suppose I have a 4 seconds signal captured at $f_s$ = 1024Hz, which gives 4,096 data array. What is the different between these 2 FFT methods (MATLAB code) [1] FFT the entire input with 4096-points FFT N = length(input); Y = fft(input)/N; [2] Divide the input into 8 segments (4096/8=512 data point each), and feed each segment to 512-points FFT, and then average the output: N = length(input); Y = zeros(1,512); for i = 1:8 segment = input(512*(i-0)+1 : 512*i); Y = Y + abs(fft(segment,512))/512/8; end Question #1: Are these 2 methods equivalent? Question #2: Is the frequency resolution for both methods equal to $\frac{f_s}{N}$ = 0.25Hz per bin?