[cma-l] Ofcom consultation: UHF and VHF spectrum planning

[Two Lochs Radio]

Does Ofcom actually publish the full criteria for assessing the availability of channels with regard ot possible interference? I don't think I have ever come across it. If they don't then I would suggest feedback in the consultation could include that they review the requirements according to the performance of reasonably modern radios, and publish an updated policy on the matter.

Industry Canada has an admirably clear and comprehensive document setting out the criteria for assessing channel availability at http://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/sf09951.html.

At a quick scan through didn't reveal any concern at all for IF image protection, and I also noticed that the interference protection contours are assessed using 50% confidence levels for field strength, whereas I believe Ofcom uses a 90% confidence, which of course results in a far bigger potential zone of intereference from any given transmission.

In the US, the FCC goes one step further by making a "Low Power FM Channel Finder" tool publicly available. It is designed to give potential applicants "a simple means to tentatively identify FM broadcast channels available in their area." They also have a zoomable nationwide map to give an idea of how many LPFM channels may be available in any given area. They do apply separation requirements in respect of second adjacent and +/-10.7MHz channels. www.fcc.gov/encyclopedia/low-power-fm-channel-finder 

Alex

  ----- Original Message ----- 
  From: Ian Hickling 
  To: Glyn Roylance 
  Cc: cma-l ; cma-l at mailman.commedia.org.uk 
  Sent: Monday, September 30, 2013 3:44 PM
  Subject: [cma-l] Ofcom consultation: UHF and VHF spectrum planning


  I had a look but couldn't find anything solid.
  Rather than compare with other Regulators who will undoubtedly have other parameters and issues, I'd rather start at the root of the matter - that there is no clear evidence that IF imaging restrictions or severe protection ratios are required these days.
  It simply needs a few controlled practical excursions into "forbidden territory" to substantiate the premise.
  I wonder who might have the courage to do that?
   


------------------------------------------------------------------------------
  Date: Mon, 30 Sep 2013 12:19:51 +0100
  Subject: Re: Ofcom consultation: UHF and VHF spectrum planning
  From: glynroylance at googlemail.com
  To: transplanfm at hotmail.com
  CC: bill.best at commedia.org.uk; cma-l at commedia.org.uk; cma-l at mailman.commedia.org.uk


  Good point Ian - I'd forgotten about the 10.7MHz problem which is quite a big limit on frequency ability.

  I think the most useful step we can take in the short remaining time is to assemble some evidence that we can present to Ofcom  to avoid them saing we are arguing with "Hearsay".

  I've started some googling to look at Protection ration and ACS.  Could you find anything concrete on 10.7 MHz problem (ie evidence other regulators use more relaxed figures) Ian?

  If we can assemble the evidence it will make it easier to formulate a strong argument. ...

  Glyn
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