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.
All questions
In this section
Friday, 13 July 2012
S
Stuart11:42 AM
Jb38
Really appreciate your reply, thanks. I've tried your suggestion, but without success. I can't understand why before, I was receiving it all, no problem at all. Did it coincide with the BBC HD switchover? Or did it coincide with the visit from the Virgin man who came to fix the internet that wasn't working. Is that possible? They were both around the same time...
| link to this comment |
J
jb385:41 PM
Stuart: If your LG TV has a manual tuning facility then you can use this to carry out a signal test "without scanning", so select the tuning menu / manual tune and enter Ch30 this being the HD mux on Crystal Palace, and if your tuning system operates in a standard fashion then as soon as you enter the mux channel number the signal strength of that channel should immediately appear, so make a note of the strength / quality seen.
Once you have noted the strength etc change the channel number to Ch23 (BBC1) and make a note of its strength, finally using the same procedure enter Ch28 (Yesterday / Film 4 etc) likewise noting its strength / quality and giving an update on results.
Should you have any problems in carrying out this procedure then please give the model number of the TV in question so that it can be checked out, as I am aware that the tuning menu's on some LG's and Samsungs aren't too flexible when it comes to manual tuning with one model actually starting to scan as soon as a channel number is entered, this defeating the object of the exercise.
Just out of interest, what type of aerial arrangements do you have?
| link to this comment |
J
jb386:43 PM
Stuart: Further to that said, on checking I see that the engineering page for Crystal Palace is indicating problems with the HD transmissions insomuch of them suffering from a very weak signal, plus that there is liable to be interruptions to the service over this week, this being the case I feel that further tests would not really serve any purpose until this situation has been sorted out, as this could be the entire cause of your problem.
If though in a week or so you find that the problems with HD are still in existence, then make another posting and an updated report can be given.
| link to this comment |
Wednesday, 18 July 2012
S
Shirley9:15 AM
My elderly father has lost itv3 on his freeview tv since the most recent switchover - how can i get this back for him please - he always loves to watch heatbeat at tea time whilst he makes my disabled mother her tea. kind regards
| link to this comment |
S
Shirley9:19 AM
Chelmsford
Postcode CM2 7LU Chelmsford Essex
| link to this comment |
Shirley's: mapS's Freeview map terrainS's terrain plot wavesS's frequency data S's Freeview Detailed Coverage
Shirley: Sudbury would seem the most likely transmitter at your father's location and looking at Streetview, I can't see a house that doesn't have an aerial on this transmitter. Sudbury is 30 degrees which is between north and north east.
The most common issue with Sudbury is that a different aerial "may" be needed to receive Commercial multiplexes/signals. Has your father had a new aerial?
Try and tune ITV3 in manually if the TV has such a facility. From Sudbury it is on UHF channel 58. Depending on the design of the receiver, it may indicate signal strength when you do this. This may give a clue as to whether there is a low signal which isn't great enough to give a picture.
Presumably you attempted a retune on 27th June. Can Pick TV (number 11) be picked up now? And can Yesterday (number 12) be picked up? If not, then the cause may be the same as with ITV3 - an aerial installed in the days of four-channel analogue.
| link to this comment |
Monday, 23 July 2012
S
Stuart1:56 PM
Hi - I have now totally lost all channels!! Hahaha. I have NO SIGNAL on all of my channels. I recently bought a variable attenuator to boost the signals or weaken them as necessary and now I have nothing at all. What on earth??
| link to this comment |
J
jb389:41 PM
Stuart: If as you have mentioned in an earlier posting that you cannot receive any picture when using a set top aerial and something which you should have been able to do, unless that is you are genuinely experiencing a very low signal caused by the "umbrella" effect, i.e: shielded by being too close to the mast, although I do feel that you are a little too far out for this type of thing to affect you.
But though on checking back on your various postings I cant say that I noticed you having mentioned at any time anything regarding your aerial arrangements, insomuch is the aerial yours? and if so where is it mounted, or is it a communal aerial system that you are connected to? as its important to know this and especially so if its communal.
However apart from that said, as you seem to have exhausted tests / things to try and this being coupled to your locality making it difficult to check / assess the problem using Google earth, as it does appear that you are located in a reasonably high density housing area have you as yet checked with anyone else close by to find out if they are also suffering from the type of problems as you are?
| link to this comment |
Tuesday, 24 July 2012
S
Stuart12:36 PM
Hi there - apologies if I haven't been clear on the aerial. We're in a purpose built flat - we're on the ground floor and we used to have sky, but that was unplugged by the Virgin engineer who came round a few weeks ago to link up the broadband. We have a communal aerial which seems to run through the virgin media box. Two days without tv - it's quite nice in some ways to unplug for a while, but I'd like to get to the bottom of the mystery. Could it be the aerial cable? I might buy another of those just in case the cable is broken inside?
| link to this comment |
J
jb381:15 PM
Stuart: Thanks for clearing that up as I suspected that something else must be involved.
What I would like you to try is if your Virgin V+ box has the name "Scientifica Atlanta" printed on the left hand side of the rear (when viewed from) then along to the right of this you will see two RF sockets one above the other, take these plugs out and couple them together then check what your signal is like on the LG as the signal will then be straight from the communal aerials distribution amplifier.
If its not terribly much better then couple the lead from the actual aerial straight into the TV, giving a report on the results.
| link to this comment |
Select more comments
Your comment please