巴特沃斯带阻数字滤波器设计matlab程序及仿真图 - 副本

1、fs=15000;T= 1/fs; rp=1;rs=40;wp1=0.11*pi;wp2=0.81*pi;ws1=0.31*pi;ws2=0.61*pi;%数字带阻滤波器技术指标wc1=(2/T)*tan(wp1/2);%频率预畸变wc2=(2/T)*tan(wp2/2);wr1=(2/T)*tan(ws1/2);wr2=(2/T)*tan(ws2/2); w0=sqrt(wc1*wc2);B=wc2-wc1;wp=1;%归一化通带截止频率ws=wp*(wr1*B) / (w02-wr12)归一化阻带截止频率N,wc=buttord(wp,ws,rp,rs,s)%3dB 设 计 模 拟 低 通

2、 滤 波 器 将零极点形式转换为传输函数形式M,N=lp2bs(Md,Nd,w0,B)%对低通滤波器进行频率变换，转换为带阻滤波器h,w=freqs(M,N);%模拟带阻滤波器的幅频响应plot(w/(2*pi),abs(h);grid;xlabel(频率 Hz);ylabel(幅度);title(模拟带阻滤波器); b,a=bilinear(M,N,15000)%对模拟滤波器双线性变换figure(1);freqz(b,a);H,W=freqz(b,a);%绘出频率响应；axis(0,1,-100,20);figure(2); plot(W*fs/(2*pi),abs(H);grid on;

3、 xlabel(频率/Hz);ylabel(幅值);n=0:199;t=n/fs; x=sin(2*pi*400*t)+3*sin(2*pi*3000*t)+2*sin(2*pi*5000*t); figure(3);subplot(311);plot(t,x);axis(0,0.01,-5,5); title(输入信号);grid on;y=filter(b,a,x);subplot(312);stem(y,.);title(输出序列);grid on;ya=y*sinc(fs*(ones(length(n),1)*t-(n/fs)*ones(1,length(t);subplot(313)

4、;plot(t,ya);axis(0,0.01,-3,3);title(输出波形);grid on; t=(0:100)/fs;figure(4) fs=1.5*10000;n=(0:100)/fs; f=sin(2*pi*400*t)+3*sin(2*pi*3000*t)+2*sin(2*pi*5000*t); y=fftfilt(b,x);H1,f1=freqz(f,1);H2,f2=freqz(y,1); f1=f1/pi*fs/2; f2=f2/pi*fs/2;););e)d sue于ut ei rnMatlabg0g ea-50dM (-10000. 01 . 02 . 03 . 0

5、4 . 05 . 06 . 07 . 08 .1 9Normalr iazde/ dsae20200400600800s-amrlqeu-h-P0000. 01 .02 . 03. 04 . 05. 06 . 07 .08 .19Normalr ia zd e/dsa Fmrpelqeu1.41.210.8值幅0.60.40.20010002000300040005000600070008000频率/Hz输入信号50-500.0010.0020.0030.0040.0050.0060.0070.008输出序列0.0120-2020406080100输出波形12014016018020020-220015010000.0010.0020.0030.0040.0050.0060.0070.0080.0090.01输入信号的频谱500010002000300040005000600070008000输出信号的频谱3020100010002000300040005000600070008000N =4wc =1.7947b =0.01860.0186a =1.00000.0762-0.