Question on acquiring 802.11b signals

I posted on a similar topic about two weeks ago but it really didn’t
help me. I am new to the world of GNU radio and have been fiddling with
my USRP and RFX2400 daughterboard to acquire 802.11b signals. At this
point, I just would like to take the fft of a chunk of spectrum so that
I may see all of the wireless signals in the vicinity and their
strengths (much like Eric B. did for the FM stations in Figure 3 of
his “Listening to FM Radio in Software” article at
http://www.linuxjournal.com/article/7505). I have been going over the
basic FM receiver code in the GNU radio tutorials. I can see how easy it
is to see different FM signals in a spectrum chunk. However, one of the
things that I’m having trouble understanding is how each 802.11 signal
is differentiated from one another (apart from the spectral mask). Could
you give me some insight into what I have to do to acquire and display
the appropriate signals. Maybe if I looked at the code which was used to
generate Figure 3 in that article it might help. Thanks in advance.


Swapneel S. Ukhalkar
BSEE UC Santa Barbara
[email protected]

On Mon, Aug 21, 2006 at 11:50:50PM -0700, Swapneel S. Ukhalkar wrote:

things that I’m having trouble understanding is how each 802.11 signal
is differentiated from one another (apart from the spectral mask). Could
you give me some insight into what I have to do to acquire and display
the appropriate signals. Maybe if I looked at the code which was used to
generate Figure 3 in that article it might help. Thanks in advance.


Swapneel S. Ukhalkar
BSEE UC Santa Barbara
[email protected]

I think using the spectral mask is the simplest thing to start with.
Other than that, you’ll need to use/build a real demodulator for the
signals of interest.

BBN’s been working on this:

http://www.mail-archive.com/[email protected]/msg05060.html

Eric