GNSS tilt sensors
This topic applies to Trimble R12i, R12, and R10 receivers with built-in tilt sensors.
Trimble receivers with built-in tilt sensors contain accelerometers that are used to calculate the degree of tilt of the receiver. These tilt sensors enable you to make sure the pole is vertical and stable, so that the receiver is level, or is within tilt tolerance.
Trimble receivers with built-in sensors also provide tilt compensation, which allows you to measure points when the pole is tilted and the receiver is not level. The type of tilt compensation available depends on the receiver. Options are:
- IMU tilt compensation: Trimble R12i receivers
- Magnetometer tilt compensation: Trimble R10 and R12 receivers
Well-calibrated tilt sensors are essential for accurate results. Trimble Access provides a number of calibration routines for your receiver. To view the Sensor calibration screen, tap and select Instrument / Tilt sensor options and then tap the Calib. softkey.

The GNSS eBubble is an electronic representation of the degree of tilt of the receiver. Use the GNSS eBubble to ensure the pole is vertical, still and stable when measuring a point.
The GNSS eBubble appears automatically when you are using a:
- Trimble R10 or R12 receiver and Tilt functions are enabled in the survey style.
- Trimble R12i receiver and eBubble functions are enabled in the survey style and the receiver is operating in GNSS-only mode.
- Trimble R12i receiver when IMU tilt compensation is enabled but the IMU is not aligned.
For more information, see GNSS eBubble tilt sensor.

Trimble R12i receivers have built-in IMU sensors that continuously determine the orientation and degree of tilt of the receiver. When combined with GNSS the receiver can continuously determine its position and correct for any amount of tilt.
IMU tilt compensation does not require a particular measurement method. When IMU tilt compensation is enabled and the IMU is aligned, IMU tilt compensation is "always on" while roving, navigating, or when measuring points using any measurement method except observed control point.
For more information, see IMU tilt compensation.

Trimble R10 and R12 receivers have a built-in magnetometer that allows you to measure points with a tilted pole using the Compensated point method. A compensated point uses the magnetometer to calculate the direction of tilt.
For more information, see Magnetometer tilt compensation.