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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
Saturday, 5 March 2011
J
Jim F
sentiment_satisfiedSilver

1:11 PM

Julian,

The ITV, C4 & C5 MUX from Oxford is on UHF channel 68 (until September).
The occasional atmospheric signal loss probably comes from Midhurst (analogue C4, nearly in the same direction as Oxford, but a bit further on).
UHF channel 68 happens to be the default RF channel for a Sky box. As the problem occurred just after Christmas, I'm wondering if a neighbour has connected their RF1 / RF2 output into their aerial, which might interfere with your signal.
You could try your TV aerial straight into an analogue TV tuned to UHF 68 and see if there's an analogue picture visible. If there is, you just have to find out which neighbour got Sky for Christmas.

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Jim F's 141 posts GB flag
Saturday, 12 March 2011
K
Ken
12:12 PM
Deal

Have recently moved to house in CT14 8AZ area near Dover. We've got a new toshiba with built in freeview that gives an excellent picture on all channels most of the time in spite of the fairly old looking aerial and the usual old brown coaxial.However,every couple of days or so,at different times we lose BBC1&2 by screen either fragmenting or blank with 'no signal' message and we then switch over to analogue which is still a fairly good picture. I realise that at some stage we will have to get a new aerial and cable,but do you think this would resolve our problem.If so can you suggest the most suitable aerial.I don't think our area goes digital until next year and I did'nt intend changing the aerial unless I had to due to the difficulty of getting to the chimney due to an extension being built. There are no buildings etc.blocking the signal. Thanks

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Ken's 3 posts GB flag
Ken's: mapK's Freeview map terrainK's terrain plot wavesK's frequency data K's Freeview Detailed Coverage
K
Ken
9:16 PM
Deal

A follow-up to my query,it looks like a missing multiplex 1 problem as its BBC3,CBBC and BBC NEWS24 as well as 1&2. I,ve made sure all video devices are disconnected as you suggest at the top of this page to eliminate local analogue interference,but still not on. Does this look like I need a wideband aerial ? Thanks Ken

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Ken's 3 posts GB flag
Ken's: mapK's Freeview map terrainK's terrain plot wavesK's frequency data K's Freeview Detailed Coverage
Sunday, 13 March 2011
M
Mike Dimmick
sentiment_very_satisfiedPlatinum

1:11 AM
Reading

Ken: you're not actually expected to get anything useful from the Dover transmitter at the moment. The problem is that you don't have line-of-sight to the transmitter, as there are hills in the way, and it's very low power right now.

It should improve next year (probably July, but it hasn't been announced yet), though it will probably never be rock-solid.

All transmissions from the Dover transmitter will be within the previous analogue aerial group. You should not need a wideband, indeed, a wideband will normally perform worse than a grouped aerial with the same number of elements. You need a Group C/D aerial, which will normally be smaller than a wideband with the same number of elements.

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Mike Dimmick's 2,486 posts GB flag
Mike's: mapM's Freeview map terrainM's terrain plot wavesM's frequency data M's Freeview Detailed Coverage
K
Ken
9:17 PM
Deal

Mike, Thanks for the reply. By the sound of it I should be thankful for the excellent freeview reception I'm already getting and just put up with a slightly inferior BBC 1&2 etc. when it starts messing about
Ken

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Ken's 3 posts GB flag
Ken's: mapK's Freeview map terrainK's terrain plot wavesK's frequency data K's Freeview Detailed Coverage
Tuesday, 15 March 2011
S
Sally
8:59 PM

Hi there - I have just bought a new flatscreen tele...and all channels are fine except BBC. Is the tele faulty or will this improve after end of March (or similar)? But actually my old tele still receives BBC ok so it must be the tele (but why??)

Tks
Sally

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Sally's 1 post GB flag
Wednesday, 16 March 2011
T
twright
8:15 PM
Uttoxeter

Hi!
We had a new aerial 18 months ago and have had great freeview reception since, until this week. Earlier this week we briefly lost all freeview but after a couple of hours it all came back again until tonight when again we have lost all freeview channels and despite checking the aerial connection and re-installing, we still have nothing. Analogue channels are also fairly poor but we are picking them up.

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twright's 1 post GB flag
twright's: mapT's Freeview map terrainT's terrain plot wavesT's frequency data T's Freeview Detailed Coverage
M
Michael
9:57 PM
Truro

I have tried to tune in a freeview box/tv on a wideband arial and am missing bbc2 itv3 channel 5 and lots of others. no other game consoles/ vcr and such like are connected. any ideas please.

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Michael's 1 post GB flag
Michael's: mapM's Freeview map terrainM's terrain plot wavesM's frequency data M's Freeview Detailed Coverage
Friday, 18 March 2011
S
SANDRA
9:20 PM

My Freeview TV has got no signal since i disconnected it to move to another part of the room. it was fine before this, and the aerial is on the roof xxx

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SANDRA's 1 post GB flag
Saturday, 19 March 2011
A
Alan Warner
12:42 AM
Bury St. Edmunds

Sandra,
If you have a aerial lead with a metal plug on (not moulded) the lead in the plug may of come loose. undo metal plug you will see braid on outside and a centre wire with insulation between them. if one strand of braid touches centre wire it will short out signal. remake plug connection so they do not touch togeather.
If you have a moulded lead it might be worth trying putting tv through a retune.
Alan.

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Alan Warner's 8 posts GB flag
Alan's: mapA's Freeview map terrainA's terrain plot wavesA's frequency data A's Freeview Detailed Coverage
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