How do I normalize this signal
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I have a noisy data set that I am trying to find peaks for (I am using the peakfinder function). The function works great when the baseline of the signal does not change, but when it does it no longer finds peaks well - I was thinking of filtering the data, but was unsure what kind of filter would actually help. Any help would be greatly appreciated. A sample below:
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/162617/image.jpeg)
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Star Strider
le 13 Mai 2014
I suggest a low-order bandpass filter, perhaps Butterworth 3 or 4. That will eliminate your baseline drift and most of the noise, making it much easier for findpeak to work.
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Greg Dionne
le 13 Mai 2014
Since your peaks appear well-defined and are spaced far enough apart, I would suggest estimating the baseline by using medfilt1().
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Greg Dionne
le 20 Mai 2014
Modifié(e) : Greg Dionne
le 20 Mai 2014
OK. It might be helpful to post your data file.
If you're not comfortable posting your data... maybe try something like:
[~,locs] = findpeaks(x-medfilt1(x,100),'MinPeakHeight',.01e4)
x(locs)
Image Analyst
le 13 Mai 2014
Some of those peaks are just barely above other peaks that don't have the red circle. Are you setting some threshold for how much a peak must exceed the "baseline" signal before it can be called a peak? What about using sgolayfilt() in the Signal Processing Toolbox. I have a demo available upon request.
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Image Analyst
le 15 Mai 2014
Sounds like you don't even have an interest in even trying to understand, and have decided in advance that you "can't really use it" without understanding it. For example, you haven't attached your data file to let anyone help you by trying things.
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