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, 18 December 2022
D
David Shepherd5:13 PM
Canterbury
Hello,
Our post code is CT1 2AR our aerial appears directed towards the Dover transmitter.
In the past few weeks we have been getting intermittant break-up and stop/start reception on some TV channels, e.g.
4 Seven is particularly bad and BBC2 is nearly as bad. Our TV shows signal strength and quality that for most channels is around 80% but for 4 Seven it at best is 25% and fluctuates to very low values.
We have also been getting problems receiving Classic FM on our digital radios which have there own built in aerials.
We had good reception prior to these latest problems. Are you aware of any issues relating to the transmitters or known obstructions that may be causing this?
regards
David
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David's: mapD's Freeview map terrainD's terrain plot wavesD's frequency data D's Freeview Detailed Coverage
C
Chris.SE8:00 PM
David Shepherd:
Hi. Up until very recently there has been quite a lot of weather related Tropospheric Ducting which has been very intermittent and variable. It doesn't normally affect all multiplexes (and so the TV channels carried on them), usually just one or two, but it does depend on where the interfering signals are coming from. This can affect TV, DAB and FM. The S/SE can often be quite vulnerable due to proximity to France etc.
If you have been having problems with BBC2, you should have had similar problems with other BBC channels as they are all carried on the same multiplex BBCA/PSB1 (except the HD ones which are on BBCB HD/PSB3).
Similarly with 4Seven on the ArtqA/COM5 multiplex you should have seen problems with eg. Dave, Pick, Quest Red etc.
See Channel listings for Industry Professionals | Freeview for which TV channels are carried on which multiplex.
You are predicted to get good reception from the Dover transmitter, but also from the Chartham Relay. I assume you've looked at your aerial to make sure it looks intact and is still pointing correctly and the downlead is secure and not flapping in the wind.
If it's pointing at Dover it should be pointing at compass bearing ~145 degrees (10 degrees S of SE), with its rods (or squashed Xs) horizontal.
If it's pointing at Chartham, the rods will be vertical pointing at compass bearing ~247 degrees (almost WSW).
If you tried retuning when you had badly pixellated pictures or intermittent/no signal - which is never recommended if you were correctly tuned - that will often just clear your correct tuning or leave you tuned to the wrong transmitter with a weak signal which can disappear.
If you are pointing at Dover, check you are correctly tuned to Dover's UHF channels as follows -
In the multiplex order BBCA/PSB1, D3&4/PSB2, BBCB HD/PSB3, SDN/COM4, ArqA/COM5, ArqB/COM6
The UHF channels you should be tuned to are C33, C35, C36, C39, C42, & C48
If you are incorrectly tuned then do a full automatic retune or a manual one on those UHF channels.
Did your aerial get replaced at some point shortly before or since Oct.2019, how old is it?
Dover is one of several transmitters whose original UHF channels were in aerial group C/D. With the 700MHz Clearance programme these were all moved to lower UHF channels now requiring a Group K aerial (although Wideband/Group T would do in good signal areas). Freeview did provide free help with aerials during the clearance programme.
Lastly, have you had a postcard at all from restoretv.uk ? If so, there's a possibility you may get interference from newer/upgraded mobile phone masts and would need a free filter.
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Tuesday, 20 December 2022
D
David Shepherd5:32 PM
Thank you so much for a very detailed answer Chris.
I shall investigate the points you raised and hopefully discover the problem.
In answer to some of the points raised I can say:
We do get issues with the co-channels you mention but not as severe.
The aerial is pointed at Dover.
The aerial is secure as is the cable. The connection/amplifier boxes are in good condition and taped against water ingress.
The aerial has not been replaced; it was here when we bought the property in 2013.
As stated earlier there was no issue with reception up to a few weeks ago so I assume the aerial is of the correct type.
We have not had a postcard from restoretv.uk.
I shall investigate the other points you kindly highlighted, particularly with respect to tuning.
Again many thanks for the expert guidance.
David
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C
Chris.SE8:06 PM
David Shepherd:
No problem, post back with more information about this amplifier when you've checked out the other things when you have time.
