Anybody got any ideas? All the commercial channels are pixellating and dropping out, driving us nuts. BBC channels don’t do it, which would tell us that there’s no problem with the BT digibox or the aeriel. The digibox is brand new anyway. We’ve tried re-tuning and it makes no difference.

Got any suggestions?

It’ll be the aerial.

I had similar, was the kick I needed to go to Virgin and thus remove said aerial from roof, ideal.

This is considered normal viewing in Wales, sorry i can’t add anything to help.

If its something that has just started to happen then it could be that your local transmitter is undergoing maintenance and is working on reduced power; lots of work being done at the moment due to frequency spectrum changes – some details here

It’s the aerial.

Ours has been doing it for a while and it got noticeably worse after the last retune. Fitted a new aerial on Monday and all is well. Looks like problem was mostly the cable. It was very brittle and had been letting in water. Just because one channel is fine doesn’t mean the system is fine. Each channel (or actually MUX, a set of channels) will have a different signal strength.

Err, it’s not pixellating, it’s macro-blocking and is a result of low signal strength causing too many errors in the stream for the box to correct.

Do you know which transmitter you receive your TV signal from? You can look it up online and get all the data about it including which channels are on which MUX. As @nickjb says, it’s likely that the channels you are having a problem with are all on the same MUX frequency.

Somewhere in the menus there should be a screen that shows signal strength and quality so try to find that.

I’ve had the cable leading from the aerial completely full of water – the outer casing becomes brittle and cracks especially where there are bends, usually where it comes round the edge of the roof. The TV would hold signal for a few minutes then “tune out”.

Channels are grouped, so you can get a set of channels working, others not.

https://ukfree.tv/transmitters/multiplexes

On your digibox, under settings somewhere will be a signal quality option that shows signal strength and quality. Pick a channel that works and take a look, then one that doesn’t and compare.

Aerial might have moved in the wind, the transmitter might be doing maintenance, water in a connector from all the rain etc.

Was told by our local aerial man that poor signal was due to valley location and strength of mobile phone network, only way to resolve is to install satellite dish instead.

BBC channels don’t do it, which would tell us that there’s no problem with the BT digibox or the aeriel.

What jamze said – you can get good signal on some channels but not others. If someone bumps into our aerial when in the loft this is exactly what we see.

And yes there’s a signal strength display mode on your telly somewhere, probably.

My satellite does this now and then. Often when there is heavy rain in the locality. I can usually fix it by tweaking the dish up by a mm as I think that it creeps down over time resulting in a slight lose in signal strength which only becomes manifest during rain. So try moving the aerial a little as a first fix

Aerial might have moved in the wind,

Happened to mine, BBC channels started blocking then disappeared after a retune. I’d used next door’s aerial as a guide to mine and can now see it’s a couple of degrees off.
You can check that the aerial’s pointing the right direction using a compass and this site

Very useful information as always from the STW collective. Thanks.

I bet the magpies bouncing on the aerial have tilted it down and I’m even more sure the old cable is cracking as it lies on the roof in full sunlight and it has been raining a lot.

Time to call a man who can.

Time to call a man who can.

Well the local TV man came and fixed it and as I anticipated, managed to sell Mts Gti a new aerial even though ours is only a few years old. The story was that cellphone signals interfere with reception on old-style aerials. Still, I guess they ain’t going to make a living by charging £50 for driving over, spending 90 minutes there and then driving home so £90 seems about reasonable.

Thanks again to all for the advice.

Err, that’s bobbins. Freeview, i.e. UK terrestrial TV, uses 474MHz to 658MHz. Mobile phone networks use a few frequencies but the lowest is at 800MHz.

I thought it was bobbins as well but I expect the TV aerial business is like the bike parts business – they wouldn’t make any money if they couldn’t talk people into buying new stuff. Apparently the mobile phone retail business is in a bit of bother at the moment for that very reason – Dixons Carphone in trouble: https://www.bbc.co.uk/news/business-48702752

Err, that’s bobbins.

Surprisingly, it’s not, it’s just rather unlikely. When 4G was rolled out, they were giving out filters to folk who’s Freeview service deteriorated. We got leaflets through the door about it and everything.

(So if aerial man was correct and it was down to 4G interference, you could’ve ordered a free filter and saved yourself £90.)

Leaflet people:

Home

Our chromecast plays hell with our terrestrial signal.

I’ve been using radio mics for long enough to know that things that can’t interfere with each other can.

It’s the aerial.

As others have said, more likely to be the cable – both more likely to deteriorate and also more effort to replace (a lot of signal problems get “fixed” by replacing the aerial with a larger one but leaving the old cable in place.

Thanks all for the contributions; the picture is now perfect and we have a shiny new but very small aerial mounted at the bottom of the huge pole so on advice from Whitestone, above, I’m going to go up on the roof this afternoon and saw off the ugly 8′ pole and redundant huge aerial. I can’t see whether the engineer replaced the cable or not but he has certainly moved it; it looks more serious than the old brown co-ax cable, some kind of slightly lumpy black plastic outer layer looking similar to the Cat 6 cabling we had installed last year for internet round the house.