數(shù)字信號處理綜合設(shè)計

1、數(shù)字信號處理綜合設(shè)計1.語音信號的頻譜分析要求首先畫出語音信號的時域波形;然后對語音信號進行頻譜分析,在MA TLAB中,可以利用函數(shù)fft對信號進行快速付立葉變換,得到信號的頻譜特性;從而加深對頻譜特性的理解。fs=20000; %語音信號采樣頻率為20000x1=wavread('d:lianxi.wav',20000; %讀取語音信號的數(shù)據(jù),賦給變量x1sound(x1,20000; %播放語音信號y1=fft(x1,1024; %對信號做1024點FFT變換f=fs*(0:511/1024;figure(1plot(x1 %做原始語音信號的時域圖形title('

2、原始語音信號'xlabel('time n'ylabel('fuzhi n'figure(2freqz(x1 %繪制原始語音信號的頻率響應(yīng)圖title('頻率響應(yīng)圖'figure(3subplot(2,1,1;plot(abs(y1(1:512 %做原始語音信號的FFT頻譜圖title('原始語音信號FFT頻譜'subplot(2,1,2;plot(f,abs(y1(1:512;title('原始語音信號頻譜'xlabel('Hz'ylabel('fuzhi' 設(shè)計數(shù)字濾波器

3、和畫出頻率響應(yīng)根據(jù)語音信號的特點給出有關(guān)濾波器的性能指標:1低通濾波器性能指標,fp=1000Hz, fc=1200 Hz,As=100dB,Ap=1dB;2高通濾波器性能指標,fc=2800 Hz,fp=3000 Hz As=100dB,Ap=1dB;3帶通濾波器性能指標,fp1=1200 Hz,fp2=3000 Hz,fc1=1000 Hz, fc2=3200 Hz,As=100dB,Ap=1dB。要求學(xué)生首先用窗函數(shù)法設(shè)計上面要求的三種濾波器,在MA TLAB中,可以利用函數(shù)fir1設(shè)計FIR濾波器,然后在用雙線性變換法設(shè)計上面要求的三種濾波器;之后再利用函數(shù)butter和cheby1設(shè)

4、計上面要求的三種IIR濾波器。最后,利用MATLAB中的函數(shù)freqz畫出各濾波器的頻率響應(yīng)。巴特沃思低通1wp=0.1*pi;ws=0.5673*pi;Rp=1;Rs=100;Fs=20000;Ts=1/Fs;wp1=2/Ts*tan(wp/2; %將模擬指標轉(zhuǎn)換成數(shù)字指標ws1=2/Ts*tan(ws/2;N,Wn=buttord(wp1,ws1,Rp,Rs,'s' %選擇濾波器的最小階數(shù)Z,P,K=buttap(N; %創(chuàng)建butterworth模擬濾波器Bap,Aap=zp2tf(Z,P,K;b,a=lp2lp(Bap,Aap,Wn;bz,az=bilinear(b,a

5、,Fs; %用雙線性變換法實現(xiàn)模擬濾波器到數(shù)字濾波器的轉(zhuǎn)換H,W=freqz(bz,az; %繪制頻率響應(yīng)曲線figure(1plot(W*Fs/(2*pi,abs(Hgridxlabel('頻率/Hz'ylabel('頻率響應(yīng)幅度'title('Butterworth'f1=filter(bz,az,x1; 巴特沃思高通2x1=wavread('d:lianxi.wav',20000;t=0:1/20000:(size(x1-1/20000;wp=2*pi*3000;ws=2*pi*1555;Rp=1;Rs=100;Fs=200

6、00;Ts=1/Fs;N,Wn=buttord(wp,ws,Rp,Rs,'s' %選擇濾波器的最小階數(shù)Z,P,K=buttap(N; %創(chuàng)建butterworth模擬濾波器Bap,Aap=zp2tf(Z,P,K;b,a=lp2hp(Bap,Aap,Wn;bz,az=bilinear(b,a,Fs; %用雙線性變換法實現(xiàn)模擬濾波器到數(shù)字濾波器的轉(zhuǎn)換H,W=freqz(bz,az; %繪制頻率響應(yīng)曲線figure(1plot(W*Fs/(2*pi,abs(Hgridxlabel('頻率/Hz'ylabel('頻率響應(yīng)幅度'title('But

7、terworth'f1=filter(bz,az,x1; 巴特沃思帶通3wp=2*pi*1200,3000;ws=2*pi*212,5546;Rp=1;Rs=100;Fs=20000;Ts=1/Fs;N,Wn=buttord(wp,ws,Rp,Rs,'s' %選擇濾波器的最小階數(shù)B,A=butter(N,Wn,'s' %創(chuàng)建buttord模擬濾波器Bz,Az=bilinear(B,A,Fs; %用雙線性變換法實現(xiàn)模擬濾波器到數(shù)字濾波器的轉(zhuǎn)換H,W=freqz(Bz,Az; %繪制頻率響應(yīng)曲線figure(1plot(W*Fs/(2*pi,abs(Hgri

