Acoustic Pressure Sensor Calibration Dashboard

Fourteen acoustic underwater pressure transmitters were lowered to increasing depths in seven incremental tests (8.6 bar → 201.6 bar target). This dashboard compares each sensor's reported pressure (sensor_bar) against the NUI reference instrument (nui_bar, ground truth). Calibration statistics are computed only in the valid range where sensors are not saturated (0–29 bar, raw 100–3000). Saturated points are shown de-emphasised in Section 2 so you can see when sensors hit the ceiling. All timestamps are Europe/Oslo local time.

NUI pressure across both test days. Shaded bands are the auto-detected test windows; the dashed red line is the 29 bar sensor saturation ceiling (~290 m water depth). Use the Plotly toolbar to zoom and pan. Above 29 bar every sensor maxes out (flat line at the top), so the meaningful accuracy comparison happens during the pressure ramps and in tests 1–2.

Select a test from the dropdown. The blue line is the NUI ground truth; coloured dots are individual sensor transmissions. Hollow/faded markers indicate saturated or below-min readings. Click an ID in the legend to hide/show it. Hover any point for full detail.

Each dot is one sensor reading. The horizontal position is the real pressure measured by NUI’s reference gauge; the vertical position is what our sensor reported for the same moment. The dashed line is where a dot would sit if the sensor were perfectly correct. The closer the dots hug that line, the more accurate the sensor. This only covers the 0–29 bar range (down to about 290 m), which is the deepest our sensors can physically measure before they max out.

This table puts numbers on the chart above, per sensor and per product type. “Bias” tells you whether a sensor tends to read slightly high (positive) or slightly low (negative) on average. “MAE” (mean absolute error) is the typical size of the miss, in bar — lower is better. As a rule of thumb, 0.1 bar is about 1 metre of water depth. “Std” shows how consistent the sensor is. The takeaway: in the validated 0–29 bar range, the sensors read the true pressure within roughly 0.1 bar (about 1 metre), which gives us empirical backing for the depth ratings.