汉宁窗设计FIR带通滤波器.docx

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1、t=0:1/2000:1;noise=3*randn(size(t));sig1=[1+0.8*sin(2*pi*5*t)+0.7*sin(2*pi*10*t)];sig2=[10*sin(2*pi*185*t+0.4*pi)+5*sin(2*pi*370*t+0.7*pi)];sig=sig1.*sig2;noisesig=sig+noise;%plot(z);ws1=0.13*pi;wp1=0.15*pi;As=44;wp2=0.4*pi;ws2=0.42*pi;Rp=1;wp=[wp1,wp

2、2];ws=[ws1ws2];delta_w=wp1-ws1;no=ceil(8*pi/delta_w);N=no+mod(no+1,2);windows=(hanning(N))';wc1=(ws1+wp1)/2;wc2=(ws2+wp2)/2;hd=ideal_lp(wc2,N)-ideal_lp(wc1,N);b=hd.*windows;[H,w]=freqz(b,1);dbH=20*log(abs(H)+eps)/max(abs(H));subplot(2,2,1);plot(w/pi,d

3、bH);subplot(2,2,2);plot(w/pi,abs(H)/pi);newsig=filter(b,1,noisesig);sig1=fft(sig,512);noisesig1=fft(noisesig,512);w=2*[0:511]/512;figure(2);subplot(3,2,1);plot(t,sig);subplot(3,2,2);plot(w,20*log10(abs(sig1)));subplot(3,2,3);plot(t,noisesig);subplot(3

4、,2,4);plot(w,20*log10(abs(noisesig1)));subplot(3,2,5);plot(t,newsig);t=0.1:1/2000:1;newsig1=fft(newsig,512);subplot(3,2,6);plot(w,20*log10(abs(newsig1)));