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High S/n margin since fault resolution

snailspace
Grafter
Posts: 56
Registered: ‎15-06-2009

High S/n margin since fault resolution

Hi Everyone
Can anyone tell me how to get my target S/N margin reduced.
I was having MAJOR speed and stability problems that eventually proved to be a BT line fault (what a surprise - not) eventually fixed after no less than three BT engineer visits over the space of more than a month.
Anyway as part of their efforts to fix (hide) the problem BT kindly adjusted my SN margin - quote from fault ticket.
Dear Mr ********
BT have made recent changes to your SNR level. Once the local exchange starts seeing lengthy connections being made, the speed should gradually increase to the maximum the line will support. We advise you keep the router powered up and plugged in as much as you can and once the dynamic line management see's a stable connection, this will increase the line speed.
I have returned the ticket to yourself, which will keep the ticket open for 14 days and if there are any other issues, please update this ticket and we maybe able to test/advise further.
Kind regards,
*******************

I should add that this 'adjustment ' made little difference at the time - indeed it made matters worse
I don't have a speed problem as such now, but would like to get as much out of the line as possible.
My current router stats are:
Bandwidth (Up/Down) [kbps/kbps]: 448 / 7,840
Data Transferred (Sent/Received) [kB/kB]: 0.00 / 0.00
Output Power (Up/Down) [dBm]: 12.0 / 19.5
Line Attenuation (Up/Down) [dB]: 13.5 / 25.0
SN Margin (Up/Down) [dB]: 23.0 / 15.0
Vendor ID (Local/Remote): TMMB / TSTC
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 0 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): 0
Error Seconds (Local/Remote): 0 / 0
FEC Errors (Up/Down): 0 / 264
CRC Errors (Up/Down): 0 / 0
HEC Errors (Up/Down): 0 / 0
Router is a Thomson TG585 v7 supplied by PN, plugged into a filtered faceplate (BT supplied) together with a single phone.
With 25.0 downstream attenuation, all advice seems to indicate that I should be able to sync at 8Mb with a downstream S/N margin of 6.
My margins seem to be very consistent - showing very little variation (<2db) whatever the time of day, weather etc
Thanks in advance for your  help/ advice.
Cheers,  Terry
22 REPLIES
Community Veteran
Posts: 19,102
Thanks: 443
Fixes: 21
Registered: ‎31-08-2007

Re: High S/n margin since fault resolution

With that line attenuation you are unlikely to ever see an SNRM of 6dB as you should have plenty of headroom. With that sync speed I'd just sit tight, leave the modem/router on 24/7 do a reboot after a couple of weeks, until the sync speed reaches 8128. If you're a gamer, you could ask for interleaving to be turned off if it is on.
James
Grafter
Posts: 21,036
Registered: ‎04-04-2007

Re: High S/n margin since fault resolution

Hiya,
It looks like the only thing that is preventing that is preventing you from receiving the full 8Mbps sync speeds is the fact that interleaving is turned on on your telephone line.
If you like I can place an order to remove interleaving from your line.
snailspace
Grafter
Posts: 56
Registered: ‎15-06-2009

Re: High S/n margin since fault resolution

Hiya Guys
Thanks for the replies.
Sorry, Anotherone, I should have said "sync at 8Mb with a downstream S/N margin of 6db or more margin".  Just lazy and couldn't be bothered to type it, I guess. Embarrassed
Thanks for your comment though
James - could you confirm that if turning off interleaving causes a problem I can have it turned back on again.
If so, could you go ahead and get it turned off for me.
Many thanks for your help both with this and with my previous challenges.  Smiley
Cheers
Terry
James
Grafter
Posts: 21,036
Registered: ‎04-04-2007

Re: High S/n margin since fault resolution

Hi Terry,
As per the ticket I've just put on your account, I've placed an order to remove interleaving, which will complete tomorrow.
I'll have no issues with reversing the change, should it be problematic at all.
snailspace
Grafter
Posts: 56
Registered: ‎15-06-2009

