Digital Region Overlap
The old analogue TV signals provided lots of nations and regions for the public service channels, and these have large areas of overlap. Places like Yeovil, Basingstoke, Colwyn Bay, King's Lynn, York and Berwick could choose the BBC and ITV services they watched.
The old low power digital TV signals were at very low levels and reception of signals from more than one transmitter was a rare event.
All Freeview boxes automatically scan the available broadcast frequencies looking for channels, and they do this from C21 to C69. Whilst scanning, if a duplicate version of a channel is found, such as another BBC One region, they are placed in the 800-899 channel range.
The 800-899 is easy to access by pressing CH- from 1, and in most programme guides is just a single scroll up.
The transmitters in Wales also put Channel 4 on "logical channel number" 8, because the fourth position is reserved for S4/C.
Quite a few people that use the Winter Hill or Mendip transmitters (or one of the relay transmitter) will probably find that they will now have:
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What can I do about this?
There are basically three options.
OPTION 1: Live with it. If the signals are strong enough you get a few extra channels (S4/C has English subtitles). There are techniques for sorting out the channel numbers below, but any future automatic scan will restore the channels to the order you now find them in.
OPTION 2: You can clear the all of the channels from the box and manually scan for the multiplex from only one transmitter. For the details, see the transmitter pages
OPTION 3: If the Freeview box has no "manual add" option, the only technique left is to pull out the aerial, start the automatic scan and insert the aerial just before the lowest channel number appears. For example, Winter Hill this is C54.
Some Freeview boxes will show a "percentage complete" as they scan, under this scheme C21 is "0%", C22 is "2%", C42 is "42%", C54 is about "66%".
Even if you manual scan, many boxes will scan during the night for new channels and may still add channels in the 800-899 range.
11:50 AM
Godalming
Look for a menu button. Then there should be something like setup/add channels/diagnostics then Automatic search. however, it depends on model specifics.
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Matt's: mapM's Freeview map terrainM's terrain plot wavesM's frequency data M's Freeview Detailed Coverage
J.ahmad: Have a look on the Freeview Retune - list of manuals | ukfree.tv - independent free digital TV advice page.
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1:45 PM
I have a 28 element group A aerial aimed at CP, but am suffering from unwanted signals from SH. The angle between CP and SH is 112 deg at my location. Do you know of any way of shielding my aerial from these emissions, or indeed any way of mitigating the problem ?
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6:58 PM
Colin Wray: As you are getting this problem at not too far away from an aerials least sensitive position, that of side on at 90 degrees from its direction of pick up, then there isnt really much chance of any normal aerial achieving what you want, although a grid or a log periodic (suitable shielded) might be slightly better in this respect.
Of course another aspect has to be taken into account, that of Crystal Palace being 38 miles away and operating on a 10Kw low power multiplex on Ch31, whereas Sandy is only 22 miles away with its Mux Ch31 operating on 20Kw.
As you can see both these things are against you, although if the TX powers at each end were reversed that would have been beneficial to you, but of course they aren't!
This being said taking it that you are referring to the Mux channel 31 problem.
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9:21 PM
Colin Wray: You could use a stacked array if you had a lot of time and were really determined. What model is your current aerial?
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12:10 AM
Yes, I was referring to the channel 31 problem, although I am also missing Mux C and Mux D. I have looked at the signal strength of every channel with only one of my two aerials connected, so I am sure Mux D absence is not due to OX C29. The absence of Mux C cannot even be blamed on digital overlap, I cannot get either from OX or CP individually.
What is a "stacked array".
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10:35 PM
Colin Wray: Please see:http://www.wrightsaerials.tv/topics/stacking-aerials.shtml and http://www.wrightsaerials….pdf
and http://www.wrightsaerials….pdf
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10:27 AM
Thanks for the links !! I have now made a chart of all the channels and changes which seems to show that most if not all conflicts will be resolved on 28th Sep 2011, so I will keep ny fingers crossed until then.
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Is anyone else having problems with STV HD? I have an Humax HDR Fox T2 and a couple of weeks ago there was problem with lip sync on this channel but only lasted one night.
This has now been 'replaced' by a really annoying 'flicker' which looks like someone is using a camera flash! It can happen from every minute to every 5 minutes which is soooo distracting!
It is the only channel which is affected so cannot be connections or the telly etc.
Along with this I am having real problems tuning in the Mux containing STV, Channel 4 and 5 etc. An autoscan results in lots of extra channel and using Manual search results them in all being grouped together under channel 0.
My transmitter is Rumster Forest.
I've only had the PVR for about three weeks and everything was fine until a week ago.
If anyone can help I'd be very, very grateful.
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1:15 PM
Liz Falconer: You should carry out a signal check on Mux Ch21 (the HD channel) to check if the quality of the signal you are receiving is reasonably stable, or if its diving up or down, which up to a point could be outwith your control albeit you are only 13 miles away from the transmitter.
I realise you have already carried out an auto-tune, but its always best blanking anything stored in the memory out before auto-tuning, this done by carrying out the first scan without the aerial being connected, then after re-connecting scan as would normally be done.
Or of course just carry out a factory re-set!
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