SNR Double When on Wireless!

[arobertson676]

I have heard that the SNR can be double when wired, but in my case the SNR is double when it is set wirelessly! I tested the same SNR setting (65415) on a wired computer and a wireless computer about a minute apart and the wireless computer casued the 7800N to connect at 1.5dB whereas the wired computer caused it to connected at 0.8dB. I also noticed that the SNR was much more variable when set via a wired connection and the errors were massive, but when wireless there were hardly any errors!

This is on 1.06d firmware. I will try the 1.06e firmware and also the 1.06f firmware to see if it occurs on these firmwares.

I'll keep this thread updated.

[roseway]

I'm afraid your observations are incorrect. The connection parameters are under the control of the modem part of the equipment, and whether the router is connected to the PC with ethernet or wireless makes no difference at all. All you're seeing is a small difference of 0.7 dB in the noise margin at two different times.

By the way, as decibels are logarithmic values, the fact that one number is about double another number doesn't mean that the SNR is doubled. A difference of 0.7 dB in fact corresponds with an arithmetic ratio of about 0.85, so it only represents a 15% change in SNR.

[Tomken]

When the SNRM drops that low and depending on your Attenuation, that could increase the possibilty of a disconnect so it could be pertinent given their current levels, but wouldn't normally be much of a possible problem if the reference was a few dBs higher.

My SNRM used to halve when wireless and on an evening when it used to drop really low (0.9 - 0.4dB from about 6dB) I used to wire up, otherwise I could end up with disconnects.

These days it only rarely drops below 2.0dB (wireless) that I know of and it's also very rare that I get a disconnect, although there are times late on an evening when I can experience some lag and on checking, it has been low with the errors mounting up.

When this happens, I normally switch the router off when I've finished for the night and have found that the SNRM has recovered substantially by mid morning.

When you say "wired computer" and "wireless computer" are you just talking about the different states of one computer or are you checking the condition of two ?

[roseway]

When you're running with such low noise margins, any interference will have a much greater effect than it would with a larger noise margin. Depending on the equipment used, it's possible that something connected with the wireless-connected device is causing extra interference and affecting the ADSL connection. But what it won't do is change the startup noise margin when the router reconnects, which is set by the target noise margin. However the noise margin changes continually by small amounts, and it's quite common for a reading taken very shortly after a reconnection to show a noise margin which differs from the target.

[arobertson676]

Thank you for your input. After posting this I realised that the connection had nothing to do with it.