menuMENU    UK Free TV logo Freeview



Click to see updates

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

Friday, 13 May 2011

7:11 AM

Kevin: Please see Freeview reception has changed? | - independent free digital TV advice . I note that your reception of multiplexes C and D are officially "marginal" from the Midhurst transmitter until switchover.

link to this comment
Briantist's 38,907 posts GB flag
Sunday, 15 May 2011
kieran r

12:11 AM

heay why cant i get a signal from oxford as in a goos signal area zip code rg23 8ds

link to this comment
kieran r's 32 posts GB flag
kieran's: mapK's Freeview map terrainK's terrain plot wavesK's frequency data K's Freeview Detailed Coverage

4:51 PM

kieran r: You are not predicted to get a signal from the Oxford transmitter, use the Hannington transmitter for a full-strength signal.

link to this comment
Briantist's 38,907 posts GB flag
Monday, 16 May 2011
1:14 PM

I have no itv or channel 4 did have until weekend, what can I do? Does not register on my hard drive recorder channels either.

link to this comment
Naomi's 1 post GB flag
Ted K
3:07 PM

Area: CB13AB
Transmitter: Sandy Heath
Digi Box: Philips DTR 220/05
Aerial: Antiference, Standard 2, XG10EW, aligned professionally.
Masthead amp - Lab Gear PUM111

Recently Mux C with Sky News, Channel E4+1 etc (on C40) has in their correct positions (ie Sky News on Ch 82) shown a menu displaying 'aerial not connected, re-check arial connection etc' and the channel ID ie 82: Sky News and will not display, then switching to a just a blank screen and I constantly get the menu saying channel list has been updated etc... The channels will appear up in the 800s (Sky News on 813).

If I do a manual scan on the frequency that is acting up it will find all the channels assigned that frequency and display them but it eventually (if I change channels) reverts to not showing. The channels will appear up in the 800s (Sky News on 813).

I have tried the suggestion of unplugging the aerial cable and switching box off for 30 seconds, then auto scan with no aerial to try and clear everything and then put aerial in and scan again to put these channels working in their correct positions. the scan comes up as previously showing the positions but still remaining blank for the Mux C (C40) and now positioned in the 800s (the new scan list shows 92 channels which is the duplicates up in the 800s). The signal strength for this frequency is off the scale so is it I am receiving from 180° opposite the Sudbury transmission and it's creating confusion as the Philips Box is just not up to it? Do I have to attenuate. I have a Samsung CRT 100hrz set with Freeview in another room and this does not have the same problem. All channels/radio appear as they should.

I have noticed that this web site displays Sandy heaths Mux C as being Very low, 16QAM-2k, 18Mb/s, MPEG2, 20,000W.

I could create a favourites section and move the channels into position but I was hoping not to have yo do this.

I have noted this on this site things seem set to occur:
NOTE: The commercial multiplexes at Sandy Heath will remain on their pre-switchover channels and powers for a period after digital switchover. SDN will then temporarily move to channel 31 (at 20kW ERP) on 31 Aug 2011, before adopting its final allocation of channel 51 on 18th April 2012. Arqiva A will adopt its final allocation of channel 52 on 23 Nov 2011. Arqiva B will temporarily move to channel 67 (at 20kW ERP) at switchover and then it will adopt its final allocation of channel 48 on 14 Sept 2011. NOTE: D3&4 and HD use transitional S1 antenna until 27 June 2012.

I guess I may have to wait until Sept 14.

link to this comment
Ted K's 2 posts GB flag
Ted's: mapT's Freeview map terrainT's terrain plot wavesT's frequency data T's Freeview Detailed Coverage
Jim F.

7:12 PM

Ted K,

I'd suspect the Philips digibox. I have a DTR100 which when given the "first time installation" will find (and display) any one of the 103 channels it finds. All I have to do is switch it to standby (wait a few seconds) and switch it back on, and it will now tell me I have 90 channels, and it has "lost" quite a few programmes. This is entirely repeatable, though the "lost" programmes can be tweaked by manually tuning the MUXs in e.g. reverse order.
Channels in the 800s are generally "bad" - a first time install (or default setting / factory reset) and manual tune shouldn't populate any 800 numbers.

link to this comment
Jim F.'s 141 posts GB flag
Tuesday, 17 May 2011

8:37 AM

Naomi: I would go over everything listed at the top of the page.

link to this comment
Briantist's 38,907 posts GB flag
Wednesday, 18 May 2011
11:18 AM

Hello Briantist,
I'm in Cambridge and have lost all channels on the 67 frequency (18, 21, 24, 85, 89) and all the radio channels at my parents house CB4 3DG, since the switchover in mid-April. However at my house in CB5 I still have all these channels using an identical aerial.
The strenght of the signal on the existing channels though seems to have increased.

link to this comment
Robin's 3 posts GB flag
Robin's: mapR's Freeview map terrainR's terrain plot wavesR's frequency data R's Freeview Detailed Coverage

11:28 AM

Robin: You might have to wait for the ArqB multiplex to move frequency and go to full power on 14th September 2011, but you shouldn't have to.

Did you do a "first time installation" at switchover?

Have you tried My Freeview box has no EPG, is blank on FIVE, ITV3, ITV4, ITV2+1, has no sound or the channel line up is wrong | - independent free digital TV advice ?

link to this comment
Briantist's 38,907 posts GB flag
Thursday, 19 May 2011
11:33 AM

Its a Medion TV with built in Freeview. I have unpluggled the aerial and gone through the 1st time installation a dozen times but the channel list does not seem to clear, exactly the same channels come back again with none of the missing channels appearing,


link to this comment
Robin's 3 posts GB flag
Robin's: mapR's Freeview map terrainR's terrain plot wavesR's frequency data R's Freeview Detailed Coverage
Select more comments

Your comment please
Please post a question, answer or commentUK Free TV is here to help people. If you are rude or disrespectful all of your posts will be deleted and you will be banned.

Privacy policy: UK Free Privacy policy.