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    Noise Margin and speed

    This is a discussion on Noise Margin and speed within the Sky Broadband help forums, part of the Sky Broadband help and support category; Hi All, My Broadband 'training period' has presumably now finished and I'm getting the following statistics: Broadband Link Downstream Upstream ...

    1. #1
      barrymung's Avatar
      barrymung is offline Sky User Member
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      Noise Margin and speed

      Hi All,

      My Broadband 'training period' has presumably now finished and I'm getting the following statistics:
      Broadband Link Downstream Upstream
      Connection Speed 6973 kbps 798 kbps
      Line Attenuation 48.5 dB 30.3 dB
      Noise Margin 6.1 dB 14.14 dB


      Do these figures seem sensible?

      Reason for asking is that I thought Sky ramped the speed up until the downstream noise margin dropped to around 4dB. Mine is above 6dB.

      Is this line therefore capable of a better speed? If so, how do I go about getting it?


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    3. #2
      gymno's Avatar
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      Re: Noise Margin and speed

      Almost 7mb downstream with an attenuation of 48.5 is excellent.

      48.5db = a line length af approximately 3.5km.
      DLM will only use a noise margin below 6db if the line is extremely good & errors don't build up causing instability.
      In practice, this usually only applies to lines around 1km long or less.

      I have 22.5db attenuation (1.4km) & DLM used a noise margin of 6db.

    4. #3
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      Re: Noise Margin and speed

      Well, I'm not complaining, just curious if i could eke some more out on the connection.

      Out of interest I rebooted the router and it's gone up a tad to 7007mbps downstream.

      3.5km sounds about right as the exchange is about 1.5 miles by road.

    5. #4
      gymno's Avatar
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      Re: Noise Margin and speed

      The speed change after a reboot is perfectly normal.

      6db is the 'target' noise margin.
      I don't know the exact figures for the profile you're on, but let's say it's 7014 / 814.
      Normally if you reboot while the nm is 0.2 or more above target, it'll 'use up' that extra margin, you'll get the full speed according to the profile & nm will return to target.

      Likewise, if you reboot when the nm is 0.2 or more below target, the opposite will happen & you'll lose a few kbps.

    6. #5
      Isitme's Avatar
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      Re: Noise Margin and speed

      Your line will be set to 7008/800kbps. With ADSL2+ you will always loose a few Kb, what you actually get will depend on the noise on your line when it is rebooted. As Gymno says, you are doing very well for your attenuation.

      TomD


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


      Useful Utilites

      http://www.nirsoft.net/utils/wifi_information_view.html/ TCPOptimiser /Test Socket

      Note - When downloading always select the Custom install or you will end up with stuff you don't want.





     

     

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