Try alumimum foil: it's cheap, easy to configure, and doesn't crash
much. Plus, it will protect your card from psychotronic mind control
(see http://zapatopi.net/afdb.html) :-)
Seriously, the way to do this is to use the signal strength indication
and move around, making a map of the signal strength, and try to climb
the gradient. This requires skill. You can also use GPS and plot
signal strength vs. location - it helps to visualize the field.
If, hypothetically, you are doing this in an office building and are
trying to find which employee has put an AP in their office, I would
recommend just walking around all the corridors and noting the places
with really high signal strengths. Signal strength is a messy
function of distance, but this should get you to within an office
width or two. Make sure you go far enough past a signal to ensure
that you see the real peak.
Outside, a useful technique is find a place that you hear the signal
and travel in a straight line (perhaps in both directions). Find the
place on the line with the strongest signal and then travel along a
perpendicular from that point, and repeat. This is of course messier
in practice.
In very close to the emitter, the signal may be so strong that you
don't get a useful signal strength indication because the card's
receiver/RSSI is saturated/out of the linear range. In that case,
covering the card in foil will knock the signal down some, perhaps
enough to bring the signal strength back into a usable range.
(Some amateur radio operators search for hidden transmitters as sport,
called 'foxhunting'. The group I've hunted with hides a transmitter
in an ammunition box and sometimes puts it under leaves and brush with
only the (olive drab as well of course) antenna sticking out. So one
has to go on signal only until the last few feet. Getting useful
signal strength out of a radio is tough at these signal levels, and
one trick is replacing the antenna with a 50 ohm terminator. Another
is listening to the third harmonic of the transmitter, but that's
tough for 2.4 GHz.)
--
Greg Troxel <[EMAIL PROTECTED]>
--
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