Is this normal?

Maverich · Apr 20, 2009, 19:02:59

Good Evening!

I have had my noise margin sitting at 14Db for the last 14 days and thought It may go down by itself although it hadn't,m so emailed Idnet regarding this. They were very quick to reply and said that they will reduce it down to 9Db and request for Interleaving to be taken off. I just arrived home and noticed that the noise margin is the same but the sync speed has been reduced. Any ideas why this maybe the case?

Glenn · Apr 20, 2009, 19:07:04

Has the router rebooted? I believe that the change of target nm takes 24 hours to come into effect

Rik · Apr 20, 2009, 19:07:15

I would guess that your router has re-synched for some reason during a period of noise. If you asked IDNet to reduce the margin today, I'd expect it to happen overnight, not immediately, afaik they have to ask BT to actually do it, and such things usually happen overnight. I'd suggest switching your router off overnight and re-connecting in the morning. If the problem persists, I suspect IDNet will be told that BT's dynamic line management software is doing its job, and that's the NM your line needs.

Maverich · Apr 20, 2009, 19:13:05

Well in the email I recieved back I was advised that the noise margin would take 2-3 hours after the email. They then went on to say that the interleaving would be taken off for 2moro morning. Think the router has rebooted as only been live for about 8 hrs where as this morning it was about 340hrs.

Baz · Apr 20, 2009, 19:14:19

do some routers tend to re boot themselves after so many hours

Rik · Apr 20, 2009, 19:24:40

The only one I know of, Baz, is the single SSID 2700, which with some firmwares reboots after 300 hours.

Rik · Apr 20, 2009, 19:25:48

Quote from: Maverich on Apr 20, 2009, 19:13:05
Well in the email I recieved back I was advised that the noise margin would take 2-3 hours after the email. They then went on to say that the interleaving would be taken off for 2moro morning. Think the router has rebooted as only been live for about 8 hrs where as this morning it was about 340hrs.

A change of this sort in the NM would probably force a re-sync. Only IDNet can tell you for sure when the change occurred. What are your d/s attenuation, NM and sync speed now?

Maverich · Apr 20, 2009, 19:28:32

This is what i'm seeing now,

Connection Speed   6176 kbps   448 kbps
Line Attenuation   31.0 db   18.0 db
Noise Margin   14.1 db   21.0 db

The connection speed was at 6272 kbps before the reboot, so not a major difference. The Noise margin is the same though. When I was with Sky the noise margin was always to low although that was a different router.

Rik · Apr 20, 2009, 19:32:24

That amount of variation is not significant, small swings are likely to occur whenever you re-sync due to variations in ambient noise on a line. The fact the NM is at 14, though, makes me wonder if the change has occurred. I'd still recommend you power the router down overnight, then see how it goes in the morning.

Maverich · Apr 20, 2009, 19:34:23

Ok will do Rik, I'll check in tomorrow morning!

Rik · Apr 20, 2009, 19:39:53

I'll keep my toes crossed for you.

Sebby · Apr 20, 2009, 22:30:49

Quote from: Maverich on Apr 20, 2009, 19:28:32
When I was with Sky the noise margin was always to low although that was a different router.

That'll be because Sky provide a Netgear router with the troubled AR7 chipset (in short, it can't sync at the right rate to achieve the target SNRM, and so the noise margin drops extremely low, sometimes into negative, often causing re-syncs).

Maverich · Apr 21, 2009, 09:28:20

Left router off for the night, just rebooted it and i'm now seeing,

Connection Speed   6080 kbps   448 kbps
Line Attenuation   31.5 db   18.0 db
Noise Margin   14.9 db   20.0 db

things look like they going backwards for me! Well of to work now

Rik · Apr 21, 2009, 09:57:06

What has happened is that the NM was set down to 9db, but BT's software picked up on instability and raised it straight back to 15db in order to maintain the connection. Your maximum stable rate, set during your initial training period, is 5.1M, so you're performing better than BT say you can.

All I can suggest is that you check your internal phone wiring, make sure there are no ring wires, and look out for potential noise sources, eg Sky boxes.

Sebby · Apr 21, 2009, 13:11:03

I agree. It's actually a pretty decent line so something's interferring.

Maverich · May 10, 2009, 14:39:19

Hi ppl,

Just an update really. I left worrying about speeds etc and then yesterday for some reason I thought i'd check my router stats,

Connection Speed   7488 kbps   448 kbps
Line Attenuation   31.0 db   18.0 db
Noise Margin   9.1 db   18.0 db

Put a rather large smile on my face

Rik · May 10, 2009, 14:47:38

Looking pretty healthy, I'd say.

Sebby · May 10, 2009, 15:47:41

D-Dan · May 10, 2009, 18:04:24

Better than mine, now. 7,424 sync with SNR 6 - 6.5 - so I suggest Shhhh! and hope it hasn't heard you

Steve

Edit: BTW - try not to power down your router now. Your BRAS should increase to 6500 over the next few days. That's when you notice the improvement.