Home› Broadband Internet
Click here to check out Digital Spy's Tech section for the latest news, updates, reviews and cheap deals.
Options

Low downstream noise margin

LION8TIGERLION8TIGER Posts: 8,484
Forum Member
✭
in Broadband Internet #1
I'm with Sky LLU and have noticed it getting lower over the past month or so, it used to be around 5db, then 3db and it has been 1.7 for the last week. Nothing wrong with the speed and not getting any disconnections .... every couple of months it will go down about 2am for a while which I presume is maintenance.
When I was with TT it was around 5-6db and if it went down to 3-4db it would keep disconnecting.

Anyone else have a low noise margin like me ?

Comments

  • Options
    michael37michael37 Posts: 2,622
    Forum Member
    ✭✭✭
    #2
    With sky the standard target SNR margin is 7db (6 in some exchanges), but if you have a very stable line of a long period of time DLM will drop it to 3db which gives around a 2Mb/s speed boost.

    Dropping to 1.7 will just be noise on the line, if the last retrain was during a time where line noise was low this can happen as a fluctuation in noise margin of up to 2db is not in any way unusual. If the line becomes unstable and starts to drop DLM will automatically bump it back to 7db.

    I'll wager if you were to check the margin at around 11AM (which is when line noise is usually at it lowest) the margin will be close to 3db.

    The drop every couple of months will be to allow DLM to recalculate the bitloadings on the line.
  • Options
    LION8TIGERLION8TIGER Posts: 8,484
    Forum Member
    ✭
    #3
    Thanks Michael, I checked at 11am and it had risen to 2.2db. I rebooted the router and its now at 3.1db. Cheers.
  • Options
    IcaraaIcaraa Posts: 6,068
    Forum Member
    ✭
    #4
    LION8TIGER wrote: »
    Thanks Michael, I checked at 11am and it had risen to 2.2db. I rebooted the router and its now at 3.1db. Cheers.

    I wouldn't restart it at all if you aren't getting disconnections, leave it to do its thing.
  • Options
    LION8TIGERLION8TIGER Posts: 8,484
    Forum Member
    ✭
    #5
    Icaraa wrote: »
    I wouldn't restart it at all if you aren't getting disconnections, leave it to do its thing.

    Yes thats what I usually do (leave it alone) but I don't think an odd reboot will affect DLM.
  • Options
    tony-wtony-w Posts: 487
    Forum Member
    ✭
    #6
    Yes, the odd reboot is not an issue,
    I have a friend who got BB, he called me up stating it was incredibly slow (under 1mb) and so I went and had a look.
    After much investigation it transpired he was turning off the router every night before bed causing the DSLAM to obviously drop the profile, the router was never on long enough to 'train' the line and achieve a stable sync, and thus increase to the lines maximum potential.
Sign In or Register to comment.