Dear all,
For my final research project, I am working with PSG data and performing spectral analyses using the FFT module of the DOMINO software by SomnoMedics. However, the results we got were very... unusual. Therefore, we decided to follow the same process with a dummy signal (see print screen example). I used C3 for the test analysis with a high pass filter of 0.5 and a low pass filter of 25 Hz. I extracted the data in bins of 0.5 Hz for frequencies below 4 Hz and in 1 Hz bins for frequencies above 4 Hz. I exported the data per second and averaged it in 30 second epochs. Below you see two graphs of the outcomes and a print screen of the readings from the dummy signal. The pattern in the lower frequencies (high for 0.5-1 Hz, lower for 1-1.5 Hz, etc.) is also visible in the real data we used. Does anyone have an explanation for these results?
Thanks in advance and kind regards,
Lise Beumeler
@Aparna Sathya Murthy, Thank you for your reply. I will do as you suggested and I will come back with the results. I also thought of this as the problem, but I do not know why this problem arises when I use 0.5 Hz bins for the lower frequencies. What do you think?
Edited: I used your suggestion. Please look at the graphs for the results. It seemed to fix the weird pattern for the lower frequencies. However, when you look at the power spectrum over the sample time, there is still an odd pattern in my opinion. The test device gives a constant pattern, so there should not be a change over time.
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