Many thanks for you answer!
In order to do A(t)exp(1i*2*pi*fc*t). A(t) has to sampled at fs>=2fc. Please let me know which of followings are right, or both OK.
- make x is (in my code above) sampled at fs=2.1*Fc, and send to collector to get 'receivedsig', and then do receivedsig.*exp(1i*2*pi*fc*t) to get carrier data.
- keep x is the same in the above code. get 'receivedsig' first at low-rate. then do interplation to add points in 'receivedsig' based on ts=1/(2.1*fc), after that, do receivedsig.*exp(1i*2*pi*fc*t)