Changing SNR

Hi,

Is there anything I can do to get BT to reset the target SNR on my line?

> adsl status
  --------------------------- ATU-R Info (hw: annex A, f/w: annex A) -----------
   Running Mode            : ADSL2+(G.992.5)       State                : SHOWTIME
   DS Actual Rate          :  6648972 bps   US Actual Rate       :  1147972 bps
   DS Attainable Rate      : 16040000 bps   US Attainable Rate   :  1148000 bps
   DS Path Mode            :        Fast    US Path Mode         :        Fast 
   DS Interleave Depth     :        1       US Interleave Depth  :        1 
   NE Current Attenuation  :       35 dB    Cur SNR Margin       :       20  dB
   DS actual PSD           :    18. 2 dB    US actual PSD        :    12. 1   dB
   ADSL Firmware Version   : 232201_A 
  -------------------------------- ATU-C Info ---------------------------------
   Far Current Attenuation :       14 dB    Far SNR Margin       :        6  dB
   CO ITU Version[0]       : 00004946       CO ITU Version[1]    : 0000544e
   DSLAM CHIPSET VENDOR    : < IFTN >

I've been synced for 327 hours so would like to try a more ambitious SNR if possible... The router is a draytek vigor 2830.

Edit: or is the problem the 'far SNR margin'?

Edited by xela (Mon 22-Oct-12 15:17:17)

1) Reboot router during daylight hours? Since you have been connected for a significant period BT DLM may sync at a lower SRNM - it needs a resync to achieve this.

2) Change ISP to one that provides this facility (BE provide this)

3) Use a router that supports reporting of SRNM data to force sync up or down (Billion 7800N does this, dont think Draytek does).

I read that to be an UPstream attenuation of 14dB with 6dB SNR giving you 1.14Mbps and for DOWNstream an attenuation of 35dB with 20dB SNR resulting in 6.65Mbps when you should be able to achieve 16.04Mbps.

Rather than trying to tackle Tech support, why not power off the modem tonight and leave it off until required tomorrow morning - bring it back up at around 8:00 AM. If that does not cause it to reset and resync, then start on Tech support.

Why so complex?

Just switch off count to ten and switch on again and see what happens

In reply to a post by MHC:

when you should be able to achieve 16.04Mbps.

I doubt! More like 11 to 12 Meg. That Attainable Rate is so much twaddle.

I know, that is why I said "I read it as ..." giving my understanding of what the figures mean which, from the original post, yj OP was possibly confused/wondering.

Belt and braces !

I have recently been trying to sort out a connection for a neighbour of a friend where teh SNR was unbelievably high. Short disconnect, no change, 3 minute disconnect, nothing. Left it off overnight and the following morning all powered up, an SNR had dropped from 22dB to 6dB and speed had trebled.

No joy with a quick reboot

> adsl status
  --------------------------- ATU-R Info (hw: annex A, f/w: annex A) -----------
   Running Mode            : ADSL2+(G.992.5)       State                : SHOWTIME
   DS Actual Rate          :  6648972 bps   US Actual Rate       :  1123914 bps
   DS Attainable Rate      : 16232000 bps   US Attainable Rate   :  1124000 bps
   DS Path Mode            :        Fast    US Path Mode         :        Fast 
   DS Interleave Depth     :        1       US Interleave Depth  :        1 
   NE Current Attenuation  :       35 dB    Cur SNR Margin       :       19  dB
   DS actual PSD           :    18. 2 dB    US actual PSD        :    12. 2   dB
   ADSL Firmware Version   : 232201_A 
  -------------------------------- ATU-C Info ---------------------------------
   Far Current Attenuation :       14 dB    Far SNR Margin       :        6  dB
   CO ITU Version[0]       : 00004946       CO ITU Version[1]    : 0000544e
   DSLAM CHIPSET VENDOR    : < IFTN >

Lots of people use this connection day and night, so I'm loathe to switch it off for a whole night. Hmm...

I doubt an overnight switch off will do much.

The sync speed is identical to earlier, which combined with the SNR Margin being well above the usual 15dB maximum, 6dB is normal. 3dB is what a very stable line will see. Leads me to suggest that the BT Wholesale DLM system has applied a banded profile on the line, and you are syncing at the maximum this allows.

So it is a case of getting BT Retail to request BT Wholesale to reset this, and allow the line to train its in a free mode.

Try the modem supplied by BT