matlab 2009 10 22 01

% program file lab2009102201.m
clear all;
clf;
dt = 0.001;
t =-0:dt:0.1;
s = 5+4*cos(2*pi*20*t);
xc1 = cos(2*pi*200*t);
x1 = s.*xc1;

xc2 = cos(2*pi*700*t);
x2 = s.*xc2;

figure(1);
subplot(311);
plot(t,s,'x');grid;hold on;
plot(t,xc1,'g');

subplot(312);
plot(t,x1);

subplot(313);
plot(t,x2);