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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
Tuesday, 30 July 2013
Briantist
sentiment_very_satisfiedOwner

10:52 PM

Tony: there are no analogue TV signals in the UK anymore....

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Briantist's 38,910 posts US flag
Saturday, 10 August 2013
D
Derek
8:10 PM

I was provided with a freeview box by the BBC. My freeview box stop working after a tear, so I bought a freeview built in TV. It worked fine for about a month then I started losing the channels slowly and now I don't get any channel at all. What is wrong?

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Derek's 1 post GB flag
J
jb38
sentiment_very_satisfiedPlatinum

9:26 PM

Derek : The problem could be caused by fault in your aerial system or even just a defective jumper lead from an aerial wall socket, should one be used! however no-one is in a position to provide more detailed advice without having knowledge of your post code or alternatively one from somewhere nearby, e.g: a shop/post office, as this would then enable an assessment to be made of the reception expected at your location as well as details of the source of, meaning transmitter station.

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jb38's 7,179 posts GB flag
Tuesday, 27 August 2013
S
Stav
8:20 PM
London

Don't have a problem any more, but just wanted to say thank you to all the helpful people on here.

I had lost all the BBC channels, out of the blue, and found a wealth of information on here that helped me pinpoint and then fix the problem. I lost all of the BBCA multiplex (i thought a multiplex was a cinema with lots of screens!) I am surrounded by phone masts (15 within 1.5km) and am soon going to add a 4g transmitter to the list. (Yes I live in North London, how did you guess.) Anyway, I re-tuned, no joy, and also did manual re-tune for the correct channel. Finally solved the problem by doing a re-tune again, and this time setting the 'regional variant' section at the end of tuning, to 'England' for primary (previously 'any') and then the secondary to 'London', (also previously 'any'). Now the original config., worked fine for the last several months, and all went pete tong in the last few days. So anyone with similar problems may want to try this before taking the advice of at800 etc who suggested buying lots of equipment.

Once again thanks to the knowledgable posters on here who helped me by giving lots of good information, that helped me track down the problem, wasting only a few mins of time rather than a fortune in unnecessary gadgetry.

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Stav's 1 post GB flag
Stav's: mapS's Freeview map terrainS's terrain plot wavesS's frequency data S's Freeview Detailed Coverage
Wednesday, 18 September 2013
N
Neil margerison
11:27 AM
Shipley

No signal reception all ok on two smart tvs until approx 11.00am then no reception on any channel on either
Bd17 6aw

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Neil margerison's 4 posts GB flag
Neil's: mapN's Freeview map terrainN's terrain plot wavesN's frequency data N's Freeview Detailed Coverage
N
Neil margerison
11:27 AM
Shipley

No signal reception, all ok on two smart tvs until approx 11.00am then no reception on any channel on either
Bd17 6aw today

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Neil margerison's 4 posts GB flag
Neil's: mapN's Freeview map terrainN's terrain plot wavesN's frequency data N's Freeview Detailed Coverage
M
Michael
sentiment_satisfiedGold

11:40 AM

Neil margerison: Radio & Television Service

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Michael's 358 posts GB flag
Friday, 4 October 2013
A
Andy
7:02 PM
Manchester

Everything on COM4/CH58 (Winter Hill)shows no picture with bad sound break up on my Sony TV. Signal strength shows as 100% with good sig quality, EPG for COM4 working. All other channels OK, have tried an attenuator; no difference. This only started ~ 2 weeks ago - no RF modulators anywhere near CH58 - no changes to kit or cabling.

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Andy's 6 posts GB flag
Andy's: mapA's Freeview map terrainA's terrain plot wavesA's frequency data A's Freeview Detailed Coverage
M
MikeB
sentiment_very_satisfiedPlatinum

8:10 PM

Andy: I've got Sony equipment, and the tuner is sensitive, but more tolerant of high signal strength than some other brands. However, mine will start to break up at around 93% - since your on 100%, your going to have problems.

Your 29km from Winter Hill, which is relatively close, and there was engineering work on the transmitter in August - which often results in the power going up. Its the signal strength which has changed, not your kit.

To paraphrase 'Jaw's' - "Your going to need a bigger attenuator". Of course if anyone else has an idea...

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MikeB's 2,579 posts GB flag
J
jb38
sentiment_very_satisfiedPlatinum

9:38 PM

Andy: When you say "good signal quality", have you observed this over about a minute or so (min) to be able to determine if any fluctuations are seen in the quality? as in practically every occasion picture break up goes hand in hand with intermittent drops in quality, these sometimes being of a rapidly occurring nature in areas surrounded by trees such as would appear to be applicable in your particular area.

The other point being, should you be using a communal aerial then you should check if anyone else is experiencing problems with their ITV3 reception.

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jb38's 7,179 posts GB flag
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