clc;
clear;
close;
t=linspace(0,1,1000);
//f=input('enter the message frequency');
f=1;
m=0.5+0.5*cos(2*%pi*f*t);
subplot(3,1,1);
plot(t,m);

title('message signal');
c=zeros(1,1000);
v=1:100:1000;
for i=1:length(v)
    c(v(i):v(i)+30)=1;
end
subplot(3,1,2);
plot(t,c);

title('carrier pulse');
pam=zeros(1,1000);
for i=1:length(v)
    pam(v(i):v(i)+30)=c(v(i))*m(v(i));
end
subplot(3,1,3);
plot(t,pam);
title('pulse amplitude modulation');

figure;
subplot(4,1,1);
plot(t,m);

title('message signal');
c1=0.5+0.5*cos(2*%pi*10*t);
subplot(4,1,2);
plot(t,c1);

title('carrier signal');
pwm=zeros(1,1000);
for i=1:1000
    if(m(i)>=c1(i))
        pwm(i)=1;
    end
end
subplot(4,1,3);
plot(t,pwm);

title('pulse width modulation');
ppm=zeros(1,1000);j=1;
for i=2:1000
    if(pwm(i-1)==1 & pwm(i)==0)
        s(j)=i;
        j=j+1;
    end
end
for i=1:length(s)
    ppm(s(i):s(i)+25)=1;
end
subplot(4,1,4);
plot(t,ppm);
title('pulse position modulation');