I have seen another line or two with Sky heading down towards the 3dB target level now, wonder if they are trying this out, in a move to ensure BT Wholesale is not faster on ADSL2+
Sky are definitely setting lines with speeds higher than they used too.
In the old days, say if my line synced at 6Mbps with 7db noise margin at 10am. This noise margin may go down to 4db by 8pm. DLM used to notice this and set the target sync lower, say 5.5Mbps. This resulted in a high noise margin 24/7 & often resulted in double digit noise margins at around 10am...
Nowadays. Say I sync at 6Mbps with a 7db noise margin at 10am. This noise margin may go down to 4db by 8pm. DLM now seems to keep this target sync, despite it regularly resulting in a low SNR. As long as it's stable DLM doesn't seem to care anymore.
If the user syncs at 10am, they will get an SNR of 4db by 8pm. If the user syncs at 8pm, their sync will be lower than 6Mbps and their noise margin will be 7db. By 10am the following day, the SNR is likely to be in double figures.
Sky are definitely not doing a 3db noise margin. At time of sync it's always 7db. However DLM is often setting syncs above what it used too like in the above example.
So when you see someone on Sky with a low SNR, it just shows that their noise margin is some-what varient... Skys NETGEAR routers used to show an SNR of 5db difference over a full day on my line. Whereas the sagem is always within 2db. So the router makes a big difference too.
Fibre is completely different as I'm sure you know.
Edited by ukhardy07 (Thu 02-Aug-12 04:20:01)