8、dxlabel('頻率/Hz'ylabel('頻率響應(yīng)幅度'title('buttord' 切比雪夫1低通fs=20000;x1=wavread('d:lianxi.wav',20000;t=0:1/20000:(size(x1-1/20000;wp=0.1*pi;ws=0.5673*pi;Rp=1;Rs=100;Fs=20000;Ts=1/Fs;wp1=2/Ts*tan(wp/2; %將模擬指標轉(zhuǎn)換成數(shù)字指標ws1=2/Ts*tan(ws/2;N,Wn=cheb1ord(wp1,ws1,Rp,Rs,'s' %選擇

9、濾波器的最小階數(shù)Z,P,K=cheby1(N,Rp,Wn,'s' %創(chuàng)建cheby1模擬濾波器Bap,Aap=zp2tf(Z,P,K;bz,az=bilinear(Bap,Aap,Fs; %用雙線性變換法實現(xiàn)模擬濾波器到數(shù)字濾波器的轉(zhuǎn)換H,W=freqz(bz,az; %繪制頻率響應(yīng)曲線figure(1plot(W*Fs/(2*pi,abs(Hgridxlabel('頻率/Hz'ylabel('頻率響應(yīng)幅度'title('cheby1'f1=filter(bz,az,x1; 切比雪夫1高通clcclear allfs=20000;

10、x1=wavread('d:lianxi.wav',20000;t=0:1/20000:(size(x1-1/20000;wp=2*pi*3000;ws=2*pi*1500;Rp=1;Rs=100;Fs=20000;Ts=1/Fs;N,Wn=cheb1ord(wp,ws,Rp,Rs,'s' %選擇濾波器的最小階數(shù)Z,P,K=cheb1ap(N,Rp;Wpn=2*pi*3000; %創(chuàng)建cheby1模擬濾波器Bap,Aap=zp2tf(Z,P,K;b,a=lp2hp(Bap,Aap,Wpn;bz,az=bilinear(b,a,Fs; %用雙線性變換法實現(xiàn)模擬濾波

11、器到數(shù)字濾波器的轉(zhuǎn)換H,W=freqz(bz,az; %繪制頻率響應(yīng)曲線figure(1plot(W*Fs/(2*pi,abs(Hgridxlabel('頻率/Hz'ylabel('頻率響應(yīng)幅度'title('cheby1'f1=filter(bz,az,x1; 切比雪夫1帶通wp=2*pi*1200,3000;ws=2*pi*212,5546;Rp=1;Rs=100;Fs=20000;Ts=1/Fs;N,Wn=cheb1ord(wp,ws,Rp,Rs,'s' %選擇濾波器的最小階數(shù)B,A=cheby1(N,Rp,Wn,'

12、s' %創(chuàng)建cheby1模擬濾波器Bz,Az=bilinear(B,A,Fs; %用雙線性變換法實現(xiàn)模擬濾波器到數(shù)字濾波器的轉(zhuǎn)換H,W=freqz(Bz,Az; %繪制頻率響應(yīng)曲線figure(1plot(W*Fs/(2*pi,abs(Hgridxlabel('頻率/Hz'ylabel('頻率響應(yīng)幅度'title('cheby1'f1=filter(Bz,Az,x1; 窗函數(shù)法低通Fs=20000;fp1=1200,fp2=3000,fs1=212,fs2=5546;wp1=2*pi*fp1/Fs,ws1=2*pi*fs1/Fs,wp2=

13、2*pi*fp2/Fs,ws2=2*pi*fs2/Fs,As=100; DB=wp1-ws1;beta=0.112*(As-8.7;M=ceil(As-8/2.285/DBwc=(wp1+ws1/2/pi,(wp2+ws2/2/pi;hn=fir1(M,wc,kaiser(M+1,beta;H,f=freqz(hn,1,1024,Fs;mag=abs(H;db=20*log10(mag+eps/max(mag;figure(1;plot(f/pi/Fs,db;xlabel('f/pi/Fs'ylabel('20logH(ejw'title('h(n的幅頻

14、特性' grid;pha=angle(H;figure(2;plot(f,pha;xlabel('n'ylabel(''title('h(n的相頻特性'figure(3;plot(hn;xlabel('n'ylabel('h(n' 高通Fs=20000;fp=3000,fs=1500;wp=2*pi*fp/Fs,ws=2*pi*fs/Fs,As=100;DB=wp-ws;beta=0.112*(As-8.7;M=ceil(As-8/2.285/DB;wc=(wp+ws/2/pi;hn=fir1(M,wc,&

15、#39;high',kaiser(M+1,beta;H,f=freqz(hn,1,1024,Fs;mag=abs(H;db=20*log10(mag+eps/max(mag;figure(1;plot(f/pi/Fs,db;xlabel('f/pi/Fs'ylabel('20logH(ejw'title('h(n的幅頻特性' grid;pha=angle(H;figure(2;plot(f,pha;xlabel('n'ylabel(''title('h(n的相頻特性'figure(3;plo

