ie classification of different stages of sleep (REM etc)
from physiological measurements eg heart rate variation.
From skimming articles and papers, I see a key factor is ratio of LF/HF ratio (of heart rate changes), where "HF" is defined as >0.15 Hz
The CSV data from O2Ring is only 1 sample every 4 seconds ie 0.25 Hz.
At that sampling frequency, an FFT can only determine up to half that,
namely 0.125 Hz (1/8 seconds). So no LF/HF ratios from that!
OTOH the O2Ring's associated mobile app, ViHealth,
has a live "Dashboard" view.
This appears to update every second, and not by repeating values
(though I can't tell if it's interpolating)
Is there a way of somehow recording such live data? Custom code?
Either from the app or directly (via Bluetooth) from the ring?
Then the possibility (at least) of sleep staging from the O2Ring data could be resurrected.
I have a funny feeling I may have misconstrued something fundamental here, but I thought I'd ask anyway. Too late for me to think it through more solidly. Erstwhile geek out of control.