IWR1642BOOST: I would like to ask a question about Zoom FFT Algorithm

Hi,

I was going through the Zoom FFT experiment using the IWR1642BOOST.

The User Guide mentions that the algorithm is based on Cooley-Tukey FFT. I compared the code with the paper of the Cooley-Tukey algorithm(see picture 2 below):

First, the Cooley-Tukey algorithms recursively re-express a DFT of a composite size N = N1*N2. So N-point sampling signal is required for calculation, but according to the TI's ZOOM FFT code, only the N1 sampling signal is used in the calculation(N1=N2).Second, according to the code, the two sets of twiddle(Fine TW and Coarse TW) are extracted after taking the remainder. This is different from the formula in the paper.

My questions are as follows:

(1) According to my understanding, the basic Cooley-Tukey algorithm is a just fast implementation of FFT. And there may be some other techniques used in TI's code of Zoom FFT algorithm, right?

(2) Can someone please explain further on the Zoom FFT algorithm used in the code or provide the algorithm documentation?

Regards 

                                                                                                   picture1  TI' ZOOM FFT code

                                                                                                      picture 2  Cooley tukey algorithm paper