Challenge11_FFT - N [16,1024] and the average execution...

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Digital Signal Processing Dr. Fred J. Taylor, Professor Lesson Title: FFT Challenge: 11 Challenge Problem The Cooley-Tukey process in, by far, the most commonly used ordering technique and is applicable to any transform length. The MATLAB FFT algorithm, reported below, is based on a Colley-Tukey ordering and is seen to accept any signal length N. FFT Discrete Fourier transform. FFT(X) is the discrete Fourier transform (DFT) of vector X. For length N input vector x, the DFT is a length N vector X, with elements N X(k) = sum x(n)*exp(-j*2*pi*(k-1)*(n-1)/N), 1 <= k <= N. n=1 Challenge: A collection of FFTs are performed for integer length
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Unformatted text preview: N [16,1024] and the average execution time displayed in Figure 1. It had been claimed that the FFT is a N log 2 ( N ) algorithm, yet the execution times are all over the map. What gives? Q. Why is the FFT latency all over the map. . Figure 1: Matlab execution delays for FFTs of length N [16,1024]. FFT - 1 Digital Signal Processing Dr. Fred J. Taylor, Professor Response The execution delays of individual radix-2 ( N =2 n ), mixed radix (( N =3*2 n , 5*2 n , 15*2 n ), and prime lengths are reported below. What conclusions may be drawn? N =2 n N =3*2 n N =5*2 n N =15*2 n N (prime) FFT - 2...
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Challenge11_FFT - N [16,1024] and the average execution...

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