find peaks

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mohammad 2011-8-31

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https://ww2.mathworks.cn/matlabcentral/answers/14885-find-peaks

does anyone know, is there code for finding peaks in a matrix that have noise? (because of this noise i cant use findpeaks command in matlab) the noise has so small amplitude in compared with amplitude of main wave. thanks

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Answer 1

Fangjun Jiang 2011-8-31

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https://ww2.mathworks.cn/matlabcentral/answers/14885-find-peaks#answer_20240

If you have noise in the data, you need to filter it first. See:

doc filter

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mohammad 2011-9-1

thanks dear Fangjun, in doc filter there is a parameter b=numerator coefficient vector, how must i calculate this?

Fangjun Jiang 2011-9-5

You don't. That is the parameter to specify your designed filter. See the example in the doc.

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Answer 2

James Tursa 2011-8-31

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https://ww2.mathworks.cn/matlabcentral/answers/14885-find-peaks#answer_20241

You might try one of the FEX submissions, e.g. PeakFinder by Nate Yoder:

http://www.mathworks.com/matlabcentral/fileexchange/25500-peakfinder

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mohammad 2011-9-1

dear James thanks for replying

my file is a .xls file. could i send this for you and help how can i use this code for this file?

Fangjun Jiang 2011-9-1

use xlsread() to read the data into MATLAB workspace first, then apply filter.

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Answer 3

Honglei Chen 2011-9-1

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https://ww2.mathworks.cn/matlabcentral/answers/14885-find-peaks#answer_20248

Hi Mohammad,

Can you explain why you cannot use findpeaks? I think you can specify MinPeakHeight to avoid false alarm from the noise.

Thanks.

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mohammad 2011-9-1

hi dear Hongle,thanks for replying

when i use findpeaks, because of noise it gives me 1000 peaks but the matrix has only 5 0r 10 desire peaks, and when i want to sort these peaks and gather 5 or 10 biggest at the first of sorting, again because of noise it gives the biggest peaks and some values (for 4 or 9 others peaks) around that biggest peak. i designed some filters for this but aren't accurate. i saw some nice codes for finding peaks of analog signals with noise but my data is in matrix and discrete form. i think there are some accurate codes for matrix form, saving my time.

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