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Standard User cjdavid
(learned) Sun 09-Jul-17 10:42:54
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noise margin values?


[link to this post]
 
Hi Guys,

I have BT infinity, and I've read people's comments about ''noise margin'. But never really understood the low and high values lol.

My current noise margin is "Noise margin "14.8 / 12.3". And I use to use a Cat 6 RJ11 cable which had a margin of 18. This is a custom cable from eBay.

Out of curiosity, is it a good thing to have a lower margin?
Standard User BatBoy
(sensei) Sun 09-Jul-17 11:33:24
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Re: noise margin values?


[re: cjdavid] [link to this post]
 
The noise margin is a trade off with sync speed and stability.
A high noise margin is associated with a lower sync speed but higher stability.
A low noise margin is associated with higher sync speed but lower stability.
The target noise margin is usually 6.
Standard User Kr1s69
(knowledge is power) Sun 09-Jul-17 11:49:04
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Re: noise margin values?


[re: cjdavid] [link to this post]
 
If you’re connecting at the maximum for your service, eg 55Mbps or 80Mbps then a higher noise margin is good as it indicates your line can support faster speeds if and when they become available.

If you’re not connecting at the maximum, it suggests your line speed has been reduced to improve stability.

Kris

Sky Fibre
Ashington (Northumberland) Exchange


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Standard User Zarjaz
(eat-sleep-adslguide) Sun 09-Jul-17 11:52:45
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Re: noise margin values?


[re: cjdavid] [link to this post]
 
Showing all the stats from the router will allow more informed opinion .

Standard User j0hn83
(committed) Mon 10-Jul-17 03:19:46
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Re: noise margin values?


[re: cjdavid] [link to this post]
 
The high noise margin suggests you already get the maximum your current package offers, or DLM has capped the line to try stabilise it.
As mentioned above the target margin is 6dB, anything above that is "spare noise margin", the more the better.
So the cable with the 18dB SNRM is the better of the 2 cables.
Standard User robertcrowther
(member) Mon 10-Jul-17 05:19:50
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Re: noise margin values?


[re: j0hn83] [link to this post]
 
Having 6dB as the target margin is no longer the case since the introduction of the new lower 3dB target margin.
Standard User j0hn83
(committed) Mon 10-Jul-17 05:28:27
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Re: noise margin values?


[re: robertcrowther] [link to this post]
 
That's being a bit picky, and is irrelevant to the OP.
In fact you've worded that like is no longer 6dB, and is now 3dB.
The default is still 6dB. Only specific lines on Huawei cabinets have lower targets, and it's 5, 4, then 3dB, providing the line remains stable at each stage.
Standard User robertcrowther
(member) Mon 10-Jul-17 05:51:21
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Re: noise margin values?


[re: j0hn83] [link to this post]
 
Not being picky at all, just giving out the correct information. As 3dB is the new default that is being rolled out to all cabinets including eci ones and the rollout should be completed by the end of August.

I'm on a eci cabinet and have the new 3dB target margin.
Standard User Zarjaz
(eat-sleep-adslguide) Mon 10-Jul-17 07:05:26
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Re: noise margin values?


[re: robertcrowther] [link to this post]
 
Do you have a link to the article saying 3db is the new default target SNR on FTTC please ?

Standard User robertcrowther
(member) Mon 10-Jul-17 08:51:32
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Re: noise margin values?


[re: Zarjaz] [link to this post]
 
I'm not sure why you've all lost your memories on the subject as it was talked about in length on this forum last year

http://forums.thinkbroadband.com/fibre/4514857-openr...
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