gen.py 文件源码

def whiteNoise(fftData, noiseLevel=80):
    '''Adds White Gaussian Noise of approx. 16dB crest to a FFT block.

    Parameters
    ----------
    fftData : array of complex floats
       Input fftData block (e.g. from F/D/T or S/W/G)
    noiseLevel : int, optional
       Average noise Level in dB [Default: -80dB]

    Returns
    -------
    noisyData : array of complex floats
       Output fftData block including white gaussian noise
    '''
    dimFactor = 10**(noiseLevel / 20)
    fftData = _np.atleast_2d(fftData)
    channels = fftData.shape[0]
    NFFT = fftData.shape[1] * 2 - 2
    nNoise = _np.random.rand(channels, NFFT)
    nNoise = dimFactor * nNoise / _np.mean(_np.abs(nNoise))
    nNoiseSpectrum = _np.fft.rfft(nNoise, axis=1)
    return fftData + nNoiseSpectrum