Signals.py 文件源码

def Filter(self, LowCorner, HighCorner, Order=3):
    """
    Butterworth bandpass filter
    """

    FS = 1./self.HDR['TSMP']

    if HighCorner >= FS/2.:
      print 'Warning: High corner must be < {0:.2f} Hz'.format(FS/2.)
      return

    if LowCorner < 0.:
      print 'Warning: Low corner must be > 0 Hz'.format(FS/2.)
      return

    # Corner frequencies
    Corners = [2.*LowCorner/FS, 2.*HighCorner/FS]

    # Butterworth filter
    b, a = _sig.butter(Order, Corners, btype='band')

    # Filtering records
    for I,S in enumerate(self.CHN):
      # self.CHN[I] = _sig.lfilter(b, a, S)
      zi = _sig.lfilter_zi(b, a);
      self.CHN[I],_ = _sig.lfilter(b, a, S, zi=zi*S[0])

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