How to extract the time interval from areas of interest from a signal?

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Alexandra 2015-11-8

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评论： Image Analyst 2015-11-10

Hello! I have a blood pressure signal that looks like this:

https://scontent-frt3-1.xx.fbcdn.net/hphotos-xfp1/v/t35.0-12/12235753_1663006193941174_746177023_o.jpg?oh=b00b341f327554927e598e49b596f72e&oe=56414AC7

and I want to find the time interval for each descent part ( in my case 4 intervals). But I don't know how since it doesn't have any pattern. If anyone can, please help me. Thank you.

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Star Strider 2015-11-10

It actually has a pattern, but you do not have a time vector in your file. You might be able to recover the time vector if you know what the heart rate was.

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Image Analyst 2015-11-8

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First you have to filter out the outliers. How are you doing that? Perhaps a median filter might work if they're not too close together. Then you can just invert the image and use findpeaks(). I can't do it because you didn't attach the actual data.

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Image Analyst 2015-11-10

Something went wrong with your original picture you attached. Please fix it.

Image Analyst 2015-11-10

在 MATLAB Online 中打开

Try this. Let me know how it goes:

signal = xlsread('presiune.xlsx');
plot(signal, 'b-');
[values, indexes] = findpeaks(-signal, 'MinPeakProminence', 25);
grid on;
hold on;
stem(indexes, 50*ones(1, length(indexes)));