Python科学计算——高低通滤波器的设计与使用

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总结：先划分窗口，再对每个窗口做高通滤波。不用先滤波再划分。

以下转载自 http://blog.csdn.net/thoughts_storms/article/details/32318921

用Python实现对一段简单的正弦叠加信号进行高、低通滤波

# -*- coding: utf-8 -*-      from scipy import signal  import numpy as np  import matplotlib.pyplot as pl  import matplotlib  import math    N = 500  fs = 5  n = [2*math.pi*fs*t/N for t in range(N)]  axis_x = np.linspace(0,1,num=N)  #设置字体文件，否则不能显示中文  myfont = matplotlib.font_manager.FontProperties(fname='c:\\windows\\fonts\\fzshjw_0.ttf')    #频率为5Hz的正弦信号  x = [math.sin(i) for i in n]  pl.subplot(221)  pl.plot(axis_x,x)  pl.title(u'5Hz的正弦信号', fontproperties=myfont)  pl.axis('tight')    xx = []  x1 = [math.sin(i*10) for i in n]  for i in range(len(x)):      xx.append(x[i] + x1[i])     pl.subplot(222)  pl.plot(axis_x,xx)  pl.title(u'5Hz与50Hz的正弦叠加信号', fontproperties=myfont)  pl.axis('tight')    b,a = signal.butter(3,0.08,'low')  sf = signal.filtfilt(b,a,xx)    pl.subplot(223)  pl.plot(axis_x,sf)  pl.title(u'低通滤波后', fontproperties=myfont)  pl.axis('tight')    b,a = signal.butter(3,0.10,'high')  sf = signal.filtfilt(b,a,xx)    pl.subplot(224)  pl.plot(axis_x,sf)  pl.title(u'高通滤波后', fontproperties=myfont)  pl.axis('tight')

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