When an ISP sets/adjusts the target SNR margin, does it have to be in 3db increments?
Or can it be by 1 or 2 db?
BT have just reduced mine, router previously reported downstream SNR margin of 14db (daytime), sync speed now inceased and IP throughput by 500 kBps. Downstream SDN margin running at 11db (daytime).
Another 3db off would suggest a further speed increase, and 11db-3db=8db.
However, at night SNR Margin drops 1 or 2 db, very occasionally by 3db briefly (ie. to 8db, but usually 910db).
If BT go a step further for me, 11db-3db=8db (daytime), less 2db at night =6db i.e. within the 6db margin with ADSL1 requires.
But if it was to occassionally drop to 5db, would that screw things up big time?
Or would the interleaving (and fact that BT set IP profile a bit lower than sync rate would accomodate) mean that this would work? And hence I could get a but more speed out?
Failing this, if BT could sdrop the SNR margin by 2db (rather than in 3db increements), then I reckon I'd be safe?
But can they change it is less than 3db increments?