信号与系统实验.pdf

——傅里叶级数及其物理意义。,掌握典型信号的频谱以及傅里叶变换的主要性质。=fourierseries(m,t)%定义傅里叶级数函数表达式%y=1/4;forn=1:my=y+4/(n*n*pi*pi)*(1-cos(n*pi/2)).*cos(n*pi.*t);endend代码如下:t=-6::6;d=-6:2:6;fxx=pulstran(t,d,'tripuls');f1=fourierseries(3,t);f2=fourierseries(9,t);f3=fourierseries(21,t);f4=fourierseries(45,t);subplot(4,1,1)plot(t,fxx,'r',t,f1,'b');gridonaxis([-66-])title('N=3')subplot(4,1,2)plot(t,fxx,'r',t,f2,'b');gridonaxis([-66-])title('N=9')subplot(4,1,3)plot(t,fxx,'r',t,f3,'b');gridonaxis([-66-])title('N=21')subplot(4,1,4)plot(t,fxx,'r',t,f4,'b');gridonaxis([-66-])title('N=45')其单边幅度谱与相位谱代码如下:a=zeros(size(n));a(1)=;forii=2:10a(ii)=abs(4/((ii-1)*(ii-1)*pi*pi)*(1-cos((ii-1)*pi/2)));endsubplot(2,1,1)n=0:pi:9*pistem(n,a,'fill','linewidth',2);axis([0,30,-0,])gridontitle('单边幅度谱')subplot(2,1,2)n=1:10;a=zeros(size(n));fori=1:10a(i)=angle(4/(i*i*pi*pi)*(1-cos(i*pi/2)))endn=0:pi:9*pistem(n,a,'fill','linewidth',2);axis([0,9*pi,-,])gridontitle('单边相位谱')xlabel('\fontsize{14}\bf|?=n|?o\rightarrow')ylabel('\fontsize{14}\bf|·n\rightarrow'):t=-6::6;f=tripuls(t,1);dw=;w=-12*pi::12*pi;F=f*exp(-j*t'*w)*;F1=abs(F);phaF=angle(F);subplot(3,1,1)plot(t,f)axis([-6601])boxonxlabel('t')ylabel('f(t)')title('单个三角脉冲的波形图')subplot(3,1,2)plot(w,F1)gridon;xlabel('\Omega')ylabel('·幅度')title('单个三角脉冲的幅度图')subplot(3,1,3)plot(w,phaF)gridon;xlabel('\Omega')ylabel('相位')title('单个三角脉冲的相位谱'):n=-20:20;F=zeros(size(n));forii=-20:20F(ii+21)=sin(ii*pi/4)/(ii*pi+eps);endF(21)=1/4;F1=abs(F);phaF=angle(F);subplot(2,1,1)stem(n,F1,'fill')title('周期矩形脉冲的幅度谱(|ó/T=1/4)')xlabel('\fontsize{14}\bfn\rightarrow')ylabel('\fontsize{14}\bf|Fn|\rightarrow')subplot(2,1,2)stem(n,phaF,'fill')title('周期矩形脉冲的相位谱(|ó/T=1/4)')xlabel('\fontsize{14}\bfn\rightarrow')ylabel('\fontsize{14}\bf|·n\rightarrow')代码如下:n=-20:20;F=zeros(size(n));forii=-20:20F(ii+21)=sin(ii