IIR和FIR滤波器_滤波器_基于matlab的熟悉滤波器设计_IIR数字滤波器_FIRIIR_fir_

clear all; clc wp=0.2*pi;ws=0.3*pi;Rp=1;As=15; wp=2*tan(wp/2);ws=2*tan(ws/2); [N,wn]=buttord(wp,ws,Rp,As,'s'); [B,A]=butter(N,wn,'s'); %离散化处理 [num,den]=bilinear(B,A,1);%双线性 [h,w]=freqz(num,den); figure(1) plot(w/pi,20*log10(abs(h)/(max(h)))); %绘制滤波器幅频特性 grid on; xlabel('w/Π'); ylabel('幅度(dB)');%显示网格线，给出横纵坐标标识 %原始心电图信号 xn1=[-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,... -2,-4,-2,0,-2,-4,-4,2,0,0,-2,-4,-2,0,0,-2,-4,-2,0,0,-4,-4,-2,-2,-4,-6,-6,-4,-4,8,-10,-8,... -6,-6,-8,-12,-10,-8,-8,-10,-12,-10,-8,-8,-10,-10,-8,-6,-6,-8,-8,-4,-2,-4,-4,-4,... 0,0,-2,-4,-2,-2,0,-4]; n=0:length(xn1)-1; figure(2); plot(n,xn1); title('原始心电信号时域波形'); grid on; figure(3); plot(n,abs(fft(xn1))); title('原始心电信号频谱'); grid on; y=filter(num,den,xn1); figure(4) plot(n,y); title('IIR滤波器滤波后心电信号'); grid on; figure(5); plot(n,abs(fft(y))); title('IIR滤波器滤波后信号心电频谱'); grid on; %采用矩形窗设计 wp=0.2*pi; ws=0.3*pi; As=15; wn=boxcar(18);%计算后N取18 N=18; nn=0:N-1; alfa=(N-1)/2; hd=sin(0.25*pi*(nn-alfa))./(pi*(nn-alfa)); h=hd.*wn'; [h1,w1]=freqz(h,1); figure(6); plot(w1/pi,20*log10(abs(h1))); title('fir滤波器'); grid on; xlabel('归一化频率/p'); ylabel('幅度/dB') % y1=filter(h,1,xn1); figure(7); plot(y1); title('fir滤波器滤波后心电信号'); grid on; figure(8); plot(0:length(y1)-1,abs(fft(y1))); title('fir滤波器滤波后信号心电频谱'); grid on;