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[bt,at]=butter(N,Wc,'s') [bd,ad ]=bilinear(bt,at,1/T)

%数字滤波器的频率响应 [hd,wd]=freqz(bd,ad,60); %画图 figure(1);

plot(wd/pi,abs(hd)),grid; axis([0,1,0,1])

xlabel('w/pi');ylabel('abs(h)')%定义X轴与Y轴的标称含义 title('数滤波器的频率响应')%定义图形名称

n=[1:56];%输入系列的长度

x=[-4,-2,0,-4,-6,-4,-2,-4,-6,-6,-4,-4,-6,-6,-2,6,12,8,0,-16,-38,-60,-84,-90,66,-32,-4,-2,-4,8,12,12,10,6,6,6,4,0,0,0,0,0,-2,-4,0,0,0,-2,-2,0,0,-2,-2,-2,-2,0] ; (3) 用所设计的滤波器对实际心电图信号抽样序列（在本实验后面给出）进行仿

真滤波处理，并分别打印出滤波前后的心电图信号波形图，观察总结滤波作

可编辑

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用与效果。 时域

可编辑

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频域

可编辑

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可编辑

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程序代码： wp=0.2*pi; ws=0.3*pi; Ap=1; As=15; T=1;

WP=(2/T)*tan(wp/2); WS=(2/T)*tan(ws/2);

[N,Wc]= buttord(WP,WS,Ap,As,'s'); [bt,at]=butter(N,Wc,'s') [bd,ad ]=bilinear(bt,at,1/T) [hd,wd]=freqz(bd,ad,n); n=[1:56];%输入系列的长度

x=[-4, -2, 0, -4, -6, -4, -2, -4, -6, -6,-4, -4, -6, -6, -2, 12, 8, 0, -16,-38,-60, -84, -90, -66, -32, -4, -2, -4, 8,12, 12, 10, 6, 6, 4, 0, 0, 0,0, 0, -2, -4, 0, 0, 0, -2, -2, 0,0, 可编辑

6, 6, -2,