Beat matching
Pair beats seen by two signals one to one, using a delay window around the known level rather than nearest neighbours, which flip between beats when the lag is near half a beat.
Studies
| Study |
Date |
Status |
Summary |
| One device delay for the PLETH across the release |
2026-10-18 |
current |
The stored ECG-to-PLETH delay was measured in 5,536 recordings, to the foot and to the steepest upstroke of each pulse. It has one peak (655 ms to the foot, 715 ms to the upstroke, in the median recording), no clusters by recording setup or SNUADC port, and no shift along the case order: one global device delay, 385 ms with an adopted R-to-foot finger PAT of 270 ms, fits the whole release, as Ruffolo et al. found in their own data. |
| Time zeros and loaded subsets |
2026-10-16 |
current |
A VitalDB time "from the start" depends on which tracks were loaded: loading a subset moves the zero to that subset's first record, seconds or hours later. The arrhythmia database's annotations count from the full file's zero. |
| Rare devices against SNUADC |
2026-10-13 |
current |
CardioQ, EV1000, Vigileo and Vigilance each get a link to the SNUADC timeline: beat matching for the CardioQ, mean arterial pressure alignment for the EV1000 and Vigileo, and a long-window fit for Vigilance's averaged heart rate. |
| Arterial pressure as a check on the PPG correction |
2026-10-11 |
current |
Arterial pressure is sampled by the same converter but has no frame and no sawtooth, so every PPG slip leaves ECG→ABP unchanged. Against it, detected slips are 97–100% real and tier A leaves about 2 ms of drift mid-tooth. |
| The PPG sawtooth and its correction |
2026-10-10 |
current |
The ECG→PPG delay creeps at 18–52 ppm and jumps up by one 33.3 ms frame at each slip, every 11–31 minutes. A tooth-by-tooth model removes it; where the correction is confident it is essentially exact on injected test data. |