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1、正弦信号%绘制连续时间信号的时域波形t=0:0.001:0.2;y=cos(2*pi*10*t);subplot(211);plot(t,y);xlabel('t单位:s','Fontsize',8);title('连续时间信号f(t)cos(20*pi*t)');%绘制抽样后的时域信号subplot(212);plot(t,y,'b:');holdon;t2=cos(2*pi*10*t2);stem(t2,y2,’filled’);xlabel('t单位:s','Fontsize',8);title('抽样信号fs(t)');
2、holdoff;图形周期矩形脉冲信号%绘制周期方波信号t=0:0.01:100;y=square(t);subplot(311);plot(t,y);axis([0,10,-3,3]);title('周期方波信号');%绘制抽样后的方波信号subplot(312);plot(t,y,'b:');holdon;t2=0:1/100:0.01;y2=square(t2);stem(t2,y2);axis([0,10,-3,3]);title('抽样信号fs(t)');holdoff;图形f1=[3,2,1,1,1,2];k1=-3:
3、2;f2=0:5;k2=-1:4;f1=[3,2,1,1,1,2];k1=-3:2;f2=0:5;k2=-1:4;k=min(min(k1),min(k2)):max(max(max(k1),max(k2));s1=zeros(1,length(k));s2=s1;i1=find((k>=min(k1))&(k<=max(k1))==1)s1(i1)=f1i2=find((k>=min(k2))&(k<=max(k2))==1)s2(i2)=f2N=64;n=0:1:N-1;x=randn(1,n);k=0:1:N-1;y=x*
4、(exp(-j*pi/N)).^(n'*k);subplot(3,1,1);stem(n,x,'filled');title('ʱÓò');subplot(3,1,2);stem(k,abs(y));title('·ùÖµ');subplot(3,1,3);stem(k,angle(y));title('Ïàλ');混叠%绘制连续时间信号的时域波形t=0:0.001:40;y=cos(2/3*pi*t);subplot(121);plot(t,y);axis([06-1.11.1])xlabel('t单位:s','Fonts
5、ize',8);title('连续时间信号f(t)');line([06],[00],'color',[000]);%绘制频谱N=300;W=2*pi*10;k=-N:N;w=-k*W/N;Y=0.01*y*exp(-j*t*w);Y=abs(Y);subplot(122);plot(w/pi,Y);axis([-2.5,2.5,0,pi*7+0.2]);title('连续信号频谱');xlabel('omega单位:pi');%采样display('pleaseinputthevalueofsampleperiod');Ts
6、=input('Ts=');%绘制采样后时域信号subplot(121);plot(t,y,'b:');holdon;t2=0:Ts:40;y2=cos(2/3*pi*t2);stem(t2,y2);axis([06-1.11.1]);xlabel('t单位:s','Fontsize',8);title('fs(t)');holdoff;%绘制采样后时域信号频谱Y2=Ts*y2*exp(-j*t2'*w);Y2=1/Ts*abs(Y2);subplot(122);plot(w/pi,Y,'b:');xlabel('omega单
7、位:pi');title('采样后频谱');holdon;plot(w/pi,Y2,'r');axis([-2.5,2.5,0,pi10]);holdoff;整数倍抽取t=0:0.00021:1;x=cos(2*pi*30*t);y=decimate(x,4);subplot(121);stem(x(1:120)),axis([0120-22]);title('元信号');subplot(122);stem(y(1:30));title('后信号');泄露n1=input('n1=');n2=input('n2=');n3=n1
8、:n2;k1=length(n3);x1=zeros(1,k);x1(1,-n1+1)=1;subplot(511)x2=ones(1,k1);x2(1,1:n2)=0;subplot(512);stem(n3,x2,'filled');title('窗函数')
