s12.m

数字信号处理的MATLAB仿真加实验指导

%a09.m
n=[0:1:99];x=cos(0.48*pi*n)+cos(0.52*pi*n);
n1=[0:1:9];y1=x(1:1:10);
subplot(3,2,1);stem(n1,y1);title('信号x(n),0<=n<=9');
axis([0,10,-2.5,2.5]);text(10.2,-2.5,'n')
Y1=dft(y1,10);magY1=abs(Y1(1:1:6));
k1=0:1:5;w1=2*pi/10*k1;
subplot(3,2,2);stem(w1/pi,magY1);title('DFT幅度');
axis([0,1,0,10]);text(1.05,0,'w')
xlabel('以pi为单位的频率')
n2=[0:1:99];y2=[x(1:1:10)zeros(1,90)];
subplot(3,2,3);stem(n2,y2);
title('信号x(n),0<=n<=9+90zeros');
axis([0,100,-2.5,2.5]);text(100.5,-2.5,'n')
Y2=dft(y2,100);magY2=abs(Y2(1:1:51));
k2=0:1:50;w2=2*pi/100*k2;
subplot(3,2,4);stem(w2/pi,magY2);title('DFT幅度');
axis([0,1,0,10]);text(1.05,0,'w')
xlabel('以pi为单位的频率')
subplot(3,2,5);stem(n,x);
title('信号x(n),0<=n<=99');
axis([0,100,-2.5,2.5]);text(100.5,-2.5,'n')
Y3=dft(x,100);magY3=abs(Y3(1:1:51));
k3=0:1:50;w3=2*pi/100*k3;
subplot(3,2,6);stem(w3/pi,magY3);title('DFT幅度');
axis([0,1,0,60]);text(1.05,0,'w')
xlabel('以pi为单位的频率')