Text equivalent
In one case, an offset develops inside a temperature sensor. In the other, the transmitted report is altered by the same amount. The reported temperatures are identical at every sample.
Both reports begin near 40°C. From 6 to 10 seconds, an additional offset increases smoothly from 0°C to 4°C. The independent thermometer continues to follow the true temperature, oscillating between 39.6°C and 40.4°C.
The discrepancy is visible. Its cause remains unresolved.
Calibration evidence or access records would be needed to investigate the cause further. The independent thermometer alone cannot distinguish a sensor fault from an altered report.
Method and evidence
These are calculated traces: 201 samples from t = 0 to 20 seconds at 0.1-second intervals. Both plots use horizontal limits of 0–20 seconds and vertical limits of 38–46°C.
T(t) = 40 + 0.4 sin(2πt/10) °C
s = clamp((t − 6)/4, 0, 1)
d(t) = 4(3s² − 2s³) °C
Case A: sensor offset b(t) = d(t). Case B: report alteration a(t) = d(t). Both reported traces are T(t) + d(t). The independent thermometer reads T(t).