How to detect peaks above a given threshold value?

Question

Sudip Paudel 2020-7-20

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/567648-how-to-detect-peaks-above-a-given-threshold-value

评论： Sudip Paudel 2020-7-22

Attach.pdf

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

4 个评论
显示 2更早的评论隐藏 2更早的评论

madhan ravi 2020-7-20

What happens when you change it to 20?

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.

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Rashedur Rahman 2020-7-20

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/567648-how-to-detect-peaks-above-a-given-threshold-value#answer_468129

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'.

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

Answer 2

Image Analyst 2020-7-20

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/567648-how-to-detect-peaks-above-a-given-threshold-value#answer_468330

编辑：Image Analyst 2020-7-20

在 MATLAB Online 中打开

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.