带通滤波器的设计matlab双线性变换法切比雪夫法

1、close allclearAp=1;As=50;fs=15000;%带通到低通的频率变换Wp1=4.5*pi*1000; Wp2=9*pi*1000;Ws1=1.5*pi*1000; Ws2=12*pi*1000;BW=Wp2-Wp1;柩通滤波器的通带宽度W0=sqrt(Wp1*Wp2);WP=1; %3一化处理WS=WP*(W0A2-Ws1A2)/(Ws1*BW);以切比雪夫模拟低通原型滤波器设计N,Wn=cheb1ord(WP,WS,Ap,As,s);B1,A1=cheby1(N,Ap,Wn,s);%由模拟低通原型滤波器变换为模拟带通滤波器B2,A2=lp2bp(B1,A1,W0,BW)

2、;h1,w1= freqs(B2,A2);%莫拟带通滤波器幅频特性曲线(dB)subplot(2,2,1);plot(w1/(2*pi),20*log(abs(h1);grid on;xlabel(HZ);ylabel(|H(jw)|.dB);title(模拟带通滤波器幅频特性曲线);%双线性变换：由模拟滤波器向数字滤波器的变换B3,A3=bilinear(B2,A2,fs);%显示传递函数系数disp(分子系数);disp(B3);disp(分母系数);disp(A3);h2,w2=freqz(B3,A3,fs);%数字带通滤波器幅频响应曲线subplot(2,2,2);plot(w2/pi

3、,abs(h2);grid on;xlabel(2*HZ);ylabel(|H(z)|);title(数字带通滤波器幅频特性曲线);瞰字带通滤波器幅频响应曲线(dB)subplot(2,2,3);plot(w2/pi,20*log10(abs(h2);grid on;xlabel(2*fs);ylabel(|H(z)|.dB);title(数字带通滤波器幅频特性曲线);瞰字带通滤波器相频特性曲线(dB)subplot(2,2,4);plot(w2/pi,angle(h2);grid on;xlabel(角频率*pi);ylabel(相位);title(数字带通滤波器相频特性曲线);喔俞入正弦波

4、波验f1=1000;f2=3000;f3=5000;%输入信号的三种频率成分f1=500;f2=3000;f3=5000;%输入信号的三种频率成分n=0:511;t=n/15000;x=sin(2*pi*t*f1)+sin(2*pi*t*f2)+sin(2*pi*t*f3);%输入信号figuresubplot(2,2,1);plot(t*1000,x);axis(0,3.5,-2,2);xlabel(时间ms);ylabel(幅度);title(输入信号)；%绘制输入信号幅频曲线y1=fft(x);fi=(0:length(y1)-1)*fs/length(y1);subplot(2,2,2

5、);plot(fi/fs,abs(y1);axis(0,0.5,0,30);xlabel(输入信号频率);title(输入信号频谱图);%绘制输入信号频谱图y=filter(B3,A3,x);%对输入信号进行滤波subplot(2,2,3);plot(t*1000,y);xlabel(时间ms);ylabel(幅度);axis(0,3.5,-2,2);title(输出信号)；%绘制输出号幅频曲线Y=fft(y);fo=(0:length(Y)-1)*fs/length(Y);subplot(2,2,4);plot(fo/fs,abs(Y);xlabel(输出信号频率);axis(0,0.5,0

6、,30);title(输出信号频谱图);%特性close allclearwp1=0.3*pi;wp2=0.6*pi;wp0=0.45*pi;ws1=0.1*pi;ws2=0.8*pi;Ap=1;As=50; T=1/15000;fs=15000;%带通到低通的频率变换Wp1=(2/T)*tan(wp1/2);Wp2=(2/T)*tan(wp2/2);Ws1=(2/T)*tan(ws1/2);Ws2=(2/T)*tan(ws2/2); Wp=(2/T)*tan(wp0/2);BW=Wp2-Wp1; %带通滤波器的通带宽度W0=sqrt(Wp1*Wp2);WP=1; %归一化处理WS=WP*(W

7、0A2-Ws1A2)/(Ws1*BW);%切比雪夫模拟低通原型滤波器设计N,Wn=cheb1ord(WP ,WS,Ap,As,s);B1,A1=cheby1(N,Ap,Wn,s);%由模拟低通原型滤波器变换为模拟带通滤波器B2,A2=lp2bp(B1,A1,W0,BW);h1,w1= freqs(B2,A2);%模拟带通滤波器幅频特性曲线(dB)subplot(2,2,1);plot(w1/(2*pi),20*log(abs(h1);grid on;xlabel(HZ);ylabel(|H(jw)|.dB);title(模拟带通滤波器幅频特性曲线);% 双线性变换：由模拟滤波器向数字滤波器的变

8、换B3,A3=bilinear(B2,A2,fs);%显示传递函数系数disp(分子系数);disp(B3);disp(分母系数);disp(A3);h2,w2=freqz(B3,A3,fs);绘制输出信号频谱图证滤波器%数字带通滤波器幅频响应曲线subplot(2,2,2);plot(w2/pi,abs(h2);grid on;xlabel(2*HZ);ylabel(|H(z)|);title(数字带通滤波器幅频特性曲线);%数字带通滤波器幅频响应曲线(dB)subplot(2,2,3);plot(w2/pi,20*log10(abs(h2);grid on;xlabel(2*fs);yla

9、bel(|H (z)|.dB);title(数字带通滤波器幅频特性曲线);%数字带通滤波器相频特性曲线(dB)subplot(2,2,4);plot(w2/pi,angle(h2);grid on;xlabel(角频率 *pi);ylabel(相位);title(数字带通滤波器相频特性曲线);%俞入正弦波波验f1=1000;f2=3000;f3=7000;%输入信号的三种频率成分 f1=500;f2=3000;f3=7000;%输入信号的三种频率成分n=0:511;t=n/15000;x=sin(2*pi*t*f1)+sin(2*pi*t*f2)+sin(2*pi*t*f3);%输入信号fig

10、uresubplot(2,2,1);plot(t*1000,x);axis(0,3.5,-2,2);xlabel(时间 ms);ylabel(幅度);title(输入信号);%绘制输入信号幅频曲线y1=fft(x);fi=(0:length(y1)-1)*fs/length(y1);subplot(2,2,2);plot(fi/fs,abs(y1);axis(0,0.5,0,30);xlabel(输入信号频率);title(输入信号频谱图);y=filter(B3,A3,x);%对输入信号进行滤波subplot(2,2,3);plot(t*1000,y);xlabel(时间 ms);ylabel(幅度);axis(0,3.5,-2,2);title(输出信号