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Single frequency interference

What to do when several channels are missing, but they are all on the same 'multiplex'

What to do when several channels are missing, but they are all
published on UK Free TV

There are several different type of interference that cause problems. This page deals with the situation where:

There are two main causes of this type of intermitted interference: The current Freeview mulitplexes are shown in this diagram. If all of your missing channels are on a single row, you have "single frequency interference":

Local analogue interference

Local analogue interference is caused by household video devices that you can attach to a television such as:
  • Sky Digibox;
  • Video cassette recorder (VCR);
  • Personal digital video recorder (PVR);
  • Games console;
If you have any of these devices, you will need to work out which of these is blocking the reception of a Freeview multiplex by turning off the suspect device and then rescanning for channels on the Freeview box.

If powering off the device restores the Freeview channels from the blocked multiplex, you will need to either stop using the problem device's RF output by disconnecting the RF output cable permanently, or by changing the RF channel number that that device uses. See, for example, How do I change the RF output channel on a Sky Digibox?

You can find a list of the frequencies that are not in use at your location by putting your postcode into the My Freeview reception and looking under the "Free RF channels" section.

Non-wideband aerial in some areas

In some places you will need a wideband aerial to receive all the Freeview multiplexes. For example in Central Birmingham, the Sutton Coldfield has multiplex D on an 'out of group', so you cannot view Film4 or ITV2+1 without an aerial upgrade.

To find out if you need an aerial upgrade, see My Freeview reception.

Help with Freeview, aerials?
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In this section
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Two frequency interference 6

Monday, 5 December 2011
6:29 PM

hi - since switchover our freeview box keeps stuttering on BBC1, 2, BBC3 but is fine on all the rest. A digital television that shares the same signal is fine.
Before switchover the box was working fine.
Any ideas - or do we just need a new box?

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julie's 1 post GB flag

8:55 PM

julie: It could well be a box problem if your device is a few years old, so maybe you could give an update on the model you are referring to, plus of course your location (pref post code) to enable your reception possibilities to be assessed.

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jb38's 7,179 posts GB flag
Thursday, 8 December 2011
4:25 PM

Suddenly multiplex 2 [channels ITV1 etc] have vanished. Nothing else is plugged into the TV directly and the only addition to the plug is an adaptor for xmas lights. My sister, in the room above, gets all the channels as normal. We are in the Mendip region.

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Laura's 1 post GB flag
Monday, 12 December 2011
Jamie McKellar
7:26 PM

I need help, I live in PA209JE area, I run an aerial cable from the living room to a booster splitter in the hallway to 2 tv's. One in my bedroom and the other in my son's bedroom. Up until the beginning of November I got all the channels with no problems on both tv's. The problem is I have now lost all the ITV channles and channel 4 and 5 etc from my sons tv. On my own tv I have no problems. The distance for both tvs are the same from the splitter. My TV has freeview built in but my son has a digi box Vision STB 01 model. I have done all the rescans as in previous posts. I have removed the PS3 which went in about the same time but to no avail. Do I need a new digi box and if so can you advise which one

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Jamie McKellar's 1 post GB flag
Dave Lindsay

8:11 PM

Jamie McKellar: Take your son's set-top box to an aerial point which you know works and then tune it. If it has manual tuning, you need to enter UHF channel 59 for ITV, C4, C5 etc from the Rothesay Town transmitter. BBC should be tuned to UHF channel 50.

"UHF channel" is the frequency the services are broadcast on. If the UHF channels are 28 for BBC or 25 for ITV, then it the receiver is tuned to the Rothesay transmitter instead which is likely to cause issues as your aerial points at Rothesay Town.

Once you get the box tuned in, don't rescan. This is because having tuned it in, you know that it is tuned correctly and therefore that any remedial work must be to the signal which feeds into it.

If the aerial cable runs up the stairs and through doorways, perhaps it has been trapped or squashed by being trodden and it is this which is the problem.

Bear in mind that different equipment has different sensitivity. So you might find that one receiver works at one aerial point when another doesn't. It might be that the former "only just" works and the latter "only just" does not work.

If there is a control on the booster, then perhaps it needs turning down. Don't assume that if it doesn't work that it needs turning up! It could be, for example, that it's running on the high side and that some slight change (increase in level) of signal has pushed it up too high.

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Dave Lindsay's 5,724 posts GB flag
Thursday, 15 December 2011
Jill Castle
8:17 PM

Until Tuesday 14th December, our digital signal was OK. Since then, digita has gone completly and analogue is fuzzy. All the cables and updated aerial seem OK. Maybe it's weather conditions. We are TN26 3SQ.

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Jill Castle's 1 post GB flag
Jill's: mapJ's Freeview map terrainJ's terrain plot wavesJ's frequency data J's Freeview Detailed Coverage
Friday, 16 December 2011
Sunday, 18 December 2011
4:18 PM

hello i need help most of my channels are gone and the ones that are left you can not watch as they have really bad signal especially channel 4, e4 channels and itv one

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soukayna's 2 posts GB flag
4:58 PM

About a week ago I retuned and was left with only multiplexes C and D. I have been retuning every day and yesterday finally got everything except multiplex 2 which I have never been able to get, and apparently can't get until the switchover in April.

Today I have lost every single channel.They all say no signal can be received.

Is there something going on generally or is it my equipment? I am in Watford and getting signal from Crystal Palace.

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G's 1 post GB flag
Monday, 19 December 2011
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