def METHOD_NAME(self):
    # Generate a noisy signal
    fs = 2400
    T = 6
    nsamples = T * fs
    t = np.linspace(0, T, nsamples, endpoint=False)
    a = 0.02
    f0 = 300
    x = 0.5 * np.sin(2 * np.pi * f0 * t)
    x += 0.25 * np.sin(2 * np.pi * 2 * f0 * t)
    x += 0.25 * np.sin(2 * np.pi * 3 * f0 * t)
    #data = x.astype(np.complex64)
    data = np.sin(2 * np.pi * f0 * t).astype(np.complex64)
    print("Len data", len(data))
    a, b = self.narrowband_iir(f0, 100, fs)
    s = a.sum() + b.sum()
    #a /= s
    #b /= s
    print(a,  b)
    filtered_data = signal_functions.iir_filter(a, b, data)
    #plt.plot(data, label='Noisy signal')
    plt.plot(np.fft.fft(filtered_data), label='Filtered signal (%g Hz)' % f0)
    plt.legend(loc='upper left')
    plt.show()