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My ITV/C4 Freeview channels have disappeared - what can I do? Is it my SCART ca

My ITV/C4 Freeview channels have disappeared - what can I do? Is it my SCART cable?

My ITV/C4 Freeview channels have disappeared - what can I do?
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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Comments
Thursday, 24 February 2011
Briantist
sentiment_very_satisfiedOwner

1:54 PM

HEATHER: Please see Single frequency interference | ukfree.tv - independent free digital TV advice .

You are in a poor area for Freeview reception, you might expect this to happen.

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Briantist's 38,910 posts GB flag
Friday, 25 February 2011
I
ian
8:37 PM
Tring

every day since sunday at exactly 5.45 we lose itv1,2,3 channel 4 and 5 more4 and e4.up to that time of day all channels are giving good reception but come 5.45 they all dissapear never had a problem before sunday :(

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ian's 7 posts GB flag
ian's: mapI's Freeview map terrainI's terrain plot wavesI's frequency data I's Freeview Detailed Coverage
I
ian
8:47 PM
Tring

yes i looked at that but nothing there that i can see is causing a problem everthing is fine till 5.45pm then we lose the channels.done a reset to factory settings and rescan but it wont even pick the lost channels up :(

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ian's 7 posts GB flag
ian's: mapI's Freeview map terrainI's terrain plot wavesI's frequency data I's Freeview Detailed Coverage
Saturday, 26 February 2011
Briantist
sentiment_very_satisfiedOwner

5:28 AM

ian: I can't see a "factory reset" helping.

You need to identify what happens at 5.45pm to cause the problem.

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Briantist's 38,910 posts GB flag
I
ian
9:19 AM

did a rescan this morning and got the lost channels back signal strength is around %70
will have to see what if anything is happening at 5.45 to cause the problem.

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ian's 7 posts GB flag
Briantist
sentiment_very_satisfiedOwner

10:01 AM

ian: It can be things like street lighting or internal things like the central heating system - if it exactly the same time, suspect something on a timer.

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Briantist's 38,910 posts GB flag
I
ian
1:19 PM

the thing is nothing's changed in the 3 years we've been on freeview always had good to very good reception even adverse weather has never been a problem.now i may be wrong but the lost channels are on mux2?could there be a problem with that?like low power or they're doing work on it ready for the switchover?

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ian's 7 posts GB flag
Briantist
sentiment_very_satisfiedOwner

2:05 PM

ian: No work is being done on the transmitters.

You might also wish to see Single frequency interference | ukfree.tv - independent free digital TV advice .

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Briantist's 38,910 posts GB flag
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