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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, 22 June 2011
James Stirling
5:04 PM

Switchover day in Glasgow, cannot get Channel 43 programmes even after many efforts of re-setting, help please

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James Stirling's 2 posts GB flag
James's: mapJ's Freeview map terrainJ's terrain plot wavesJ's frequency data J's Freeview Detailed Coverage
Tuesday, 28 June 2011
George F
8:34 PM

Live in Lochwinnoch Scotland and use the Black Hill TX which gave me flawless digital terrestrial until the 2nd retune when I lost the BBC multiplex. Connected the aerial direct to TV and managed to tune the missing 20odd channels but signal strength is only 50% while all other multiplexes are at 95% or better.
BBC channels show No Signal or cycle on/off or pixelate on all programmes.
The aerial is Wideband Triax 52, a year old and the signal is good. Other folk in the area are having the same problem.
I updated the Sony TV software and during the auto-startup, the system found analogue broadcasting on Channel 61. The local BBC multiplex is on channel 60, too close I would have thought.
I am still waiting for a reply from Engineering as to whether this is causing the problem.

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George F's 1 post GB flag
George's: mapG's Freeview map terrainG's terrain plot wavesG's frequency data G's Freeview Detailed Coverage
Sunday, 17 July 2011

10:09 PM

George F: Your signal is probably too strong. If you have a booster or amplifier, disconnect it from your system. If you don't, then you may have to fit an attenuator.

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Briantist's 38,915 posts GB flag
Wednesday, 20 July 2011
3:49 PM


Any help appreciated. Brand new freeview Aerial and cable installed today, Chimney mounted. Cable running running directly to TV with no VCR or set top box in the chain.

I think it is running to Bluebell Hill (not sure as I didn't install it, but nothing on C or D which are supposedly good signals.


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Ian's 1 post GB flag
Ian's: mapI's Freeview map terrainI's terrain plot wavesI's frequency data I's Freeview Detailed Coverage

4:59 PM

Hi ian call the aerial riggers back to check if you have done it yourself call iut someone and have it done right

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Mazbar's 384 posts GB flag
Mazbar's: mapM's Freeview map terrainM's terrain plot wavesM's frequency data M's Freeview Detailed Coverage

5:52 PM

Ian: Purely for information purposes, the trade predictor for your post code presently indicates reception from Bluebell Hill being possible on Ch's 59(BBC.A) - 42(MuxC) - 39(MuxD) - 45(MuxB)

Sudbury on the other hand showing a superior signal on Ch's 41 - 44 - 47, but with Ch49 being poor with Mux's B,C & D not possible.

Predictors, even trade ones, having to be taken with a pinch of salt, as local conditions dictate what in reality is actually possible.

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jb38's 7,179 posts GB flag
7:20 PM

My panasonic tv has been working fine for 2 months, this sunday channels itv chn 4 5 more 4 all dissapeared. we did plug in the vcr on this date but got them back by scanning, and on monday all disapeared again. rescanning does not seem to be working. the ariel was fitted two months ago and the other 2 tv's in the house work fine?

any ideas?
Thank you

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Jessica's 2 posts GB flag

8:06 PM

Jessica try and disconect the vcr an rescan If you get your channels back you know its the vcr try this or you could call your aerial man he might be able to sort it out but there might be a call out charge if his aerial is ok

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Mazbar's 384 posts GB flag
Mazbar's: mapM's Freeview map terrainM's terrain plot wavesM's frequency data M's Freeview Detailed Coverage

9:14 PM

Jessica: Without wishing to intrude on what Mazbar has said, but just to add that "if" this only happens on the TV that the VCR is used with then the chances are that its RF output channel is clashing with the digital one.

If this does apply, then you can alter the VCR's RF output channel on the rear of older models, or if a later type of VCR via the menu.

This of course only applies if you are feeding the aerial to the TV via the VCR, i.e: looping in / out.

By the way on older VCR's you will see a small hole with 21 - 68 circling it, a small flat screwdriver being all that is necessary to "slowly" turn the adjuster whilst viewing the TV channel with the problem.

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jb38's 7,179 posts GB flag
Friday, 22 July 2011
4:14 PM

Hi guys,

Thanks for all that, just wanted to clarify, The ariel lead from the wall is going into a box (small box installed by the ariels guys) a wire then comes from this box and into the vcr, another lead then comes from the vcr and into the ariel hole in the tv. What I did was to connect via scart lead the vcr to the tv? the tv has been fine for 2 months, would the fact that the ariel is not connected straight to the tv be causing this problem now? the scart has now been removed but the leads mentioned before are still connected?
thanks in advance for your help.

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Jessica's 2 posts GB flag
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