我正在努力为扬声器编写交叉滤波器。此函数旨在创建一个虚拟输入信号,然后可以对其进行滤波,但是当我在调用该函数时更改频率和顺序时,它将不再在图表上正确绘制滤波后的频率。
在 scipy 网站上,他们说建议在过滤时使用二阶部分格式,以避免传递函数(ba)格式出现数字错误,但我现在不确定这是最好的解决方案,或者我在这里忽略了一个简单的错误.
看:
sosfilt:https ://docs.scipy.org/doc/scipy/reference/generated/scipy.signal.sosfilt.html#scipy.signal.sosfilt
黄油: https ://docs.scipy.org/doc/scipy/reference/generated/scipy.signal.butter.html#scipy.signal.butter
更新 - 这似乎发生在更高的频率(我使用 3000 Hz 截止)与 .butter、.sosfilt 和 .irrfilter、.lfilter 命令
from scipy.signal import butter, sosfilt
import matplotlib.pyplot as plt
import numpy as np
def demo(f_s=1000,fc=15,fmin=10,fmax=20,n=10,nf=2):
# demo filtered signal
t = np.linspace(0,(15/fc),f_s,False) # sample size should give roughly ten peaks
# generate signal
inputf = np.linspace(fmin,fmax,nf)
# starts off with only the two frequencies,
# can add more to check how the filter will respond
sig = 0
for i in inputf:
sig += np.sin(2*np.pi*i*t)
# returns the filtered signal over a given time
fig, (ax1, ax2) = plt.subplots(2, 1, sharex=True)
ax1.plot(t, sig)
ax1.set_title('Initail sinusoidial signal from {} to {} Hz'.format(fmin,fmax))
ax1.axis([0, (15/fc), -nf, nf])
sosh = butter(n, fc, 'hp', fs=f_s, output='sos') #highpass
sosl = butter(n, fc, 'lp', fs=f_s, output='sos') #lowpass
filteredh = sosfilt(sosh, sig) #filtered high-pass
filteredl = sosfilt(sosl, sig) #filtered low-pass
ax2.plot(t, filteredh) # visualised high-pass signal
ax2.plot(t, filteredl) # visualised low-pass signal
ax2.set_title('After {} Hz Cut-off (high and low)-pass filter'.format(fc))
ax2.axis([0, (15/fc), -nf, nf])
ax2.set_xlabel('Time [seconds]')
plt.tight_layout()
plt.show()
demo()