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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.

Help with Freeview, aerials?
How do I get a test card with Freeview1
I would like to know if it is possible to receive UK terrestrial Freeview servic2
I have been told I would receive too much singal from my Freeview tansmitter as 3
Can my Freeview box receive more than one BBC and ITV region?4
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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
Sunday, 1 December 2013
J
jamie stevens
sentiment_satisfiedSilver

5:20 PM
Havant

Emma:

for people to assist with likely problems its easy to know the postcode of the property, we can then check the local terrain and which transmitter your using.

If a signal is marginal (iffy) then you are more likely to have problems at night rather than during the day.





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jamie stevens's 207 posts GB
Monday, 2 December 2013
E
Emma
7:44 AM
Newton Abbot

Ah ok, my postcode is TQ12 3AN....Thanks

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Emma's 3 posts GB
Thursday, 12 December 2013
M
Mr Fowler
7:07 PM
Burnham-on-crouch

CM0 8QD, like everyone else here we have 2 aerials, one aimed at Sudbury, one aimed at Dover. We've had intermittent reception on the commercial channels in the last 2 days.
The aerials feed into the vhf and uhf inputs on an amplified splitter. What is the best way of feeding 2 aerial signals - both into the vhf input? Should we only feed one full signal transmitter, and one public broadcast transmitter into the splitter? Regrettably yhe local Burnham on Crouch public service transmitter beams in the opposite direction to our house.

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Mr Fowler's 1 post GB
MikeP
sentiment_very_satisfiedPlatinum

8:08 PM

Mr Fowler:
Using the VHF input is a real problem. The signals you are want to use are *UHF* so will not pass through a VHF filtered input properly.

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MikeP's 3,056 posts GB
Dave Lindsay
sentiment_very_satisfiedPlatinum

8:09 PM

Mr Fowler: Over the last couple of days there has been a lot of reports of co-channel interference, with reception of French channels reported. The area affected, according to reports seen on this website is the east of England from Yorkshire southwards through East Anglia and Cambridgeshire to Kent and Sussex.

Ideally, two TV aerials should be combined using a diplexer:

Television Aerial Boosters / Amplifiers, Splitters, Diplexers & Triplexers

Unfortunately though, the PSB and COM channels used by Sudbury and Dover respectively can't be combined with a C51 diplexer as COM6 wouldn't be available (it being on C48).

Alternatively, combining Burnham and Dover with said diplexer would leave you without COM6 from Dover and without PSB2 (C49) from Burnham.

I would suggest that the Burnham relay might serve you, the coverage map on this site appearing to be wrong. I say this having looked at the photos of the transmitter:

mb21 - The Transmission Gallery

The trough antenna part way up the tower points to Sudbury which is roughly due north. The sets of crossed logs at the top are the broadcast antennas and are pointing roughly 45 degrees clockwise of the receive trough. This would make sense as Burnham-on-Crouch is to the north east of this site!

You appear to have clear line-of-sight to Dover which is 41 miles away:


Terrain between ( m a.g.l.) and (antenna m a.g.l.) - Optimising UK DTT Freeview and Radio aerial location


The downside is that this is over 15 miles of water which can be prone to mist which might inhibit the signal. It is also the case that your aerial is pointing towards France.

Clearly there is no given as far as receiving the COM channels goes. Despite also being 41 miles away, you don't have line-of-sight with Crystal Palace. If you did then that would be possible to diplex with Burnham or Sudbury for PSBs.

One observation I will make is that the bearing of the Burnham relay and of Bluebell Hill in Kent is only three degrees apart, and they are both horizontally polarised.

The terrain plot would suggest that you probably have line-of-sight to it at 25 miles:


Terrain between ( m a.g.l.) and (antenna m a.g.l.) - Optimising UK DTT Freeview and Radio aerial location


Despite this, Digital UK suggests that reception may be variable, apart from PSB2 which it thinks may be non-existant. Do take what it says with a pinch of salt, predictors never been exact.

I can't see any other transmitter that the predictor perhaps "thinks" might degrade your reception. I wonder if the beam from the transmitter is tilted low, so that it doesn't carry as far (towards the horizon), its intended service area being Kent, after all.

As Bluebell Hill's channels and those of Burnham-on-Crouch are Group B (strictly speaking Bluebell's COM6 on C54 is just outside, but that's probably neither here nor there) use your Sudbury aerial, particularly if it's a Group B one. Turn it to Bluebell Hill and see if you can receive its COM channels (and its PSBs for that matter).

The point is that by changing from using Sudbury for PSBs to using Burnham relay, you could potentially give yourself another possible source of COM channels. Even if, having turned your Sudbury-facing aerial to Burnham, you find that Bluebell Hill's COMs aren't good enough, you would still have the possibility of Dover as it stands now.

