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SNR for 1&2mb

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SNR for 1&2mb

can any one tell me what the noise (db) limit for 1 and 2mb to work?
27 REPLIES
Community Veteran
Posts: 6,983
Thanks: 8
Registered: 10-04-2007

SNR for 1&2mb

There are no fixed limits that I have seen but in general you need it to above 10dB.
The higher the figure you get the better.
N/A

SNR for 1&2mb

Attenuation
28 dB - Downstream
48 dB - Upstream
is that good enough for 2mb?
N/A

SNR for 1&2mb

post your SNR (Signal to noise ratio) too...
LiamM
Grafter
Posts: 5,636
Registered: 12-08-2007

SNR for 1&2mb

If you have an attenuation like that, then your SNR should be OK. You're certainly fine for 2Mb with those figures. If your SNR is around 15+ I would be confident for you.
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SNR for 1&2mb

Noise Margin
29 dB Upstream
3 dB Downstream

Output Power
12.5 dBm Upstream
14.5 dBm Downstream

Attenuation
28 dB Upstream
48 dB Downstream

I dont seem to have an SNR,
but can you work out the ration from that available data?
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SNR for 1&2mb

Cool so its looking good then, i just hope iam can actually recieve 2mb ADSL now Cheesy
Community Veteran
Posts: 6,983
Thanks: 8
Registered: 10-04-2007

SNR for 1&2mb

Noise margin is the Signal to noise ratio.
The 3 db figure doesn't look too promising though.
Also I have to dispute Liams statement that they should be fine for 2mb as 48dB is actually over the top for the current BT limits.
However it may still work even if it is out of the 43dB limit.
N/A

SNR for 1&2mb

oooh what a downer.
so i might only get 1mb when iam upgraded Tongue
Community Veteran
Posts: 6,983
Thanks: 8
Registered: 10-04-2007

SNR for 1&2mb

BT's current limits are very conservative and you may find that having a slightly higher loss will not stop it working at 2mB.
Time will tell. Smiley
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SNR for 1&2mb

Unfortunately I don't think you'll get 2MB at the moment, I had 44db attenuation, 23db s/n, and only managed to get upgraded from 512 to 1mb - this took a manual order as the BT checker said I wouldn't be able to receive anything over 512.

John
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SNR for 1&2mb

Any ideas what i would get with thse stats.

snr=34.6db down / 30db up
line attenuation 43.8db down / 22db up

checker says upto 2 meg but not sure
chymorva
Grafter
Posts: 275
Registered: 29-08-2007

SNR for 1&2mb

Hi,

Your ADSL line stats are split into 2 - Upstream (what you send) and Downstream (what you receive).

Generally speaking the worse stats are the Downstream figures so just look at them.

There are 2 statistics that you are interested in:
1. Attenuation.
2. SNR (Signal to Noise Ratio - sometimes called Noise Margin).

The Attenuation figure shows how much of the original signal is lost between the exchange and your router/modem. The lower the figure the better. For 1MB a figure of 60dB or less is required, for 2MB a figure of 43dB or less is required.

The SNR figure shows how strong the signal is in relation to the noise (or interference) on your line. The higher the figure the better. It is generally accepted that a SNR of less than 10dB may suffer from dropouts (occasional loss of signal).

It is slightly more complicated than that so if you are on the borderline it might or might not work.

To make an analogy with a person talking:
If conditions are quiet you may hear somebody a long way off although what you hear is much quieter than the original - High attenuation but high SNR. Equally if conditions are noisy you may not hear somebody close by (eg at a disco!!) - Low attenuation but low SNR also.

So SNR=34.6dB is good.
Attn=43.8dB is borderline for 2MB

Hope this helps.
Community Veteran
Posts: 14,469
Registered: 30-07-2007

SNR for 1&2mb

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SNR for 1&2mb

Ta. Many thanks