Re: signal strength problem for multiple ap's w/ the same essid

[Sven <sr12 duke edu>]

On Tue, 2005-02-01 at 11:57 -0500, Dan Williams wrote:
> On Tue, 2005-02-01 at 11:47 -0500, Sven wrote:
> > On Tue, 2005-02-01 at 11:35 -0500, Dan Williams wrote:
> > > > apart from that: could it be that NM sometimes takes the signal strength
> > > > form the wrong AP (in the situation i described, with AP's with the same
> > > > essid)? and what about the change in signal strengths? 
> > > 
> > > No, it always uses the signal strength as reported by the card using
> > > SIOCGIWSTATS, namely it uses the exact same values you see in the "Link
> > > Quality  x/y" section of 'iwconfig', and simply does "% = x / y * 100".
> > > Note that /proc/net/wireless doesn't report any maximum quality, but
> > > iwconfig does.
> > 
> > i guess you know best, but: how come iwconfig says "Link Quality=30/94"
> > and changing according to distance etc from AP, but NM applet says
> > "Wireless network connection (75%)" when 30/94*100 is 32??? 
> 
> CVS currently has a few locking issues that may cause the applet not to
> be able to talk to NetworkManager at points and therefore not be able to
> update the quality.  You'll also need to make sure you've got CVS from
> late yesterday (I committed around 3PM EST and gnome.org anoncvs takes a
> while to sync).  Once I get the locking thing fixed, we should see if
> this is still a problem.

i'm using NM that has the following first few lines in it Changelog:
2005-01-29  Dan Williams  <dcbw    >

        * initscript/RedHat/NetworkManager
                - Don't spit out sysctl stuff to console
....

and one more observation: man iwconfig says

       Link quality
              Overall  quality of the link. May be based on the level of
con-
              tention 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.

       Signal level
              Received signal strength (RSSI - how strong the received
signal
              is). May be arbitrary units or dBm, iwconfig uses  driver
meta
              information to interpret the raw value given
by /proc/net/wire-
              less and display the proper unit or maximum value (using 8
bit
              arithmetic).  In  Ad-Hoc  mode,  this  may be undefined
and you
              should use iwspy.

       Noise level
              Background noise level (when no packet is transmitted).
Similar
              comments as for Signal level.

which to me seems to indicate that the values iwconfig spits out are
directly correlated to /proc/net/wireless. at least for me,
in /proc/net/wireless link quality = level - noise is the same as x in
Link Quality=x/y in iwconfig.

Sven