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surge protection and SNR

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surge protection and SNR

I have my ADSL filter plugged into a surge protector before it goes into the phone line - will this be affecting my SNR margin?
13 REPLIES
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surge protection and SNR

I think this question has been asked before, but I can't remember the original answer given.

In theory it could, but I would have thought the difference made would be minimal and not worth changing your setup.
Community Veteran
Posts: 14,469
Registered: 30-07-2007

surge protection and SNR

May depend of the quality of the surge protector. If you modem/router shows SNR, just try it with and without it and you will know. If your modem/router does not show SNR, there is no way to find out.
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surge protection and SNR

Is it possible the difference could be enough to affect what bandwidth i get on MaxDSL?
Community Veteran
Posts: 14,469
Registered: 30-07-2007

surge protection and SNR

Without knowing what the difference actually is (if any) and what SNR you are currently getting, that question cannot be answered.
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surge protection and SNR

i posted my SNR stats on another thread but will repeat here:
downstream: 15.8 SNR, 48,4 line attenuation
upstream: 28.0 SNR, 31.5 line attenuation
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surge protection and SNR

But have you tried this without your connection being protected? and what are the results? This would surely tell you how much an impact, if any, your surge protector is making.
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surge protection and SNR

I plan to test without the surge protector tonight (When no-one else is sharing the connection) and will post new stats
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surge protection and SNR

ok, new stats:
upstream: 28.0 db SNR, 31.5 attenutation
downstream: 18.5 SNR, 48.4 attenuation
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surge protection and SNR

From your new stats, I would say it's having quite an impact. What make is your surge protector?
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surge protection and SNR

It's built into my power extension which i purchased from Argos. Was wondering for a while if the ADSL would even work using it.
Community Veteran
Posts: 14,469
Registered: 30-07-2007

surge protection and SNR

Are you sure the 18.5 SNR is not a typo and you really meant 15.8 as all the other figures are the same.
N/A

surge protection and SNR

Just double-checked it
tis correct
Community Veteran
Posts: 14,469
Registered: 30-07-2007

surge protection and SNR

OK.

So you have your answer, it does affect it by 3dB. Whether that is enough to limit your faster speed I'm still not sure as routers don;t always give out the correct or accurate readings.

Often, an increase in speed (512k->1Mb 1Mb -> 2Mb) results in a SNR decrease of between 3 & 6dB and sometimes more. As long as your SNR is above 10dB after any speed upgrade things should be OK. If it drops below 10dB then problems may occur and BT may decide your line quality is not good enough for a faster speed. Even so, 48dB is above the limit for 2Mb (43dB) so a speed upgrade may not be possible yet.