Question

If we store the signal row wise and compute the L point DFT at each column, the resulting array must be multiplied by which of the following factors?

(a) WN^lq

(b) WN^pq

(c) WN^lq

(d) WN^pm

I got this question in an online quiz.

I would like to ask this question from Efficient Computation of DFT FFT Algorithms in section DFT Efficient Computation – Fast Fourier Transform Algorithms of Digital Signal Processing

Answer 1

Correct answer is (d) WN^pm

Explanation: According to the second algorithm of divide and conquer approach, if the input signal is stored in row wise, then we calculate the L point DFT of each column and we multiply the resulting array by the factor WN^pm.