[cma-l] Community Radio on AM

Tony Bailey ravensound at pilgrimsound.co.uk
Fri Sep 26 13:14:42 BST 2014 

Hello Ian,

Briefly, protection ratios: Italy has in the past been fairly 
unregulated let us say, however, they do appear to have a very large 
number of stations on band 2.  So far as I can tell from the available 
info, there are some city sites at high power with what looks like 
around 40+ db co-channel protection (which broadly seems to comply with 
ITU-R BS 412-9) with a much larger number at low power sharing the 
channel at greater distances.  Question: What rule has been revised 
here?  CR sub band:  Have a look at 87.7 I think they are all long term 
RSLs. This is in effect a CR sub-band already.

Regards,  Tony Bailey

On 25/09/14 12:51, Ian Hickling wrote:
> To me the problem is very simple - the archaic rules that govern 
> potential interference on VHF/FM services need to be revised.
> CR will not get - and doesn't need - its own Band II sector.
> There are 204 channels available virtually everywhere - there is 
> plenty of room for everyone.
> Italy as one case alone has proved this.
>
> ------------------------------------------------------------------------
> Date: Thu, 25 Sep 2014 09:43:17 +0100
> From: ravensound at pilgrimsound.co.uk
> To: cma-l at mailman.commedia.org.uk
> Subject: Re: [cma-l] Community Radio on AM
>
> From an AM perspective, the old steam radio has been there and done 
> most of this - sharing channels, synchronised oscillators - jamming - 
> offset carriers you name it, all to try to overcome the limitations of 
> the spectrum.  If you have super expensive receivers it helps, the 
> problem with that is we increasingly don't have that option.  At least 
> with a ferrite rod antenna you could null out (even jamming) the 
> unwanted station.  There is also the strategic need to limit 
> competition - once again AM has been there: it was strongly argued for 
> years that there was no room on the medium wave band for commercial radio!
>
> I don't believe you will get anywhere with this until the community 
> has it's own slice of the cake in band 2 (as do the BBC and ILR in 
> principle).  It has long been accepted that low power radio should 
> have a separate allocation. As I understand it, there are now ways to 
> reduce the 2.2 MHz national network slot, doing this with all five 
> would release two chunks for CR.  Surely there is an argument that if 
> the nationals are not going to move to DAB yet, they are squatters?
>
> Regards,  Tony Bailey
>
> On 25/09/14 08:23, Ian Hickling wrote:
>
>     I don't agree that ".....proper computerised tools are needed to
>     do it properly" Glyn - sorry.
>     Computerised tools have got us into the farce that we are
>     currently in.
>     Certainly we need proper planning - but after that we need
>     practical onsite trials as you say with measurement and analysis.
>     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.
>     So Ofcom *could* do it but won't.
>     Lots of us *can* do it - but Ofcom doesn't accept that concept.
>
>     ------------------------------------------------------------------------
>     From: tlr at gairloch.co.uk <mailto:tlr at gairloch.co.uk>
>     To: info at a-bc.co.uk <mailto:info at a-bc.co.uk>
>     Date: Wed, 24 Sep 2014 18:11:01 +0100
>     CC: cma-l at mailman.commedia.org.uk
>     <mailto:cma-l at mailman.commedia.org.uk>
>     Subject: Re: [cma-l] Community Radio on AM
>
>     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.
>     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.
>     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.
>     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.
>
>     Alex
>
>
>
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