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Prequal vs sync for VDSL

  • 31-08-2014 9:04pm
    #1
    Nonoperational
    Registered Users, Registered Users 2 Posts: 7,401 ✭✭✭


    Hi.

    My line prequals for 76Mbit since vectoring. However I have noticed no increase in my downstream SNR just the upstream. Before hand the prequal was 46Mbit.


    My question is, if the line prequals for 76Mbit, should I be able to get this? Why would the downstream SNR not improve after vectoring when it looks like it should have?

    The only strange thing I can see is that the DS2 loop attenuation is higher than the DS3.

    Thanks


Comments

  • #2
    ED E
    Registered Users, Registered Users 2 Posts: 36,170 ✭✭✭✭ED E


    Prequal is a best guess, not a perfect measurement, what's your sync speed?


  • #3
    Nonoperational
    Registered Users, Registered Users 2 Posts: 7,401 ✭✭✭Nonoperational


    OK, that's what I thought thanks. My sync speed is 50Mbit now with an SNR of 9. Before vectoring and G.INP it was 50Mbit with an SNR of 6. However the change in SNR happened after G.INP. The vectoring only increased the upstream SNR.

    I am only about 500m from the cabinet. I wonder is there something in the internal wiring of the apartment complex that is affecting things a bit.

    You can see here the attenuation is higher in the DS2 band than the DS3 band which I believe is causing the line to perform more poorly than it might do. Anyone any clues?

    I also think Vodafones SNR target of 10 is very conservative. Was working perfectly at 6 before.

    ScreenShot2014-09-01at162217_zps1a6f9f35.png


  • #4
    ED E
    Registered Users, Registered Users 2 Posts: 36,170 ✭✭✭✭ED E


    Yeah, that looks like there something up. The DS2 not being in line would suggest a certain frequency is encountering greater loss than the rest, I think. Could be other parallel cabling inducing onto yours. I wonder perhaps what the spectrum overlap is like between ADSL2+ and VDSL2+, if you had neighbours not upgraded to VDSL they could be interfering on a portion of spectrum and obviously not benefiting from vectoring.

    Think I saw it in a tech doc, will have to look. You had your ISP check it yeah?


  • #5
    Nonoperational
    Registered Users, Registered Users 2 Posts: 7,401 ✭✭✭Nonoperational


    Ya I remember looking up the frequencies before. Not a huge amount of info out there all the same.

    Yep, I contacted Vodafone today. I live in an apartment and the lines terminate in a basement here and are distributed to the apartments then. The problem is that if the issue is beyond the telephone pole then I'm probably not going to get it sorted.

    It's not a big deal, it's very stable on 50Mbit now, it's just it would be nice to have it operating to full speed all the same. I should probably ask one of the neighbours on fibre how they are getting on. Don't really know them though. Don't really want to be that guy that knocks on their door with a laptop asking if I can check the sync speeds of their broadband!


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