How to calculate RMS and Crest Factor of separate data and combine into one file and one plot

Question

Pasu Surananchanok 2022-3-1

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https://ww2.mathworks.cn/matlabcentral/answers/1660890-how-to-calculate-rms-and-crest-factor-of-separate-data-and-combine-into-one-file-and-one-plot

回答： Mathieu NOE 2022-3-1

Hello,

In case that I have the separate 123 mat files (bearing1_1_1.mat to bearing 1_1_123.mat) and I would like to calculate RMS and Crest Factor of each file and combine to one file.

In addition, how to plot the RMS into the graph like an attached picture (RMS of data 1 to data 123), how should I write the script?

Thanks for your kind supports

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Answer 1

Mathieu NOE 2022-3-1

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https://ww2.mathworks.cn/matlabcentral/answers/1660890-how-to-calculate-rms-and-crest-factor-of-separate-data-and-combine-into-one-file-and-one-plot#answer_907255

在 MATLAB Online 中打开

hello

this is my suggestion - maybe you will have to do a few mods according how the data is stored in your mat files (not supplied)

fileDir = pwd; % current directory or specify the target directory
S = dir(fullfile(fileDir,'bearing*.mat')); % get list of data files in directory
S = natsortfiles(S); % sort file names into natural order (what matlab does not do well) , see FEX : 
           %(https://fr.mathworks.com/matlabcentral/fileexchange/47434-natural-order-filename-sort)
for k = 1:length(S)
    
    data = load(fullfile(fileDir, S(k).name)); 
    time = data.time;
    signal = data.signal;
    
    signal_rms(k) = sqrt(mean(signal.^2));
    CrestFactor(k) = max(abs(signal))/signal_rms(k);
        
end
figure
plot((1:k),signal_rms)
figure
plot((1:k),CrestFactor)

FYI I created some dummy data files to test the above code

Fs = 1000;
dt = 1/Fs;
for ci = 1:123
    baseFileName = ['bearing_1_1_' num2str(ci) '.mat'];
    time = 0:dt:1; % time vector
    signal = ci*sin(2*pi*ci*time)+ 0.1*ci*rand(size(time)); % non constant amplitude and freq signal vector
    
    save(baseFileName,'time','signal');
    
end