18 Jun
2009
18 Jun
'09
1:16 p.m.
2.4 and 5GHz license-free Wifi is license free because the frequencies are shared with the ISM (Industrial/Scientific/Medical) services. In an industrial area, competing WiFi is the least of your worries. These frequencies are also used by industrial grade heating units. Got anyone in the neighbourhood running a large plastic shrink wrap machine, for example?
Good point.
You can't directly detect these other users with a Wifi transceiver. Depending on the nature of the interference you *might* be able to hear it directly on a scanner (if you can find one that covers those frequencies), but you really need a good spectrum analyzer to tell what's going on.
Check out http://www.ubnt.com/airview/ for a decent one. There is also wispy.