Forum: GNU Radio Detecting a carrier

Hi list..
I'm implementing a FHSS and i have some trouble detecting my carriers, i
was triying to use the example usrp_spectrum_sense.py to see how they do 
it
but i'm still in the same trouble, does anyone knows a good reference or
have an explanation about how the detect the level of interference o
carriers?
i can see mi carriers on the uhd_fft without any troubles, but how can i
extract that value? and use it for my demod process?

Thanks