Solar8000 pulse rate (PLETH_HR)¶

Pulse rate from the oximeter, over about 12 beats.

Stub

Imported from the time-source table; the full page is still to be written.


Name in the dataset	`Solar8000/PLETH_HR`
Type	numeric
Device	Solar8000 monitor
Stamped by	Recorder PC clock
Unit	/min

Measurement space¶

Time side (as stamped): the true time lies between -16.6 s and -2.8 s from the stamp: the delay range plus the interval one value describes.

Time¶

From UTC to the stored time stamp¶

Derived from this signal's timing table; a written chain is still to come.

The clock path first (UTC to the clock that stamps or spaces the samples), then the signal's own path to its stored time. Each bar: the time shift or error the step introduces (pale) and what is left after the atlas's correction (solid), on a log scale; dashed when estimated or assumed.

UTC

The reference every chain starts from.

Recorder PC clock

sync assumed 3 ms – 900 ms · clock link, parameter

Windows time synchronisation to the hospital's time server every 8–24 h (assumed), drifting a few ppm in between. Not observable in the release: dates are shifted to 2100. No step of 0.5 s or more was found.

Recorder PC clock

transport measured 2.8 s – 4.6 s

Delay from the end of the interval a value describes to its stamp.

Stored time stamp

window measured 8 s – 12 s

The width of the interval one value or sample stands for.

Timing¶

Against the working reference. Delay: from the end of the interval a value describes to its stamp. Interval: how wide that interval is.

Form	Delay	Interval	Clock domain	Status	Evidence
as stamped (default)	2.8 s – 4.6 s	8 s – 12 s	Solar8000 numerics	measured	delay 2.4-4.2 s + 0.4 s PLETH; ~12 beats

Combine it with other signals in the synchronisation planner.

Value¶

Its value side is still to be described.

Observations¶

Observation	Status	Summary
Monitor numerics describe the past, never the future	established	Every monitor numeric describes a window of 3–30 s or more that ended 1–9 s before its stamp. None is stamped before its data exist, so the stamps already respect the availability rule.
SpO₂ freezes in low perfusion	established	During low perfusion SpO₂ mostly holds its last value rather than blanking (55–70% of 5–20 s episodes); when the probe comes off it blanks within about a second.

Studies¶

Study	Date	Status	Summary
How the monitors compute their numbers	2026-10-12	current	Recomputing each monitor numeric from its own waveform finds a short, simple algorithm for every one (a median, an exponential average or a time mean over 3–30 s) and a delay of 2–9 s behind the newest data it uses. No value is stamped before its data exist.
SpO₂ and pulse rate latency from step events	2026-10-12	current	SpO₂ cannot be recomputed from one plethysmogram, so its timing comes from events that change the PLETH abruptly. SpO₂ lags the recorded PLETH by about 4 s and then smooths over roughly 10–20 s.

Tags: stub