x=linspace(0,2*pi,1000);
y=1*sin(2*pi*x);
figure;
subplot(3,1,1);
plot(y);
z=4*sin(2*pi*x*10);
subplot(3,1,2);
plot(z);
m=1;
a=m*cos(2*pi*10*x);
n=awgn(a,1/2);
d=amdemod(z,10,100);
figure;
subplot(5,1,1),plot(x,y);
title('modulating signal');
xlabel('time');
ylabel('amplitude');
subplot(5,1,2),plot(x,z);
title('carrier signal');
xlabel('time');
ylabel('amplitude');
subplot(5,1,3),plot(x,a);
title('modulated signal without noise');
xlabel('time');
ylabel('amplitude');
subplot(5,1,4),plot(x,n);
title('modulated signal with noise');
xlabel('time');
ylabel('amplitude');
subplot(5,1,5),plot(x,d);
title('dmodulated signal');
xlabel('time');
ylabel('amplitude');
figure(2);
freqz(a);
m=abs((fft(a)));
figure;
plot(m);