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Freeview intermittent interference

When you get occasional sound loss or picture freezes

When you get occasional sound loss or picture freezes
Published on by on UK Free TV

There are several different types of interference that cause problems. This page deals with the situation where:

There are two main causes of this type of intermittent 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: <img src="data:image/png;base64,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" class="xico" style="vertical-align:text-bottom" alt=" link icon"> link iconMaplin: 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.

Freeview, aerials?
My Freeview box has no EPG, is blank on FIVE, ITV3, ITV4, ITV2+1, has no sound o1
I have now lost all signal can you tell me what the problem might be?2
My ITV/C4 Freeview channels have disappeared - what can I do? Is it my SCART ca3
Our digital signal for ITV has disappeared in the last week - can you tell me w4
My high gain aerial can't get all the Freeview channels I expected5
In this section
Which free digital TV system will give me the most reliable reception?1
High pressure causing channel loss through "Inversion"2
Digital Region Overlap3
Freeview reception has changed?4
Two frequency interference 5
Single frequency interference6

Wednesday, 19 November 2014
10:27 PM

Kevin Ross: Your about 25km from Black Hill, so not that far. Have a look at the signal strength...

link to this
MikeB's 1,152 posts Gold Gold GB
Kevin Ross
11:08 PM Glasgow

Hi mike. Thanks. But my signal strength is 70-76% for most channels with the HD oNes all being 76 so too strong a signal would not seem to be the problem especially as my problem only started 4 weeks ago. Any other suggestions?

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Kevin Ross's 5 posts GB
Kevin's: Freeview map terrain plot frequency data R&TI Service digitaluk trade DAB coverage
Thursday, 20 November 2014
Dave Lindsay
12:30 AM

Kevin Ross: Have you checked that you are tuned to Black Hill rather than Darvel, assuming your aerial points to it? Darvel's channels are lower down and will therefore be picked up before Black Hill's.


BBC One = C22
STV = C25
BBC One HD = C28
ITV3 = C23
Pick = C26
4Music = C29

Black Hill's six channels are 46, 43, 40(HD), 41, 44 ,47

link to this
Dave Lindsay's 5,291 posts Platinum Platinum GB
Kevin Ross
6:43 PM Glasgow

Dave. Can I choose which transmitter I can pick UK? It's a communal aerial. Also, it's a problem that's only just started 3 weeks ago and almost always only on hd channels and very rarely SD

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Kevin Ross's 5 posts GB
Kevin's: Freeview map terrain plot frequency data R&TI Service digitaluk trade DAB coverage
Dave Lindsay
8:28 PM

Kevin Ross: The UHF channel numbers I gave above are normally given on the signal strength screen. Confirm that those of Black Hill are tuned rather than those of Darvel.(I assume here that your aerial points to Black Hill which is due east.)

If you find that it is tuned incorrectly then you need to retune, either by:

- clearing what's already stored and manually tuning the five (six if it's HD) channels, or;
- having the aerial unplugged for the first portion of the scan where Darvel's channels are one way to avoid it. Plug in at 30% or once it's scanned UHF channel 30 if it gives channel numbers.

However, this only need be done if it's tuned incorrectly.

Communal aerial systems are often filtered so as to only allow through from the aerial the frequencies used by the designated transmitter. Therefore, under such circumstances it's not possible to pick up the "wrong" transmitter.

Any 4G 800MHz filter should be fitted before any signal amplifer/booster as the 4G signal can overload it. As it's a communal system then it will have an amplifier and so fitting the filter in your dwelling won't stop the 4G signal from going through the amp.

See if others in the block have the same issue. The fact that they don't doesn't necessarily mean that it isn't an aerial system problem but the fact that you have been provided with a 4G filter suggests that your address could be expected to issues. In which case you need to contact the party responsible for the aerial system to get it put right.

You will not need a filter adjacent to your TV/box as the system will be filtered, so it will serve no purpose.

My advice would be to keep it. at800 (the organisation giving out these filters) is only giving one per address. If you know someone who needs two you might like to donate your unwanted one, rather than throwing it in the bin.

link to this
Dave Lindsay's 5,291 posts Platinum Platinum GB
Kevin Ross
10:15 PM Glasgow

Thanks Dave. My tv and youview box are tuned into black hill but when I check the quality of signal on hd channels the bar fluctuates wildly! What do you think is the cause?

link to this
Kevin Ross's 5 posts GB
Kevin's: Freeview map terrain plot frequency data R&TI Service digitaluk trade DAB coverage
Friday, 21 November 2014
Dave Lindsay
12:02 AM

Kevin Ross: Try a different lead from wall socket to Youview box. If the problem remains then it rather points to the issue being with the signal that is coming out of the wall socket, in which case it doesn't actually matter what the issue is as it's not your job to fix it - you simply report it to the responsible party.

But the fact that the 4G filter arrived and that the signal is poor suggests that it could be a 4G signal overloading the amplifier, which needs an engineer sort it.

link to this
Dave Lindsay's 5,291 posts Platinum Platinum GB
Monday, 24 November 2014
8:13 PM Cambridge

Michael: Thank you everyone for your comments. I have since tried a TV with inbuilt freeview which worked fine, suggesting that the signal quality etc is good. But we realised that my old box was not picking up at least some of the HD channels. So it appears that the problem might be my old box, being unable to receive HD, with the problem now very much with the non-HD channels BBC1 and 2 when we often get no picture at all, while channel 3 and others are generally reasonable.Could it be that non-HD BBC1 and 2 have become weaker over the past few weeks, and now are weaker in some way than other non-HD channels? Not sure about the correct terminology by the way.

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Michael's 2 posts GB
Michael's: Freeview map terrain plot frequency data R&TI Service digitaluk trade DAB coverage
9:22 PM

Michael: You tried in with another device - what was the transmitter the TV was tuned into, and what where the signal/quality levels?

Assuming they were fine, and it was to Sandy Heath, two things occur to me.

Firstly, your problems are still with BBC1 & 2. They tend to be more powerful signals, so if you do have too high a signal strength (and you are really pretty close to the transmitter), they will be the first ones to really have a problem. The TV you tested might just have a rather less sensitive tuner than the box.

There is no reason why BBC1 & 2 might have become weaker suddenly, so logically, if the signal is weaker, it must be something in your system at fault. Since the TV you tested was fine (it would be nice to know the make and model, as well as the readings), I suspect that its the box, and its simply a bit more sensitive, hence the no signal problems, etc.

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MikeB's 1,152 posts Gold Gold GB
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