试验三周期信号的傅里叶级数分析及MATLAB实现

1、实验三周期信号的傅里叶级数分析及 MATLA欧现一、实验目的：.利用MATLA殴现周期信号的分解与合成，并图示仿真结果；.用MATLA映现周期信号的频谱，画图观察和分析周期信号的频谱；.通过MATLAB寸周期信号频谱的仿真，进一步加深对周期信号频谱理论知识的 理解。二、实验内容9.1 (a):程序：display(Please input the value of m傅里叶级数展开项数);m=input(m=);t=-3*pi:0.01:3*pi;n=round(length(t)/4);f=cos(t).*(heaviside(t+2.5*pi)-heaviside(t+1.5*pi)+he

2、aviside(t+0.5*pi)-heaviside(t-0.5*pi)+heaviside(t-1.5*pi)-heaviside(t-2.5*pi);y=zeros(m+1,max(size(t);y(m+1,:)=f;figure(1);plot(t/pi,y(m+1,:);grid;axis(-3 3 -1 1.5);title(半波余弦)；xlabel(单位：pi,Fontsize,8);x=zeros(size(t);kk=1;syms tx nT=2*pi;fx=sym(cos(tx);Nn=30;An=zeros(m+1,1);Bn=zeros(m+1,1);a0=2*int

3、(fx,tx,-T/4,T/4)/Tan=2*int(fx*cos(2*pi*(n+eps/2)*tx/T),tx,-T/4,T/4)/Tbn=2*int(fx*sin(2*pi*(n+eps/2)*tx/T),tx,-T/4,T/4)/TAn(1)=double(vpa(a0,Nn);An(2)=0.5;for k=2:mAn(k+1)=double(vpa(subs(an,n,k),Nn);Bn(k+1)=double(vpa(subs(bn,n,k),Nn);endy(1,:)=1/pi;y(2,:)=1/pi+1/2*cos(t);x=1/pi+1/2*cos(t);for k=2:6

4、pause;x=x+(-2*cos(pi*k/2)/pi/(kA2-1)*cos(k*t);y(k+1),:)=x;plot(t/pi,y(m+1,:);hold on;plot(t/pi,y(k+1),:);hold off;grid;axis(-3 3 -1 1.5);title(strcat(第,kk,次谐波叠加)；xlabel(单位:pi,Fontsize,8);kk=strcat(kk,、,num2str(k);endpause;plot(t/pi,y(m+1,:);grid;axis(-3 3 -1 1.5);title(谐波叠加)；xlabel(单位：pi,Fontsize,8)

5、;a0 =2/pian =162259276829213363391578010288128*(-sin(9007199254740991/1801439850948 1984*pi)*cos(1/2*pi*n)+cos(9007199254740991/18014398509481984*pi)*sin(1/2* pi*n)/(-81129638414606681695789005144063+18014398509481984*n+81129638 414606681695789005144064*nA2)/pi bn =013回区igure 19.3:display( Please in

6、put the value of T,tao and Nf);T=input( T=); tao=input( tao= );Nf=input( Nf=); syms xnk Nn=32;An=zeros(Nf+1,1);Bn=zeros(Nf+1,1); f=x/tao;a0=2*int(f,x,0,tao)/T;an=2*int(f*cos(n*x),x,0,tao)/T;bn=2*int(f*sin(n*x),x,0,tao)/T;An(1)=double(vpa(a0,Nn); for k=1:NfAn(k+1)=double(vpa(subs(an,n,k),Nn);Bn(k+1)=

7、double(vpa(subs(bn,n,k),Nn); end cn=sqrt(An.*An+Bn.*Bn);m=0:Nf; stem(m,cn); hold on ; plot(m,cn);xlabel(幅度谱 omega , Fontsize ,8)Please input the value of T,tao and NfT=10tao=2Nf=30Please input the value of T,tao and NfT=50tao=2Nf=30Please input the value of T,tao and NfT=100tao=2Nf=30Please input the value of T,tao and NfT=10tao=1Nf=30Please input the value of T,tao and NfT=10tao=3Nf=30Please input the value of T,tao an