This is what I call Noise Impact!

Recently had Sky ADSL2+ BB installed (still in the training phase). Initially it synched up at ~10Mbps downstream with ~6dB SNR, and ran thereabouts for a couple of days fairly stabley.

I then started get swathes of disconnections (loss of synch) between around 9am and 5pm - each resynch would see the line come up with the same 6dB SNR but with ~1Mbps less line speed. Over 10 - 15 minutes the SNR would drop to zero, then resynch again.... and again.. each time resynching at lower and lower speeds. After 5pm the router would resynch back up to ~10Mbps / 6dB and be fine until the following morning.

Yesterday however, that final resynch did not occur and I ended up at ~1Mbps / 31dB. So I thought I would leave it like that and see if it could hold on through the next day without a loss of synch. Fired up RouterStats Lite to monitor things... the image linked below is the result (use the magnify glass tool button to see the full size image)...

http://i1066.photobucket.com/albums/u402/premmy9912/...

Something is obliterating the downstream frequencies with interference. Time to break out the portable radio - something that noisy should be pretty easy to pickup I reckon

Wish me luck!

Edited by deleted (Thu 05-Feb-15 00:40:04)

You don't have a Sky box plugged into the line with no filter, (or possibly a faulty one), do you? Given the time of day and the interference-free time it isn't likely, but worth just checking. Or a kitchen TV that was on at that time?

Where is the router in relation to anything else electrical?

No Sky box. Just the Sky router > new filter > new master socket - nothing else attached to the line at all.

No TVs in use in the premises.

Router is the only powered device in the room that it is in. Only other things powered during the time of that chart was my laptop (permanently on), microwave (intermittent use), fridge/freezer which kicks in and out all day and night, electric shower for 10 mins or so. Whatever is causing that >30dB hit is external to my premises.

I suspect the two square lumps either side of the massive dip are a neighbour's heating going off for the night, then coming on again in the morning. That looks to be a ~2dB hit.

I worked in DSL support for years so I know this will be a fun one to get resolved

looks like central heating problem..slow deterioration from sudden start @0700 ish and gradual improvement afternoon when the house is warmed up by the sun and sudden switch off at 2200.??

Unlikely. Yes, pump and boiler starting up could cause it and a continuous pump running would keep the noise level high. And whilst warming up during the day is a possibility the heating would kick in occasionally and certainly after dark I would expect the heating to be on up until maybe 22:00 or a little later. There is nothing after 13:30 or so.

An easy way to check would be to turn off CH at a fixed time say 10:00 and ask the neighbours to do likewise at 11:00 and 12:00

Maybe a neighbour has a solar PV installation facing South East and the inverter kicks in at sunrise and finally stops in te early afternoon?

I would be also walking the cable route back to t the cabinet and potentially exchange and looking for businesses that are close by.

Updated charts for both noise and speed...

SNR:
http://i1066.photobucket.com/albums/u402/premmy9912/...

Speed:
http://i1066.photobucket.com/albums/u402/premmy9912/...

Ended up on ~7Mbps / ~8dB once the interference subsided today at around midday. Which means I'm in for a boat load of reconnections tommorow when it kicks in again.

Interesting the times are not consistent each day, which would seem to indicate something being manually switched on / off. Will be keeping an eye on it over the weekend - may give a clue as to whether it is residential / commercial. If I have the line routing correct (all underground so hard to be sure) - then the line passes in close proximity to a parade of shops and a small trading / light industrial estate plus some residential on its way to the exchange.

I suspect there is more than one source of interference. Check out the squared off bump of ~2.5db each night at the top of each curve...
http://i1066.photobucket.com/albums/u402/premmy9912/...

That would be consistent with central heating going off for the night.

You can easily check that. After it has gone off, leave for 30 minutes, turn on, run for 30 minutes and then turn off.

You have tried the obvious, and tried a different router ?

Indeed so ~if~ I knew whose heating it was. Certainly not mine