[SATLUG] WLAN frequency detection

Tom Weeks tweeksjunk2 at theweeks.org
Sat Jan 26 11:54:06 CST 2008


On Friday 25 January 2008 16:51:16 john mashl wrote:
>   hey yall
>
> I have been working for a wireless internet service provider horizion
> telecom/ranch wireless here in seguin.
>
> hwtx.com    or   ctxu.com
>
> somtimes we get signal interference and i have been wondering if there
> is a way to "see" what outher frequencys might be causing the problem.
> we use the motorolla canpopy product line that uses the 2.4 ghz band
> for the subscriber modules. when we do an a.p. scan the radio will
> tell us that there are outher frequencys in use but nothing specific.
> would baudline help or does anybody have any outher suggestions for
> scanning the 2.4 ghz bandwidth

Last year at XCSSA we did a demo of the WiSpy frequency scanning system.  
Here's some of the scanning that I did of my own house:
	http://theweeks.org/tmp/PICS/WISPY/

These are RF waterfall spectrograms showing various RF emissions around my 
house.  The column of noise on the left is RF noise generated by having my 
WiSpy hooked directly to my laptop.  Separating the scanner from the laptop 
via USB cable fixes it.  But that various photos show what ping flooding, 
checking email, and even 5GHz DSS phones can generate RF noise in the 2.4 GHz 
spectrum.

The 2GHz column in the middle here:
	http://theweeks.org/tmp/PICS/WISPY/Home-RF-cumulative+x10.png
is caused by X10 2.4GHz wireless video, and the noise on the right is caused 
by an X10 RF remote.

When I got my WiSpy, they were still $100.. Now I think they're $200:
	http://www.thinkgeek.com/gadgets/electronic/80ce/

Tweeks


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