misc.py 文件源码

def low_cut_filter(x, fs, cutoff=70):
    """Low cut filter

    Parameters
    ---------
    x : array, shape(`samples`)
        Waveform sequence
    fs: array, int
        Sampling frequency
    cutoff : float, optional
        Cutoff frequency of low cut filter
        Default set to 70 [Hz]

    Returns
    ---------
    lcf_x : array, shape(`samples`)
        Low cut filtered waveform sequence
    """

    nyquist = fs // 2
    norm_cutoff = cutoff / nyquist

    # low cut filter
    fil = firwin(255, norm_cutoff, pass_zero=False)
    lcf_x = lfilter(fil, 1, x)

    return lcf_x