# Magnetometer calibration

Trimble recommends calibrating the magnetometer in the R10 or R12 receiver:

- Each time you replace the battery.
- If the GNSS receiver suffers severe abuse such as a pole drop.
- If the temperature inside the receiver is more than 30° Celsius different to when the GNSS eBubble calibration was performed. This high temperature invalidates the GNSS eBubble calibration, which in turn invalidates the magnetometer alignment.

The performance of the magnetometer is affected by nearby metal objects (for example, vehicles or heavy machinery) or objects that generate magnetic fields (for example, high voltage overhead or underground power lines). Always calibrate the magnetometer away from sources of magnetic disturbance. In practice this usually means outdoors. (Calibrating the magnetometer near sources of magnetic disturbance does not "correct" for the interference caused by these objects.)

To calibrate the magnetometer

Calibration routines should not be left incomplete. You should not need to navigate to a different screen during the calibration, but if you choose to navigate to a different screen, Trimble recommends that you first complete the calibration process, or tap Cancel to cancel the calibration.

1. Tap and select Instrument / Tilt sensor options.
2. Tap the Calib. softkey to open the Sensor calibration screen.
3. In the Sensor calibration screen, tap Calibrate beside Magnetometer calibration status.
4. Detach the receiver from the pole.
5. Tap Start. Rotate the receiver as shown on‑screen for a minimum of 12 different orientations, until calibration is complete.
6. Tap Accept.
7. Reattach the receiver to the pole. Use the GNSS eBubble to make sure the pole is as vertical as possible.
8. Tap Calibrate beside Magnetometer alignment status.
9. Tap Start. Rotate the receiver slowly and smoothly around its vertical axis until calibration is complete.

10. Tap Accept.

    The details of the calibration are stored in the job. To review them, tap and select Job data / Review job