# AT360 eBubble options

If the active target has built-in tilt sensors and you are performing a conventional survey, an eBubble (electronic bubble) showing tilt information for the target is available. To configure the eBubble, you can:

- Tap in the eBubble window.
- Tap and select Instrument / eBubble options.

You can configure the following settings:

Option | Description
--- | ---
eBubble sensitivity | The bubble moves 2 mm for the specified sensitivity angle. To decrease sensitivity select a large angle.
Tilt tolerance | Defines the maximum radius that the target can tilt and be considered in tolerance. The allowable range is 0.001 m to 1.000 m. The tilt distance shown is calculated using the current target height.

If you have more than one tilt sensor connected, you can also tap the AT360 softkey from the eBubble options screen for a different sensor. Changing the eBubble settings for one sensor changes the eBubble settings for all connected tilt sensors.

eBubble calibration

To calibrate the eBubble tap the Calib softkey and then tap the Calibrate button to begin tilt calibration. Level the instrument with the calibrated reference and brace against movement. Tap Start. The calibration information is stored in the job.

A well‑calibrated eBubble is of vital importance. The accuracy of tilt information used to display the eBubble, and stored with measured points, is totally dependent on the calibration of the tilt sensors inside the active target. Using a poorly‑calibrated eBubble will directly degrade the accuracy of the coordinates measured using the eBubble as a level reference. Great care should be taken when you are calibrating the eBubble to ensure the most accurate tilt information is available at all times.

Bubble reference: Calibrate the eBubble against a properly calibrated physical bubble. The accuracy of the eBubble depends totally on the accuracy of the physical bubble used to calibrate it.

Pole stability: When calibrating the eBubble, the pole the active target is on should be as vertical and as stable as possible. In practice this means using at least a bipod to hold the pole as still as possible.

Pole straightness: A bent pole will affect the tilt measured by the sensors in the active target. If you calibrate the eBubble using a bent pole and then change poles, the accuracy of points will be affected. Also, if you calibrate using a straight pole and then change to a bent pole, the target will not be plumb even though the eBubble will say it is, again affecting the accuracy of the measured points.

Abuse: If the active target suffers severe abuse such as a pole drop, you should recalibrate the eBubble.

For more information, refer to the active target documentation.

eBubble display

To display the eBubble, tap the eBubble softkey.

Bubble color | Meaning
--- | ---
Green | You are within the defined tilt tolerance.
Red | You are outside the defined tilt tolerance.

- To move the eBubble window to a new position on the screen, tap and hold on the eBubble and drag to a new position.
- To show or hide the eBubble from any screen, press Ctrl + L.