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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?
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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
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Digital Region Overlap4
Freeview reception has changed?5
Two frequency interference 6

Monday, 7 October 2013
7:54 PM

My other kit. Pioneer, JVC, Thompson is fine on SDN/COM4. I found this re issues with Sony/Panasonic in the NE:
"In the past, such problems have often been caused by the way data transmitted with the TV signal has been processed by certain makes and models of receiver. A fix was applied to the data associated with COM4/SDN multiplex channels from the North East Pontop Pike transmitter back in in January 2013." Are there plans for this fix to be applied to Winter Hill ?

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Andy's 6 posts GB flag
Andy's: mapA's Freeview map terrainA's terrain plot wavesA's frequency data A's Freeview Detailed Coverage
Monday, 28 October 2013
4:15 PM

I have resolved the problem with my Sony equipment. I borrowed a 4G filter - channel 58 appeared like magic...strange how my Pioneer, JVC, Goodmans, Thompson kit was unaffected...

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Andy's 6 posts GB flag

5:05 PM

Andy: Whatever works! Of course why it works is another matter...

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MikeB's 2,579 posts GB flag

9:31 PM

Andy : Its certainly a bit of a puzzle as to why the problem was only affecting your Sony TV, although judging by that said in your latest report now suggests the reason for as being connected with technical aspects of your Sony TV's tuner, insomuch that if its RF input circuit is somewhat more wideband than that of the tuners used in your other equipment then this will result in it having a higher level of vulnerability to out of band interference, and when taking this possibility into account "if" any 4G testing was taking place from the mobile phone masts on top of the Manchester College Fielden Campus, which as well as being located at only a short distance away "is" extremely close to the signal path from the Winter Hill transmitter, then this could well be the reason for the Ch58 reception difficulty and why your newly acquired 4G filter has seemingly cured the problem.

As apart from that I cant think of any other reason.

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jb38's 7,179 posts GB flag
Monday, 11 November 2013
12:12 AM

I have 2 TV's. I lost all transmission on upstairs TV and downstairs only get BBC1 and 2. I have a booster box for both TVs in my bedroom which supplies both TVs. The downstairs TV signal goes through the downstairs TV. It had been fine then the aerialbecame weak with the high winds. My neighbour has this huge aerial in his garden that he uses for his hobby listening to world wide shipping forecasts. Could this effect my TV? What could be the problem? How can I boost the weak signal to the antenna? Thank you kindly

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debra's 1 post GB flag

8:11 AM

debra: Judging by what you have said would suggest that your problem is possibly being caused by either a faulty connection where the coax joins into the aerial or that water has entered same, or alternatively that the aerial itself has been moved out of alignment by the wind.

You should also check that your booster box hasn't failed by observing if switching its power supply off makes any difference to what you can view, although a more accurate test is to temporarily bypass the booster by connecting the aerial directly into the TV's aerial socket.

As far as your neighbours aerial is concerned, provided its used for that said then it can safely be eliminated as being in any way connected with your problem.

By the way, any queries involving reception should always be accompanied by a post code or alternatively one from nearby, e.g: a shop / Post Office etc, as its impossible to check details of the transmitter covering the area without same.

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jb38's 7,179 posts GB flag
Sunday, 8 December 2013
5:32 PM

I have lost all the channels on the D3 and 4 and SDN signals.

My STB reset itself a week ago and despite following all the advice I have still not been able to get it back.

I live in a large block of flats and I can only assume the aerial is on top of the flats as we plug it into the wall.

Any suggestions would be helpful. I have reset it and tried to search manually but nothing.

I live in E10 5NZ.

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Izzy's 1 post GB flag
Izzy's: mapI's Freeview map terrainI's terrain plot wavesI's frequency data I's Freeview Detailed Coverage

6:19 PM

Izzy : Boxes should not automatically "reset" themselves unless it has developed and internal fault, however if you are meaning that it carried out an "automatic channel update" or alternatively a software same then at 10 miles away from the Crystal Palace transmitter there is no reason why you should not have picked up ITV1 or ITV3 on a subsequent rescan, that is assuming that you did unplug the box from the mains supply for about a minute or so before connecting it up again and carrying out the retune?

The other point being, that you should try a make an enquiry with a neighbour just to verify that they are not also being affected in a similar fashion to yourself, as should a problem have occurred in the communal aerial feed to your part of the block it always affects a number of outlets.

It would also assist if the model number of the box was known.

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jb38's 7,179 posts GB flag
Thursday, 12 December 2013
Nigel Love
6:06 PM

I have been told that our reception problems here in Eastbourne for the last 48 hours are due to "co-channel interference from the Amiens transmitter in France due to weather conditions". What is this about, it has never happened before, and what weather conditions? All non-HD BBC TV and radio channels have vanished!

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Nigel Love's 2 posts GB flag
Nigel's: mapN's Freeview map terrainN's terrain plot wavesN's frequency data N's Freeview Detailed Coverage
Friday, 3 January 2014
11:08 PM


I'm unable to find any of the HD channels on Crystal Palace C33 COM7 (BBC FOUR HD, BBC NEWS HD etc). My TV, a Samsung 8000 series, reports signal strength of 100% on the other HD channels, but 0% on channel 33. Any ideas?


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Silvio's 1 post GB flag
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