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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.

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Sunday, 29 July 2018

3:57 PM


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.

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MikeP's 3,056 posts PT flag
Saturday, 16 February 2019
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.

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G JAMES's 2 posts GB flag

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 3,056 posts GB flag
Sunday, 17 February 2019
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 flag
Sunday, 9 June 2019
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 flag
Monday, 2 September 2019
Martin Quinn
9:35 PM

Hi there,
We have had problems receiving the multiplex channel 27 BBC A on 522.0MHz, which takes out the main BBC channels reports little or no signal strength - a picture rarely forms.

Channel 21 shows zero signal strength and no picture will form.

However channel 24 comes in with 100% signal strength - perfect picture across all channels on that multiplex.

This problem started around late July as an intermittent loss of picture on channel 27 multiplex, and has got progressively worse to the point where our Samsung smart TV shows the occasional 'still' picture and sound bite from a BBC channel.

Any ideas you may have would be appreciated

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Martin Quinn's 1 post GB flag
Tuesday, 3 September 2019

8:08 PM

Martin Quinn:

Please could you tell us your full post code. Then tell us the reported signal strengths of all the multiplexes available to you. That information will help us contributors to form a 'picture' of your signal conditions.

One thought is that you may have too much signal, hence the request for the strengths.

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MikeP's 3,056 posts GB flag
Wednesday, 4 September 2019

7:48 AM

Martin Quinn:

Check that you don't have any "boxes" video recorders etc that have an RF output set anywhere in those lower channels. If so, retune them to somewhere above all the channels your current transmitter uses. We don't know which it is (you didn't say) hence MikeP's request for the postcode.

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Chris.SE's 4,151 posts GB flag
Wednesday, 6 November 2019
1:24 PM
Haywards Heath

Heathfield Transmitter:- my signal strength on C47 (682 MHz) has crashed over the past couple of days. Down to 30% or below, with huge bit error with consequential freezing/blocking. Quality still 100% though. Other channels and frequencies are fine.
Postcode RH16 3RX.

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SteveK's 15 posts GB flag
SteveK's: mapS's Freeview map terrainS's terrain plot wavesS's frequency data S's Freeview Detailed Coverage

2:44 PM


There is Planned Engineering this week at Heathfield according to Planned engineering works | Freeview
"Meridian Heathfield Main Possible weak signal"
This is probably due to a fault last Saturday with the BBCA/PSB1 mulitplex. Any of the multiplexes could be affected by the engineering work.
Your signal strength should recover in due course.

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Chris.SE's 4,151 posts GB flag
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