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Standard User matthewcl375
(learned) Sat 02-Feb-13 20:25:47
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Re: Slow internet/low IP profile/high noise margin on Tesco


[re: 4M2] [link to this post]
 
It's a good guide but I've read through it about 5 times now and it still doesn't make sense, I am just looking for an explanation of whether a rise in SNR Margin is good/bad i.e. does it signify that there is more or less noise on the line?
Standard User 4M2
(fountain of knowledge) Sat 02-Feb-13 20:37:06
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Re: Slow internet/low IP profile/high noise margin on Tesco


[re: matthewcl375] [link to this post]
 
In reply to a post by matthewcl375:
It's a good guide but I've read through it about 5 times now and it still doesn't make sense, I am just looking for an explanation of whether a rise in SNR Margin is good/bad i.e. does it signify that there is more or less noise on the line?


OK - here's an extreme example: RouterStatsLite running displaying a steady 9dB SNRM, then a sudden burst of noise on the line, the SNRM drops to zero dB and the ADSL connection is dropped - a very unstable situation caused by an intermittent line fault.
Standard User matthewcl375
(regular) Sat 02-Feb-13 20:44:09
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Re: Slow internet/low IP profile/high noise margin on Tesco


[re: 4M2] [link to this post]
 
So if we took your example a step further, when the ADSL comes back up (if it ever does) the router will be showing a higher SNR Margin than before, to provide a buffer in case the SNR drops again?


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Standard User 4M2
(fountain of knowledge) Sat 02-Feb-13 21:08:02
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Re: Slow internet/low IP profile/high noise margin on Tesco


[re: matthewcl375] [link to this post]
 
The router resync'd almost immediately after the very short burst of noise back to a 9dB SNRM at the same sync rate - that was an ADSL MAX connection.

The sync time SNRM is the key and how much it fluctuates over time whilst the ADSL connection is continuously up. For maximum stability a sync time margin is set that allows for noise events, without dropping the connection and allowing the best possible corresponding sync speed. My example was an extreme noise event with a multitude of errors where there was not enough margin to cope.
Standard User matthewcl375
(regular) Sat 02-Feb-13 21:42:29
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Re: Slow internet/low IP profile/high noise margin on Tesco


[re: 4M2] [link to this post]
 
What I've gathered so far is that me having a SNR Margin of 16.6db means that my connection is very stable, but from looking at router stats the SNR Margin could be lower and I would still be getting a stable link.

How would I work out what my SNR Target as set by the DLM is right now?

P.s. This guide makes a lot more sense

Edited by matthewcl375 (Sat 02-Feb-13 21:54:50)

Standard User 4M2
(fountain of knowledge) Sat 02-Feb-13 21:56:54
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Re: Slow internet/low IP profile/high noise margin on Tesco


[re: matthewcl375] [link to this post]
 
In reply to a post by matthewcl375:
What I've gathered so far is that me having a SNR Margin of 16.6db means that my connection is very stable, but from looking at router stats the SNR Margin could be lower and I would still be getting a stable link.

How would I work out what my SNR Target as set by the DLM is right now?


Historically your line has probably been unstable...

Personally I wouldn't mess about with ADSL MAX if 21CN WBC (ADSL2+) is available at the exchange. Partial LLU could be even better although that's probably over the boss's budget smile
Standard User matthewcl375
(regular) Sat 02-Feb-13 22:10:36
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Re: Slow internet/low IP profile/high noise margin on Tesco


[re: 4M2] [link to this post]
 
Correct, last friday-saturday we had so much noise that we couldn't hear callers on the phone crazy A new line was then installed by BT on sunday, but by then we had lost DSL sync so many times in the previous few days that I can only assume the SNR Margin was jacked right up to allow for any future problems, bringing our throughput down by about half from 8Mbps to where it is now...

And I would upgrade to ADSL2+ if I was in charge tongue

Edited by matthewcl375 (Sat 02-Feb-13 22:11:55)

Standard User RobertoS
(sensei) Sat 02-Feb-13 22:42:35
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Re: Slow internet/low IP profile/high noise margin on Tesco


[re: matthewcl375] [link to this post]
 
In reply to a post by matthewcl375:
P.s. This guide makes a lot more sense
smile
But did you click the link at the bottom of that page, to "High Noise margin"?

My broadband basic info/help site - www.robertos.me.uk | Domains,website and mail hosting - Tsohost.
Connection - Plusnet UnLim Fibre (FTTC). Sync ~ 54.3/15.4Mbps @ 600m. - BQM

"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Allergy information: This post was manufactured in an environment where nuts are present. It may include traces of understatement, litotes and humour.
Standard User matthewcl375
(regular) Sat 02-Feb-13 23:35:18
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Re: Slow internet/low IP profile/high noise margin on Tesco


[re: RobertoS] [link to this post]
 
Just read it now laugh So it seems that my problem would be the one described on the site under 4 "The more awkward cause".

Just had a thought, on the site it says that sometimes the SNR Margin Target increase is set by a BT engineer rather than the DLM. Could this have happened in my case or is it more likely to have been an automatic thing considering the amount of noise and disconnections on my line prior to the repair?

Thanks
Standard User RobertoS
(sensei) Sun 03-Feb-13 00:05:01
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Re: Slow internet/low IP profile/high noise margin on Tesco


[re: matthewcl375] [link to this post]
 
Hard to say. It would only be set by an engineer in response to a fault report where he couldn't find, or couldn't be bothered to find, or hadn't got the time to find the cause. Before the visit which resulted in the repair. They wouldn't repair and set high at the same time.

Setting it high gives the stability. Job done as far as Openreach and BT Wholesale are concerned. Their priorities are not always the same as the end user's frown.

My broadband basic info/help site - www.robertos.me.uk | Domains,website and mail hosting - Tsohost.
Connection - Plusnet UnLim Fibre (FTTC). Sync ~ 54.3/15.4Mbps @ 600m. - BQM

"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Allergy information: This post was manufactured in an environment where nuts are present. It may include traces of understatement, litotes and humour.
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