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geaves
Expert
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Message 1 of 9

Understanding Noise Margin

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I am currently still in 'training mode' for my adsl2+, ends tomorrow Smiley Happy the upside is the IP profile has increased to 5000 from 3000 so that's a step in the right direction.

 

But what I am failing to understand is the noise margin, I 'work' from home and checking the Hub info in the morning the noise margin is anywhere between 9.2 & 10.2. Late afternoon this has decreased to below 9, then during the evening it will continue to decrease, the lowest I have seen so far is 7.2. But in the morning it's back up again, whilst I appreciate that this can fluctuate there does appear to be a pattern, so will it settle? or is it going to continue to fluctuate.

 

Hub is plugged into master, and is on 24/7, the 17070 noise test produces nothing no clicks, no hiss.

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Raven2010
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Message 2 of 9

Re: Understanding Noise Margin

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fluctuation between 6 and 12 Db is perfectly normal and should cause you no problem at all.

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PheeragHfre
Recognised Expert
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Message 3 of 9

Re: Understanding Noise Margin

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@geaves wrote:

I am currently still in 'training mode' for my adsl2+, ends tomorrow Smiley Happy the upside is the IP profile has increased to 5000 from 3000 so that's a step in the right direction.

 

But what I am failing to understand is the noise margin, I 'work' from home and checking the Hub info in the morning the noise margin is anywhere between 9.2 & 10.2. Late afternoon this has decreased to below 9, then during the evening it will continue to decrease, the lowest I have seen so far is 7.2. But in the morning it's back up again, whilst I appreciate that this can fluctuate there does appear to be a pattern, so will it settle? or is it going to continue to fluctuate.

 

Hub is plugged into master, and is on 24/7, the 17070 noise test produces nothing no clicks, no hiss.

 


 

noise margin snr snrm

 

Quote:

 

On virtually all lines the background noise rises as the sun falls and falls again as the sun rises. This mainly due to the effect the sun has on the radio-reflecting layer of the atmosphere, particularly medium-wave signals.  So the noise margin (SNRM) will fall near dusk and not fully recover till well after dawn. Other causes are covered in Miscellaneous Nasties on the Troubleshooting pages.

 

The effect of this higher background noise at night is that if a connection is made at these times the sync speed will be lower than in the daytime when the noise is lower.

 

"I have this awful feeling someone is watching every move I make (one of my pet hates is router location tagging)." Marvin (A paranoid Android)
geaves
Expert
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Message 4 of 9

Re: Understanding Noise Margin

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Many thanks for link lot of relevant and useful info on that site.

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spacepilot
Aspiring Expert
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Message 5 of 9

Re: Understanding Noise Margin

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from personal experience -

noise margin stats are a big red herring, that the help desk fob people off with, in the hope that they will go away. in September, my line was fixed, after a couple of months none existant speeds - less than 400Kb (and 3 years running at about 4mb, from a peak of 7mb). my new speed was maintained at 8128Kb, on a line capable of upto 12mb. my noise margin was a massive 24.7 down, and 25.2 up. dispite this. my speed never varied. (that is right... 24.7 / 25.2).

 

if you listened to the help desk people, with a noise margin of 24, i would be incapable of any service. i had 8mb... case point and proof that noise margin stats are, for the want of a better word, a load of tosh. 

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PheeragHfre
Recognised Expert
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Message 6 of 9

Re: Understanding Noise Margin

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@spacepilot

 

Have you ever tried to listen to a medium wave radio station with lots of whistles crackles & buzzes?

 

It is an important aspect when dealing with ADSL signals but not the only one. Smiley Indifferent

"I have this awful feeling someone is watching every move I make (one of my pet hates is router location tagging)." Marvin (A paranoid Android)
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hamish72
Recognised Expert
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Message 7 of 9

Re: Understanding Noise Margin

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Seen quite a few lines like yours but for the vast majority profile and thus speeds do follow the noise margins

 

The entire system is a very un precise science and as the saying goes the "exception proves the rule"

 

there are so many variables I'm just amazed it works as well as it dose Smiley Very Happy

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IanC
Recognised Expert
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Message 8 of 9

Re: Understanding Noise Margin

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@spacepilot wrote:

from personal experience -

noise margin stats are a big red herring,

 

Not at all. The noise margin is very relevant - it's a major factor in deciding how fast a line can go.

 

in September, my line was fixed, after a couple of months none existant speeds - less than 400Kb (and 3 years running at about 4mb, from a peak of 7mb). my new speed was maintained at 8128Kb, on a line capable of upto 12mb. my noise margin was a massive 24.7 down, and 25.2 up. dispite this. my speed never varied. (that is right... 24.7 / 25.2).

 

That's to be expected. Your line is running as fast as possible on its current service (8128Kbps is the max for DSLMax) yet your wires are capable of more, therefore you have margin in hand.

 

if you listened to the help desk people, with a noise margin of 24, i would be incapable of any service. 

i had 8mb... case point and proof that noise margin stats are, for the want of a better word, a load of tosh. 

 

Just because you don't understand noise margin, doesn't mean it's tosh 🙂

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NilSatisOptimum
Recognised Expert
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Message 9 of 9

Re: Understanding Noise Margin

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The same here IanC

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