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Standard User Xnbz
(newbie) Thu 16-Jul-15 15:26:38
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Noise margin too low


[link to this post]
 
Having some issues with my ADSL2+ Connection

http://gyazo.com/89f884313ce435d95ac8786bc8f3fe82

You might think 13.5 snr aint too bad, it isnt, it does hold the sync w/o a problem, but, i am planning to upgrade my service, i am only 2.5km away from exchange so i should be getting about 13 mbps if we go by attenuation, but the snr is whats holding me back, i was looking for tips on how to improve snr, i am not using a spliter btw.
Standard User bobble_bob
(fountain of knowledge) Thu 16-Jul-15 15:29:42
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Re: Noise margin too low


[re: Xnbz] [link to this post]
 
Are you on LLU?
Standard User Xnbz
(newbie) Thu 16-Jul-15 15:31:20
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Re: Noise margin too low


[re: bobble_bob] [link to this post]
 
Yes.


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Standard User XRaySpeX
(eat-sleep-adslguide) Thu 16-Jul-15 21:50:40
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Re: Noise margin too low


[re: Xnbz] [link to this post]
 
Too low? How'd you work that out? It's too high!
In reply to a post by Xnbz:
so i should be getting about 13 mbps if we go by attenuation
Only with a NM of 3 to 6 dB, as is the normal standard.

Who's your ISP? I'd say you're being capped. Also on upstream.

What do you mean you are not using a splitter? Don't you have a phone plugged in? Have you tried connecting to the hidden test socket?

What uograde you planning & why?

1999: Freeserve 48K Dial-Up => 2005: Wanadoo 1 Meg BB => 2007: Orange 2 Meg BB => 2008: Orange 8 Meg LLU => 2010: Orange 16 Meg LLU => 2011: Orange 20 Meg WBC

Edited by XRaySpeX (Thu 16-Jul-15 21:56:53)

Standard User RobertoS
(elder) Thu 16-Jul-15 22:18:29
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Re: Noise margin too low


[re: XRaySpeX] [link to this post]
 
And what else other than a phone has he got plugged into his phone line/extensions.

The indispensable man or woman passes from the scene, and what happens next is more or less the same thing as was happening before.
My broadband basic info/help site - www.robertos.me.uk. Domains, site and mail hosting - Tsohost.
Connection - Plusnet UnLim Fibre (FTTC). Sync 57676/14040kbps @ 600m. - BQM
Standard User bobble_bob
(fountain of knowledge) Thu 16-Jul-15 22:43:28
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Re: Noise margin too low


[re: Xnbz] [link to this post]
 
In which case you can change your target noise margin manually (or your ISP can). BT has it set automatically by the DLM, but with LLU you can change it yourself. I suspect its set too high so a call to your ISP should be able to lower it if you tell them what to set it up (6db for example)

Also if you have migrated to TTB LLU, there default noise margin is 11db which is way too high.

Edited by bobble_bob (Thu 16-Jul-15 22:44:53)

Standard User XRaySpeX
(eat-sleep-adslguide) Thu 16-Jul-15 23:34:58
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Re: Noise margin too low


[re: RobertoS] [link to this post]
 
In reply to a post by RobertoS:
And what else other than a phone has he got plugged into his phone line/extensions.
Nothing of course!

1999: Freeserve 48K Dial-Up => 2005: Wanadoo 1 Meg BB => 2007: Orange 2 Meg BB => 2008: Orange 8 Meg LLU => 2010: Orange 16 Meg LLU => 2011: Orange 20 Meg WBC
Standard User Xnbz
(newbie) Thu 16-Jul-15 23:52:02
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Re: Noise margin too low


[re: bobble_bob] [link to this post]
 
Ok so im kind of getting confused with this 'target' thingy, when i said im not using a splitter i ment that there is no phone being used on the line.



Isnt it better if you have lower attunuation?

And isnt it better if you have a higher SNR?


Well, right now, my SNR is 17, thats acceptable, but only for my current speed, if i upgrade its gonna drop, but the thing is that i cant even upgrade cuz the cap for 45 attunuation is 6-7 mb

So im confused as to how im being capped and i need some more explanation on target noise

Thank you
Standard User XRaySpeX
(eat-sleep-adslguide) Fri 17-Jul-15 00:27:07
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Re: Noise margin too low


[re: Xnbz] [link to this post]
 
In reply to a post by Xnbz:
Isn't it better if you have lower attenuation?
Yes, but generally you can't change it. Is is basically your line length.
In reply to a post by Xnbz:
And isn't it better if you have a higher SNR?
No, The higher the (sync-time) NM, the lower the sync speed will be to compensate for the greater allowed noise within that margin.

If you upgrade to what?
i can't even upgrade cuz the cap for 45 attenuation is 6-7 mb
Don;t understand this at all? Please explain. What 45 attn? Yours is 35. What cap? Do you mean the estimate for a 45 db attn? It's not a cap but a prediction. It's not hard & fast.

Is the upgrade you are talking about a house move from a place with a 35 dB attn. to one with a 45 dB attn.? That's the only way your attn. will change.

1999: Freeserve 48K Dial-Up => 2005: Wanadoo 1 Meg BB => 2007: Orange 2 Meg BB => 2008: Orange 8 Meg LLU => 2010: Orange 16 Meg LLU => 2011: Orange 20 Meg WBC
Standard User RobertoS
(elder) Fri 17-Jul-15 00:33:35
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Re: Noise margin too low


[re: Xnbz] [link to this post]
 
Attenuation is almost completely determined by the cable length between you and the exchange on ADSLx, or you and the cabinet on FTTC.

Standard SNR (actually it isn't SNR it is SNR Margin) on BT Wholesale is 6dB and should be more than sufficient for most lines.

Except on lines with low attenuation, which sync at the maximum speed for their product, having the SNRM as low as will maintain connection is what is wanted. A rise of 3dB in sync-time SNRM costs 500-750kbps on ADSL Max and as much as 1.2Mbps on ADSL2+.

I have an in-depth explanation of how it works on this page.

The indispensable man or woman passes from the scene, and what happens next is more or less the same thing as was happening before.
My broadband basic info/help site - www.robertos.me.uk. Domains, site and mail hosting - Tsohost.
Connection - Plusnet UnLim Fibre (FTTC). Sync 57676/14040kbps @ 600m. - BQM
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