Practical application of complex FFT Is there any application where one may need to compute the FFT of a complex-valued signal? I am interested in cases where the FFT of the complex-valued signal is of primary interest and is not an intermediate step in a larger computation, so cases like using analytic signals in the computation of the Pseudo-Wigner-Ville distribution is not of interest to me.
An SDR app (for example one for an RTL-SDR device plugged into a Raspberry Pi's USB port) which displays the RF spectrum of an IQ baseband signal uses the FFT of a complex input.  This allows showing the RF spectrum both above and below the PLL frequency.