My ITV/C4 Freeview channels have disappeared - what can I do? Is it my SCART ca
Brian Butterworth published on UK Free TV It is a feature of television signals that they can be effected by the weather. Aside from the obvious damaged that can be caused by wind or torrential rain, the onset of summer can cause a more intriguing problem called "inversion".
Basically, when the sun heats up the land, the hot air can get trapped below cold air at high level. This creates an "inversion layer" which acts like a polished mirror to TV signals. This causes two problems: you can receive both the original and a reflected signal from your own transmitter (on analogue TV this appears as "ghosting") or interference from TV transmitters that are normally too far distant.
The ITV/C4 multiplex of channels (ITV-1, ITV-2, ITV-3, ITV-4, CITV, C4, More4, E4, Quizcall) use a transmission "mode" called 64QAM, and it is sadly much more prone to these problems.
So, whilst a loft-mounted aerial will provide reception at some time, it will fail at others. The only real solution is to mount the aerial (or a new Class I aerial) outside on a pole, but some people report that changing the cable from the aerial to the set-top box to the high-grade satellite cable can also help.
The SCART connection, by the way, only carries a single TV picture, not the Freeview transmission multiplexes, so if this is disconnected it will result in degradation to every channel at once.
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Saturday, 4 May 2013
Dennis: It appears to be the case that Sudbury's COM channels 58, 60 and 56 are not as good as the Public Service (PSB) ones. This is particularly on your side of the transmitter.
Refer to the Sudbury transmitter page on this site. "Nick" from Hollesley finds all the COM channels hit and miss with the PSBs being strong.
If the picture is lost, or is breaking up, I wouldn't retune as this will achieve nothing positive. You will only ever get the same result, or else loose the channel completely from your receiver. The receiver, having stored C58, will lock on to it if it is available, providing the best picture possible.
The thing with digital is that there is signal strength and signal quality. A receiver requires the strength to be above its minimum threshold in order to resolve a picture (providing it is of sufficient quality).
The question is: is your difficulty resulting from the strength dropping to below that needed for your receiver or is the strength still there but instead the quality is diminished?
Make a note of the strength at different times, i.e. when it's not working and when it does work, and see if there is a difference. Also, compare the strengths of C60 (Pick TV) and C56 (Film4).
Don't compare strengths between different receivers as the meters aren't worthy of comparison. Only compare different channels with the same receiver.
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Dennis2:41 PM
Woodbridge
Hello Dave.
I have checked the signals but I don't receive anything on C60.
However C41 and C44 have 100% quality and strength,C56 has 100% quality, 80% strength and is fine, but C58 has 70-80% quality and 70% strength so is unwatchable. When (hopefully) C58 returns I wiill check the signal again.
Many thanks for the advice.
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Dennis's: mapD's Freeview map terrainD's terrain plot wavesD's frequency data D's Freeview Detailed Coverage
Dennis: In addition to the caution that you may be unable to receive 56, 58 and 60 reliably at your location, it is worth pointing out that your aerial that was installed in the days of analogue may not be best suited to picking up 56, 58 and 60.
The four analogue channels were Group B (the middle of the band), of which 41 and 44 are in. However, the three COM channels are in the top third of the band, Group C/D. Thus the sensitivity of a Group B aerial on higher channels may not be sufficient.
If you are still using a Group B aerial and the issue is the signal level dropping (and not the quality being lost) then a signal amplifier may help, or of course so too may a replacement aerial. If it is quality that is being lost rather than strength then no amount of amplification will right that.
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Dennis3:30 PM
Woodbridge
Hello Dave,
Looks like I should invest in a new aerial, it can't do any harm!Thanks again for your help.
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Dennis's: mapD's Freeview map terrainD's terrain plot wavesD's frequency data D's Freeview Detailed Coverage
Thursday, 9 May 2013
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Ganesh4:04 PM
Romford
Hello,
I am not recieving the following channels :
Channel 4, Channel 5, ITV 1 and ITV 2.
I stay in Romford . Recently moved into this apartments.
I have connected to Freeview directly to my digital TV.
Could you help me?
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Ganesh's: mapG's Freeview map terrainG's terrain plot wavesG's frequency data G's Freeview Detailed Coverage
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Malcolm Wilkes5:32 PM
Torpoint
Just noticed I have lost freeview channels 1 to 9 on my Panasonic 37" TV in the lounge. Other portable tvs' in the house with a free box work okay. When I press for channel 1 ( BBC1 ) message comes up saying Invalid Channel with 302 as the channel. Just wondering if this is a fault with the TV. aNY IDEAS ?
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Malcolm's: mapM's Freeview map terrainM's terrain plot wavesM's frequency data M's Freeview Detailed Coverage
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Catherine5:33 PM
Hi jb38
Re your comments last week, yes I did mean ITV2+1. I have checked my aerial connectors while watching ITV2+1 and as checked the the wall socket was pushed in properly the signal got worse. It got better after a few seconds of leaving it alone though. However, prior to this my signal has been much worse again for about a week, down to the 30s again, rather than 50%. When I twiddled the aeriel it went down to 24%, but within less than a minute went but to 30s. But still unwatchable.
fOR Film4, I also checked the signal on mux Ch52, without scanning as you suggested, and the signal and quality were both 0%. My neighbours signal was strong on both channels
I have also noticed that both E4+1 and sky news (I watch on EPG channel 82) have both lost their signal strength and are unwatchable, so overall it's getting worse.
Thanks again for the help.
Catherine
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jb3811:51 PM
Catherine: Judging by what you have reported is inclined to suggest that either the jumper cable between the wall socket and your TV is defective, or alternatively that your neighbours are possibly receiving Freeview from the local Ilchester Crescent relay transmitter and not Mendip, albeit that Mendip is indicated as being superior for reception.
I would therefore like you to carry out a signal check whilst on ITV2+1 for the purpose of noting the mux channel number shown along with the strength, because if the signal is from Mendip then it should be 48, whereas 42 if from Ilchester Crescent.
Try the same test on Sky news (same mux as E4+1) noting the mux channel number seen, Mendip being Ch56 and with Ilchester Crescent being Ch45, if though nothing is seen when you select Sky news on the EPG listings then try a manual tune signal check (using the procedure previously described) on each of the two mux channel numbers mentioned, giving an update on results.
If your communal aerial system is within sight then have a look to see if the elements of the aerial are mounted vertically (up and downwards) or horizontal, as that gives a clue as to the transmitter its facing, plus it would also be of assistance if you provided the model number of your TV, this to enable its menu system to be checked out should the manual be available.
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Friday, 10 May 2013
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nic1:08 AM
tonight all itvs c4 e4 film 4 channels have disappeared after retuning following on from a no signal error message. all other freeview channels are playing ok. have retuned tv and reset the freeview box. pe7 is overlapped by 2 transmitters and neither show as having any faults. are you aware of any issues
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nic: You might like to have a look at the Freeview reception has changed? | Freeview Interference | ukfree.tv - 10 years of independent, free digital TV advice page.
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