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    Noise margin

    This is a discussion on Noise margin within the Sky Router forums, part of the Sky Broadband help category; Why is my downstream noise margin so high and could this explain why I sometimes get such incredible download speeds?? ...

    1. #1
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      Noise margin

      Why is my downstream noise margin so high and could this explain why I sometimes get such incredible download speeds??


      ADSL Link Downstream Upstream
      Connection Speed 5312 kbps 448 kbps
      Line Attenuation 49 db 14.5 db
      Noise Margin 2147483646 db 26 db



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    3. #2
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      Re: Noise margin

      Your noise margin is either as close to infinity as makes no difference, or its a bug in your router.

      dbs are ratios and logarithmic. eg.

      6 db is a voltage ratio of 2:1

      60db is a voltage ratio of 1000:1

      120db is a voltage ratio of 1,000,000:1


    4. #3
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      Re: Noise margin

      There's a bug in the router software that causes negative noise margin values to be displayed as very high positive numbers. Whoever wrote that part of the software probably didn't anticipate the possibility that the noise margin would ever go to a value less than zero because it is, on the face of it, impossible. However, the changing noise margin value displayed by the router is just an estimate because it's impossible to actually know what the noise margin is without resynchronising the modem. So a value which is actually just above zero, might be estimated to be at a value below zero.

      As for the peculiar high speeds, that download speed of 43290 simply isn't possible with ADSL - not even if you lived actually inside the telephone exchange, although I can't really explain how that happened though. It could be a "phase of the moon" type bug on the speed tester site.

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      Re: Noise margin

      Moved to the router forum

      As you're on Connect it is also extremely odd for your noise margin to be able to drop to close to zero as Connect uses an exchange based rate adaption process which shouldn't allow this.

      Sounds like you may have a line quality problem which the DLM can't handle the way it is intended to - (DLM is part of the RAMBo system, which analyses performance statistics from the DSLAMs for the end user’s line and adjusts the profile (sync/noise margin) when required).

      Are you in the first 10 days since connection?

    6. #5
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      Re: Noise margin

      The only time I have seen a speed as high as that on Speedtest was done by using PSP, Paint Shop Pro that is.

      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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      Re: Noise margin

      …or if you happen to have a co-located server at one of speedtest.net's testing sites…


     

     

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