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Sudden drop in signal margin

mike0381
Grafter
Posts: 88
Registered: 14-02-2012

Sudden drop in signal margin

Hi,
I've posted before about my broadband disconnection problems, but now I have something to add to that.
My SNR ratio I think is set at 9db as it is quite unstable at anything lower.  The last few days however I have been having sudden big drops to 16.5db down.  This causes a drop in  sync speed from around 2,500 to 1,500 giving me a very slow download speed.
If the router is rebooted/resynced the SNR goes straight back to 9 / 9.5db and sync speed is back to normal.  It can be working normally for 15 hrs or more and just suddenly drop.

Please can you offer any help for this?

Thanks.

Michael
7 REPLIES
itsme
Grafter
Posts: 5,924
Thanks: 1
Registered: 07-04-2007

Re: Sudden drop in signal margin

The 9dB is a SNR Margin and what's probably happening with your line is the modem is losing sync when there is a lot of noise on the line it's resyncing but to maintain the 9dB it has to sync at a lower the rate. Then the noise disappear and as the SNRM is being dynamically read it will register a higher value. If you leave the modem long enough, several days or weeks, the exchange will force a retrain to sync at a higher rate with a 9dB margin.
jojopillo
Grafter
Posts: 9,786
Registered: 16-06-2010

Re: Sudden drop in signal margin

Hi Michael,
sorry to see you're back again. How is your connection set up. Can't remember from last time. Did you have a test socket/extensions at all.
Jojo Smiley
mike0381
Grafter
Posts: 88
Registered: 14-02-2012

Re: Sudden drop in signal margin

Hiya Jo,  oh yes I'm back!   Roll eyes    I don't have any extensions and I am plugged into the test socket.  
Although my connection still drops sometimes when I get a local telephone call, managed to live with it as long as my IP profile didn't drop as a result, which it didn't do too often.
But now the signal margin keeps going from 9db to 16.5db my profile has dropped to 1mb.  If I resync it goes back to 9db and a better sync speed but I still keep the 1mb obviously as my profile hasn't had the needed time to change.  So it's quite annoying!  Grin    
jojopillo
Grafter
Posts: 9,786
Registered: 16-06-2010

Re: Sudden drop in signal margin

Hi Michael,
I'd say raise a fault and let the engineer come out this time.
Jojo Smiley
Community Veteran
Posts: 26,686
Thanks: 910
Fixes: 10
Registered: 10-04-2007

Re: Sudden drop in signal margin

If you can demonstrate that by ringing your home phone using your mobile (and leave it ringing) the noise margin goes all over the show that's a solid fault you can show to the engineer.
jelv (a.k.a Spoon Whittler)
   Why I have left Plusnet (warning: long post!)   
Broadband: Andrews & Arnold Home::1 (FTTC 80/20)
Line rental: Pulse 8 Home Line Rental (£13/month)
Mobile: iD mobile (£4/month)
mike0381
Grafter
Posts: 88
Registered: 14-02-2012

Re: Sudden drop in signal margin

Thanks for your help.  Wink      I lost sync about 30 mins ago after it was up for around a day and a half.  But it actually reconnected with a normal signal margin level this time, so perhaps that particular problem is over.
But I'm still waiting for my IP profile to go back up from 1mb to 2mb.  I know it has to be stable for a while before that happens, oh well, looks like I'll have a longer wait now it's decided to resync.  lol
My line isn't perfect, I know that, so an engineer visit may be on the cards regarding the disconnection issue.  Undecided
jojopillo
Grafter
Posts: 9,786
Registered: 16-06-2010

Re: Sudden drop in signal margin

Hi Michael,
I've just ran a line check and it was showing as out of sync, but the BT profile is 1500, so I've moved our up to match that.
Jojo Smiley