Simplified FFT plotting and cleaned up some code formatting.

tools/plot_waveform.py

@@ -50,9 +50,8 @@ while not timeiter.finished:
     timeiter.iternext()
 
 # Calculate frequency spectra of waveform
-fs = 1/dt
-power = 20*np.log10(np.abs(np.fft.rfft(waveform)))
-f = np.linspace(0, fs/2, len(power))
+power = 20 * np.log10(np.abs(np.fft.fft(waveform))**2)
+f = np.fft.fftfreq(power.size, d=dt)
 
 # Shift powers so any spectra with negative DC component will start at zero
 power -= np.amax(power)