Re: High S/n margin since fault resolution

Magic!! Smiley
Thanks again, James
grahamcannon
Newbie
Posts: 8
Registered: ‎30-06-2007

Re: High S/n margin since fault resolution

Hi
I have a similar problem with a High Noise Margin and consequent loss of speed.
For as long as I can remember my router has synced at 8128 with a Noise margin of 9dB (Attenuation 24 - 26 dB) - mybroadbandspeed would give 6.5 mbps. (Line Profile 7150)
This was so stable that I stopped checking it !
Recently (Sunday 28th June) my download speed dropped dramatially to 448 kbps. This stabalised by Monday 29th to 4.5 mbps. (Line profile 5000)
My router stats now are :
                          Downstream  Upstream
   
Data rate(Kbps)  6656                  832
   
Noise Margin      15                      14
Attenuation(dB)  26                      13

Briefly this last Monday (6th July) the downstream went to 7648 kbps / 12dB - but a thunderstorm and power cut put a stop to that and it returned to 6650 / 15.
I have been resyncing each day - with reference to the above should I just leave the router on and wait for the figures to improve and get my 8128 sync back,  or do you  need to take any action ?
My line is interleaved - will removing this improve things ?

Regards
Graham Cannon

James
Grafter
Posts: 21,036
Registered: ‎04-04-2007

Re: High S/n margin since fault resolution

Hi Graham,
Interleaving won't be affecting your sync speed to that degree.
Daily resyncs are a good idea.  If it's not been sorted come tomorrow, give me a shoult and I'll get something raised with BT.
grahamcannon
Newbie
Posts: 8
Registered: ‎30-06-2007

Re: High S/n margin since fault resolution

Hi  James,

Thanks for the quick reply  Smiley
I will come back to you with an update tomorrow.

Regards
Graham
grahamcannon
Newbie
Posts: 8
Registered: ‎30-06-2007

Re: High S/n margin since fault resolution

Hi James,
Re-synced this morning - still 6592 / 15.
Can you get Bt to have a look at it ?

Thanks
Graham
James
Grafter
Posts: 21,036
Registered: ‎04-04-2007

Re: High S/n margin since fault resolution

Graham - Thanks.
Just for my benefit, are you aware of anything that happened to cause your SNR to go considerably higher?
Fault on the line, increased noise and that sort of thing?
grahamcannon
Newbie
Posts: 8
Registered: ‎30-06-2007

Re: High S/n margin since fault resolution

Hi James,

I might have found the cause of the problem
It seems that the master socket did not have the filter on it for some time ( - the router is connected to a BT fitted extension in my office)  - this was apparently reconnected a couple of weeks ago so when I checked it when I noticed the issue it was in place and everything seemed OK :-(
I have tested the router at the extension and the master socket (now with filter) - no difference in syncing.
Sorry for not mentioning this earlier, but I have only just found out myself - I am now trying to explain the significance of the 'little white box' to my wife  Sad

I presume that the increased noise on the line due to not having the filter could be that cause of the problem ?

Regards
(A red-faced) Graham
James
Grafter
Posts: 21,036
Registered: ‎04-04-2007

Re: High S/n margin since fault resolution

Hi Graham,
That almost definitely will be the cause.  Good spot Smiley
snailspace
Grafter
Posts: 56
Registered: ‎15-06-2009

Re: High S/n margin since fault resolution

Quote from: Jameseh
Hi Terry,
As per the ticket I've just put on your account, I've placed an order to remove interleaving, which will complete tomorrow.
I'll have no issues with reversing the change, should it be problematic at all.

Thanks again, James - seems to have done the trick with no issues so far.  Have been synced at 8Mb for 3days+ now with SN margin always 12.5-13.5db.  BT profile has just gone up to 7150. Smiley
Just waiting for PN to follow suit now.
Cheers, Terry
James
Grafter
Posts: 21,036
Registered: ‎04-04-2007

Re: High S/n margin since fault resolution

Hi Terry,
It looks like our profiling changed around 6pm on Saturday.