hemantharma asked . 2020-08-06

Plot fft and peaks on same plot

I am having trying to plot the fft and its peaks on the same plot. I have read that passing the frequency vector in findpeaks will allow the second argument to be in frequency so i have done that in the code i provided below on line 13. However, I am having a hard time plotting the peaks and the fft on the same plot. If someone could point out how to plot this that would be appreciated.

%take the fourier transform
xdft = fft(x);
xdft = xdft(1:length(x)/2+1);
% create a frequency vector
freq = 0:Fs/length(x):Fs/2;
% plot magnitude
figure(2)
semilogx(freq,20*log10(abs(xdft)));
xlabel('f(Hz)');
title('FFT of signal');
 
%locs is now in frequency 
[pks,frqs] = findpeaks(abs(X),freq);
figure(3)
plot(xdft(locs), pks, 'or')

FFT , MATLAB , PLOT