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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
Saturday, 10 November 2012
J
jb38
sentiment_very_satisfiedPlatinum

7:30 PM

Lesley Gyford: Anyone advising on a problem such as yours cannot do so with any level of accuracy without having knowledge of your location, this in the form of a post code or one from somewhere nearby (e.g: a shop) as only then can the reception predictor be accessed, this facility giving an idea of the signal levels expected in your area.

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jb38's 7,179 posts GB flag
Monday, 24 December 2012
A
Andrew
4:08 PM
Wallingford

I can not receive itv1and channel 4 and the other stations on the same multiplex. Has been fine for years but channels are pixelated and unwatchable? Have tried both auto and manual retunes.

This has happened in the laste few weeks. Postcode is ox10 9hp.

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Andrew's 2 posts GB flag
Andrew's: mapA's Freeview map terrainA's terrain plot wavesA's frequency data A's Freeview Detailed Coverage
J
jb38
sentiment_very_satisfiedPlatinum

6:53 PM

Andrew: Oxford is indicated as your best bet for reception although Crystal Palace and Hanningtom are also shown as being possible, but if you are receiving from Oxford then try manually tuning in mux Ch60 as the programmes mentioned as missing are on that transmitter.

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jb38's 7,179 posts GB flag
M
Mazbar
sentiment_satisfiedGold

6:59 PM

Andrew : as you have said you have allready tryed a manual tune if your coax comes straight from the aerial to your tv or stb have a look at the coax plug for rust or a milky white this could mean your coax is damaged this can start problems on one channel befor affecting others. Trees can also affect only one channel more than others .

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Mazbar's 384 posts GB flag
Tuesday, 25 December 2012
A
Andrew
9:51 AM
Wallingford

Thanks to both jb38 and Mazbar for taking the trouble to respond on Xmas eve. I discovered that my immediate neighbour lost the same channels a few weeks ago but was able to recover them a day or so later. He has a rather recent freeview tv whilst I am still using a set top box which is 4 to 5 years old. I will check the aerial as well which is also not new.

I will try and let you know if I resolve it ...or not!

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Andrew's 2 posts GB flag
Andrew's: mapA's Freeview map terrainA's terrain plot wavesA's frequency data A's Freeview Detailed Coverage
J
jb38
sentiment_very_satisfiedPlatinum

12:27 PM

Andrew : Yes thanks for the update, but with regards to the mux transmitter used by these programmes, its most likely still there in your boxes memory but is sitting at a level just under the reception threshold for your receivers tuner hence why you are unable to see anything, and this being something you can check by carrying a signal strength test, because provided that you have not carried out a retune (which might lose it) then it will still give an indication of strength / quality even on a blank screen.

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jb38's 7,179 posts GB flag
Wednesday, 9 January 2013
D
Dave
3:06 PM

We're receiving from Pontop Pike. As of last night 8 Jan, our 2 yr old Panasonic TV reports "No Service" on any of the previously perfect CH50 stations (10-ITV3, 38-Quest, etc). They still appear in the Program Guide & Signal strength and quality are both maximum; I've tried resetting, retuning, and confirmed that everything's still tuned to Pontop Pike.
Annoyingly, our Humax PVR (on the same aerial) is unaffected, (I've disconnected it to eliminate possible problems). Our two other small TVs (Samsung and Asda cheapie) are also still working perfectly.
A neighbour with a similar Panasonic has exactly the same problem.
Any ideas?

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Dave's 7 posts GB flag
Dave Lindsay
sentiment_very_satisfiedPlatinum

3:25 PM

Dave: See the page for Pontop Pike where two other people with Panasonics have reported exactly the same issue with the same channel.

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Dave Lindsay's 5,724 posts GB flag
D
Dave
3:56 PM

Thanks Dave, I've just spoken to the retailer (John Lewis) who spoke to Panasonic while I was on hold who, in turn, said they've had several complaints about this; I was assured they'll be looking into this and there may be a s/w update in the near future.
Perhaps this post could/should be moved onto the Pontop Pike page?
Dave

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Dave's 7 posts GB flag
Dave Lindsay
sentiment_very_satisfiedPlatinum

4:12 PM

Dave: I have posted a link on the Pontop Pike page referring back to your posting.

link to this comment
Dave Lindsay's 5,724 posts GB flag
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