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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Tuesday, 14 May 2013
J
jb387:26 AM
Matt: In addition to that said, I had also meant to ask if both TV's involved are connected directly into a wall plate? because if they are and not via any other devices such as a recorder, then your problem could be caused by a fault in the communal aerial distribution amplifier, this being why its always best policy to enquire with others on the same system before over concentrating on your own, which judging by what you have said would appear to be quite straightforward.
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Matt9:56 AM
Hi JB
Yes both TV's plug straight into wall sockets, via an aerial cable is only about a metre long. Could that be causing a problem?
Nobody else in the apartments next to me have said they are having any problems.
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D
Dennis3:59 PM
Woodbridge
Hello Dave,
Since getting your advice I have been checking signal strength and quality on a daily basis with no change.I have arranged an aerial fitter to call tomorrow but this afternoon the programs on CH58 are back! The quality is lower than before @6-7, the strength is also lower @6, but the programs are totaly watchable.The other channels haven't changed.Any thoughts?
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Dennis's: mapD's Freeview map terrainD's terrain plot wavesD's frequency data D's Freeview Detailed Coverage
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jb3811:54 PM
Manchester
Matt: The 1 metre long jumper leads being used on the TV's should be perfectly OK as its most unlikely that both would be defective, although I still have suspicions as far as the feed from the communal aerial distribution amplifier is concerned, because even although others might not be experiencing any problems all that really indicates is that the distribution amp is still powered up and not that there isn't a fault somewhere on your feed from the amp, this only being revealed with the aid of a signal meter being coupled into the wall plate, or indeed simply by being able to verify the line by using another brand of TV with a somewhat more flexible tuner system to that of the LG / Samsungs
Its really a case of looking at the problem in a logical way, insomuch that your installation (unlike some) is in no way complex, as you simply have two TV's and with each being coupled via jumper leads into a communal aerial socket but with reception being poor on both sets, and so when excluding that mentioned in the previous paragraph (re: feed fault) that only leaves either your jumper leads or the TV's themselves as being responsible for the problem, although more so where the tuners are concerned which might well be the same type fitted in both sets. (Samsung brand)
On using a test code of M15 5TL I note that the area is one dominated by two storey flats, and with a large communal aerial being installed on the top of the building on the corner Royce road / Reilly street, the aerial apparently facing Winter Hill.
And with reference to these type of apartment blocks, if you are located in one of the higher level apartments it would have been interesting to know if you could pick up a signal on Ch50 using either a set top aerial or a short length of wire (about 1.5metres or so) connected into the aerial socket, (middle of anyway) of your TV, because if you could then you could try the elusive Ch59.
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jb38's: mapJ's Freeview map terrainJ's terrain plot wavesJ's frequency data J's Freeview Detailed Coverage
Wednesday, 15 May 2013
Dennis: TBH I'm not entirely sure what to read into your results (I'm not a professional installer).
I was thinking that they may clearly indicate whether this is a quality issue or a strength one. Let us know how it goes.
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Sunday, 19 May 2013
M
Matt10:27 PM
Hi JB
I have had a mini breakthrough of sorts. It seems there is a some sort of splitter box in the storage cupboard. It has 2 switches - 'A' and 'B'
B was clicked, so I flicked it on to 'A' and rescanned on both TV's - now the Samsung TV in the master bedroom picks up every channel but the main TV still has the same problem.
Does that give any indication into what the problem may be?
Thanks in advance
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Monday, 20 May 2013
J
jb3812:20 AM
Matt: Progress! but of a limited nature, however with reference to the box you mentioned, is anything else seen printed on it such as a type number?, also if by two switches you are really meaning a two position switch, that is a single switch that can slide two ways, A one side / B the other, then this would suggest that the common input to the box cannot feed the signal to both rooms at the same time, although I would certainly find it a bit odd if this was the case as it could indicate that the switch is for some other purpose.
If your TV's are easily moveable then you should temporarily try the main room TV connected into the master bedrooms aerial connection followed by carrying out a rescan on it, OR alternatively (and maybe a better test) check to see if the master bedrooms TV (which has been tuned) still works when connected into the main TV's aerial connection, if you get a "no signal" message or possibly a blank screen, then flick the switch back to its original "B" position and see if this makes any difference, giving an update on results.
It would also be of assistance if you could indicate the number of cables you see going into the box referred to, and whether or not the cables are hard wired into it or are fitted with connectors.
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D
Dennis7:23 PM
Woodbridge
Aerial fitter arrived, checked the signal and found a fault with the cable from the t.v. to the aerial wall socket.He replaced the cable which improved the signal strength and quality. I will now see how it goes.
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Dennis's: mapD's Freeview map terrainD's terrain plot wavesD's frequency data D's Freeview Detailed Coverage
D
Dennis7:27 PM
Woodbridge
Sorry Dave I missed your name off my last. Thanks for all your advice
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Dennis's: mapD's Freeview map terrainD's terrain plot wavesD's frequency data D's Freeview Detailed Coverage
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Matt8:21 PM
Hi JB
My breakthrough was short lived. All the channels have gone again so i decided to get out the trusty apartment manual. I have found out the splitter box that I thought may have been the key to this is just to change the switch from analogue to digital apparently for when the switchover took place. It says that A is for Analogue and B for Digital signals if this makes any sense? It don't get why I would have received any channels on 'analogue' though?
Anyhow, I have flicked it back to switch 'B' as I think it should be for digital signals - and I am back to square one! No channels in the master bedroom and the ones I described before in the main living room. I have linked a picture of the splitter box below if this holds any clues to the answer?
ImageShack® - Online Photo and Video Hosting
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