You can calibrate GeoLink preferably with the model. It can be done usually anywhere and resulting angle deviation is very very small. Only in case when there is a nearby magnet/servo/motor (within around 10cm range) then there is big problem for calibration and operation.

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Spirit System developer

Likewise! I got a used GeoLink from a mate and calibrated it that the reading was "0" when the heli was facing north. Usually, on every compass rose, the number linked to north is zero, no? Only after reading the manual I realized that the readout should be 90. Confused me no end. Maybe that could be changed in a future update?

Best regards - Paco