[Discuss-gnuradio] RF Energy during pkt reception (spectrum sense + bbn code)

[Shravan Rayanchu]

Hello everyone,

I am trying to plot the RF power spectrum obtained a during packet
reception. For this, I have merged usrp_spectrum_sense.py with
bbn_80211_rx.py. To make it easier to understand, I have put a figure
illustrating the resultant flow graph at
http://www.cs.wisc.edu/~shravan/pkt_energy.jpg

usrp_c is used as a source and then there are two separate paths that
the samples take. One gives us the power spectrum and the other tells
us whenever a packet is received. I am basically interested in knowing
the output of the power spectrum part when a packet is received on the
bbn part of the flow graph i.e. I want to "plot the power spectrum for
exactly those samples which result in a packet being received on the
bbn part of the flow graph".

The problem I am facing is how to correlate the samples i.e. how would
I know which samples resulted in a packet and then plot the spectrum
for those samples ...?  Can I keep track of something like a global
sample number which I can use .. ? The issue seems to be complicated
because of how scheduling is performed ..

I would appreciate it if you can throw in ideas ..

Thanks for the help,

Shravan