In Datum & Map, you need to have two projects. You cannot work with only one project like you can in the receiver. Project A will be the project with WGS 1984 positions and project B will be the project with the local coordinates.

1.    Open Datum & Map.

2.    Select project A in the top-right window.

3.    Select project B in the bottom-right window.

4.    Click on the Match tab at the bottom of the program window.

5.    Right-click in the upper-right window and select Configuration.

6.    Set the configuration screen as shown below: Note the height mode.

7.    Match the points you want to use in the transformation. Make sure that all points are matched in position only. If you match any of the points in height, the geoid model will be ignored and the heights will simply be shifted from WGS 1874 to the local height.

8.    Click on the Results tab at the bottom of the program window.

9.    Right-click on the blank portion of the screen and select Store...

10.  Give the transformation a name, select to distribute residual by 1/distance and click okay.

11.  Go to the Coordinate System Management screen in SKI-Pro or LGO and right click on the one-step coordinate system you just created and select Properties from the pop-up menu. In this case, the ellipsoid used to define the geoid model that you enter here must be WGS 1984.

Your coordinate system is now ready for use in SKI-Pro or LGO.

13.  Make sure that the new coordinate system is attached to project A, open that project, and go to the Points tab.

14.  Select the Local Grid view and then from the top pull-down menu select Tools | Compute Geoid Separations. The ortho heights will now be shown. Remember that SKI-Pro does not compute the geoid separations automatically.

15.  Transfer the coordinate system to the card (The geoid is not transferred) by right-clicking on the coordinate system and selecting Send To | PC Card. This will put the the coordinate system in \GeoDB\GPSTRF.DAT for System 500, or \DBX\TRFSET.DAT for System 1200.

16.  Create a geoid model field file using the same geoid model attached to your coordnate system and put it in the Data\GPS\Geoid directory on the card.

17.  Put the card into the receiver and transfer the coordinate system to the receiver RAM.

18.  You can either transfer the geoid model to the system RAM, or leave it on the PC Card.

19.  Edit the one-step coordinate system you just transferred and select the geoid model field you want to use in the Geoid field.

Your one-step coordinate system is now ready to give you orthometric heights by adding the geoid separation from the model to the ellispoid height the rover has computed relative to the base station. This method relies on the Base having a correct ellipsoidal height. If you wish to adjust the system to a known ortho height at a point, you will need to edit the base's ellipsoidal height appropriately.