Python科学计算（三）——高低通滤波器的设计与使用

# -*- 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')