_filtering.py 文件源码

def fir1(N, Wn):
    # Variables definition :
    nbands = len(Wn) + 1
    ff = np.array((0, Wn[0], Wn[0], Wn[1], Wn[1], 1))

    f0 = np.mean(ff[2:4])
    L = N + 1

    mags = np.array(range(nbands)) % 2
    aa = np.ravel(repmat(mags, 2, 1), order='F')

    # Get filter coefficients :
    h = firls(L - 1, ff, aa)

    # Apply a window to coefficients :
    Wind = np.hamming(L)
    b = np.matrix(h.T * Wind)
    c = np.matrix(np.exp(-1j * 2 * np.pi * (f0 / 2) * np.array(range(L))))
    b = b / abs(c * b.T)

    return np.ndarray.squeeze(np.array(b)), 1


####################################################################
# - Filt the signal :
####################################################################