Freeview intermittent interference
Brian Butterworth published on UK Free TV There are several different types of interference that cause problems. This page deals with the situation where:
- Freeview reception is perfect or near-perfect most of the time
- The audio on TV and radio channels mutes momentarily a few times each minute
- The picture on a Freeview channel freezes a few times each minute
There are two main causes of this type of intermittent interference:
- 'Induction' interference
- Mobile phone interference
Induction interference
Induction interference is caused by mains-powered household devices that contain a large motor, such as:- Washing machine;
- Tumble dryer;
- Central heating pump or combination boiler;
- Fridge;
- Freezer;
- Power tools (drills, jigsaws etc)
- Vacuum cleaners;
- Water pumps;
- Automatic doors
You can identify if one or more of these devices is causing the Freeview reception problem by powering off the devices.
If one of these devices is causing the problem, then the reception problem can usually be solved by using a mains filter device and use it on the Freeview boxes mains connection.
Such as device is this: Maplin: 6-Way Flat Screen and HDTV Surge Protector and Mains Filter.
Mobile phone interference
If you keep a mobile phone by your Freeview box or digital television, keep it further away!This also applies to other transmitters such as baby monitors, video senders, walkie talkies, and portable phones.
Help with Freeview, aerials?
Friday, 20 December 2024
J
Jo1:22 PM
Abergele
Hi there,
I have been checking, through loads of your posts, and found them all really helpful. Unfortunately I haven't found anything that makes sense... except for this article. I am wondering if one of my neighbours has installed something that is causing interference. My channels have been off more than on, with no particular pattern, for a couple of weeks. They ALL went off for no reason a couple of weeks ago. I am thinking trying a a surge protector/filter might help? Unfortunately the link no longer works. Do you perhaps know another, please?
This site is fab, thank you for all the info!
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Jo's: mapJ's Freeview map terrainJ's terrain plot wavesJ's frequency data J's Freeview Detailed Coverage
Saturday, 21 December 2024
C
Chris.SE3:55 AM
Jo:
Hello Jo, sorry nearly missed your post amongst all the spam that's been appearing.
To start, just a point of clarity, a "surge" filter would be of no help whatsoever, that doesn't suppress interference of any type it just helps protect equipment from any mains power surges.
Whilst it's possible your neighbour(s) may have installed something causing electrical interference, it's one of the less likely problems. So we need to check other things and eliminate possibilities.
First, we need to establish which transmitter your are receiving, as you could receive at least two!
Your most likely is Moel-Y-Parc which is just under 19km away and you have line of sight to it (assuming no obstructions from nearby trees, local buildings etc).
The aerial should be pointing at compass bearing 117 degrees that's a few degrees south of ESE and its rods (or squashed Xs) should be horizontal.
Where is it located? On a chimney, wall, loft etc. Roughly how old is it?
If it's external, check the coax downlead is secure and not flapping in the wind.
2nd, do you have any aerial amp/splitter to feed more than one TV/box? (Make and model if you can say).
Are your signal OK at present? but do read on and check -
Like most main transmitters, Moel-Y-Parc has been having planned engineering at various times where the signal may be reduced or interrupted - the latter usually only for short periods. One thing you shouldn't do is retune when you have no signal, you can't tune to signals that aren't there!
The usual result is to clear the correct tuning and sometimes where you can get signals from more than one transmitter you get tuned to weak and unreliable signals from another transmitter.
So if you have retuned at any time you were having problems it will be best to check in your TV tuning section that you are correctly tunes the the Moel-Y-Parc UHF channels (assuming your aerial points at it - IF it doesn't, tell us which way it points and which regional news you normally get).
In the multiplex order BBCA/PSB1, D3&4/PSB2, BBCB HD/PSB3, SDN/COM4, ArqA/COM5, ArqB/COM6
The UHF channels are C45, C39, C42, C33, C36, and C48
For which TV Channels are carried on which multiplex see
Channel listings for Industry Professionals | Freeview
Please update us on the situation.
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Tuesday, 2 September 2025
Hi,
Live in Cardiff, and get my freeview mainly from Mendip.
Sig strength and quality up in the very high 90's.
Over the last month or so, the UHF sig has been breaking up quite a bit.
Thinking its possibly due to the increase of tall cranes and buildings going up.
However, if I go onto the HD channels, no problems, but of course the HD channels are a bit limited.
Any clues as to what may be the problem?
Also happens to a lesser extent from Wenvoe as well.
Thanks
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Wednesday, 3 September 2025
C
Chris.SE6:58 AM
Ian Kennedy:
Most likely a mixture or even combination of factors through different periods over the recent weeks..
Planned Engineering being one, Wenvoe is currently listed and Mendip had been a couple of weeks ago (and may well be listed again in coming weeks!). This can mean the transmitter or some of the multiplexes may be on reduced power for some periods or they may be using the Reserve Antenna which is lower down the mast. This can mean you may receive a lower signal strength and that can also be dependant on your local topography.
The other significant factor in recent times is weather conditions. High pressure weather systems sometimes result in what's called Tropospheric ducting where signals from distant transmitters travel a lot further than normal so any transmission on the same channels result in co-channel interference (CCI). Not all multiplexes are affected as the conditions can be frequency dependant and it depends on where the interference is coming from as not all UHF channels will be the same from a given transmitter which could be anywhere in the UK or (nearby) Europe! The usual effect of this depending on the strength of the interfering signals, is in the first instance to see the Quality % start fluctuating (it should be 100% in normal conditions). If the interference is strong enough, signal strength will also appear to drop and both can eventually become 0% as the combination of the signals appear to be just "noise" to the receiver.
Another possibility is interference from a new/upgraded mobile phone mast that's started using the 700MHz band, but this would normally be a constant interference so you wouldn't normally see fluctuations in quality or signal strength. Where this is most likely, you ought to have had a postcard from Restore TV about that possibility - have you? Unfortunately not everyone has, but in any event, they can/will supply Free Filters to eliminate the problem.
Do NOT retune when you have any such conditions as this can just clear the correct tuning - unless you manually tune the UHF channels of your chosen transmitter but again with strong CCI this can still result in incorrect tuning.
HTH.
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