四川大學(xué)信號與系統(tǒng)實驗報告

1、四川大學(xué)信號與系統(tǒng)實驗報告實驗報告課程名稱信號與系統(tǒng)實驗名稱信號與lti系統(tǒng)的時頻域分析實驗時間2017年6月15日學(xué)院電子信息學(xué)院指導(dǎo)教師周新志學(xué)生姓名班級學(xué)號學(xué)院(系)電子信息學(xué)院專業(yè)信息安全 實驗報告 （2）aclear;h1=0.0031,0.0044,-0.0031,-0.0272,-0.0346,0.0374,0.1921,0.3279,0.3279,0.192 1,0.0374,-0.0346,-0.0272,-0.0031,0.0044,0.0031;k1=0:15;n=-4:4;x1=cos(0.25*pi*n);y1=conv(h1,x1);%計算序列f1與f2的卷積和fk

2、0=k1(1)+n(1);%計算序列f非零樣值的起點位置k3=length(x1)+length(h1)-2;%計算卷積和f的非零樣值的寬度k=k0:k0+k3;%確定卷積和f非零樣值的序號向量subplot(2,2,1);stem(k,y1);title(x1n與h1n的卷積和y1n);xlabel(k);ylabel(y1k);x2=cos(1.25*pi*n);y2=conv(h1,x2);subplot(2,2,2);stem(k,y2);title(x2n與h1n的卷積和y2n); xlabel(k); ylabel(y2k);x3=x1+x2;y3=conv(h1,x3);subp

3、lot(2,2,3);stem(k,y3);title(x3n與h1n的卷積和y3n);xlabel(k);ylabel(y3k);b.clear;h2=-0.0238,0.0562,-0.0575,-0.1302,0.5252, -0.6842,-0.3129,5.6197,5.6197, -0.3129,-0.6842,0.5252,-0.1302,-0.0575,0.0562,-0.0238;k1=0:15;n=-4:4;x1=cos(0.25*pi*n);y1=conv(h2,x1);%計算序列f1與f2的卷積和fk0=k1(1)+n(1); %計算序列f非零樣值的起點位置k3=len

4、gth(x1)+length(h2)-2; %計算卷積和f的非零樣值的寬度k=k0:k0+k3; %確定卷積和f非零樣值的序號向量subplot(2,2,1);stem(k,y1);title(x1n與h2n的卷積和y1n);xlabel(k);ylabel(y1k);x2=cos(1.25*pi*n);y2=conv(h2,x2);subplot(2,2,2);stem(k,y2);title(x2n與h2n的卷積和y2n);xlabel(k); ylabel(y2k); x3=x1+x2;y3=conv(h2,x3);subplot(2,2,3);stem(k,y3);title(x3n與

5、h2n的卷積和y3n); xlabel(k);ylabel(y3k);3.(a)fs=128;t=1/fs;l=256;n=0:1:l-1;x1=cos(0.25*pi*n);x2=cos(1.25*pi*n);x3=x2+x1;n = 2nextpow2(l);x1=fft(x1,n)/n*2;x2=fft(x2,n)/n*2;x3=fft(x3,n)/n*2;f=fs/n*(0:1:n-1);figure;subplot(2,1,1);plot(f,abs(x1);title(幅值頻譜);xlabel(頻率(hz);ylabel(幅值);subplot(2,1,2); plot(f,angle(x1); title(相位頻譜); xlabel(頻率(hz); ylabel(相位); figure; subplot(2,1,1);plot(f,abs(x2); title(幅值頻譜); xlabel(頻率(hz); ylabel(幅值); subplot(2,1,2);plot(f,angle(x2); title(相位頻譜); xlabel(頻率(hz); ylabel(相位); figure;subplot(2,1,1);plot(f,abs(x3); title(幅值頻譜); xlabel(頻率(hz);