How to find the max value of amplitude in Fast Fourier Transform function?

Question

Michael Wang 2020-5-9

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/524176-how-to-find-the-max-value-of-amplitude-in-fast-fourier-transform-function

评论： Peng Li 2020-5-11

The question is aksing to find the max value of amplitude in Fast Fourier Transform function and display the related requency value named as freq_max

Here is the sample codes I have done below.

The last two raws of the codes I have done is based on this webpage Q&A

https://www.mathworks.com/matlabcentral/answers/448809-finding-maximum-value-of-a-plot

I am not really sure if this method is correct for me to solve in Fast Fourier Transform function issue?

% the head of coding is to read any data as xxx.csv
% because it is not the main issue of the problem, so I ignore those coding to make the rest of the coding clearly.
Fs = 360.;
T = 1./Fs;
L = length(ecgData);
t = (0:L-1)*T;
% Set up for FFT
NFFT = 2^nextpow2(L);                      % Next power of 2 from length of y
%Calculate the FFT of the ecg data
Y = fft(ecgData,NFFT);
%Construct the points along the frequency axis
freq = Fs/2*linspace(0,1,NFFT/2+1);
SSAS = 2*abs(Y(1:NFFT/2+1));
%[SSAS_max, index] = max(SSAS);
%freq_max = freq(index);