Yes - BUT is there noise or crackling on the line - especially when the problem occurs??

The Talktalk names mean nothing, unless we know what inpulise settings etc are involved.

You can tweak a line to make it more or less sensiitve to noise, and not by just changing the noise margin.

If old profile was better, why not request a move back to it?

There's no noise or crackling on the line, this was resolved for me back in June last year.

I have requested being put back onto the initial profile but I've been told that they are still investigating and whilst they do this they want it left on the 15dB profile.

Any chance of some stats from your router ,or a DMT graph of the ADSL tones they may give a clue what is going on, But the fact that you still are seeing disconnections whilst on a very high (any over 12db) and different ADSL modes Then it suggests a fault , maybe it's not with the line plant, maybe it's the equipment in the telephone exchange at fault ,do you know if that was this checked when the engineer repaired the line fault ?
I would make a formal complaint to the senior manager of your ISP Do this via letter sent to sign for, keep a copy of your letter ,As their overseas support is a complete waist of time , have you managed to speak with anyone English yet ? assuming that they still employ English call center staff, who may actually be trained and have some degree of knowledge ,unlike their counterparts that don't deviate from the script

Edited by tommy45 (Wed 02-May-12 13:36:18)

I've done some longer plots, unfortunately they are in the evening again, I have noticed that it starts drop the connection only in the evenings, then at around 4:30am it seems to stabilise. If the connection get used then you get the graphs below.

http://img.photobucket.com/albums/v280/IAmATeaf/sync...
http://img.photobucket.com/albums/v280/IAmATeaf/sync...
http://img.photobucket.com/albums/v280/IAmATeaf/snr-...
http://img.photobucket.com/albums/v280/IAmATeaf/snr-...

These are pics of the actual router stats, the 2nd pic also shows the upstream SNR margin and attenuation which both randomly drop to zero:

http://img.photobucket.com/albums/v280/IAmATeaf/rout...
http://img.photobucket.com/albums/v280/IAmATeaf/rout...

Am going to find out how to do a DMT graph.

EDIT: I've just checked and the DMT tool doesn't work with the DGN1000

Edited by deleted (Thu 03-May-12 20:56:28)

I think and I'm hopeful I may have found the problem, well a problem at least. The junction box where the line from the pole hits my house had come loose and flopped down so that water could run along the wires and enter the junction box. So I've gone and borrowed a neighbours ladder and re-secured it so that water can't run into it.

I didn't open the box up but am hopeful that if any water did manage to get in it will naturally drain away or at least dry over time. Just a case of waiting now to see if my Rod Hull-esk endeavours up a ladder were worth it.

Water ingress is a problem where there is more than one line running through the cable, you may pick up the battery off another line. If only one line, then the problem may be due to corrosion in the connectors. So your remedial work to the junction box is unlikely to cleared the problem.

Ask if TalkTalk will run a CIDT test on your line, when the router is in sync, does this pass ??

I adjusted the junction box on Saturday and now since Sunday the line is now stable with no drops or re-syncs, the only problem is that due to the earlier problems the SNR margin has been increased to 12dB and TT now won't drop it down back to 6dB as they claim that it's their automatic system that has managed to stabilise the line. They also reckon that if the line is stable then their system will automatically drop the SNR margin in 3dB chunks so there's no need to do anything.

I'll ask if they performed a CIDT test.

One question, why would setting the modem to G.DMT make the line more stable?

I was told to leave the modem set to Auto, the line is supposed to be ADSL2 but when playing around I've found that setting the modem to ADSL2 means there's no sync at all, ADSL2+, modem syncs but my upstream attenuation and SNR margin keep on dropping to 0 and the line will drop and re-sync every few hours. If I set the modem to G.DMT then no more fluctuations on my upstream and the line never drops.

What does all the actually mean? I know the obvious answer to keep the modem set to G.DMT but I'm curious

Very unusual for it not to connect on ADSL2, which is often the best setting on dodgy lines.

G.DMT (ADSL) is more stable than ADSL2+ because ADSL2+ uses twice the frequency range, the same as G.DMT plus the same number above those. Those higher frequencies have two problems.

First, they attenuate more, which is why on long lines they become useless and there is no speed gain, and second they are more prone to interference. Noise.

As a general rule the higher the speed the more errors there will be, on G.DMT or ADSL2+, and more noise almost by definition means more errors.

High error rates can trigger a disconnection and reconnection.