I have edited benchmark_tx.py to shift between 3 different frequencies, depending upon which one is free after sensing the apectrum. i have made a separate program which senses the spectrum and it is called in benchmark_tx.
Thus the system switches between transmit (benchmark_tx) and receive (sensing) mode on a regular basis.
This works fine.
The problem arises when i want to show on the situation of the spectrum on a FFT Plot. I ran the GRC flowgraph (USRP Source-->FFT Sink) in parallel with the above mentioned programs. But it doesnt work.
Can someone help me in finding out how to add FFT Plot in the above programs.