If it was something as simple as a Sky Box though, surely it wouldn't be so regular. The noise drops on the dot at 7pm and appears again at 10.30pm - exactly same time each day.

It's been happening since 20th November by looks of it. 20th November has no significance as far as I can remember though.

Can't find anything in my house on a timer, I've tried turning off all electrical device apart from router but nothing.

Met office weather for 20th November:

The 20th was a day of sunshine and scattered showers, with the south-east remaining mainly dry, but it turned much colder in a north-west wind.

The start of last winter was very mild but looks like it was possibly this date when things turned colder... That points possibly to a central heating system somewhere. It could be that they switched central heating back on and perhaps there is a fault in a central heating system that means when the heating is "off" it is causing load interference that doesn't occur when it is running (which could explain the counter intuitive timing)?

Another excerpt from Met Office:

November began dry and exceptionally mild but often cloudy with widespread fog. The rest of the month was generally mild, dull and changeable with south-westerly winds. It was very windy at times with persistent rain across the Pennines and Cumbrian fells. There was a brief cold snap on the 20th to 23rd.

Edited by ian72 (Fri 29-Apr-16 08:38:54)

Do you have anything that will show like a 'bits per bin' type graph for your line ? If you do you may be able to find the part of the signal that's going when the source gets turned on, and that way listen more accurately with a radio,

The problem with errors though is continuous apart from the 3,5 hours every evening. That points away from heating - who leaves heating and hot water on 24 hours/day?

The two questions are: what is causing the errors? And what is suppressing them in the evening? which will the lead to: is it the device being turned off? or going into active mode? or another close-by device having a filter on the power lines which is absorbing e interference?

That is unlikely to show it as there are large numbers of FEC errors. So the bins are still being filled however the data is being corrupted which requires the correction.

I am vaguely wondering if there is a fault with the heating that is having the opposite effect to what you would normally expect. The timings of lower errors occurs at the sort of time I would expect heating might be on - perhaps an electric fire somewhere that when turned on full blast causes no noise but when essentially off is causing an overload through a resistor somewhere.

I know it seems a long shot but when things are running full power they can sometimes be fine but when "throttled down" can cause issues. Light bulbs can cause no interference at full power but when dimmed down to a certain level can cause interference. If the device is not fully turned off at the mains then the method of it being "off" could itself cause interference.

EDIT : In fact a timer clock itself could cause this? The timer itself is turned on at the mains. But, whilst the timer is off it is doing something to stop current being passed on - if it is a dodgy timer this could cause interference that may disappear when that block is released.

Edited by ian72 (Fri 29-Apr-16 09:47:55)

Go back to some of my previous comments and they are in the same vein.


For example, a power supply when unloaded can be very "noisy", put it on load and the noise is quashed.. Or noise from one device is being suppressed by something else turned on for those hours - which is almost certainly on a timer.

The OP is going to turn off everything and see if there is any effect ... if that fails it points to the potential for it being outside and as Zarjaz says they are even harder to locate - he has yet to be taught the full Ju-Ju dance though!


The OP has checked for timers and has yet to find anything as far as I can remember.

Yes I've checked for timers and turned off most stuff in the house to no avail. I'm planning on turning everything apart from router off on Sunday morning (at the fuse box) when i can get the wife and kids out of the house for a few hrs.

Good point.

If the OP can do it, he might the ask the engineer to do a DLM reset, that'll lose the error correction and then maybe it'll be visible ?

Oh, and it'll be Sod's Law the engineer attends when the source is off.

In reply to a post by Zarjaz:

Good point.

If the OP can do it, he might the ask the engineer to do a DLM reset, that'll lose the error correction and then maybe it'll be visible ?

Oh, and it'll be Sod's Law the engineer attends when the source is off.

not much chance ... the off period, or when it is suppressed is 18:55 to 22:25