SNUADC values are 10-bit codes, though the device is documented as 12-bit¶

Every SNUADC channel in the release stores codes 0–1023 and nothing above: 10 bits, a step of 0.0098746 V. The VitalRecorder device list describes the SNUADC as a 12-bit converter.


Status	open: seen, not explained.
Devices	SNUADC
Variables	ECG lead II (SNUADC), Arterial pressure (SNUADC), Plethysmogram (SNUADC)

What it means¶

The resolution is the 10-bit step: 0.00987 mV for ECG, 0.987 mmHg for ART, CVP and FEM, 0.395 units for PLETH. Anyone assuming the documented 12 bits would expect steps four times finer than the data hold.

What is done about it¶

The atlas uses the observed 10-bit step. Why the documented and stored resolutions differ is open: an older 10-bit SNUADC, or 12-bit readings reduced to 10 bits before transmission.

Evidence¶

Study	Date	Status	Summary
Value resolution of every signal	2026-10-19	draft	How finely every waveform and numeric track in the release records its values. The SNUADC waveforms are 10-bit codes, though VitalRecorder's documentation describes the SNUADC as 12-bit; Primus waveforms use about 10 bits of 12; BIS EEG is a 16-bit grid of 0.05 µV. Numerics are 32-bit floats on decimal grids of 1, 0.1, 0.01 or 0.001, one per track; settings sit on coarser grids of 10 or 100.

References¶

VitalDB. VitalRecorder supported devices. VitalDB documentation. Accessed 19 October 2026. ↗
VitalDB. VitalRecorder configuration file (vr.conf) guide. VitalDB documentation. Accessed 19 October 2026. ↗

Figures¶

Two log-scale code histograms from 0 to about 1000; ECG reaches 1023 with a spike there; the region above 1023 is empty and shaded. — Samples at each stored code over the whole release, one bin per code, for ECG II and ART. ECG reaches every code from 0 to 1023 and piles up at both ends (clipping); no SNUADC channel has a code above 1023, where a 12-bit converter would continue to 4095.