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Attenuation & SNR Margin ???


Attenuation & SNR Margin ???


i'm basically obsorbing any information i can get on ADSL / Wireless /etc
but could someone be able to explain Attenuation & SNR Margin, in detail
and what numbers are better etc.

My Router Displays:

Near End: 10.5
Far End: 13.0
SNR Margin:
Near End: 35
Far End: 31

Thanks for any help :lol:
Community Veteran
Posts: 6,983
Thanks: 8
Registered: 10-04-2007

Attenuation & SNR Margin ???

Attenuation is a measure of the loss in your line between you and the telephone exchange. It is expressed in dbs which is short for decibels.
The two figures of near end (You) and far end (the telphone exchange) are different because each direction of transmission uses a different range of frequencies.
The way the db notation works is that for every 3 dbs (almost) there is a reduction of 1 half of the power from the original signal so in your case you are seeing about 1 tenth of the original signal and the the exchange is seeinng about one twentieth of the signal from you. (the 10dbs and the 13dbs)

The SNR margin means the Signal to Noise Ratio of the line and the higher the figure here the better. From your figures the noise level is over one thousand times less than the signal.

Your line is brilliant and I can only conclude that you must live almost next door to the exchange.

Hope the above makes it all a bit clearer for you.

Attenuation & SNR Margin ???

Whats abut these figures

Downstream Upstream
SNR Margin 13.9 22.0 dB
Line Attenuation 56.9 31.5 dB

What fighres do you need to get 1MB service?


Attenuation & SNR Margin ???

I don't think theres been any published figures yet regarding the
1meg service in terms of line attenuation that differ from the 512K
service. Your line attenuation seems slightly high but it really
depends on the tests BT will carry out.
One requirement is that your line must be 3.5Km or less
from the exchange.
If you submit your phone number on
This site
you'll get an initial indication if your line supports up to 2Meg.

Attenuation & SNR Margin ???

What fighres do you need to get 1MB service?