fir.py 文件源码

def another():
# plot the figure of signals
  fig = plt.figure(1)
  ax = fig.add_subplot(311)
  ax.set_title('input signal')
  ax.plot(t[1:Npts],x[1:Npts])    # just plot part of the signal
  ax = fig.add_subplot(312)
  ax.set_title('expected signal')
  ax.plot(t[1:Npts],xo[1:Npts])
  ax = fig.add_subplot(313)
  ax.set_title('filtered signal')
  ax.plot(t[1:Npts],y[1:Npts])
  fig.savefig('pic1.png')

# plot the mag & phase response of the LPF
  w,h = signal.freqz(b,1)
  hdb = 20 * np.log10(np.abs(h))
  hphs = np.unwrap(np.arctan2(np.imag(h),np.real(h)))
  fig2=plt.figure(2)
  ax2 = fig2.add_subplot(211)
  ax2.set_title('frequency response')
  ax2.plot(w/max(w),hdb)
  ax2 = fig2.add_subplot(212)
  ax2.set_title('phase response')
  ax2.plot(w/max(w),hphs)
  fig2.savefig('pic2.png')