SNR Reset

rscott · Nov 26, 2008, 17:12:52

BT's delightful DLM appears to have got stuck.. For reasons which are unclear to me, I seem to have a 15db margin instead of the usual 6. It may have been due to BT recabling half the village earlier this year.

I've tweaked it down to about 11db on my router, and it's been stable for 35 days.
I just rebooted the router - hoped DLM might have reduced the margin a little, but no.

Does anyone know if IDNet able to persuade BT to sort this? I had a lot of problems getting it sorted by my previous ISP. I'd been trying for about 2 months, then migrated away when their prices increased..

Rik · Nov 26, 2008, 17:16:40

Hi and welcome to the forum.

You need to maintain a stable connection for 14+ days for the target NM to drop by 3db and then repeat that in 3dn stages back to 6db. Using tweaks will generally stop the BT software from doing this, unfortunately.

You could try asking IDNet, but BT are usually reluctant to make the change manually unless they have a record of a cleared fault which would have accounted for the increased target NM.

rscott · Nov 26, 2008, 17:18:50

The last session was up for 35 days, with an SNR of between 9 and 12, depending on the time of day.

I guess I could untweak the router, then I'm syncing below my FTR, so BT might decide to sort it then.

Rik · Nov 26, 2008, 17:19:50

That would be a better approach. What are your stats?

rscott · Nov 26, 2008, 17:22:10

These are the current (tweaked) settings:-

Bearer Generic Info Downstream Upstream
Margin [dB] : 10.0 23.0
Attenuation [dB] : 43.0 25.0
OutputPower [dBm] : 19.5 11.5

Total Available Bandwidth Cells/s Kbit/s
Downstream : 8679 3680
Upstream : 1056 448

Rik · Nov 26, 2008, 17:23:36

You should definitely be doing a lot better than that. I take it you've eliminated any potential problems with your own wiring?

kinmel · Nov 26, 2008, 17:32:55

Quote from: Rik on Nov 26, 2008, 17:16:40
You could try asking IDNet, but BT are usually reluctant to make the change manually unless they have a record of a cleared fault which would have accounted for the increased target NM.

Recently my SNR would jump for no reason to 9dB and stick there. Each time IDNet was able to get it reset to 6dB and eventually it just stayed at 6dB, Support should be able to help you now.

rscott · Nov 26, 2008, 17:34:16

Yep. It's the older style master socket (no removable faceplate). Router is plugged into the master (via a filter), with an extension for the phone. Extension has bell wire disconnected.

Stats are the same when plugged directly into the master.

I'm in a fairly rural location, with overground power & phone lines (sharing the same poles..), so am not expecting miracles - I'd just like to get back to the 4500- 5200 speeds I used to get.

Stats below, with router tweak removed. My FTR is 2800...

Bearer Generic Info Downstream Upstream
Margin [dB] : 15.5 23.0
Attenuation [dB] : 43.0 25.0
OutputPower [dBm] : 18.5 11.5

Total Available Bandwidth Cells/s Kbit/s
Downstream : 5735 2432
Upstream : 1056 448

Rik · Nov 26, 2008, 17:36:01

That margin is certainly killing you, you should be at around 3,800-4,500k on those figures.

rscott · Nov 26, 2008, 17:44:25

I've asked IDNet support to see if BT can reduce the SNR back to 9db. That seems to be a stable value.

I get the feeling BT have upset a few other lines in the village as well - I know of one more which has dropped from 6500 sync speeds to around 3500.

Rik · Nov 26, 2008, 17:45:39

Ouch! Keep us posted.

Steve · Nov 26, 2008, 17:47:12

If its below the FSR can't this be logged as a fault? Perhaps a 2wire BT may give some stability

rscott · Nov 26, 2008, 17:51:18

Just checked a phone local phone numbers on samknows.com . They're all reporting much slower speeds than they used to.

Certainly seems like BT have been rerouting cables again.

stevethegas - I'm running a speedtouch 546 at the moment. It's generally stable - uptimes are usually measured in weeks not days.

Rik · Nov 26, 2008, 17:54:53

There does seem to have been a general trend in the past 12-18 months for BT lines to be allowed to degrade.

Sebby · Nov 26, 2008, 19:13:38

As the DLM hasn't reduced the target SNRM automatically (which, in my experience, it rarely does) it's worth checking with IDNet whether they can convince BT to do it manually.