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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
Wednesday, 2 November 2011
P
Peter Leaver
2:08 PM

I live in Headington, Oxford and had a new aerial fitted a couple of years ago pointing to Beckley. The signal was so strong the installer put in a connector which reduced the strength of the signal and we had perfect picture and sound until changeover.

Since changeover 1 and 2 I get intermittent breakup of sound and/or picture noticeably on BBC1 news (maybe because we watch more news than anything else). I removed the connector and it was even worse.

I understand that the signal from Beckley is now 5 times stronger than it used to be - so is my connector not reducing the signal enough now?

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Peter Leaver's 1 post GB flag
D
Dave
9:12 PM
Newquay

Hi,

I live in Newquay, Cornwall. I have a Sony 32CX523 with inbuilt HD freeview. Ever since moving to this property in September 2011 our reception has been variable. For the past week we've had no reception to HD channels and it appears from the multiplexes info above we have access only to multiplexes 1, B and D. Can you recommend what steps I should follow to imrove reception? I've tried to tune in with a stand alone freeview box but receive exactly the same channels as the inbuilt HD freeview tuner so know there's no issue with the TV. I've retuned the TV multiple times although have not yet tried without the coax in the back and then retuning with it in. When retuning the previously extensive list of channels narrowed down to only multiplexes 1, B and D.

Any help you can offer will be hugely appreciated.

Cheers.

Thanks.

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Dave's 3 posts GB flag
Dave's: mapD's Freeview map terrainD's terrain plot wavesD's frequency data D's Freeview Detailed Coverage
Thursday, 3 November 2011
Friday, 4 November 2011
R
Robert
8:20 PM
Chichester

Robbo3
Hi, I did a retune as requested six days ago, ITV 3 and ITV3+1 have now gone missing,all other channels are perfect, signal strength is up the top of the scale. I live in Sussex and am on the Rowridge Isle of Wight transmitter. I have a Sony T.V. with no ITV3 and a Humax with no ITV 3. Thanks in advance if anyone can help.

link to this comment
Robert's 1 post GB flag
Robert's: mapR's Freeview map terrainR's terrain plot wavesR's frequency data R's Freeview Detailed Coverage
J
jb38
sentiment_very_satisfiedPlatinum

8:52 PM

Robert: Assuming that you cant get any other programmes on that Mux either like QVC(16) or Quest(38), you should scrub everything already stored by carrying out a factory reset (or default setting) then manually tune in Mux Ch30 which ITV3 is on, then after storing anything received ("if" that is!) add the other multiplexes by using "search for additional channels" or whatever its called on your TV / Humax box.

Sometimes a weak signal can be captured on a device if its Mux channel specifically tuned in, rather than it being searched for as part of a re-scan.

Shoud by any chance you are presently able to receive QVC or Quest, still try out whats been said.

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jb38's 7,179 posts GB flag
Saturday, 5 November 2011
L
Louise
12:13 AM
Todmorden

Hello, I have a digital tele the only thing it is plugged into now is the aerial that points at Emley moor and reports above average signal strength (no boxes, games consoles). I have unplugged retuned, replugged retuned etc. I can only receive 21 channels (10 tv, 11 radio) all BBC. They are all good quality - what can I do to receive more channels? Only just trying freeview because we have sacked Sky.
Thank you

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Louise's 1 post GB flag
Louise's: mapL's Freeview map terrainL's terrain plot wavesL's frequency data L's Freeview Detailed Coverage
J
jb38
sentiment_very_satisfiedPlatinum

8:18 AM

Louise: Are you sure that the aerial is pointing towards Emley Moor? and not your local Todmorden transmitter and which you appear to be right on the doorstep of, this being a Freeview "light" (PSB) station and so you will not have the same selection of channels as you would do from a main station, plus it has to be said that reception of Emley Moor is not shown as being possible on the trade predictor.

Just to confirm where you are receiving from, when you are carrying out a signal check note the Mux channel number being shown along with the strength indications, Todmordens BBC1 on Ch49 / ITV on Ch45, whereas Emley Moor has BBC1 on Ch47 / ITV Ch44.

As you have dropped using Sky you might have been better off using the Sky dish with a Freesat receiver, as nothing would require to be altered the dish working with any satellite device.

You could also have a look at the way your aerials is mounted, as for Todmorden the elements will be mounted vertically (straight up and down) whereas Emley Moor is horizontal.

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jb38's 7,179 posts GB flag
Sunday, 6 November 2011
C
CH
11:51 PM
Chelmsford

My Humax PVR 8000T has recently, even after a full auto retune, been able to pick up only BBC1 (CH1), BBC2 (CH2), BBC3 (CH7), PickTV (CH11), Dave (CH19), Davejavue (CH25) and E4+1 (CH29). These seem to be on Mux 1 and Mux C, but I cannot get other channels on these muxes. I've tried a manual tune on the centre frequencies of the mux channels to no benefit. We're using the CP transmitter as suggested by the trade predictor for postcode CM1. Finally, a new Sony TV connected to the same cable gets a full spectrum of channels. Any ideas? Thanks in advance

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CH's 1 post GB flag
CH's: mapC's Freeview map terrainC's terrain plot wavesC's frequency data C's Freeview Detailed Coverage
Monday, 7 November 2011
M
Martin Thompson
1:00 PM
Gloucester

In the past few days I have had no (or poor) reception on ITV4 and Yesterday. I've tried clearing the channel list and reinstalling and it makes no difference. Has something changed around here? My postcode is GL2 9PQ

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Martin Thompson's 1 post GB flag
Martin's: mapM's Freeview map terrainM's terrain plot wavesM's frequency data M's Freeview Detailed Coverage
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