Synchronous Demodulation

At the other end of the transmission channel, to recover the original signal, we

can use synchronous demodulation:

a) Multiply g(x) by another factor of

> h:=x -> g(x)*cos(30*x);

The Fourier transform of this new function h(x) now consists of three superposed copies of the

transform of f:

> FTRh := omega->evalf(int(h(x)*cos(omega*x),x=0..4));

> FTIh := omega->evalf(int(h(x)*sin(omega*x),x=0..4));

> FPSh := omega->sqrt(FTRh(omega)^2+FTIh(omega)^2);

> plot(FPSh(omega),omega=-80..80,numpoints=300);

>