How to sample a transfer function (angular spectrum) in the frequency domain?

1. How do you get transfer function in FFT?
2. How can we convert our transfer functions from the Laplace domain to the frequency domain?

How do you get transfer function in FFT?

Let A(f) and B(f) be the FFT's from a(t) respectively b(t). Then you're supposed to take the inverse FFT from B(f)/A(f). It will result in an array of real values that identifies the transfer function with respect to time.

How can we convert our transfer functions from the Laplace domain to the frequency domain?

The Laplace transform can be viewed as an extension of the Fourier transform where complex frequency s is used instead of imaginary frequency jω. Considering this, it is easy to convert from the Laplace domain to the frequency domain by substituting jω for s in the Laplace transfer functions.