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Standard User sjr
(knowledge is power) Wed 09-Feb-11 11:49:22
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SNR tweaks on long lines


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Short summary, I've been helping somebody out on another (non BB related) forum. He's on Sky LLU but on the end of a long line with downstream attenuation of 67db. He's getting a 2Mb connection from that so that's not bad at all for the line length. However, he's put the DGTeam firmware on a DG834GT and tried to eke a bit more speed by lowering the SNR percentage. Lowering the percentage doesn't gain anything in connection speed, but raising it does reduce the connection speed. Is it just the case that on such a long line SNR tweaks just don't work or is there anything partcular to Sky as to why this shouldn't make any difference?
Standard User MHC
(legend) Wed 09-Feb-11 12:22:23
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Re: SNR tweaks on long lines


[re: sjr] [link to this post]
 
Have you thought about suggesting a different router?

The BT Business Hub - 2wire2700HGV has excellent long line performance and can often improve the speed slightly and if circumstances are right it will sync at 3dB and hold that down to 0dB.

They can be acquired for £5 to £10 although some do sell for more.





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Standard User BatBoy
(legend) Wed 09-Feb-11 12:38:40
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Re: SNR tweaks on long lines


[re: sjr] [link to this post]
 
In reply to a post by sjr:
Short summary, I've been helping somebody out on another (non BB related) forum. He's on Sky LLU but on the end of a long line with downstream attenuation of 67db. He's getting a 2Mb connection from that so that's not bad at all for the line length. However, he's put the DGTeam firmware on a DG834GT and tried to eke a bit more speed by lowering the SNR percentage. Lowering the percentage doesn't gain anything in connection speed, but raising it does reduce the connection speed. Is it just the case that on such a long line SNR tweaks just don't work or is there anything partcular to Sky as to why this shouldn't make any difference?
Yes, Sky run DLM to set a stable profile. You need to ask Sky to put the connection on a Gaming profile, which removes DLM and uncaps the line.



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Standard User RobertoS
(sensei) Wed 09-Feb-11 12:38:54
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Re: SNR tweaks on long lines


[re: sjr] [link to this post]
 
What's the SNRM it connects at untweaked, and is it always the same sync? If so, what sync, 2048kbps?

It could be the line has been capped previously for stability. The sync-SNRM may show that to be the case.

My broadband basic info/help site - www.robertos.me.uk
My domains,website and mail hosting - Tsohost. Internet connection - O2 Standard.
Standard User sjr
(knowledge is power) Wed 09-Feb-11 12:47:26
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Re: SNR tweaks on long lines


[re: sjr] [link to this post]
 
Thanks for the replies everybody. SNR is about 7.1db untweaked so bang on for Sky's default. Line capping is the most likely culprit by the sound of things as regardless of margin the sync is 2045 with the odd kb or two variance.
Standard User RobertoS
(sensei) Wed 09-Feb-11 13:58:39
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Re: SNR tweaks on long lines


[re: sjr] [link to this post]
 
Very likely then. The O2 LLU 8Mbps cap could vary between 8099and 8192kbps, normally 8191, with noise margin at the default 6dB.

My broadband basic info/help site - www.robertos.me.uk
My domains,website and mail hosting - Tsohost. Internet connection - O2 Standard.
Standard User Chrysalis
(eat-sleep-adslguide) Fri 11-Feb-11 00:58:33
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Re: SNR tweaks on long lines


[re: sjr] [link to this post]
 
if reducing the snrm doesnt buff up speed then its probably also capped. Isp's have started doing this in the last year or 2 I expect to counter snrm tweaking tools.
Standard User sjr
(knowledge is power) Fri 11-Feb-11 15:54:08
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Re: SNR tweaks on long lines


[re: Chrysalis] [link to this post]
 
Yes I think capping is in play here so I've suggested he gets in touch with Sky to see if there is a cap and get it removed if possible.
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