3dB Noise Margin

[nellisere]

Ok, so I need help understanding the noise margin. Everywhere I look, people are saying that a higher noise margin is better, so why are Sky settings people to 3dB? I had DLM run in February, and that set me to 3dB noise margin, I haven't really had any problems with it, but I just need some more help understand if 3dB is great, or if it isn't.
Thanks

[gymno]

The lower the noise margin, the higher the potential speeds.
With it though comes a potentially higher error rate.

DLM only applies a 3db noise margin to lines that are good enough to handle it & where the resultant error count is acceptable.

The difference between 3 & 6db usually means about 2mbps, so if you have 20mb now, you'd probably only get 18mb at 6db.

[nellisere]

Ahh I see. I was on 6dB I think with 13Mbps sync speeds, got to 15.5Mbps sync speeds with 3dB. Thanks for that, was just worried because everyone was saying a higher noise margin is better.

[gymno]

People may be referring to the increased stability from fewer errors that a higher margin gives.

DLM seems to be quite strict regarding the quality of line it will apply 3db to though, so i wouldn't be concerned about yours.

It recently retrained my line & tried 3db for 24 hours on 2 occasions while it was running.
Despite experiencing no problems & ending up with an amazing 22mbps, on both occasions it deemed my line to be unsuitable & reverted to 6db.

Here's my day by day account of DLM training which finished yesterday:
http://www.skyuser.co.uk/forum/sky-d...g-new-dlm.html