seperate sample data into sub-vectors

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Christian 2020-6-20

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关闭： Christian 2020-8-12

sample data.txt

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I am currently trying to do a frequency analysis on some sample data from a sensor. Therefore I want to seperate the different sections of the large sample data vector into independent ones. The picture shows the sample data. Each section is a two spiked amplitude with some idling before and after. I figured I could use a threshold to get all the data above set values. But I need some of the iddle before and after that. With the current threshold 5000 samples before the first and after the last data of each amplitude should do.

% determine how many samples there are in total
N=length(SampleData);
% generate sample domain for plot
x=linspace(1,N,N);
PositiveThreshold = 500;
NegativeThreshold = -500;
% get the samples above the threshold
dataIdx = SampleData > PositiveThreshold | SampleData < NegativeThreshold;
SamplePtsAboveThres = x(dataIdx);

How do I get 5000 samples before and after each amplitude and how do I seperate that into independent vecors? Should I use a for loop?

You help is very appreciated!

Edit: I could seperate the vectors by hand but I hoped for something smarter which does that automated.

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dpb 2020-6-23

Another "trick" is to negate the waveform and then use findpeaks again -- excepting now you're finding minima. I've not played much with it to find a flat top region, but wouldn't put it past being able to make that work pretty well for these data with some experimenting.

Christian 2020-6-24