| Gaps and unbroken segments in every waveform |
2026-10-19 |
draft |
Every gap and every unbroken segment in the 6,388 recordings, per waveform. The curves are not smooth: a cliff at about 18 s in every device marks the recorder's pauses, SNUADC segments stop at 5 hours, Primus segments at about 2.0 hours and BIS segments at about 2.3 hours (each device's correction cycle), and BIS's short gaps grow with the time since the last one (clock resynchronisations, not lost data). |
| Message sizes and the steps between records |
2026-10-19 |
draft |
Every record in every waveform: SNUADC writes messages of 100 samples (0.2 s), Primus 30 (0.48 s), BIS 16 (0.125 s), CardioQ no fixed size. Backward steps outnumber gaps by about a hundred to one and come from a few recordings with duplicated or interleaved records. Primus gaps are whole lost messages; most SNUADC and BIS gaps are not. |
| The SNUADC clock through the Solar8000 numerics, whole release |
2026-10-19 |
current |
On the SNUADC's own sample count, the delay from the waveform to the PC-stamped Solar8000 heart rate and mean arterial pressure ramps at the SNUADC's drift against the PC, measured without its stamps or resets. In recordings with whole reset intervals it agrees with them (−63 ppm; median difference +1.5 ppm, 581 recordings). It is too noisy per recording, and in recordings under about 4 h its rate is biased toward zero, so it cannot yet speak for recordings without resets. |
| What each break in the stamps is |
2026-10-19 |
draft |
Every step between waveform records in the release, sorted by mechanism: written twice, a SNUADC clock reset, interleaved streams, a pause shared by every device, whole messages, less than a message, or a fraction of a message beyond whole ones. A continuity test with controls shows which classes lose data: shared pauses and most longer SNUADC gaps do; steps under one message, and SNUADC's lone one-message steps, mostly do not. |
| Identifying the recording setup of every case |
2026-10-18 |
open |
Recognising which equipment made each recording, from its serial ports and, where those fall short, from clock fingerprints, so that per-setup values can be used for every case. |
| Paced ECG as an independent clock |
2026-10-17 |
current |
Fixed-rate pacing gives a clock the recording chain cannot touch. Timing paced beats on three timelines shows that each SNUADC step-mode correction loses about 18 ms of signal, and that nothing else breaks the sample stream. |
| Recorder PC clock steps and recording pauses |
2026-10-17 |
current |
A step of the recorder PC clock would move every device's stamps at once. Searching all 6,388 files for such simultaneous jumps found none of 0.5 s or more; what moves everything together is recording pauses. |
| Records out of order at SNUADC resets, and where the lost time goes |
2026-10-17 |
current |
At every SNUADC reset the five records after it are written out of order: two continue the old timing and three start the new. Put back in order, the waveform runs on with no samples missing; the 18–20 ms lost at each reset goes missing inside the last old-timing record, and an extra zero sample follows. |
| SNUADC stamp arithmetic |
2026-10-17 |
current |
Between corrections the SNUADC block stamps run −0.95 ppm against the sample count: each 0.2 s increment is about 0.19 µs short. This, not clock drift, is the "about −1 ppm" seen in frequent-correction mode. |
| The vitaldb package's loading conventions |
2026-10-17 |
current |
The vitaldb Python package sets time zero from the tracks loaded, places waveform blocks by rounding their stamps up to a sample, and lets overlapping blocks overwrite each other. Each choice moves or loses samples. |
| 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. |
| Two heart-rate delay groups, one poll apart |
2026-10-13 |
current |
Solar8000 heart rate reaches the recorder either about 1.9 s or about 4.2 s after its window ends: one 2 s poll apart. The group belongs to the recording PC, stays fixed through a case, and on some PCs varies from case to case. |
| Closing loops in the timing graph |
2026-10-13 |
current |
Where two independent routes reach the same clock, the offsets around the loop must sum to zero. Three measured loops close within their noise; the BIS loop closes up to a constant latency; the proposed EMR loop is not a loop at all. |
| The SNUADC firmware |
2026-10-13 |
current |
The public SNUADC firmware explains the board's timing: it sends no time stamps, samples on its 16 MHz crystal, loses time rather than bunching samples after a stall, reads its channels one after another, and truncates its values. A predicted fault at the microsecond counter's wrap was not found in the data. |
| Recovering the time of day |
2026-10-12 |
current |
The release shifts every case to start at 2100-01-01 00:00 UTC, removing the date and the time of day. The time of day (Korean local time) can be recovered to the minute from the admission date and the seconds of the EMR times. |
| Anaesthesia record times are rounded up |
2026-10-12 |
current |
Anaesthesia start and end entered on a 5-minute mark sit 90–290 s later, against device markers, than entries typed to the minute. Rounding up to the next 5 minutes fits every one of 11 markers better than rounding to the nearest or down. |
| The stamp sawtooth model for SNUADC and BIS |
2026-10-12 |
current |
Fitting each track's record stamps against its sample count as a drift with corrections (a sawtooth) puts SNUADC and BIS on one timeline without any artefact. Checked against shared bursts, the EEG–ECG timing error falls from about 790 ms on the recorded stamps to 33 ms with one constant per SNUADC mode in the pilot, and 42 ms over the whole release. |
| Clock corrections in every file |
2026-10-11 |
current |
A scan of all 6,388 files for the jumps where the recorder re-synchronises a device's stamps. Each device type has its own correction signature; only SNUADC and BIS correct clearly enough to measure their drift. |
| Physical units, shared drift and time order |
2026-10-11 |
current |
Device drift rates cluster into units: about 8 SNUADC boards and 8–18 BIS monitors. Part of the drift is shared by both devices of a case and changes between cases: the recorder PC's own rate. Case order carries no time information. |