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Line attenuation

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  • 03-08-2008 10:28pm
    #1
    nesf
    Registered Users Posts: 27,645 ✭✭✭✭


    I'm just curious, apart from distance, what can affect line attenuation? I'm getting 63dB downstream at 400m from the exchange and am trying to figure out why it's so high. The odd time the modem reports it as 15dB which is a glitch?

    Line stats:

    Statistics Downstream Upstream
    Line Rate 4064 Kbps 640 Kbps
    Noise Margin 5.9 dB 6.0 dB
    Line Attenuation 63.0 dB 31.5 dB
    Output Power 19.8 dBm 12.2 dBm

    Speed Test:

    304466891.png


Comments

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    #2
    leeroybrown
    Closed Accounts Posts: 7,563 ✭✭✭leeroybrown


    Attenuation should normally just be a function of line distance from the exchange. It's important to remember though, that the straight line distance between your phone socket and the exchange does not necessarily reflect the length of cable between your modem and the DSLAM. You wouldn't be the first customer to find an extra 1km of cable between your house and it.

    Problems with the line could also be a factor. Do you have any extra phone extensions in the house that could be causing degradation?


  • Options
    #3
    nesf
    Registered Users Posts: 27,645 ✭✭✭✭nesf


    leeroybrown wrote: »
    Problems with the line could also be a factor. Do you have any extra phone extensions in the house that could be causing degradation?

    It's an apartment building, rather than a house which may have something to do with it. There's one other socket in the bedroom but nothing is plugged into it.


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    #4
    rc28
    Registered Users Posts: 2,246 ✭✭✭rc28


    There is something seriously wrong with your connection. 63 is the highest (worst) figure for attenuation that a router can display, also your noise margin figures are just on the knife edge between constant disconnects and a few disconnects. You say you live close to the exchange so the lower figure you occasionally see is probably the true attenuation you should have all the time. It would appear to be faulty wiring in either your flat or somewhere else in the building. You need to talk to your landlord as I can't see how else you are going to solve this- BT tech support won't help as Eircom own the lines and they can only be sent out if there is a 'true' fault with your line ie your phone just isn't working but in this case it is, except performing nowhere near the standard it should be.
    Have you tried a different router?


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    #5
    lucernarian
    Registered Users Posts: 9,235 ✭✭✭lucernarian


    There's definetely a fault with the line or modem. Look at how high the sync rate is, despite the attenuation. The line itself has extremely little noise or crosstalk, which wouldn't be the case if the line was too long.

    I think it's a loose wire or bad join somewhere. Short circuit or water ingress far less likely, as sync is still being achieved. Try the troubleshooting steps mentioned in one of the sticky threads. Basically involves plugging nothing into the phoneline but the router and a short phone cord for it. And trying a new router.


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