16、t(hn;xlabel('n'ylabel('h(n' 帶通Fs=20000;fp1=1200,fp2=3000,fs1=212,fs2=5546;wp1=2*pi*fp1/Fs,ws1=2*pi*fs1/Fs,wp2=2*pi*fp2/Fs,ws2=2*pi*fs2/Fs,As=100; DB=wp1-ws1;beta=0.112*(As-8.7;M=ceil(As-8/2.285/DBwc=(wp1+ws1/2/pi,(wp2+ws2/2/pi;hn=fir1(M,wc,kaiser(M+1,beta;H,f=freqz(hn,1,1024,Fs;mag=a

17、bs(H;db=20*log10(mag+eps/max(mag;figure(1;plot(f/pi/Fs,db;xlabel('f/pi/Fs'ylabel('20logH(ejw'title('h(n的幅頻特性'grid;pha=angle(H;figure(2;plot(f,pha;xlabel('n'ylabel(''title('h(n的相頻特性'figure(3;plot(hn;xlabel('n'ylabel('h(n' 4.用濾波器對信號進行濾波比較

18、FIR和IIR兩種濾波器的性能,然后用性能好的各濾波器分別對采集的信號進行濾波,在MATLAB中, FIR濾波器利用函數(shù)fftfilt對信號進行濾波,IIR濾波器利用函數(shù)filter對信號進行濾波。通過比較巴特沃思性能比較好6.回放語音信號在MATLAB中,函數(shù)sound可以對聲音進行回放。其調(diào)用格式:sound(x,fs,bits;可以感覺濾波前后的聲音有變化。低通:fs=20000;x1=wavread('d:lianxi.wav',20000;t=0:1/20000:(size(x1-1/20000;wp=0.1*pi;ws=0.5673*pi;Rp=1;Rs=100;F

19、s=20000;Ts=1/Fs;wp1=2/Ts*tan(wp/2; %將模擬指標轉(zhuǎn)換成數(shù)字指標ws1=2/Ts*tan(ws/2;N,Wn=buttord(wp1,ws1,Rp,Rs,'s' %選擇濾波器的最小階數(shù)Z,P,K=buttap(N; %創(chuàng)建butterworth模擬濾波器Bap,Aap=zp2tf(Z,P,K;b,a=lp2lp(Bap,Aap,Wn;bz,az=bilinear(b,a,Fs; %用雙線性變換法實現(xiàn)模擬濾波器到數(shù)字濾波器的轉(zhuǎn)換H,W=freqz(bz,az; %繪制頻率響應(yīng)曲線figure(1plot(W*Fs/(2*pi,abs(Hgridxl

20、abel('頻率/Hz'ylabel('頻率響應(yīng)幅度'title('Butterworth'f1=filter(bz,az,x1;figure(2subplot(2,1,1plot(t,x1 %畫出濾波前的時域圖title('濾波前的時域波形'subplot(2,1,2plot(t,f1; %畫出濾波后的時域圖title('濾波后的時域波形'sound(f1,20000; %播放濾波后的信號F0=fft(f1,1024;f=fs*(0:511/1024;figure(3y1=fft(x1,1024;subplot(

21、2,1,1;plot(f,abs(y1(1:512; %畫出濾波前的頻譜圖title('濾波前的頻譜'xlabel('Hz'ylabel('fuzhi'subplot(2,1,2F1=plot(f,abs(F0(1:512; %畫出濾波后的頻譜圖title('濾波后的頻譜'xlabel('Hz'ylabel('fuzhi'圖 聲音略高通:程序fs=20000;x1=wavread('d:lianxi.wav',20000;t=0:1/20000:(size(x1-1/20000;wp

22、=2*pi*3000;ws=2*pi*1555;Rp=1;Rs=100;Fs=20000;Ts=1/Fs;N,Wn=buttord(wp,ws,Rp,Rs,'s' %選擇濾波器的最小階數(shù)Z,P,K=buttap(N; %創(chuàng)建butterworth模擬濾波器Bap,Aap=zp2tf(Z,P,K;b,a=lp2hp(Bap,Aap,Wn;bz,az=bilinear(b,a,Fs; %用雙線性變換法實現(xiàn)模擬濾波器到數(shù)字濾波器的轉(zhuǎn)換H,W=freqz(bz,az; %繪制頻率響應(yīng)曲線figure(1plot(W*Fs/(2*pi,abs(Hgridxlabel('頻率/Hz

23、'ylabel('頻率響應(yīng)幅度'title('Butterworth'f1=filter(bz,az,x1;figure(2subplot(2,1,1plot(t,x1 %畫出濾波前的時域圖title('濾波前的時域波形'subplot(2,1,2plot(t,f1; %畫出濾波后的時域圖title('濾波后的時域波形'sound(f1,20000; %播放濾波后的信號F0=fft(f1,1024;f=fs*(0:511/1024;figure(3y1=fft(x1,1024;subplot(2,1,1;plot(f,abs(y1(1:512; %畫出濾波前的頻譜圖title('濾波前的頻譜'xlabel('Hz'ylabel('fuzhi'subplot(2,1,2F1=plot(f,abs(F0(1:512; %畫出濾波后的頻譜圖title('濾波后的頻譜'xlabel('Hz'ylabel('fuzhi' 帶通:程序fs=20000;