Clear Filters
Clear Filters

How to integrate filter function into matlab code

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Hello,
I am trying to batch process a bunch of EMG files using a matlab code. Part of the processing is to filter all EMG data using a 6th order butterworth bandpass filter from 30 to 300 Hz. I used filterBuilder and created a variable 'Hbp' to process my first file. So in my code i just had:
RPbandpass=filter(Hbp,RP_ROI);
I clear the workspace after each file so i can no longer just reference Hbp without going through filter builder again. I looked into the code generation options of filterBuidlder where i can generate a function that returns filter as output or generate fuction that filters my data. Both of those gave me some code but i'm not sure how exactly to implement that into my main code file. I am guessing that i want to have a bandpassfilter function saved and stored in my matlab directory that my code can reference but not sure how to do that. Any other solutions or tips are welcome and thank you for your help in advance!

Accepted Answer

Bora Eryilmaz
Bora Eryilmaz on 12 Dec 2022
Edited: Bora Eryilmaz on 12 Dec 2022
You can create the Butterworth filter directly and use it in your code without needing to store anything:
Fs = 2000; % Sampling rate 2000 Hz
bandPassRange = [30 300]; % in Hz.
% Note that the filter order will be 2 * 3.
[b,a] = butter(3, bandPassRange / (Fs/2), 'bandpass')
b = 1×7
0.0383 0 -0.1149 0 0.1149 0 -0.0383
a = 1×7
1.0000 -4.1361 7.2416 -6.9952 3.9888 -1.2706 0.1717
freqz(b,a,[],Fs)
  4 Comments
Bora Eryilmaz
Bora Eryilmaz on 13 Dec 2022
Edited: Bora Eryilmaz on 13 Dec 2022
Save the above code as a MATLAB script into an M file and run it again next time you need it.
Alternatively, you can save the Hd object into a MAT file as a variable using the save command.

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