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Single frequency interference

What to do when several channels are missing, but they are all on the same 'multiplex'

What to do when several channels are missing, but they are all
published on UK Free TV

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

There are two main causes of this type of intermitted interference: The current Freeview mulitplexes are shown in this diagram. If all of your missing channels are on a single row, you have "single frequency interference":



Local analogue interference

Local analogue interference is caused by household video devices that you can attach to a television such as:
  • Sky Digibox;
  • Video cassette recorder (VCR);
  • Personal digital video recorder (PVR);
  • Games console;
If you have any of these devices, you will need to work out which of these is blocking the reception of a Freeview multiplex by turning off the suspect device and then rescanning for channels on the Freeview box.

If powering off the device restores the Freeview channels from the blocked multiplex, you will need to either stop using the problem device's RF output by disconnecting the RF output cable permanently, or by changing the RF channel number that that device uses. See, for example, How do I change the RF output channel on a Sky Digibox?

You can find a list of the frequencies that are not in use at your location by putting your postcode into the My Freeview reception and looking under the "Free RF channels" section.

Non-wideband aerial in some areas

In some places you will need a wideband aerial to receive all the Freeview multiplexes. For example in Central Birmingham, the Sutton Coldfield has multiplex D on an 'out of group', so you cannot view Film4 or ITV2+1 without an aerial upgrade.

To find out if you need an aerial upgrade, see My Freeview reception.

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
Is it true that my 87 year old mother is entitled to a FREE upgrade when the ana5
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
Monday, 6 June 2011
P
PeterAW
5:37 PM
Lincoln

PeterAW: Thanks for the help - sorry not to reply before, but I've been away for a few days. I solved it by taking out the signal booster and tuning the TV directly plugged into the aerial socket on the wall after reading more about the problems on this site.



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PeterAW's 2 posts GB flag
PeterAW's: mapP's Freeview map terrainP's terrain plot wavesP's frequency data P's Freeview Detailed Coverage
Briantist
sentiment_very_satisfiedOwner

9:22 PM

PeterAW: Yes, that is often the best thing to do.

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Briantist's 38,910 posts GB flag
Tuesday, 7 June 2011
M
mark
10:14 PM
Warwick

Hi, I live in Warwick CV34 6GB. I have a TV with built-in freeview tuner, the aerial is loft-mounted and was there when I moved in. It has been mostly fine for about a year now but over the past week the signal has become very poor, to the point now where I cannot pick up any channels. I checked the antenna and nothing appears broken, I have set it to face at 331° for the Sutton Coldfield mast as shown here UK digital TV reception predictor No joy though. Any suggestions? Can't see why it would just drop out altogether!

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mark's 1 post GB flag
mark's: mapM's Freeview map terrainM's terrain plot wavesM's frequency data M's Freeview Detailed Coverage
Wednesday, 8 June 2011
Briantist
sentiment_very_satisfiedOwner

7:51 AM

mark: You might want to consider moving the aerial to the roof, as loft mounted aerials are unreliable for Freeview reception.

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Briantist's 38,910 posts GB flag
Tuesday, 14 June 2011
J
Jamie
10:27 AM

Hello, I live in Sheffield S12 - ive just connected our Hd freeview tv in our bedroom straight from the aerial on the roof (this is the only t.v running of the roof aerial) The only channels i get are the bbc dtv (apart from cbeebies) and bbc1/2, itv1 and ch4 in analogue. I can get teletext epg,and the red button. Could it be the direction of my aerial? as most of the aerials on my streets face the opposite way to mine. Thank you.

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Jamie's 9 posts GB flag
Monday, 20 June 2011
D
David Martin
9:07 PM

Hello there. I have just installed Free sat HD into my bedroom but as soon as I plug it all in (NOT switched on) it gives interference on the Sky + downstairs in the way of light banding. Its watchable but annoying. I am aware the TV in the bedroom is a 26'' lcd Bush about 2 years old and probably has poor screening but its odd as it not even switched on. I guess its gathering some sort of noise (EMF). My house is a new Taylor Wimpey house so electrics should be good. The Free sat set up works perfect but obviously sends noise through the cable to LNB and thus Sky downstairs. I have tried different sockets as well to no avail.

I wonder if you or any of you gentleman have any suggestions? I have tried a HDMI & power lead with the magnet shrouds on with little help. Would it be worth putting a quality face plate on wall or is there something I can plug in between wall & plug to reduce ''noise''?

Any help would be great guys.

Regards

Dave

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David Martin's 1 post GB flag
J
John M
10:01 PM

After the switchover and retuning i recieved the free hd channels on my panasonic tv with built in freeview hd but it only lasted a week or two. My arial is pointing at the malvern repeater and my postcode is wr141rs.I have re scanned a lot of times to no avail.
will it work again or do i need freesat?

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John M's 1 post GB flag
Tuesday, 21 June 2011
J
Jm F
sentiment_satisfiedSilver

8:23 PM

John M - Malvern hasn't had DSO yet (DSO1 is 7th September and DSO 2 is 21st September), so it doesn't have any HD content until DSO2.
From where you are, The Wrekin transmitter is directly behind the Malvern relay (but 65km away from you). It transmits the HD programmes on UHF channel 30, so I'm wondering if you've tuned into that during "lift" conditions.

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Jm F's 141 posts GB flag
J
Jm F
sentiment_satisfiedSilver

8:33 PM

David Martin - You may have an issue with earth connections from either of your TVs. The Sky+ box and the Freesat box won't have an earth connection, but the TVs probably have. Could you isolate the TV set in the bedroom (take out mains plug and aerial lead, leaving the Freesat box plugged in with F connectors attached) and see if the "light banding" stops?

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Jm F's 141 posts GB flag
J
jb38
sentiment_very_satisfiedPlatinum

9:23 PM

David Martin: If I could just add to Jm F reply to you by asking what brand / model of HD box you have fitted in the bedroom? and when you say "not switched on" are you meaning the wall socket switch or on the actual box itself? as on some models there can be a difference between these two actions.

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jb38's 7,179 posts GB flag
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