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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 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.

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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
Friday, 18 February 2022
P
Paul Taylor
5:08 PM
Rotherham

Why does my Panasonic TV switch itself off and then on again a few seconds later?
I have a Panasonic TX-L32D25B. It's about 11 years old and basically still works fine. The current software is showing as 2.408. It is not connected to the Internet and never has been. We only use Freeview.
The aerial system is over 30 years old but we do not have any other problems.
We are at Rotherham (Post Code S60 5NP). As far as I know we receive signal from Emley Moor with a horizontal aerial but people nearby receive from Sheffield with a vertical mount so we could be in a dual transmitter zone. (I was once told by an aerial installer that the people down the road have to receive from Sheffield because the hill I live on is in the way of Emley Moor.)

This problem has occurred several times over the last few years. Our local TV repair shop once told me that it was something to do with an off-air component (maybe from the BBC) affecting the software on certain Panasonic models. He advised to disable the off-air update feature through the Setup Menu options. He also said to switch the set off at the mains and after few seconds Press and Hold the Red Power Button on the Handset : switch the set on at the mains while holding the Red Power Button until the picture appeared. I did all this and after a few attempts everything worked ok........until next time which could be months later.

This has happened again recently............
The TV set had been on from about 19:30.
From 20:00 to 21:30 we had been watching a pre-recorded program from our Panasonic DVD recorder (DMR-BW780) connected via an AV/HDMI input.
After 21:30 we found a program on MORE4 (Channel-18) and watched the last half of it via the TV tuner until it finished at 22:00.
We found the same program on MORE4+1 (Channel 86) starting at 22:00 so we set about watching the first half.
After about 10 minutes the TV switched itself off then on again after a few seconds.
This happened a few times so I did the bit with Red Power Button etc but the set still kept failing so we gave up and switched to ITV1 News-at-Ten on Channel-3. But the TV still kept going on and off.
So I switched to the DVD Recorder on the AV/HDMI input : set the DVD to ITV1 on Channel-3 and watched the rest of the news without any problem.
Then watched another program (or recording) via the DVD recorder for another hour without any problem.
The next morning it switched off and on once while tuned to BBC1 on Channel-1.
Dare I say it's been ok since then??!!

Online comments suggest it is some kind of overheating problem in the TV but I'm not convinced about that. As I see it the original suggestion by my local TV shop about some off-air component affecting the TV software (but not the DVD recorder) does make some sense especially when tuned to a non-mainstream channel. Something similar to this has happened in the past with an obscure channel but I can't remember which one.

It may or may not be a relevant aside we used to have a problem with the DVD recorder. If it was tuned to CHANNEL4 (Channel-4) or any of its associates CHANNEL4+1 : MORE4 : 47 : etc but not CHANNEL4_HD - it used to lock up and get stuck on that channel. Eventually I found a work-around to get off it. It seemed to happen after about 21:00 as if CHANNEL4 was transmitting some sort of parental control feature. I haven't noticed it recently so might have been sorted but it did seem to be caused by some off-air signal rather than a problem with the DVD recorder. It didn't affect the TV and it would all work correctly the next day until about 21:00.

Apologies for the lengthy description. I've read some your Q&A and have tried to answer some questions before you need to ask.
My question is...... Are there any off-air signals that could cause this problem? Any ideas to help could be useful. The TV set is proving to be unreliable. Maybe we need to replace it but that could create as many problems as it solves.

Many Thanks

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Paul Taylor's 4 posts GB
Saturday, 19 February 2022
C
Chris.SE
sentiment_very_satisfiedPlatinum

8:22 AM

Paul Taylor:

I'm not familiar with your set, but a few things occurred to me as I was reading.

My first reaction was to do with the DVD Recorder. I've certainly come across stories where the signal to the set disappears at various times depending on what recordings have been set - this is on the assumption your aerial is fed through the recorder and then on to the TV.

So my first question is - are you sure the set is actually switching off? Or is the screen just going black and no sound for those few seconds?

My next thought was that if it was anything to do with anything in the transmitted signal, the this would undoubtedly be as a result of a bug in the set's firmware. You mentioned the set has never been connected to the internet so I guess it's never had any firmware update, so if there was a bug, it could be fixed in a later update.

You said your aerial installation was around 30 years old, but wasn't giving you any problems. Are you absolutely sure of that? Where is the aerial? If it's external then water ingress could be an issue. Is the downlead secure or can it flap about a bit in the wind? Degradation of an aerial installation can reduce the signal somewhat and if it's become marginal then anything that affects the received signal could mean it disappears briefly. Having said that, and considering the periodicity of your issue it may only happen under certain weather conditions.

Have a look through your TV's tuning sections and see if you can find the Signal Strength and Quality figures (or Error/BER) for each UHF channel multiplex and post the figures for each. This may help eliminate or identify any signal issues.

I'd be inclined to connect the set to the internet and look for a firmware update - there is one. If you can't do it that way, you can download it from here -
Download Information of TV 2010-year Models for UK | Download | TV | Digital AV | Support | Panasonic Global
The page also has information on how to do it using that method.

One other idea, make sure your HDMI leads are not close to any aerial or flyleads especially if the aerial and flyleads are not high quality double screened types as HDMI has been known to cause interference.

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Chris.SE's 2,960 posts GB
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