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Dave Lindsay's 5,724 posts GB
Thursday, 26 December 2013
T
Terry
10:58 AM

I have the picture and sound breaking up on the following channels 19/21/22/24/35/40/45/47/83/85.

It happens on very clear sunny days and in any weather conditions.

I don't use any boxes and just receive the regular free channels.

I live in West Yorkshire in the Bingley Bradford area

Any advise?

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Terry's 1 post GB
Dave Lindsay
sentiment_very_satisfiedPlatinum

11:37 PM

Terry: Where (which transmitter) is you aerial pointing?

Due to the hilly terrain of the area there isn't just one transmitter used.

The signal strength screen usually gives the UHF channel or frequency the receiver is tuned to. This will allow you to identify whether it is tuned to the transmitter to which your aerial faces, or incorrectly to another one.

The two main transmitters which serve the area are Keighley and Idle. Reception Emley Moor may be possible in places.

All the services you identify are carried on the same multiplex (same signal). So if it's wrong for one it will be wrong for all. For that reason just focus on checking one (e.g 19).

If your aerial points to Keighley then it should be tuned to C60 (786MHz). If it is Idle then it is C39 (618MHz).

If it's on the wrong one then rectification may be to have the aerial unplugged during the portion of the scan which the unwanted one is scanned. More advice on this based on your findings.

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Dave Lindsay's 5,724 posts GB
Sunday, 5 January 2014
A
Adam Cohen-Rose
10:05 PM
St. Albans

I'm getting dreadful reception in St Albans and I don't understand what's going on.

I've been retuning my receiver (EyeTV Hybrid connected to an iMac) all afternoon and keep on receiving 100% signal strength and low signal quality as follows:

signal quality 30-60%:
BBCA 658Mhz C44 Hemel

signal quality 10-40%:
SDN 506MHz C25 Crystal Palace

signal quality 0-40%:
ArqA 482MHz C22 Crystal Palace
D3+4 514Mhz C26 Crystal Palace
ArqB 746MHz C55 Hemel

signal quality 0%:
ArqB 529.8MHz C28- Crystal Palace
BBCA 490MHz C23 Crystal Palace
D3+4 634MHz C41 Hemel
SDN 706MHz C50 Hemel
ArqA 778MHz C59 Hemel

I know the BBCA 490MHz C23 signal was very strong yesterday morning as I recorded something and there's no interference in the recording.

I've got a shielded aerial cable (Profigold PGV8905) from the aerial socket to the tuner and there's nothing else connected to the aerial cable until it gets to the aerial outside, pointing south to the Crystal Palace transmitter.

We do have a 4G mast just the other side of the park from the back of our house -- pretty much in the way of the Crystal Palace transmitter, but wouldn't this just affect frequencies around 800MHz?

I suspect some interference but I don't know where it's coming from. The only electrical things powered up in that corner of the room are the iMac (Wi-Fi & Bluetooth turned off), the wired keyboard and mouse, a USB hub and the EyeTV Hybrid itself.

On some of the channels the reception improves when I touch the metal on the end of the aerial cable where it's plugged in to the EyeTV Hybrid.

Can anyone give me any suggestions, or recommend someone reasonably local who could help me diagnose what's going on?

Thanks in advance!

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Adam Cohen-Rose's 1 post GB
Monday, 13 January 2014
D
DaveW
2:39 PM

I have a problem with Freeview intermittent interference. When my son goes into his bedroom (room located directly under the loft aerial) the picture on all our 4 Freeview TV's begin to break up badly.
Got him to turn his mobile off the other night and the problem seemed to go away.

We have Freesat in the living room which work great - no problems at all.

I have a fairly new digital aerial and Triax Wolsey WFAV425 masthead amplifier (mains powered) which I fitted in the loft prior to DSO when the signal was very weak.

Picture break-up seems to happen randomly, whenever he's in his bedroom - not just when he's using his mobile. When he's out of the house everything works fine - no interference at all.

I guess I don't need the powered amp now so should I remove it? what would you recommend I use to connect all the coax terminals back to the aerial?

Any other advice on this problem would be most welcome

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DaveW's 3 posts GB
J
jb38
sentiment_very_satisfiedPlatinum

5:04 PM

DaveW: As the WFAV25 is a 10 - 25dB variable gain device is the problem still evident when the amp is set on its lowest setting?

It would also have been of assistance if a post code had been supplied, as this would then have enabled access to the reception predictor / info on the transmitters covering your area.

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jb38's 7,179 posts GB
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