remember asking my MP sometime in the
70�s to lodge a written question about an available
frequency to The Home Secretary, only to receive the
reply that 101 point something was �used to track
otters� . <o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal" style="background:white"><span
style="font-family:"Tahoma","sans-serif";color:black">I
did have it confirmed that 102.2 was assigned wrongly
and should have been able to accommodate several UK
allocations but apparently the spectrum had been badly
assigned at a too high a power in the East of England,
(flat terrain) thereby rendering the space sterile
for a large part of the country. <o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal" style="background:white"><span
style="font-family:"Tahoma","sans-serif";color:black">In
summary there are many issues (and many question)
surrounding spectrum allocation and the regulator of
the day always hold the mystery ticket. The �beauty
contest� of selecting future licence holders compounds
the decision process. The reality is that the only
policy is to switch to DAB so any FM debate is a waste
of time. <o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal" style="background:white"><span
style="font-family:"Tahoma","sans-serif";color:black">Hope
this helps<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal" style="background:white"><span
style="font-family:"Tahoma","sans-serif";color:black">Bob<o:p></o:p></span></p>
</div>
<div>
<div>
<p class="MsoNormal" style="background:white"><span
style="color:black"> <o:p></o:p></span></p>
</div>
</div>
</div>
</blockquote>
</div>
</blockquote>
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