Split every current signal into N segments of Length L

Hello! I have a 3 phase raw current signal that I want to split into 100 segments of 0.1 second so as to reduce the data size for signal processing and takes only the peak to peak and amplitude maximum values. How can I archieve this in MATLAB?

[dpb]

Well, 0.1s of your signal will be however many points is 0.1/dt where dt is your sample rate.

Many of the signal processing toolbox functions work by windowing or virtually all Matlab functions will treat columns of an array as independent observations and operate by column.

Answer 1

[Star Strider]

Assuming I understand waht you want to do, I would use the Signal Processing Toolbox buffer function to do that.

You would have to calculate ‘L’ (number of samples) based on your sampling frequency (in samples/time unit), so if the time units are seconds L = 0.1*sampling_frequency.

The buffer function returns the segments in column-major order, so you can do the fft on the output of your buffer call:

FT = buffer(your_signal, L)/L;

will return the scaled complex Fourier transform of each column.

[Star Strider]

It looks correct, however I can only run parts of it so I cannot say for certain.

If you want to elimiinate the D-C offset, the best way to do that is:

Y = fft(X-mean(X));             % FFT

f = Fs*(0:(L/2))/L;
P2 = abs(Y/L);
P1 = P2(1:numel(f));

and delete this assignment:

P1(2:end-1) = 2*P1(2:end-1);    % <- DELETE

[Chloe Sim]

Okay! Noted! Thank you for the response! Is there a way to view the 512 segments? How can I extract data from each of the 512 segments?

[Star Strider]

One way iis to plot all of them at once:

plot(t, y)

or:

plot(f, P1)

depending on which ones you want to plot.

The surf and mesh functions are also options, depending on what you want. You will have to experiment with those, however:

mesh(y)

and:

mesh(P1)

will do to start with.

[Star Strider]

Yes. The segments are columns in ‘y’, so it operates on them by default, unless you specify a different dimension (specifically dimension 2), in which case it will operate across the rows (that does not make sense in this context).

[Chloe Sim]

Okays! Thank you so much for helping me!

[Star Strider]

As always, my pleasure!