How to detect peaks above a given threshold value?

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Sudip Paudel
Sudip Paudel 2020-7-20
评论： Sudip Paudel 2020-7-22
findpeaks() can detect multiple peaks if there is/are change in direction(s) even if the values are above the specified threshold (see arrows in the attached pdf file).
J=a vector;
findpeaks(J,'MinPeakHeight',Threshold);hold on;
yline(Threshold,'--','LineWidth',3);
hold off
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Sudip Paudel
Sudip Paudel 2020-7-20
Hi Madhan, we will not detect other peaks if I change the threshold value to 20. My goal is to count it only once if the signal goes above the threshold value until it goes below the specified threshold.

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Rashedur Rahman
Rashedur Rahman 2020-7-20
Hi Sudip.
The function 'findpeaks' can take several input arguments for finding peaks according to criteria. You can use multiple arguments to adjust your peak finding algorithm. I will suggest you to read the description of 'findpeaks'. ('https://www.mathworks.com/help/signal/ref/findpeaks.html').
Another way is to apply a filter to smoothen the signal and then apply 'findpeaks'.

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Image Analyst
Image Analyst 2020-7-20
编辑：Image Analyst 2020-7-20
Try flattening the signal by subtracting that red trend line. Then set the values of the signal below the threshold to zero and then call findpeaks()
smoothedSignal = movmean(signal, 101);
flattenedSignal = signal - smoothedSignal;
flattenedSignal(flattenedSignal < someThreshold) = 0;
[peakValues, indexesOfPeaks] = findpeaks(flattenedSignal);
Attach your data in a .mat file if you need more help.

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