'Normal' SNR evening drop?

Hi everyone,

Was just wondering what magnitude of decrease in SNR margin most people see due the various factors at play during the evening? My line now has a traget SNR margin of 15db and sits rock solid at that all day long. Once the evening begins it starts to jump all over the place and will always eventually go negative and force a resync. Is a drop of over 15db from optimum daytime performance to be expected or could something be wrong somewhere?

Thanks

Edited by thompsbd (Tue 06-Mar-07 23:21:23)

It sounds like your internal wiring may be prone to noise pickup, I rarely see more than a 5db swing during the night hours. How is your router connected, eg at the master socket, via a hard-wired extension or using a 'flying lead' extension?

Internal wiring is the main culprit, but some lines are more badly affected than others. I have 2 ADSL lines here - one line is much worse than the other (ironically the one with the better attenuation figure), and the lines take an identical route - the only difference is that the line with the worse SNR and SNR drift is about 12 feet longer than the other (one master socket is in one of the bedrooms, and the other is in the lounge).

My router is connected using a short shielded RJ11 cable to a filtered faceplate on the master socket. Strange thing is that I have a second line into the house (along the same physical cable) which isn't experiencing similar SNR drops. It has a target SNR of 6db and hasn't resynced for ages. I'm struggling to identify anything my end which could be causing it.

Brian

I have a similar drop and have tried all the usual suggestions including ferrite rings and two stage UPS and they make absolutely no difference whatsoever. The problem is external. The initial sync in the morning when I turn the router on gives around 4500 which would give a profile of 3.5mb which I sometimes have, however I have been trying different things and have found if I sync around 3700 the line will not drop but of course with a lower 3mb profile. It depends whether you need the extra speed or just want a stable line.

Ferrite rings are of no use whatsoever. The problem is that the wanted and unwanted signals are the same frequency, and ferrite rings will attenuate both the wanted and unwanted signals.

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Ferrite rings are of no use whatsoever. The problem is that the wanted and unwanted signals are the same frequency, and ferrite rings will attenuate both the wanted and unwanted signals.

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I have put them on the power leads not the adsl leads, the idea being to remove AM frequency noise picked up via the overhead and other wires. I am on a very rural site all our power is via overhead wires.

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I am on a very rural site all our power is via overhead wires.

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Same here, but the inductance of the electricity meter usually takes out these frequencies, which is why Home Plug won't work between houses.

My old house used to see a 10db drop in the evenings most of the time. New location moves probably about 2db if that. Both on the same exchange

Old location, lots of lights further from the exchange, new one hardly any lights, very close to the exchange.

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Same here, but the inductance of the electricity meter usually takes out these frequencies

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That interesting, I had not heard of that before. Our meter is 180 mtrs away