Usrp_spectrum_sense.py , gr_plot_psd and periodogram

GNU Radio
1

Hello All,
I have few doubts regarding usrp_sepctrum_sense.py and
gr_plot_psd :

  • Does usrp_sepctrum_sense.py use normal periodogram or any other
    non-parametric PSD estimation method(like Barlett and/or Welch) ?
  • Does gr_plot_psd use overlap and add method or just the overlap
    method(I get this doubt because gr_plot_psd already considers file as
    blocks) ?

Thanks in advance.

Regards,
Ravi Sharan