Hello,
I recently ran an experiment using the USRP2 to collect I&Q samples
using
usrp2_rx_cfile.py. I want to detect when the an 802.11b channel is busy
using these raw samples.
I’ve seen the use of the filter y[n] = alpha*x[n] + (1-alpha)*y[n-1]
with
alpha as 0.001 in the carrier sensing BBN 802.11 code. The default
threshold
was set to 30 dB.
I’ve imported the data to Matlab and calculated the magnitude squared of
each sample and ran it through this filter, but it appears that the data
does not match the packets that I sent.
The carrier sensing code might correspond to the USRP, but are there any
direct changes I would need to make for the USRP2 to use the carrier
sensing
code?
I’ve read through this post:
http://www.ruby-forum.com/topic/120841
but it deals with the USRP at the FPGA level.
Anyone have any suggestions?
Thanks,
Miklos Christine