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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

Comments
Monday, 11 April 2011
J
John Davenport
6:37 PM

Help!
Rdcently, for maybe 4-6 weeks, there is a problem with getting MUX1/PSB1 on CH22 during periods of high pressure in Lighwater GU18 5 - a fringe reception area for Crystal Palace - leading to severe pixellation and unwatchable ITV1/CH4/CH5/ITV2 etc, particulary from late afternoon into the evening.

Crystal palace is 26m/41km at 78 deg from here.

Plenty of signal and no problems with other MUXs from CH25 to 34

Is there another digital MUX in south east Engalnad or across the channel that is in 'line of site' after trophospheric reflection?

Having a wideband aerial plus amplifier aerial I may try and point at a more local transmitter - Guildford - does anyone know whether the Guildford transmitter has directional transmission? My reception not helped by being positioned in a dip with trees partially obscuring siganl paths.

Analaogue TV Ch23 - 27 all good with Unix 52 wideband aerial fitted a few years ago.

Can't put up with this for a year until DSO

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John Davenport's 1 post GB flag
Tuesday, 12 April 2011
Wednesday, 13 April 2011
S
sue
5:07 PM
Dudley

Got no freeview channels except bbc 4 and radio since yesterday , 12th april , It was fine when I went out and like this when I returned. my son and daughter and myself have tried re-tuning manually and automatically to no avail. My aerial is on the roof and no problems of late until this... Don,t know what else to do Can anyone help? We.ve turned it off at the plug and nothing changed..

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sue's 1 post GB flag
sue's: mapS's Freeview map terrainS's terrain plot wavesS's frequency data S's Freeview Detailed Coverage
M
Mike Dimmick
sentiment_very_satisfiedPlatinum

6:19 PM

Sue: You're probably using the Brierley Hill transmitter. This was off-air during the day yesterday and today for some engineering works. It should now be back on - work was due to finish at 6pm.

You will probably need to retune again as the box has most likely forgotten where all the channels live, when you retuned it earlier.

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Mike Dimmick's 2,486 posts GB flag
Thursday, 14 April 2011
R
Rachel
9:10 PM

I live in Cheltenham GL50 and I have interference with all channels on Multiplex 2 e.g ITV2, channel 5, More 4 etc. I have tried resetting factory settings, moving electronic equipment from around the TV but these channels still have interference. Any advise most welcome. (51.9057,-2.0716) 

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Rachel's 1 post GB flag
Friday, 15 April 2011
Briantist
sentiment_very_satisfiedOwner

7:54 AM

Rachel: I would wait until next Wednesday when the Ridge Hill transmitter completes switchover.

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Briantist's 38,910 posts GB flag
P
Pete
7:22 PM
Grantham

I cannot get ITV CH4 or CH5 on my freeview box or my integrated freeview tv since tues 12 April I have tried retuning both to no avail. I have had no trouble untill now. I assume that the signal strength has been reduced, will it be restored sometime soon?
I live in Grantham about 12 miles from Waltham transmitter.

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Pete's 1 post GB flag
Pete's: mapP's Freeview map terrainP's terrain plot wavesP's frequency data P's Freeview Detailed Coverage
Saturday, 16 April 2011
Wednesday, 20 April 2011
J
joihn quinn
5:10 PM

i have three televisions an alba,technika,and a sony bravia all have lost channels 12,15,24,and 30 sence change over at sandy heath transmitter can someone tell me when this will resolved please
john q

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joihn quinn's 1 post GB flag
Briantist
sentiment_very_satisfiedOwner

5:13 PM

joihn quinn: You will have to wait until 14th September 2011 when the ArqB multiplex is put on full power on C48.

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Briantist's 38,910 posts GB flag
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