Usrp_spectrum_sense using problem

Hello, everyone!
I am a new comer of USRP, I want to do some work about spectrum
sense.
But how can I use usrp_spectrum_sense.py?

1. Is the following command correct?
   sudo python usrp_spectrum_sense.py -RB --tune-delay=10e-3

–dwell-delay=100e-3 2.3G 2.5G > file.tr
2. What is the meaning of the result?
3. After saving the result, how can I get the results of spectrum
analyzer ? Using the FFT function of Matlab, or any other GNURadio
tools?
4. After the platform of USRP/USRP2, is any other GNURadio functions
except that usrp_spectrum_sense.py?