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?
Sunday, 26 June 2016
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Sharon lloyd2:01 AM
Bristol
Hello
I have excellent reception daytime and evening but in the early morning, around 1pm I either lose reception entirely or experience severe digital dropout which makes any viewing impossible. I am situated in Bristol, BS2 0 LN to be precise.
The reception is excellent again at 5:00pm when I get up for work. If you give me any explanation as to why this is happening it would be most appreciated.
Kind regards
Sharon Lloyd
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Sharon's: mapS's Freeview map terrainS's terrain plot wavesS's frequency data S's Freeview Detailed Coverage
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Richard Cooper9:21 AM
Norwich
Sharon lloyd: Hi Sharon. According to Digital UK, you should be using the Bristol Barton House City Centre Freeview Light relay transmitter. This transmitter transmits at a low power of only 18 watts per group of channels. When I sat up late one night, I noticed a drop in signal strength between 1 a.m and 5 a.m myself and I'm using a main 100 000 watts per mux transmitter. Perhaps this is something that the transmitters are set to do overnight when there are few people watching television? By the way, if it is after one in the morning, we call this 1 a.m., not p.m.! a.m. is Latin for 'anti meridien', meaning 'before midday, whereas p.m. stands for 'post meridien', meaning 'after midday'. Think of 'posterior' meaning 'the rear'. p.m. is the rear end of the day! There are no faults or engineering works on your transmitter, so I'd suggest you check all of your aerial lead connections at the tv end and the wall plate end. Also, make sure you're not trying to watch your t.v. near an operating washing machine or fridge/freezer or mobile phone, because any of these can cause interference. Hope these comments help, Rchard, Norwich.
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Richard's: mapR's Freeview map terrainR's terrain plot wavesR's frequency data R's Freeview Detailed Coverage
MikeP
1:28 PM
1:28 PM
Richard:
I noticed in your response to Sharon Lloyd that you wondered whether the transmitters were set to reduce their power output at night. They are not. They radiate the same ERP all day and all night. If they didn't, they would not meet the requirement to serve the PSB channels to the whole of their service area all the time, the 'finge' areas becoming unserved due to lack of signal strength.
That has been the case since about 1954 when the early ITV transmitters started and were set up under an Act of Parliament. Those service requirements still apply today for all PSB services, but may be different for commercial transmissions. However, the equipment needed to turn dow the power of just the commercial services is not cheap and the saving does not warrant the expense.
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Richard Cooper1:50 PM
Norwich
MikeP: Hi Mike. Thank you for enlightening me regarding transmittter output power obligations on PSB providers since the year of my birth! Richard, Norwich. ~I also note that you've put lip sync issues in Salisbury down to viewers' equipment, in terms of decoding abilities, rather than transmission/broadcaster issues! Richard, Norwich.
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Richard's: mapR's Freeview map terrainR's terrain plot wavesR's frequency data R's Freeview Detailed Coverage
Monday, 4 July 2016
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Sharon lloyd1:22 AM
Bristol
Thanks for your help, really appreciated. I'll check out out my cabling ,etc. Apologies for putting "pm", I do know the difference but well done on knowing what time period I meant.
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Sharon's: mapS's Freeview map terrainS's terrain plot wavesS's frequency data S's Freeview Detailed Coverage
MikeP
1:27 PM
1:27 PM
Richard Cooper:
It is always difficult to determine whether lip sync issues are due to transmission or reception equipment. As it is not very common these days, the first check is the reception equipment. But as more and more people in the area served by the same transmitter were reporting the same problem it became clearer that it was more likely to be the transmission equipment end. Hence the first check, the viewers' equipment, and then the suggestion to contact BBC and hence Arqiva who operate the transmitters. I stated that the contact with BBC/Arqiva was worth following up. As it was subsequently proved to be at the transmitter equipment then those of us, me included, making the suggestion have been proved correct.
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Richard Cooper3:03 PM
Norwich
MikeP: Indeed. I only once experienced lip sync issues back in the day of one of my first digital set-top boxes. I may have been the 'ondigital' box, which I finally parted with just before DSO. I can't remember now, whether the issue was transmission or reception-based, but I probably did a re-tune. In any event, the issue cleared up without my going to the effort of contacting the Radio Authority or whoever one was supposed to contact back then. In the recent case of lip sync on HD in Salisbury, the right thing was for viewers to check their receiving equipment first, following this up with contacting the Beeb and/or Arqiva once satisfied that there was nothing amiss with receiving equipment. Richard, Norwich.
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Richard's: mapR's Freeview map terrainR's terrain plot wavesR's frequency data R's Freeview Detailed Coverage
Sunday, 12 February 2017
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Stephen4:56 PM
Nuneaton
I live in the cv10 0te area and get it from the Sutton Coalfield transmitter. I have had almost non existent reception since shortly after Christmas on all channels except BBC1,BBC2,ITV,C4 and Channel 5 all the others are impossible to watch most of the time , but even these 5 channels can be affected .On occasions I have recorded programmes that are perfect at the start and then suddenly deteriorate; or are unwatchable until part way through when they become perfect. It is almost as though something is being switched on or off. The reception is perfect usually, although in previous years there has been slight interference in winter.
Any idea what is happening?
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Stephen's: ...
MikeP
8:17 PM
8:17 PM
Stephen:
You are only 22 km from the Sutton Coldfield transmitter so should be getting very good signals. In fact they may be too strong and that is known to cause the type of problems you're experiencing. So please will you check what the signal strength is reported as by your TV set for each of the multiplexes used at Sutton Coldfield. You should check channels 43, 46, 40, 42, 45, 39, 33 and 35. Then report back here.
If the signals are greater than 85% it is definitely possible your have too much signal. If that is so, then search for 'too much of a good thing' on this website where Briantist has given guidance about how to resolve that problem.
If, on the other hand, your signal strengths are below 50% then you probably have a problem with your aerial cables. In that case, check them for integrity and make sure that water cannot enter the cables and that all the connections are in perfect condition.
It is not the transmitter else over a million viewers would be complaining!
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Tuesday, 14 February 2017
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Stephen1:37 PM
Stephen: I have checked the signal strengths as requested.
43,71%: 46,69%: 40, not there: 42,71%: 45,70%: 39,72%: 33,not there: 35,55%.
I did not say that I have a Humax FVP-400T 1TB recorder connected. When I first got the interference I disconnected the recorder and plugged the aerial into the TV and still experienced reduced interference. I then reconnected the recorder .
On Saturday the 12th there was bad interference so I disconnected the recorder and found decent reception directly through the TV. After E-mailing you, about 22:15 hrs I reconnected the recorder and found perfect reception on all channels. This has not changed to date.
I am wondering whether there is a problem with the TV end of the aerial connector, but since it is working now I don't intend to mess with it.
All though I wonder about the dramatic variability of reception previously.
Thanks for your help
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