wireless/gnome
Matthew Saltzman
mjs at clemson.edu
Tue Mar 18 03:23:02 UTC 2008
On Tue, 2008-03-18 at 00:44 +0000, Jonathan Underwood wrote:
> 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.
See also the bottom three articles at http://www.ces.clemson.edu/linux/
for some other interesting material.
>
> J.
>
>
--
Matthew Saltzman
Clemson University Mathematical Sciences
mjs AT clemson DOT edu
http://www.math.clemson.edu/~mjs
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