general_hamming(M, alpha, sym=True)
The generalized Hamming window is constructed by multiplying a rectangular window by one period of a cosine function .
The generalized Hamming window is defined as
$$w(n) = \alpha - \left(1 - \alpha\right) \cos\left(\frac{2\pi{n}}{M-1}\right)\qquad 0 \leq n \leq M-1$$Both the common Hamming window and Hann window are special cases of the generalized Hamming window with $\alpha$ = 0.54 and $\alpha$ = 0.5, respectively .
Number of points in the output window. If zero or less, an empty array is returned.
The window coefficient, $\alpha$
When True (default), generates a symmetric window, for use in filter design. When False, generates a periodic window, for use in spectral analysis.
The window, with the maximum value normalized to 1 (though the value 1 does not appear if M is even and :None:None:`sym` is True).
Return a generalized Hamming window.
The Sentinel-1A/B Instrument Processing Facility uses generalized Hamming windows in the processing of spaceborne Synthetic Aperture Radar (SAR) data . The facility uses various values for the $\alpha$ parameter based on operating mode of the SAR instrument. Some common $\alpha$ values include 0.75, 0.7 and 0.52 . As an example, we plot these different windows.
>>> from scipy.signal.windows import general_hamming
... from scipy.fft import fft, fftshift
... import matplotlib.pyplot as plt
>>> fig1, spatial_plot = plt.subplots()
... spatial_plot.set_title("Generalized Hamming Windows")
... spatial_plot.set_ylabel("Amplitude")
... spatial_plot.set_xlabel("Sample")
>>> fig2, freq_plot = plt.subplots()
... freq_plot.set_title("Frequency Responses")
... freq_plot.set_ylabel("Normalized magnitude [dB]")
... freq_plot.set_xlabel("Normalized frequency [cycles per sample]")
>>> for alpha in [0.75, 0.7, 0.52]:See :
... window = general_hamming(41, alpha)
... spatial_plot.plot(window, label="{:.2f}".format(alpha))
... A = fft(window, 2048) / (len(window)/2.0)
... freq = np.linspace(-0.5, 0.5, len(A))
... response = 20 * np.log10(np.abs(fftshift(A / abs(A).max())))
... freq_plot.plot(freq, response, label="{:.2f}".format(alpha))
... freq_plot.legend(loc="upper right")
... spatial_plot.legend(loc="upper right")
The following pages refer to to this document either explicitly or contain code examples using this.
scipy.signal.windows._windows.get_window
scipy.signal.windows._windows.general_hamming
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