[mythtv-users] UK Crystal Palace OTA reception issue on CH55

Mike Perkins mikep at randomtraveller.org.uk
Thu Mar 11 23:06:07 UTC 2021

On 11/03/2021 22:49, David Watkins wrote:
> I'm a long time UK MythTV user, originally recording analog TV and now
> DVBT2 dfreeview,  always broadcast from the Crystal Palace transmitter to
> the same roof mounted aerial that was on the house when I bought it.  I'm 5
> miles from the transmitter, with a reasonably good line of sight.
> The aerial looks like this one
> https://www.toolstation.com/loft-outdoor-tv-aerial-kit/p79595?
> but it's showing its 25+ years age and has a couple of bent elements which
> can't help.
> Nevertheless I've not had reception problems till recently when I've
> started getting regular MythTV recording failures for BBC 4 HD.
> BBC 4 HD is a relatively recent addition to the lineup and I think I can
> see the likely issue.  It's on a high-frequency low power multiplex.
> Looking here:
> https://ukfree.tv/transmitters/tv/Crystal_Palace
> I see that BBC 4HD is on the highest frequency multiplex (CH55 746MHZ) at
> 43kW, whereas all the other multiplexes I record from are below 700MHz and
> at 200kW.
> When the Crystal Palace Transmitter went digital I think I determined my
> aerial was suitable, but I'm fairly sure that at that time all multiplexes
> were on channel numbers less than 40?  I'm guessing that my aerial may not
> be suitable for the higher frequency multiplexes that have since appeared?
> So I've got two questions:
> Should my aerial be suitable for 746MHz - in which case I might look at the
> cabling and splitters.
> Is it worth worrying about that multiplex when the above website says this
> about it.
> *Being removed from Freeview (for 5G use) after November 2020*
> Does anyone here have any inside information about when/if that is likely
> to happen?  I could just remove BBC4 HD from my lineup and make do with the
> SD version.
If your aerial is that old it likely can't handle the range of frequencies we are expected to cover 
now. I recently had to replace ours (water ingress at the connecting box, filling the honeycomb 
cable with water) and the new designs cover a much wider range of channels.

I have to say that within 5 miles of CP you'd probably get a signal with a wire coathanger!

Some of the top end channels - I think 60 and up - are being sold off to 5G and the existing 
multiplexes crammed into the spaces below. In theory it seems to be a good idea but we all know 
about the difference between theory and practice.

The fact that the multiplex is disappearing soon doesn't mean that you'll lose any channels. All it 
means is that you'll have to rescan your channels to find it again. You may find, if you do it soon, 
that BBC 4HD is also being transmitted on another multiplex in preparation for the move.

You'll need to rescan soon, anyway. BBC3 is returning to the airwaves and doubtless that will mean a 


Mike Perkins

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