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SR71BB
Aspiring Contributor
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Message 1 of 21

!

 
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Paul608085
Expert
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Message 2 of 21

Re: Random disconnects on a new connection

You said that "The noise level on such a short line seems to be very high."

Do you mean that you are hearing noise on voice calls? In which case have you done a quiet line test by dialling 17070?

I'm just wondering if you are confusing "noise level" with the noise margin figures that you quoted. For noise margin, the higher the figures the better, (generally). Your figures of "15.5 / 12.7" are very good.

Noise margin is basically the difference between the wanted broadband signal level and the unwanted noise. If the noise margin is too low, then the hub can have difficulty in differentiating between wanted signal and unwanted noise, leading to errors and lower speeds.

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SR71BB
Aspiring Contributor
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Message 3 of 21

 
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SR71BB
Aspiring Contributor
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Message 4 of 21

 
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Paul608085
Expert
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Message 5 of 21

Re: Random disconnects on a new connection

For the downstream at least, the minimum desirable is around 6dB I believe? I have also been told that this depends on the manufacturer of the equipment in the serving cabinet, and can potentially be as low as 3dB and still be satisfactory, (noted that you may be connected directly to the exchange).

For comparison, I am 50 metres, (by cable), from my cabinet and my noise margin figures are 16.0 / 10.6

SNR and Noise Margin is basically the just different names for the same thing - the difference between the noise floor and the wanted signal. As I said before, generally more is better for this figure, though provided it never drops below the minimum there is nothing to be gained. ie my current downstream measurement is 10.6dB and AFAIK it could go down to say 4dB and my speed and connection would be unaffected(?).

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SR71BB
Aspiring Contributor
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Message 6 of 21

 
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SR71BB
Aspiring Contributor
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Message 7 of 21

 
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imjolly
Distinguished Sage
Distinguished Sage
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Message 8 of 21

Re: Random disconnects on a new connection

On FTTC you are not connected to the exchange but to a street cabinet.  However I think in your case you originally had EO (exchange only) line and ould not get FTTC.  OPENREACH then built cabinet outside exchange which allowed connection like yours to get FTTC.

Your noise margin is high  because your attainable being so close to cabinet is far higher than your connection speed of 80mb.  This will not reduce and stands you in good stead should FTTC ever allow higher connection speed.

SNR IS signal to noise ration which is not the same as noise margin which is what the routers show.

Are you on digital voice as that would explain why dslchecker does not recognise your phone number

 

 

 

 



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Paul608085
Expert
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Message 9 of 21

Re: Random disconnects on a new connection

@imjolly 

"SNR IS signal to noise ration which is not the same as noise margin which is what the routers show."

For my understanding, can you explain the difference between Signal to Noise Ratio and Noise Margin please?

 

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licquorice
Distinguished Sage
Distinguished Sage
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Message 10 of 21

Re: Random disconnects on a new connection

Signal to noise ratio is exactly that, the ratio of signal level to noise level. SNR margin is the amount of margin the signal has over the noise level.