In the CHAT study, the EDF file contains different signals with different sample rates. These signals do not come with a timestamp array bu only signal values array. My question are these signals aligned in terms of time, that is for example does the first value in SAO2 correspond in time to the first value recorded by the Pleth signal, eventhough both signals have a differrent sampling rate? Or is there an unknown offset in time between the different signals?
You can read up on the EDF specification here:
All signal values start from the beginning of the recording, so they are aligned in that regard.
Imagine if a "data record" is 1 second and you have two signals, one that is 1 Hz and the other is 10 Hz. The first value for the first signal will represent the value between the start of the recording and 1 second (1 data record). The first 10 values for the second signal will represent 10 readings between the start of the recording and 1 second (1 data record) (put otherwise, 0-0.1s, 0.1-0.2s, 0.2-0.3s, etc.)