In reply to a post by MrSaffron:

7 Meg sync at 43 db attenuiation is not impossible just rare, ADSL has often exceeded expectations, even with the high loop density the UK has now.

I know, I never expected to get such high speeds and my router maintaining them too. Maybe its because I am on the edge of speed that I see such a seasonal variation, the very best is only possible in winter and I lose 2 db+ of SNR come the warmer weather. Of course the SNR increase gave me the ability to get the 7 mb speed. Cone April/May, if it's the same next year, SNR will drop and so will my speed.

The idea of atmospheric moisture explaining it, the cable is underground and we've had a wet and/or humid summer. A wet winter in theory would cause speed to drop closer to summer speeds.
What amazes me is that this is only plain old ADSL1 and I'm not that far from the max for it. With a much longer line and ADSL2+ at my old home I only gained a couple of hundred kb/s from ADSL2+, here there's no option for it apart from the two LLU providers with a not-good reputation. This may be weird but I could slow down if I changed to the more modern tech.

Thing with my line that find odd is the fact that the attenuation shows a seasonal increase so does the sync rate, and if it decreases again so does the sync,
not as you would expect, normally higher atten =lower sync very odd i think

In reply to a post by tommy45:

Thing with my line that find odd is the fact that the attenuation shows a seasonal increase so does the sync rate, and if it decreases again so does the sync,
not as you would expect, normally higher atten =lower sync very odd i think

Attenuation always effects speed as far as I know, it's a measure of loss in the line, so the higher the attenuation the lower the speed. My attenuation remains the same all year round. I used to have an underground cable that had varying attenuation according to the weather, the wetter, the higher the attenuation and the lower the sync. The reason, after talking to OR engineers, was water in the joints. They said the old line needed replacing but BT wouldn't do so until all the phones failed. I've never heard of increased attenuation leading to increased sync though. I can't think of any explanation for that.

In reply to a post by kritifile:

The idea of atmospheric moisture explaining it, the cable is underground and we've had a wet and/or humid summer. A wet winter in theory would cause speed to drop closer to summer speeds.

Does not matter whether the cable is above or under ground interfering noise will penetrate the ground for several metres It is not just the low level atmosphere but right up to the troposphere. Long range transmissions are always better in the summer when compared to winter because there is less attenuation.

Well all i can say is my line loves the winter and hates the summer, spring summer synch is around 3.8 meg and autum winter synch is at around 4.8 i stepped up from 4.5 to 4.8 3 days ago