Shai, i think you should not use PPG data for that aim. Don't believe a word of Apple stuff...PPG is not robust enough (no matter how youfilter, it's not just noise, you can not tell artifact from real if arrhythmia comes in..). They may sell...but it's basically a simple marketing oiperation. Use ECG (mayvbe from chest straps for example.)

Thanks for the message. But I am trying to use PPG because we collect it during MRI scan not from Apple products..

OK, i understand

Hi Shai, with ppg signal you should filter high frequency noise before detecting peak and valley for HRV calculations. Still have low frequency noise like base line and motion artifacts in ppg, please refer to some my articles.