四川大学信号与系统实验报告

1、四川大学信号与系统实验报告实验报告课程名称信号与系统实验名称信号与lti系统的时频域分析实验时间2017年6月15日学院电子信息学院指导教师周新志学生姓名班级学号学院(系)电子信息学院专业信息安全 实验报告 （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);%计算序列f1与f2的卷积和fk

2、0=k1(1)+n(1);%计算序列f非零样值的起点位置k3=length(x1)+length(h1)-2;%计算卷积和f的非零样值的宽度k=k0:k0+k3;%确定卷积和f非零样值的序号向量subplot(2,2,1);stem(k,y1);title(x1n与h1n的卷积和y1n);xlabel(k);ylabel(y1k);x2=cos(1.25*pi*n);y2=conv(h1,x2);subplot(2,2,2);stem(k,y2);title(x2n与h1n的卷积和y2n); xlabel(k); ylabel(y2k);x3=x1+x2;y3=conv(h1,x3);subp

3、lot(2,2,3);stem(k,y3);title(x3n与h1n的卷积和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);%计算序列f1与f2的卷积和fk0=k1(1)+n(1); %计算序列f非零样值的起点位置k3=len

4、gth(x1)+length(h2)-2; %计算卷积和f的非零样值的宽度k=k0:k0+k3; %确定卷积和f非零样值的序号向量subplot(2,2,1);stem(k,y1);title(x1n与h2n的卷积和y1n);xlabel(k);ylabel(y1k);x2=cos(1.25*pi*n);y2=conv(h2,x2);subplot(2,2,2);stem(k,y2);title(x2n与h2n的卷积和y2n);xlabel(k); ylabel(y2k); x3=x1+x2;y3=conv(h2,x3);subplot(2,2,3);stem(k,y3);title(x3n与

5、h2n的卷积和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(幅值频谱);xlabel(频率(hz);ylabel(幅值);subplot(2,1,2); plot(f,angle(x1); title(相位频谱); xlabel(频率(hz); ylabel(相位); figure; subplot(2,1,1);plot(f,abs(x2); title(幅值频谱); xlabel(频率(hz); ylabel(幅值); subplot(2,1,2);plot(f,angle(x2); title(相位频谱); xlabel(频率(hz); ylabel(相位); figure;subplot(2,1,1);plot(f,abs(x3); title(幅值频谱); xlabel(频率(hz);