How to Segment EMG data into time intervals

I have 2 minutes of filtered data that needs to be segmented into 20msec intervals, how would I go about doing that? It was collected at 2048 Hz and there is a total of 245762 data points.

Answer 1

[Star Strider]

One option is the Signal Processing Toolbox buffer function.

It uses samples as one of its arguments, however that is straightforward to calculate:

Fs = 2048;                                              % Sampling Frequency (samples/sec)
segment = 0.02;                                         % Segments (20 ms)
Samples = round(Fs * segment);                          % Sample Length

I use round here, however fix, floor or ceil would also work, depending on what you want.

[Ryan Chhiba]

So for the buffer fuction,

y = buffer (x,n,p)
x= emgsignal
n= _____
p= Samples

What would be n? 0.02 (20 ms)?

[Star Strider]

Unless you want to overlap them (that is likely not desirable here), just use:

Fs = 2048;                                              % Sampling Frequency (samples/sec)
segment = 0.02;                                         % Segments (20 ms)
Samples = round(Fs * segment);                          % Sample Length
y = buffer(x,Samples);

or:

[y,z] = buffer(x,Samples);

depending on what you want to do, and want as a result, so ‘n’ is ‘Samples’ in my code.

Of interest, the documentation requires that ‘n’ is ‘positive real scalar’, so the functions creating it as an integer may not be required. I included those because I always specify ‘n’ as an integer.

[Ryan Chhiba]

Okay, that makes more sense thank you!

[Star Strider]

As always, my pleasure!