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    • 1 Post By gymno

    Line attenuation and noise margin - what do my figures mean?

    This is a discussion on Line attenuation and noise margin - what do my figures mean? within the Speed tests and how to get better results forums, part of the Sky Broadband help and support category; I am getting Fibre activated this Thursday, and I have received a new router (SR102), which I plugged in on ...

    1. #1
      burnley_lad's Avatar
      burnley_lad is offline Sky User Member
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      Line attenuation and noise margin - what do my figures mean?

      I am getting Fibre activated this Thursday, and I have received a new router (SR102), which I plugged in on Friday. I have also invested in a better quality cable to go from my adsl socket to the router (cat5e), so I feel I have done as much as I can (with the exception of getting a vDSL faceplate) to get ready for Fibre.

      From looking around on here, I have noticed a lot of people have been posting their line attenuation and noise margin figures. Whilst I understand what line attenuation and noise margin means, I am struggling to get my head round whether the figures I currently have are good or bad, and whether or not they will change when Fibre is activated.

      Here are my current figures - can anyone offer any comments on them? Thanks!

      Connection Speed 12708 kbps 1196 kbps
      Line Attenuation 31.0 dB 17.0 dB
      Noise Margin 6.1 dB 7.7 dB


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    3. #2
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      Re: Line attenuation and noise margin - what do my figures mean?

      It's impossible to say.

      Attenuation only affects the section of copper cable.
      On ADSL this is from your property to the phone exchange & 31db downstream = approximately 2.2km line length.

      On fibre, the line is only copper between the property & the street cabinet.
      So the closer your cabinet is, the lower the attenuation & the higher the potential speed.

      There's some good info & links in THIS recent thread regarding cabinet identification & proximity.

      Although slightly low, your current 12.7Mbps at 6db margin is acceptable for a 31db line.
      This means that there's unlikely to be any faults anywhere.
      Last edited by gymno; 08-03-15 at 10:53 AM.
      siege2 likes this.

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      Re: Line attenuation and noise margin - what do my figures mean?

      They will change when you get fibre but in the meantime if your master socket has a test socket you could check whether your internal telephone wiring is having any detrimental effect by seeing if they change significantly with the router plugged, via an ADSL filter, directly into the test socket.

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      Re: Line attenuation and noise margin - what do my figures mean?

      Just realised i posted a link back to your own thread burnley_lad.
      Oops.

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    9. #5
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      Re: Line attenuation and noise margin - what do my figures mean?

      I have Fibre activated on Wednesday, and here are my new stats - how do these look? Also why is the line attenuation for upload 0.0db?

      Broadband Link Downstream Upstream
      Connection Speed 39998 kbps 9999 kbps
      Line Attenuation 8.3 dB 0.0 dB
      Noise Margin 25.9 dB 22.22 dB

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      Re: Line attenuation and noise margin - what do my figures mean?

      Short answer. You have a good line that is capable of higher speed but is limited by the product you have purchased.
      As for the 0.0 dB U/S line attenuation. This is not a true figure afaik the DSLAMs in the street cabinets do not report a value back to your router.

      Have you asked Sky for a speed estimate if you were to take Sky Fibre Pro?

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      Re: Line attenuation and noise margin - what do my figures mean?

      In my case as the copper length is 1Km I'm told by the Openreach engineer not to pay for or upgrade to the higher speed product as the actual speed will not increase due to line length.
      It is surprising how much different line length is to actual distance.
      Your Sync. speed may well come down after the DLM as finished assessing your line and performance.

    13. #8
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      Re: Line attenuation and noise margin - what do my figures mean?

      Your Sync. speed may well come down after the DLM as finished assessing your line and performance.
      The very low attenuation indicates this is a very short line, probably within 100m. With the very high noise margin, he could probably get 100Mb if it were available

      TomD


      Please note the views and recommendations in my posts are my own and in no way reflect the views of SkyUser.


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