wireless/gnome

[Jonathan Underwood]

On 18/03/2008, Jonathan Underwood <jonathan.underwood at gmail.com> wrote:
> On 17/03/2008, Timothy Murphy <gayleard at eircom.net> wrote:
>  > John W. Linville wrote:
>  >
>  >  >>> > Well if I out my mouse pointer on the nm-applet icon I get the
>  >  message:
>  >  >> > Wireless Network Connection to ??? (98%)
>  >  >> > I assume 98% is a measure of signal strength.
>  >  >>
>  >  >> I can't think of anything it could possibly be 98% of ...
>  >  >
>  >  > That's probably because you are intentionally obtuse, and apparently
>  >  > on a jihad against NetworkManager...
>  >
>  >
>  > I'm unintentionally obtuse.
>  >  What is this signal strength 98% of?
>  >
>
>
> I'd guess it means that 98% of the transmitted signal intensity is
>  being received by the wireless card. Although I have to admit, I do
>  wonder how that is calculated, and whether it takes into account the
>  1/r^2 fall off of signal emitted in the full sphere.
>

Actually, for those that are interested:

http://www.wildpackets.com/elements/whitepapers/Converting_Signal_Strength.pdf

explains things fairly well, although how this "link quality"
percentage is calculated is rather opaque. It seems to be some
aggregate value of signal strength, signal-to-noise and various other
factors. May also be vendor dependent. According to iwconfig manpage:

"Overall quality of the link. May be based on the level of contention
or interference, the bit or frame error rate, how  good  the  received
 signal  is,  some timing synchronisation, or other hardware metric.
This is an aggregate value, and depends totally on the driver and
hardware."

In any case, it seems it's a value exposed by the kernel in /proc/net/wireless.

J.