Coordinate system

Use this projection type when the job will contain observations only from a conventional instrument and you are using a local scale factor to reduce distances to the local coordinate system.

If you are working in a small area and are not sure which coordinate system to use, select the Scale factor only projection and enter a scale factor of 1.000.

1. In the Select coordinate system screen, select Scale factor only.
2. Enter a value in the Scale factor field.
3. Tap Store.

Use this method for jobs that will contain conventional or GNSS observations or both.

To customize the list of coordinate systems available, see To customize the coordinate system database

1. In the Select coordinate system screen, select Select from library. Tap Next.

2. From the lists, select the required System and Zone.

   Drag your finger up the list to scroll, or press the first letter of the country name on the keypad to jump to that section of the list.

3. If the job will contain GNSS observations and you want to use a geoid model or datum grid file, you must have copied these files to the controller.
   1. To select a geoid model, enable the Use geoid model switch. Select the file in the Geoid model field.

   2. To select a datum grid file, enable the Use datum grid switch. Select the file in the Datum grid field.

      The semi‑major axis and flattening values for the selected datum grid file are displayed. These details overwrite any already provided by a specified projection.

4. Select the type of Coordinates to use. The default is grid. To use ground coordinates, see To set up a ground coordinate system.
5. Enter the Project height. See Project height.
6. Tap Store.

Use this method to key in your own parameters, particularly if you have your own projection files you want to use or if the job will contain GNSS observations and you want to key in a site calibration adjustment.

1. In the Select coordinate system screen, select Key in parameters. Tap Next.

2. Tap Projection.

   1. Fill out the details for the projection.

      Drag your finger up the list to scroll, or press the first letter of the country name on the keypad to jump to that section of the list.

   2. Select the type of Coordinates to use. The default is grid. To use ground coordinates, see To set up a ground coordinate system.
   3. Enter the Project height. See Project height.
   4. Tap Accept.
3. If the job will contain only observations from a conventional instrument, tap Store.
4. If the job will contain GNSS observations, or a combination of conventional and GNSS observations:

   1. To specify the datum transformation, tap Datum trans.

      To use a datum grid file, select Datum grid in the Type field and select the Datum grid file to use.

      The semi‑major axis and flattening values for the selected datum grid file are displayed. These details overwrite any already provided by a specified projection.

   2. To use a geoid model file, tap Vert. adjustment and select Geoid model and select the Geoid model file.

      The remaining fields in the Horizontal adjustment and Vertical adjustment screens are filled out when you perform a site calibration. See GNSS observations and local coordinate systems and Site calibration.

   3. Tap Store.

Use this method if you want to measure points using GNSS observations using a coordinate system with an undefined projection and datum, or if you do not know what the coordinate system settings should be.

1. In the Select coordinate system screen, select No projection/no datum. Tap Next.
2. To use ground coordinates after a site calibration, set the Coordinates field to Ground and enter the average site height in the Project height field. Alternatively, set the Coordinates field to Grid.
3. To calculate a geoid vertical adjustment after a site calibration, select the Use geoid model check box and then select the geoid model file.

Any points measured using GNSS are displayed only as WGS‑84 coordinates.

When you perform a site calibration, the software calculates a Transverse Mercator projection and a Molodensky three‑parameter datum transformation using the supplied control points. The project height is used to compute a scale factor for the projection so that ground coordinates can be computed at elevation. See Site calibration.

Use this projection type when the Broadcast format is set to RTCM RTK and the broadcast datum definition messages are broadcast by the VRS network.

1. In the Select coordinate system screen, select Broadcast RTCM.
2. Select the appropriate projection parameters for your location.
3. Select the type of Broadcast RTCM messages to include. See Broadcast RTCM messages.
4. Select the type of Coordinates to use. The default is grid. To use ground coordinates, see To set up a ground coordinate system.
5. Enter the Project height. See Project height.
6. Tap Store.

The name of the coordinate system indicates whether the coordinate system was selected from the library, was later modified, or whether the coordinate system is user defined.

When the coordinate system is:

• Selected from the library:

  • The Coordinate system field displays "Zonename (SystemName)".

    Changing the geoid model or project height does not change the name of the coordinate system

  • Editing any projection or datum parameters changes the coordinate system name to "Local site". To remove these changes and revert to the original name of the coordinate system, you must reselect it from the library. If you overlay a GNSS site calibration over this “Local site” the name of the coordinate system remains “Local site”.
  • Completing a GNSS site calibration changes the coordinate system name to "Zonename (Site)". If you disable the site calibration (by keying in parameters) the coordinate system name reverts to the original name.
  • Editing any horizontal adjustment or vertical adjustment parameters changes the coordinate system name to "Zonename (Site)". If you remove these changes, the coordinate system name reverts to the original name.
• Defined using No projection/no datum, completing a GNSS site calibration changes the coordinate system name to "Local site".
• Defined using Key in parameters, the coordinate system name is "Local site".