# To automatically calibrate points

When you use this function to measure calibration points, the calibration calculations are performed and stored automatically.

If you do not define a projection and datum transformation, a transverse mercator projection will be used.

1. Set your automatic calibration settings in the Site calibration screen.

1. To view the Site calibration screen, do one of the following:

- Tap and select Settings / Survey styles. Select the required survey style. Tap Site calibration.
- When you measure a calibration point, tap Options.

2. Select the Auto calibrate check box to display calibration residuals only if the calibration tolerances are exceeded.
3. Configure the naming relationship between the grid and Global coordinates.
4. Tap Accept.

2. Enter the grid coordinates of your calibration points. Key these in, transfer them from your office computer, or measure them using a conventional total station.

For keyed in coordinates check that the coordinate fields are North, East, and Elevation. If they are not, tap Options and change the Coordinate view to Grid. See Coordinate view settings. Key in the known grid coordinates and tap Enter.

Select the Control point check box. (This ensures that the point is not overwritten by a measured point.)

For transferred coordinates make sure that these coordinates are:

- transferred as grid coordinates (N, E, E), not as Global coordinates (L, L, H)
- control class points

3. Measure each point as a calibration point.

1. In the Method field, select Calibration point.
2. Enter the grid point name. The software names the GNSS point automatically, using the naming relationship that you configured earlier.

Once the point has been measured, the Auto‑calibrate function matches the points (grid and Global coordinates), and calculates and stores the calibration. The calibration is applied to all previously measured points in the database.

4. When you measure the next calibration point, a new calibration is calculated using all of the calibration points. It is stored and applied to all previously measured points.

When one point has been calibrated, or a projection and datum transformation have been defined, the Find softkey appears. You can use this to navigate to the next point.

If the calibration residuals are exceeded, consider removing the point with the most extreme residuals. Do one of the following:

- If at least four points are left after removing that point, recalibrate using the remaining points.
- If not enough points are left after removing that point, measure it again and recalibrate.

It may be necessary to remove (remeasure) more than one point. To remove a point from the calibration calculations:

1. Highlight the point name and tap Enter.
2. In the Use field, select Off and tap Enter. The calibration is recalculated and the new residuals are displayed.
3. Tap Apply to accept the calibration.

To view the results of an automatic calibration:

1. Tap and select Measure / Site calibration. The Site calibration screen appears.
2. Tap Results to see the Calibration results.