Numpy 中的海明
汉明窗是通过使用加权余弦形成的锥形
Parameters(numpy.hamming(M)):
M : int Number of points in the output window.
If zero or less, an empty array is returned.
Returns:
out : array
窗口，最大值归一化为 1(只有当样本数为奇数时，才会出现值 1)。 例:
import numpy as np
print(np.hamming(12))
输出:
[ 0.08 0.15302337 0.34890909 0.60546483 0.84123594 0.98136677
0.98136677 0.84123594 0.60546483 0.34890909 0.15302337 0.08 ]
绘制窗口及其频率响应(需要 SciPy 和 matplotlib): 对于窗口:
import numpy as np
import matplotlib.pyplot as plt
from numpy.fft import fft, fftshift
window = np.hamming(51)
plt.plot(window)
plt.title("Hamming window")
plt.ylabel("Amplitude")
plt.xlabel("Sample")
plt.show()
输出:
频率:
import numpy as np
import matplotlib.pyplot as plt
from numpy.fft import fft, fftshift
window = np.hamming(51)
plt.figure()
A = fft(window, 2048) / 25.5
mag = np.abs(fftshift(A))
freq = np.linspace(-0.5, 0.5, len(A))
response = 20 * np.log10(mag)
response = np.clip(response, -100, 100)
plt.plot(freq, response)
plt.title("Frequency response of Hamming window")
plt.ylabel("Magnitude [dB]")
plt.xlabel("Normalized frequency [cycles per sample]")
plt.axis('tight')
plt.show()
输出:
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