Single frequency interference
Brian Butterworth published on UK Free TV There are several different type of interference that cause problems. This page deals with the situation where:
- Freeview reception is perfect or near-perfect most of the time
- Several channels are missing, but they are all on the same 'multiplex'
Local analogue interference
Local analogue interference is caused by household video devices that you can attach to a television such as: 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?
Monday, 7 November 2011
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jb384:18 PM
CH: Although you have carried out an auto-tune its really a default setting one you require to carry out on that model, this being accessed from the installation menu, as although that particular model of Humax is of the older variety it has an extremely sensitive tuner, and as such is liable to have its memory loaded with data picked up from elsewhere and which can cause all sorts of problems.
Please note though! that although the manual for that Humax model indicates that its only configuration settings (made by yourself) plus channel lists that will be lost, I cannot guarantee that anything you previously stored in the hard drive wont be included, albeit that in theory it shouldn't as its not the hard drive you are re-setting.
As far as reception is concerned, reception from Crystal Palace is indicated as reasonably good except for ITV1 (Mux Ch22) this classed as variable, however the signal from the main Muxes from Sudbury are indicated as consistently better and so the Humax may well have picked these up, especially so where ITV1 (Mux Ch41) is concerned.
Once the Humax is factory re-set you could then carry out an auto-tune and see what comes up, however I would be inclined not to, but manually tune in ITV1 (Mux Ch41) from Sudbury and see if you get anything, as you are very likely to be picking up Sudbury on the near rear of your aerial, Crystal Palace @ 225 degrees and Sudbury @ 35 degrees.
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jb384:51 PM
Martin Thompson: The problem you might be experiencing could be caused by the fact that you are forecast as having just about an equal level of reception from both Sutton Coldfield and Ridge Hill, with Mendip running as a close second.
Depending entirely on the TV / box you are using, they usually lock onto the first strongest signal picked up as they scan upwards from Ch21, this meaning that any station with lower channel number multiplexes will take the lead pushing any duplicate EPG channel numbers picked up into the 800 ranges, so have a check up there and see if there is another ITV4.
What I would do is delete everything stored by carrying out a re-tune without the aerial being connected, then once completed reconnect same and try manually tuning in the Mux ITV4 uses from each station in turn, noting the signal strength / quality in each case and saving the one that's the best, then using "search for extra channels" (or whatever its called on your device) to recover the remaining multiplexes.
ITV4 from :- Ridge Hill Mux Ch27 / Sutton.C Mux Ch39 / Mendip Mux Ch52.
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Dave9:23 PM
Newquay
Hi Briantist,
Thanks for your reply my posting of 2nd November 2011. Unfortunately I still experience issues with reception. I have, however, noticed that when I sit closer to the cox going from the wall to the tv my reception improves. Could this signal interference? The only other electrical item close is the electricity meter on the outside of the wall.
THanks.
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Dave's: mapD's Freeview map terrainD's terrain plot wavesD's frequency data D's Freeview Detailed Coverage
Dave: It could indicate the cable is faulty, quite a lot of Freeview problems can be solved by using new "fly leads".
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Dave10:19 PM
Newquay
Thanks Briantist. I've tried with three leads and all give the same result. I'm stumped.
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Dave's: mapD's Freeview map terrainD's terrain plot wavesD's frequency data D's Freeview Detailed Coverage
Tuesday, 8 November 2011
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jb3810:33 AM
Dave: I would be inclined to make enquiries with your neighbours to find out what kind of reception they get, and of what programmes! as your area can be iffy for reception and the problem might not just be confined to your own set up.
If though they give glowing reports with their "Freeview" reception, then try and have a look at the aerial fitted on their property to make sure its facing the same direction as yours, you being forecast as being able to receive from both Redruth (@ 15 mls) and Caradon Hill (@ 29mls) the latter indicating the best albeit further away.
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Saturday, 12 November 2011
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Mark Fletcher1:01 AM
Halifax
Louise.Todmorden.Hard to say without a full postcode.First of all is your aerial mounted outside,in the loft or an inside set top antenna,and more importantly is it polarised vertically or horizontally.As JB38 correctly informs most of Todmorden itself have external vertically polarised antenna's and only a small minority have external horizontally polarised aerials,some towards Emley Moor but a few especially the high ground parts of Todmorden can pick up signals from Winter Hill.Having twice previously resided in Todmorden myself,Walsden OL14 7SJ (different house numbers though) the town is home to five relay transmitters Cornholme,Lydgate,Todmorden,Walsden and Walsden South (all Freeview lite masts) although the far south of Walsden can tune into Freeview Lite broadcasts from the Littleborough relay which have BBC1 North West and ITV1 Granada programming.If you stated you ditched Sky but still retain the satellite dish outside have you considered Freesat which is subscription free satellite TV considering Todmorden in general will hardly ever receive SDN,ArqA and ArqB multiplexes from Freeview terrestrial TV whatsoever,only BBCA,D3+4 and for some BBCB (HD) on either Freeview HD (+) boxes,or full HD 1080p TV sets with Freeview HD built in.
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Mark's: mapM's Freeview map terrainM's terrain plot wavesM's frequency data M's Freeview Detailed Coverage
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Mark Fletcher1:24 AM
Halifax
Louise,Todmorden.A few things i forgot to add.Is your digital TV HD ready for which you will not receive Freeview HD channels at all whatsoever without a suitable Freeview (+) HD set top box,or is it a full HD 1080p TV set with integrated Freeview HD.The BBC channels you mentioned is the BBC1 on channel 1 on your programme list receiving the local news from Look North in Leeds or the local news from North West Tonight in Manchester.The reason pardon my intrusion in asking is in 2009 i understand that BBC1 on all Todmorden relays have changed the regional news programming from North West Tonight to Look North (Emley Moor),while in 1982 Todmorden changed ITV regions from Granada TV to Yorkshire TV,thus the ITV regional news changed from Granada Reports (or Tonight back then ?) to Calendar (Emley Moor).I understand both these changes have proved very unpopular in Todmorden as such.
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Mark's: mapM's Freeview map terrainM's terrain plot wavesM's frequency data M's Freeview Detailed Coverage
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itsleon!4:53 PM
Southend-on-sea
HI having an isue atm. On weds lost group 1/2/a/d (basically all bbc except bbc4 has gone and all itv's are missing) However Groups b/c come through perfectly as before.
I have checked the reception in my built in freeview in my tv and it shows as good. Ive tried re scanning and still do not get that channels back. Have also unplugged all other devices and purchased a better booster to no avail. Any ideas? I live in southend so pick up crystal palace or bluebell hill. I am at a loss.
Many thanks,
Leon
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itsleon!'s: mapI's Freeview map terrainI's terrain plot wavesI's frequency data I's Freeview Detailed Coverage
Sunday, 13 November 2011
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Neil10:58 PM
Scunthorpe
interference sounds great we are doing things again on the cheap or so called cheap and everything is going wrong again, Tonight i have lost about 20 channels from my freeview why are some of the multiplexers only running on low power 4000 watts and some are running on 150.000 watts it is nonesence.
Neil
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Neil's: mapN's Freeview map terrainN's terrain plot wavesN's frequency data N's Freeview Detailed Coverage
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