PPG Peak, HRV, and BPM Detection Flow

What I checked first

The baseline PPG source runs at 100 Hz and calculates first/second differences and peak intervals. A separate HRV module keeps four peaks, forms three gaps, rejects gaps outside a 20% margin, and then calculates BPM.

Source view

• The newer PPG variant combines a slope sign change with a refractory interval to suppress duplicate peaks.
• The HRV module computes a gap average and margin and returns BPM=0 when intervals are inconsistent.
• No saved accuracy evaluation is present, so this page documents the algorithm structure only.

Code path

GapAvr = (Gap1 + Gap2 + Gap3) / 3;
margin = GapAvr / 5;
if (all_gaps_within_margin) {
    bpm = 60 * 1000 / GapAvr;
}

Key terms

1. peak interval
2. refractory period
3. HRV
4. BPM

Review sequence

1. peak interval
2. refractory period → HRV
3. BPM