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Why Has My Line Rate Dropped (SNR Now 14+dB)?

Community Veteran
Posts: 1,139
Thanks: 4
Registered: 20-07-2007

Why Has My Line Rate Dropped (SNR Now 14+dB)?

I'm confused!

For months I've had a stable MaxDSL service - almost no disconnections, a stable rate of 7,000 and my modem has always sync'd at 7,616kbps. During this time my SNR has varied between 10 and 12dB with Interleaving switched on.

During the last couple of weeks my modem has started syncing at a lower rate (varies between around 6,800 and 7,200) and my stable rate has dropped to 6,500. I could understand this if I was struggling with a low noise margin but at these lower sync rates, my SNR is now 14-15dB.

I thought that MaxDSL would work with much lower noise margins than this so any idea why this might be happening. Does anyone have any suggestions how I can get my sync rate back up?

Thanks - Bob
7 REPLIES
Community Veteran
Posts: 1,139
Thanks: 4
Registered: 20-07-2007

Why Has My Line Rate Dropped (SNR Now 14+dB)?

Anyone got any suggestions? stable rate has now fallen to 6,000.

Bob
N/A

Why Has My Line Rate Dropped (SNR Now 14+dB)?

Maybe somebody else had an unstable line and BT accidentally increased your SNR margin?
Not as crazy as it sounds, as on another forum I was reading about a couple of people who were jumpered to Pipex LLU only they'd never signed up for it, weren't Pipex customers, and the LLU jumpering ceased their connection, in effect. It took several weeks and a lot of evidence to convince everyone, including BTw, what had happened really had.
It even seems that I had my reported line fault fixed with no notification of an engineer's visit because Openreach ahd the wrong address. PlusNet were never told that BTw had done anything, although they had, and a couple of days later the engineers were 2 doors up!

I don't know if anyone has succeeded in getting their SNR margin reduced, but in theory if you stay up for at least 14 days with no disconnections or resyncs it's supposed to happen with DLM. I don't know if it ever has though.

A higher SNR margin will reduce your sync speed. High SNR is good if it's caused by a good line. The induced increased margin is supposed to be for bad lines, to increase stability at the expense of speed.
ady
Grafter
Posts: 289
Registered: 25-09-2007

Why Has My Line Rate Dropped (SNR Now 14+dB)?

my SNR has gone upto 15db
and i havent disconnected in weeks, so my sync has dropped from 2mb to 1.5mb, not fun
Community Veteran
Posts: 1,139
Thanks: 4
Registered: 20-07-2007

Why Has My Line Rate Dropped (SNR Now 14+dB)?

So are we saying there is nothing that can be done? My line rate seems to be getting worse by the day - I've logged on this morning and I'm now syncing at 6,560 with a SNR of 16dB.

Strange though, as I type my connection has just dropped. I've never had any problems with dropped connections before until last week when lots of people were reporting problems. I've also noticed that this thread http://portal.plus.net/central/forums/viewtopic.php?t=50701 is active again so maybe the plusnet problem has returned.

Am I right in thinking that if there is a problem that causes disconnections then BT will keep pushing up my SNR (and dropping my line rate)?

Very frustrating.

Bob
Community Veteran
Posts: 6,983
Thanks: 8
Registered: 10-04-2007

Why Has My Line Rate Dropped (SNR Now 14+dB)?

You're not alone with this.
My line synced at 7616 and was rock stead all through the 10 days training period and for the next two weeks after that.
Suddenly things went haywire with my sync dropping to the 3000 mark.
It has climbed back up now and varies between 6000 and just into the 7100 region.
However I am getting a strange disconnect symptom several times a day.
Although the ADSL light is still solid and the router says it's connected the speeds up and down report as zero :?

The only way to get it working again is to restart the router.
Have tried 3 different routers and filters so I'm at a loss as to just what is causing this or why the massive drop in sync rate occured.
It's all very frustrating though. Cry
N/A

Why Has My Line Rate Dropped (SNR Now 14+dB)?

I had interleaving turned on and my SNR margin increased as a first attempt to cure a gault.
I didn't want my SNR increased because it worked ok for me at higher sync before the fault mysteriously appeared.
Since then I still get a lot of error including a few thousand CRC errors a day, but have not had a disconnection after the last BT fix.
Saturday evening my connection dropped for no apparent reason.
Maybe it's something to do with so many exchanges being red? Losing sync shouldn't be connected with any PlusNet problems.
Lorian
Grafter
Posts: 699
Registered: 31-07-2007

Why Has My Line Rate Dropped (SNR Now 14+dB)?

My target SNR has been bumped recently for no reason.