Does the aerial have plain rods or squashed Xs? Does it have a coloured green bung in either end or is it black? Does it have a flat metal grid on the back or is it a more elaborate arrangement with several rods, maybe even a log-periodic? Some typical examples -
https://www.aerialsandtv.….jpg
https://www.aerialsandtv.….jpg
https://www.aerialsandtv.….jpg
https://www.aerialsandtv.….jpg
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Saturday, 1 April 2023
B
Brian Gooden7:57 AM
Have Sutton Coldfield transmissions on Com5 channels reduced since the regional HD changeover on BBC news etc? I continually get Com5 channel drop out, to the extent that the Sony Android set keeps retuning and dropping Channels such as Sky News, Pick, Food Channel off the EPG, and retune does not bring them back. Redditch is on the fringe for signal reception, but since installing a new amplified aerial system 4 years ago the reception has always been good until now. Retune will not bring channels back.
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C
Chris.SE4:38 PM
Brian Gooden:
There've been no transmission power changes at Sutton Coldfield (or elsewhere) all the multiplexes transmit at 200kW. The only "transmission" change was the closure of the Temporary COM7 HD multiplex in June 2022, The BBC's HD channels except BBC News are now on PSB3/BBCB HD.
There have been TV channel changes/swaps of the COM multiplexes by some of the commercial operators.
See Channel listings for Industry Professionals | Freeview for what should be an up-to-date list of which TV channels are carried on which multiplex.
You won't get a Local multiplex in Redditch.
Sutton Coldfield had been on Planned Engineering in the latter part of March so if your set auto-retuned when COM5/ArqA was down it may have tuned into the weaker Bromsgrove signal which could be on a side-lobe (or even within the beamwidth) of your aerial,
I suggest you turn OFF any auto (re-)tune function if possible, it is generally more trouble that it is worth often clearing correct tuning or tuning to incorrect signals during transmitter maintenance or even weather related signal disruption.
Check in your TV's tuning section that you are correctly tuned to Sutton Coldfield's UHF channels -
The multiplexes are C43, C46, C40+, C42, C45, C39+ that's in the order BBCA/PSB1, D3&4/PSB2, BBCB HD/PSB3, SDN/COM4, ArqA/COM5, ArqB/COM6
(ignore the + sets cope with that automatically).
As you haven't given a full postcode I can't give accurate comment about your likely predicted reception, but quite a few locations in the W/NW of Redditch & some other parts can get reliable signals from Sutton Coldfield. Check in your TV Tuning Section for where it may show UHF channel Signal Strength and Quality and post the figures for each one. This may give a clue to anything unusual that might be occurring.
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Saturday, 7 October 2023
R
Ron Riordan10:14 PM
Hi Ron from royal Wotton Bassett Swindon we have had intermittent poor signal all day today any reason for that ? Sn4 8ld has
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Ron's: mapR's Freeview map terrainR's terrain plot wavesR's frequency data R's Freeview Detailed Coverage
Monday, 9 October 2023
C
Chris.SE12:37 AM
Ron Riordan:
Apart from the Planned Engineering, at the Mendip transmitter, it could well be current weather conditions affecting you, they have been causing Tropospheric Ducting affecting much of the south coast and southern parts of the country on Saturday and now extending into the Midlands and North of the country through Sunday including East Anglia. This causes interfering signals from distant transmitters in Europe or the UK to affect reception of your wanted signals. This can periodically last, seconds, minutes and sometimes much longer - Do NOT Retune.
There is nothing you can do about this apart from wait for conditions to change, or use online streaming if available.
IF you did retune, you be best manually retuning the UHF channels for your transmitter.
The BBC have issued warnings -
High pressure weather conditions impacting TV & Radio services - 6th October | Help receiving TV and radio
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Friday, 20 October 2023
G
Geoff. Doxon2:09 PM
When Is Kendal (Oxenholme) Transmitter going to transmit the Digital channels. It was suggested that it would be in November 2023.
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C
Chris.SE3:17 PM
Geoff. Doxon:
Your question is rather puzzling! Which Digital channels are you referring to?
I take it you are referring to the transmitter to the ESE of Kendal, rather than the Kendal Fell transmitter to the West. In any event both transmit Freeview Digital TV signals (although it's only the 3 PSB multiplexes). Only the Kendal transmitter transmitter DAB radio signals.
However you should have no problem receiving that or several other main transmitters unless you are right in the bottom of a valley in which case we'd need a full postcode to try and check predicted reception. Also you need to be specific as to which digital signals or stations (TV or Radio) you are trying/wanting to receive.
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