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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?
Can I attach a Freeview digibox to a Combi TV/Video unit?1
My high gain aerial can't get all the Freeview channels I expected2
I can't get Freeview yet, when will it start in my area?3
Are there plans to extend the range of regional variations on Freeview?4
How can I Receive Freeview on two TVs using one box?5
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, 29 July 2018
MikeP
sentiment_very_satisfiedPlatinum

3:57 PM

Andy:

Does this occur at regular times of day? Which transmitter do you receive from (a full post code will help us contributors)?

As for filtering, it all depends on what and where the source is, so that will need to be investigated.

You may wish to consult the BBC Reception Advice Service, look at BBC - Television - Help Receiving TV and Radio for mor information and contact details.



link to this comment
MikeP's 2,936 posts PT
Saturday, 16 February 2019
G
G JAMES
6:26 PM

Post Code SA200YF
BBC A Single frequency line - did have intermittent picture/sound. Having followed all recommended procedures, I have no 'Channel 60' i.e. BBC1, BBC2, BBC News, Radio Wales nor Radio Cymru.
UHF CH. 60, 786000khz on bandwidth 8Mhz =Signal strength 46% and signal quality 0%, whereas for example UHF CH 53 frequency 730000khz has signal strength 74% and signal quality 100%.
Is this a TV fault or Carmel Transmitter fault.
date 16.02.2019 at 18.25hrs
Any assistance further guidance appreciated.
Many thanks.

link to this comment
G JAMES's 2 posts GB
MikeP
sentiment_very_satisfiedPlatinum

10:23 PM

G James:

Looking at the Digital UK Coverage Checker at Coverage Checker - Detailed View shows you should have good reception of all channels.

That suggests you may have a problems mwith your aerial system. So please check all the cables and connections. Unplug all coaxial plug/sockets and refit. Then recheck the signal strengths for the various multiplexes broadcast to you location.



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MikeP's 2,936 posts GB
Sunday, 17 February 2019
G
G JAMES
8:06 PM

MikeP: Many thanks for your advice Mike. Played around with the aerial coax lead connections without success. However after replacing the coax cable with an old one all channels now fully operational. Have ordered a new lead just to ensure signal input is optimised. Once again many thanks. Gary

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G JAMES's 2 posts GB
Sunday, 9 June 2019
M
Michael Hargreave Mawson
10:01 AM

I don't have any of these devices, but the description fits my problem exactly. Could the intermittent interference (on BBCA) be caused by a neighbour's device? How far away might it be?

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Michael Hargreave Mawson's 1 post GB
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