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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?
How do I get a test card with Freeview1
I would like to know if it is possible to receive UK terrestrial Freeview servic2
I have been told I would receive too much singal from my Freeview tansmitter as 3
Can my Freeview box receive more than one BBC and ITV region?4
Is it true that my 87 year old mother is entitled to a FREE upgrade when the ana5
In this section
Official aerial installers guide to the TV spectrum future1
Which free digital TV system will give me the most reliable reception?2
High pressure causing channel loss through "Inversion"3
Digital Region Overlap4
Freeview reception has changed?5
Two frequency interference 6

Wednesday, 21 December 2011

8:08 AM

G: Please see Freeview reception has changed? | - independent free digital TV advice - it is hard to be sure without a full postcode.

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Briantist's 38,915 posts GB flag
Thursday, 22 December 2011
3:45 PM

My Transmitter is Rowbridge (IOW) My postcode is BH23 2NN. I have a roof ariel feeding 3 televisions by way of a small ariel splitter. It was working OK until 3 days ago and now I cannot get ITV1 or channel 4. Every other channel is Ok. Any Idears of whats wrong? Please
James Simpson

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James's 1 post GB flag
James's: mapJ's Freeview map terrainJ's terrain plot wavesJ's frequency data J's Freeview Detailed Coverage
Wednesday, 4 January 2012
12:01 PM

Am getting single freq interference on MUX 2 (itv etc). am in south london using Crystal Palace (i believe).
Both my Humax pvr 9150t and another freeview box in teh house have same issue. BOT feeding from same ariel on the roof.
theres no new means of interference in our house that can cause probs so am at a loss.
could recent storms be the cause?

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blueluny's 1 post GB flag
blueluny's: mapB's Freeview map terrainB's terrain plot wavesB's frequency data B's Freeview Detailed Coverage
Tuesday, 10 January 2012
2:40 AM

could be the signal is low as crystal palace transmitter changes in april the switchover for you

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spenc's 7 posts GB flag
spenc's: mapS's Freeview map terrainS's terrain plot wavesS's frequency data S's Freeview Detailed Coverage
Friday, 20 January 2012
allison Brown
9:44 PM

Hi I can see how you have solved it seems everyones problems hope you can help with mine. I checked the signal link it looks like Croydon/Crystal Palace SW9 . I retuned my TV which is ready for the switchover and had all the channels. On auto retune I lost ITV1
I have auto retuned a few times and cannot get ITV and above channels back.I also did the scan without the aerial as suggested and then started again with the aerial plugged in. I use an indoor aerial and have never had a problem in the last 2 years. I have unplugged the DVD the only other device plugged in and tried auto retune. ITV comes up in the 5 programmes found although not available on the guide DTV 76 found and radio 24 found. ITV 2 +1(no ITV2) and ITV 4 E4 +1 (no E4)
How do I get the ITV channels back and E4?

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allison Brown's 1 post GB flag
allison's: mapA's Freeview map terrainA's terrain plot wavesA's frequency data A's Freeview Detailed Coverage
Dave Lindsay

10:17 PM

allison Brown: You need to manually tune to UHF channel 22. This is where the missing channels are carried.

You may need to move your aerial in order for it to become available.

Once you have all the channels stored, don't retune (until switchover) if you get "no signal" or break-up; the remedy is to move the aerial. Retuning in such circumstances just causes more problems.

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Dave Lindsay's 5,724 posts GB flag
10:21 PM

Sorry email

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allison's 2 posts GB flag
allison's: mapA's Freeview map terrainA's terrain plot wavesA's frequency data A's Freeview Detailed Coverage
11:33 PM

Great I have them back yeh although lost BBC 4 . I think I am just going to forget about 'tuning'
Thanks for the help.

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allison's 2 posts GB flag
allison's: mapA's Freeview map terrainA's terrain plot wavesA's frequency data A's Freeview Detailed Coverage
Saturday, 21 January 2012
Dave Lindsay

11:22 AM

allison: BBC Four is carried on Mux B which is on Ch28. So do the manual tuning thing and select channel 28. Again, you might have to move your aerial for it to become available.

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Dave Lindsay's 5,724 posts GB flag
Wednesday, 8 February 2012
1:16 PM

Although not really interference (but neither are aerial group problems), selective fading due to multi-path effects, e.g. diffraction around an obstruction, could also knock out a single multiplex.

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David's 2 posts GB flag
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