Fourier Transform of a Pulse Train (Frequency Comb Simulation)
Let us first see the theory.  By pulse train I guess you mean a periodic function from minus infinity to plus infinity.  Your pulse train will have the Fourier series(FS) in stead of Fourier transform(FT).  Fortunately the FT of a single pulse and the FS of the pulse train are related.  Let the pulse train be periodic with P Hz.  Then the FS of the pulse train will be sampled version of FT with a sampling rate of P Hz.  i.e. except for a scaling factor, the FS values are the samples of the FT sampled at P Hz. And the single pulse FT is a sinc function.  Thus pulse train will have FS coefficients which are samples of the sinc function.