Problem: The Ts is very big(.07),T0 itself is 1/13 =.076.There are not many steps generating to plot an accurate graph. Fix: Ts can be decreased ,inorder to increase the number of steps and we can get a better graph.Let Ts= .07/50.
F0 =13;
T0 =1/F0;
Ts = 0.07/50;
t = 0:Ts:13*T0;
x = real(exp(j*(2*pi*F0*t-pi/2)));
plot(t,x)
