Expected ratio between up/down line attenuation?

Hi,

Since moving into my house 10 months ago I've been trying to improve Broadband speeds with little success. I'm plugged into the master socket (the old style, not an NTE5 split-faceplate one) with no extensions connected, using a WAG200G. Speeds are ~3MB, and as the crow flies I'm 1.5km from the exchange, but expect the real line length to be ~3-3.5km.

What I have noticed when looking at other people's connection figures is that line attenuations are often roughly balanced in a 2:1 or 3:1 ratio (eg 36 downstream, 18 upstream). My figures are:
Downstream Margin: 14 db
Upstream Margin: 25 db
Downstream Line Attenuation: 42 db
Upstream Line Attenuation: 12 db
Downstream Transmit Power: 12 db
Upstream Transmit Power: 18 db

(Downstream margin can fall to 4-5db in the evenings)

I am wondering, does the imbalance in ratio between downstream line attenuation and upstream line attenuation imply a fault in the wiring of my line? Living in a city I'm sure there must be something wrong, but what I'm not sure!

Edited by reywob (Fri 04-Jul-08 10:36:38)

while not answering your question, did you disconnect your ring wire?
http://www.dslzoneuk.net/socket.php

The high noise margins on your line indicate that there may be a fault (possibly intermittent). Get your ISP to run some checks. The downstream attenuation is largely dependant on sync speed, since the higher frequency tones are attenuated more.

Yes, I've (cough) disconnected this in the master socket, but have the right tools to replace it if BT come round. Once disconnected the line sync speed has been anywhere between 3000kbps and 5100kbps, but hasn't remained at the higher sync speeds long enough for the line profile to stay above 3000kbps.