# Acoustic Pressure Sensor Calibration Dashboard

Field test 2026-06-23 & 2026-06-24 | 7 pressure tests, 14 sensor IDs, NUI reference at 1 Hz (local time)

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.

## 1 — Full test run overview

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.

## 2 — Per-test detail

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.

## 3 — How accurately do the sensors read the true pressure?

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.

## 4 — The accuracy in numbers

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.

ID | Type | N | Bias (bar) | Std (bar) | MAE (bar) | MaxAbs (bar)
--- | --- | --- | --- | --- | --- | ---
Per sensor ID (sorted by MAE, valid range 0–29 bar)
119 | 9mm Press epoxy sleeve | 41 | +0.034 | 0.071 | 0.054 | 0.330
115 | 9mm Press | 44 | +0.026 | 0.152 | 0.075 | 0.635
102 | 6mm Press | 55 | +0.062 | 0.088 | 0.087 | 0.405
107 | 7mm Press | 58 | +0.066 | 0.083 | 0.090 | 0.370
123 | 13mm Press | 39 | +0.084 | 0.159 | 0.091 | 0.789
114 | 9mm Press | 52 | +0.053 | 0.122 | 0.093 | 0.569
128 | 13mm Press v2 lithium | 51 | +0.067 | 0.109 | 0.093 | 0.542
129 | 13mm Press v2 lithium | 29 | +0.082 | 0.105 | 0.094 | 0.405
103 | 6mm Press | 23 | +0.081 | 0.056 | 0.095 | 0.140
118 | 9mm Press epoxy sleeve | 40 | +0.049 | 0.192 | 0.102 | 0.770
106 | 7mm Press | 55 | +0.097 | 0.103 | 0.105 | 0.712
122 | 13mm Press | 55 | +0.063 | 0.153 | 0.111 | 0.590
134 | 16mm Press | 30 | +0.089 | 0.223 | 0.121 | 1.186
135 | 16mm Press | 27 | -0.214 | 1.346 | 0.345 | 6.905
Per sensor type
9mm Press epoxy sleeve | 81 | +0.041 | 0.143 | 0.077 | —
9mm Press | 96 | +0.041 | 0.136 | 0.085 | —
6mm Press | 78 | +0.067 | 0.080 | 0.089 | —
13mm Press v2 lithium | 80 | +0.073 | 0.107 | 0.093 | —
7mm Press | 113 | +0.081 | 0.094 | 0.097 | —
13mm Press | 94 | +0.072 | 0.155 | 0.103 | —
16mm Press | 57 | -0.055 | 0.944 | 0.227 | —

Takeaway: In the validated 0–29 bar range (raw 100–3000, sensor not saturated), 13 of 14 sensors track true pressure within a mean absolute error of < 0.13 bar (< 1.3 m water). The best-performing sensor achieves MAE = 0.054 bar. ID 135 (16mm Press) is the outlier with MAE = 0.345 bar and high variance (std = 1.346 bar) — it warrants individual inspection. Above 29 bar the sensor output saturates at raw = 3000 (290 m depth); readings in that range are flagged and excluded from calibration statistics.