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Thread: SNR Margin and Line Attenuation - What do they mean?

  1. #1
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    Thumbs up SNR Margin and Line Attenuation - What do they mean?

    There have been many posts regarding SNR and Line Attenuation.

    SNR
    SNR means Signal to Noise Ratio. Simply put divide the Signal value by Noise Value and you get SNR. You need high SNR for a stable connection. In general, a higher signal to noise ratio will result in less errors.

    • 6bB. or below = Bad and will experience no line synchronisation and frequent disconnections
    • 7dB-10dB. = Fair but does not leave much room for variances in conditions.
    • 11dB-20dB. = Good with little or no disconnection problems
    • 20dB-28dB. = Excellent
    • 29dB. or above = Outstanding


    Note that most modems display value as SNR Margin and not pure SNR.

    SNR Margin
    You can think of SNR margin as the measure of quality of the service; it defines the ability of the service to work error free during noise bursts.

    This is a measure of the difference between your current SNR and the SNR that is required to keep a reliable service at your connection speed. If your SNR is very close to the minimum required SNR, you are more likely to suffer intermittent connection faults, or slowdowns. You need a high margin to ensure that bursts of interference don't cause constant disconnections.

    With traditional broadband, the higher the SNR Margin, the better. With MaxDSL the faster speeds are only available as a trade-off with what your line can reliably support. The Target SNR Margin is about 6dB. If your broadband is provided through an LLU (Local Loop Unbundled) network, this target SNR Margin may be as high as 12dB.

    Line Attenuation
    In gerneral, attenuation is the loss of signal over distance. Unfortunately, dB loss is not just dependent on distance. It also depends on cable type and gauge (which can differ over the length of the cable), the number and location other connection points on the cable.

    • 20bB. and below = Outstanding
    • 20dB-30dB. = Excellent
    • 30dB-40dB. = Very Good
    • 40dB-50dB. = Good
    • 50dB-60dB. = Poor and may experience connectivity issues
    • 60dB. and above = Bad and will experience connectivity issues

    Line attenuation also affects your speed.

    • 75 dB+: Out of range for broadband
    • 60-75 dB: max speed up to 512kbps
    • 43-60dB: max speed up to 1Mbps
    • 0-42dB: speed up to 2Mbps+


    Please comment on this article.

    (and if you give me reputation on this, I shall return the favour)

  2. #2
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    Thanks just4kix it was good to about it...can u also state the difference b/w adsl+ and g.dmt

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    Quote Originally Posted by just4kix View Post
    (and if you give me reputation on this, I shall return the favour)
    Lessons from corporates! Given by management guru just4kix!
    ^^Thanks for d info! I've added to ur reputation, now its ur turn!

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    Quote Originally Posted by gurusam View Post
    Thanks just4kix it was good to about it...can u also state the difference b/w adsl+ and g.dmt
    Basically it is the technology difference.

    G.DMT is ADSL1 whereas ADSL2+ is, well, ADSL2+.

    Refer these articles: G.DMT and ADSL2+

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    Thumbs up

    added repo

    and thanks for such a nice and informative post

    you are rocking just4kix :rockon:

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    I too added repo for just4kix for this post but the repo power of just4kix has not increased??

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    Each repo gives a point. I have 36 points so far. I do not know how Rep Power is calculated.

    Post something informative and I promise that I will return your favours.

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    just4kix u r kix smart buddy i think u r the favourite here .................. Cheers buddy..........................

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    If you get problems regarding those shits then how do we fix it?

    Nice article ,by the way.

    best regards,
    Spectre

  10. #10
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    Wink

    J4X you are tempting me to one more Modem / Router crash !!!
    I'll surely be up on something Tonight !!!

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