Create signal block based on a threshold

Hi there,

I have a signal which is saved as a csv file. I'm trying to break up the signal into individual blocks of a fixed length (say 100 samples) for analysis (fft, wavelet, amplitude etc) when a threshold is crossed. If, the threshold was to be placed at 5, I still need the a bit before the threshold included in the block (say 30 of the 100 samples before the major peak, 70 after). How would i go about this, only getting 1 block output per signal pulse.

Many thanks in advance!

Answer 1

[Sammit Jain]

Hi Angus,

I'm assuming that the csv file has been imported into the MATLAB workspace. If you encountered issues while importing the csv, you may look at: https://www.mathworks.com/matlabcentral/answers/72545-how-to-import-csv-file-in-matlab

Let us say it had 600 samples, and it was broken down into 6 blocks of 100 samples each.

For the sake of this example, let us consider each block to be of length 10 samples.

Consider one such block B = [4 3 2 2 10 1 5 20 9 1].

B = [4 3 2 2 10 1 5 20 9 1];
idx = find(B > 5);
peak_idx = idx(1);

thresholded_sample = B(1:peak_idx-1);

In this case thresholded_sample will have [4 3 2 2]