How to store values in an array in MATLAB

Question

Say I have performed FFT on a set of data and i have the frequency and amplitude values. I want to find the highest amplitude in each FFT block. The I need to find the frequency and amplitude of the points that are atleast greater than 0.4 times the max amplitude and save them in an array.. How can i do this?? I tried the following method by I keep getting an empty matrix....

% the code after FFT
peak_points = [];

    fmin = 60;
    fmax = 1000;
    region_of_interest = fmax>f & f>fmin;
    froi = f(region_of_interest);

    [p_max,loc] = max(seg_fft2(region_of_interest));

    p_max;
    fpeaks = froi(loc);

    [points, locatn] = findpeaks(seg_fft2(region_of_interest));

    if points > 0.4*p_max
        peak_points = [peak_points ; points locatn]
    end

Im bad with arrays.. So I cant seem to figure this out. Would appreciate someone's help in this... Thanks in advance...

grantnz · Accepted Answer · 2013-09-30 07:36:21Z

1

Are you intending to do the seg_ffr2 on the region of interest logical array or on froi?

or maybe points is vector and you should have:

aboveMax = points > 0.4*p_max;
if any(aboveMax)   
        peak_points = [peak_points ; points(aboveMax) locatn(aboveMax)]
end

edited Sep 30, 2013 at 7:36

answered Sep 30, 2013 at 6:58

grantnz

7,4431 gold badge33 silver badges38 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

user2482542 Over a year ago

Well I need to only consider the region between 60 Hz and 100 Hz and find the max in that region. The line region_of_interest = fmax>f & f>fmin; defines that region, so seg_fft2 is done on that...

user2482542 Over a year ago

Thank you. It works fine in detecting the correct amplitudes. However locatn(aboveMax) doesn't give me the frequency of the point. What can I do to get the frequency value??

Collectives™ on Stack Overflow

How to store values in an array in MATLAB

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related