1、实验三 傅立叶变换与分析信工程序设计实验：%信号一 r=0.02;t=-5:r:5;n=500;k=-n:n;w=k*2*pi/n;f=exp(-3*t).*stepfun(t,0);F=f*exp(-j*t*w)*r;F1=abs(F);P1=angle(F);subplot(3,2,1);plot(t,f);grid;xlabel(t);ylabel(f);title(f(t)=e-3t*u(t);subplot(3,2,2);plot(w,F1);grid;xlabel(w);ylabel(幅频特性曲线 );subplot(3,2,3);plot(w,P1*180/pi);grid;xl
2、abel(w);ylabel(相频特性曲线 );%信号二r=0.02;t=-5:r:5;n=500;k=-n:n;w=k*2*pi/n;f=exp(-3*(t-4).*stepfun(t,4);F=f*exp(-j*t*w)*r;F1=abs(F);P1=angle(F);subplot(3,2,4);plot(t,f);grid;xlabel(t);ylabel(f);title(f(t-4);subplot(3,2,5);plot(w,F1);grid;xlabel(w);ylabel(幅频特性曲线 );subplot(3,2,6);plot(w,P1);xlabel(w);ylabel(相频特性曲线 );%信号三r=0.02;t=-2:r:2;n=500;k=-n:n;w=k*2*pi/n;f1=exp(-3*t).*stepfun(t,0);f=f1.*exp(-j*4*t);F=f*exp(-j*t*w)*r;F1=real(F);subplot(2,2,1);plot(t,f);xlabel(t);ylabel(f(t);title(f(t)*e-j*4*t);subplot(2,2,2);plot(w,F1);xlabel(w);ylabel(F(jw);title(频谱 F(jw);信号一截图：信号二截图：信号三截图：
