Changes

The modulation used was: -T 1600 -m 1000 -w

This modulation means:

-T 1600 program modulator with a 1,6ms modulation sweep time

-m 1000 make 1000 consecutive measurements

-w write and save the captured data into text files

The 1.000 measurement files were captured and processed later with matlab. FFT was made for each measurement obtaining the next 2D plot: