MATLAB: Why does findpeaks detects minimas

accelerationdetect maximasfindpeaksSignal Processing Toolbox

I got the data of an acceleration sensor and I want to detect only the local maximas, I used

 plot(data);
 findpeaks(data);

but it also detected the minimas, but why?

With

findpeaks(data,'MINPEAKHEIGHT',2);

it worked as I expected the function to work, but I can't use 2 as a static threshold for my application. Did I something wrong, that it also detects the minimas or do I have to find a way to implement an adaptive threshold?

Best Answer

It is not detecting minima, it is detecting noise peaks near the minima. The findpeaks function has a number of name-value pair arguments that can help you detect only what you want. Consider MinPeakHeight and MinPeakDistance, and others to get the result you want.

Related Solutions

MATLAB: Findpeaks ( ‘WidthReference’,’halfheight’ ) not finding width of peak

I think you wanted this instead:

findpeaks(sgf,'MinPeakProminence',0.003,'WidthReference','halfheight','Annotate','extents');
[pks,locs,widths,proms]=findpeaks(sgf,'MinPeakProminence',0.003,'WidthReference','halfheight');

(use the same settings for when you plot without output arguments vs. when you do your assignment).

MATLAB: Findpeaks for different thresholds

Thresholds = linspace(x1,x2,n);
for thresh_idx = 1 : length(Thresholds)
    Threshold1=linspace(x1,x2,n);
    [pks, locs] = findpeaks(data, 'MinPeakHeight', Threshold1);
    Results(thresh_idx).Threshold1 = Threshold1;
    Results(thresh_idx).pks1 = pks;
    Results(thresh_idx).locs1 = locs;
end

Best Answer

Related Solutions

MATLAB: Findpeaks ( ‘WidthRefe​rence’,’ha​lfheight’ ) not finding width of peak

MATLAB: Findpeaks for different thresholds

Related Question

MATLAB: Findpeaks ( ‘WidthReference’,’halfheight’ ) not finding width of peak