擅长:python、mysql、java
<p>重采样信号的频谱应具有与输入信号相同频率的音调,只是在较小的奈奎斯特带宽内。你知道吗</p>
<pre><code>import numpy as np
import matplotlib.pyplot as plt
from scipy import signal
import scipy.fftpack as fft
fs = 100 # sample rate
rsample=50 # downsample frequency
fTwo=10 # frequency of the signal
n = np.arange(1024)
y = np.sin(2*np.pi*fTwo/fs*n)
y_res = signal.resample(y, len(n)/2)
Y = fft.fftshift(fft.fft(y))
f = -fs*np.arange(-512, 512)/1024
Y_res = fft.fftshift(fft.fft(y_res, 1024))
f_res = -fs/2*np.arange(-512, 512)/1024
plt.figure(1)
plt.subplot(211)
plt.stem(f, abs(Y))
plt.subplot(212)
plt.stem(f_res, abs(Y_res))
plt.show()
</code></pre>
<p><a href="https://i.stack.imgur.com/0TpM7.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/0TpM7.png" alt="enter image description here"/></a></p>
<p>音调仍然是10。你知道吗</p>