tf_methods.py 文件源码

def DFT(x, w, N):
        """ Discrete Fourier Transformation(Analysis) of a given real input signal
        via an FFT implementation from scipy. Single channel is being supported.
        Args:
            x       : (array) Real time domain input signal
            w       : (array) Desired windowing function
            N       : (int)   FFT size
        Returns:
            magX    : (2D ndarray) Magnitude Spectrum
            phsX    : (2D ndarray) Phase Spectrum
        """

        # Half spectrum size containing DC component
        hlfN = (N/2)+1

        # Half window size. Two parameters to perform zero-phase windowing technique
        hw1 = int(math.floor((w.size+1)/2))
        hw2 = int(math.floor(w.size/2))

        # Window the input signal
        winx = x*w

        # Initialize FFT buffer with zeros and perform zero-phase windowing
        fftbuffer = np.zeros(N)
        fftbuffer[:hw1] = winx[hw2:]
        fftbuffer[-hw2:] = winx[:hw2]

        # Compute DFT via scipy's FFT implementation
        X = fft(fftbuffer)

        # Acquire magnitude and phase spectrum
        magX = (np.abs(X[:hlfN]))
        phsX = (np.angle(X[:hlfN]))

        return magX, phsX