IIR.zip_inventedyck_temperature3vd_低通滤波器_工频干扰_数字滤波器

clear all; 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]; figure; subplot(1,2,1); n=0:55; stem(n,x,'.'); axis([0,56,-100,50]); xlabel('n'); ylabel('x(n)'); title('滤波前心电图信号采样序列'); grid on; %通过设计的滤波器的差分方程，对心电图采样序列进行滤波处理 B=[0.09036,0.09036*2,0.09036]; A1=[1,-1.2686,0.7051]; A2=[1,-1.0106,0.3583]; A3=[1,-0.9044,0.2155]; y1=filter(B,A1,x); y2=filter(B,A2,y1); y3=filter(B,A3,y2); subplot(1,2,2); n=0:55; stem(n,y3,'.'); axis([0,56,-100,50]); xlabel('n'); ylabel('y(n)'); grid on; title('滤波后心电图信号采样序列'); %绘制滤波器的幅频响应曲线 m=200; n=0:m-1; [h1,w]=freqz(B,A1,m); [h2,w]=freqz(B,A2,m); [h3,w]=freqz(B,A3,m); h4=h1.*h2.*h3; %h4=h4.*h3; figure; subplot(1,1,1);plot(n/m,abs(h4)); title('幅频响应特性曲线'); xlabel('\omega\\pi'); ylabel('幅度'); grid on ;