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MaxDSL - SNR query

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MaxDSL - SNR query

My line was re-graded to maxDSL (from 2Mb to 8Mb) my line sync was 8128 with a SNR of 6-7dB, before the re-grade it was a steady 27dB.

I read somewhere that when your sync speed doubles your SNR drops by around 6dB therefore I was expecting a drop of around 12dB not 20dB, does this sound right?
4 REPLIES
JonathanW
Grafter
Posts: 2,648
Registered: 02-10-2007

MaxDSL - SNR query

6-7dB sounds a little low for a sync of 8128, what time of day did you take that reading? As its possible that at different times of day your SNR might fluctuate, if that's the lowest your SNR drops then you should be fine, but if it drops bellow that then you'll probably find your speed dropping as the BT equipment tries to maintain a stable line for you.
hop
Grafter
Posts: 109
Registered: 02-08-2007

MaxDSL - SNR query

Mine has done exactly the same (now 5 or 6db, was mid 20's). I'm 2 days into the training, so we'll see what happens. Sync is around 7500 to 8096 (still varying).

I'm expecting a final speed of 4 or 5Mbps, so I guess things will stabilise over the next few days, with a lower sync and better SNR.
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MaxDSL - SNR query

Quote
6-7dB sounds a little low for a sync of 8128, what time of day did you take that reading?

It was during the first few days when the line sync varied between 8128 and 7616. Looking at the logs it didn't seem to matter what time of day it was.

This is now day 8 since the re-grade and for the past 2-3 days sync speed seems to be now fixed at 7616 with SNR still fluctuating between 7 and 10.
Plusnet Staff
Plusnet Staff
Posts: 12,169
Thanks: 18
Fixes: 1
Registered: 04-04-2007

MaxDSL - SNR query

Hi,

6dB is towards the low end as Jon says, part of the initial 10 days tries to work out how faster your line will support, it can get it a bit wrong to start with and sync a little too how, but as you've seen it'll lower the speed a little to increase the SNR and keep it more stable. 7-10dB is probably about right.