巴特沃斯低通滤波器.rar

N=1000; xt=xtg(N); % Wp=0.24*pi;Ws=0.3*pi;Rp=0.1;Rs=60;fs=1000; % [N, Wn] = buttord(Wp, Ws, 0.1, 60, 's'); % [B,A]=butter(N, Wn,'s'); %N阶, Wn ，模拟 % [num1,den1]=impinvar(B,A,1000); % B, A, fs % [h1,w]=freqz(num1,den1); % f=w/pi*500; % subplot(2,1,1) % plot(f, abs(h1)); grid; % xlabel('f/Hz');ylabel('H(z)');title('脉冲响应不变法设计的巴特沃斯低通滤波器') % Results=filter(num1,den1,xt); % subplot(2,1,2) % plot(Results);grid; % xlabel('f/Hz');ylabel('Yw(t)');title('噪声滤除后的信号波形') % wc=2*1000*tan(2*pi*120/(2*1000)); % wr=2*1000*tan(2*pi*150/(2*1000)); % [n,wn]=buttord(wc,wr,0.1,60,'s'); % [B,A]=butter(n,wn,'low','s'); % [num2,den2]=bilinear(B,A,1000); % [h2,w]=freqz(num2,den2); % f=w/pi*500; % % f=(2/pi)*(fs/2); % subplot(2,1,1) % plot(f, abs(h2)); grid; % xlabel('f/Hz');ylabel('H(z)');title('双线性变换法设计的巴特沃斯低通滤波器') % Results=filter(num2,den2,xt); % subplot(2,1,2) % plot(Results);grid; % xlabel('f/Hz');ylabel('Yw(t)');title('噪声滤除后的信号波形') % wc=2*1000*tan(2*pi*120/(2*1000)); % wr=2*1000*tan(2*pi*150/(2*1000)); % [n,wn]=cheb1ord(wc,wr,0.1,60,'s'); % [B,A]=cheby1(n,0.1,wn,'low','s'); % [num2,den2]=bilinear(B,A,1000); % [h2,w]=freqz(num2,den2); % f=w/pi*500; % % f=(2/pi)*(fs/2); % subplot(2,1,1) % plot(f, abs(h2)); grid; % xlabel('f/Hz');ylabel('H(z)');title('双线性变换法设计的切比雪夫低通滤波器') % Results=filter(num2,den2,xt); % subplot(2,1,2) % plot(Results);grid; % xlabel('f/Hz');ylabel('Yw(t)');title('噪声滤除后的信号波形') wc=2*1000*tan(2*pi*120/(2*1000)); wr=2*1000*tan(2*pi*150/(2*1000)); [n,wn]=ellipord(wc,wr,0.1,60,'s'); [B,A]=ellip(n,0.1,60,wn,'low','s'); [num2,den2]=bilinear(B,A,1000); [h2,w]=freqz(num2,den2); f=w/pi*500; % f=(2/pi)*(fs/2); subplot(2,1,1) plot(f, abs(h2)); grid; xlabel('f/Hz');ylabel('H(z)');title('双线性变换法设计的椭圆低通滤波器') Results=filter(num2,den2,xt); subplot(2,1,2) plot(Results);grid; xlabel('f/Hz');ylabel('Yw(t)');title('噪声滤除后的信号波形')