[Discuss-gnuradio] fft display frequency spotting

[cswiger]

Gang - getting an accurate frequency reading from an fft display is pretty
easy. This works for me:


   import wx.lib.evtmgr as em

  ...

   # add an fft display to panel_7, nice size, avg on and weaver IF
   # offset
   fft = fftsink.fft_sink_c (self.fg, self.panel_7, fft_size=512, \
     sample_rate=af_sample_rate, baseband_freq=-1.8e3, average=True, \
     size=(680,240))
   self.fg.connect (self.xlate_L, fft)

   # for mouse position reporting on fft display
   em.eventManager.Register(self.Mouse, wx.EVT_LEFT_DOWN, fft.win)

  ...

   def Mouse(self,event):
       fRel = ( event.GetX() - 48 ) / 15.2 - 20
       print eng_notation.num_to_str(self.frequency + (fRel*1e3))


Voila - just click on the peak or feature of interest and read it's
frequency off the console. Change centers, scales and offsets to fit
your freq range and window size.

--Chuck