Change sampling frequency of a dataset

1

Hi!

I created a while ago a dataset with 250 subjects. Now, I am suspicious that the sampling frequency that I used when importing it to Brainstorm is wrong. How can I check the sampling frequency that I selected for those registers? Besides, can I modify the sampling frequency of the subjects in that database without removing and re-importing them?

Thank you very muvh in advance!

2

You load any imported epoch into your Matlab workspace (e.g. right-click on the file > File > Export to Matlab > DataMat), and execute:

>> sfreq = 1 ./ (DataMat.Time(2)-DataMat.Time(1))
sfreq =
  600.0000

Or:

>> sfreq = mean(1 ./ diff(DataMat.Time))
sfreq =
  600.0000

You can modify this manually, at least on one file, by updating the Time field.
https://neuroimage.usc.edu/brainstorm/Tutorials/Scripting#Custom_processing

Then you can select this file in Process1, followed by all the other trials in your database explorer, and use the process "Standardize > Uniform epoch time".
image

3

Thank you very much, as always it was what I needed :smiley: