t=-1:0.01:3; 
m=zeros(size(t)); 
for i=1:length(t) 
if (t(i)>=0.1)&(t(i)<1) 
m(i)=t(i); 
elseif (t(i)>1)&(t(i)<=1.9) 
m(i)=-t(i)+2; 
else 
m(i)=0; 
end 
end 
subplot(131);
plot(t,m,'b') 
grid on
ts=0.001;
t0=0:ts:0.4;
fc=50;
fs=1/ts;
x=amod(m,fc,fs,'amssb');
subplot(132);
plot(t0,x,'r')                                                                                                 
t1=0:ts:.4;
z=ademodce(x,fs,'amssb');
subplot(133);
plot(t1,z,'r')