# To simulate a connection to a GNSS receiver

The GNSS emulator allows you to test, demonstrate, or deliver training with Trimble Access using a simulated connection to a GNSS receiver. This removes the need to be outdoors and connected to a real GNSS receiver.

The GNSS emulator can be used on controllers or desktop computers that have Trimble Access installed.

- The GNSS emulator is a pre-recorded set of outputs from a receiver and cannot change based on real‑time commands from the software. This means that some functions cannot be used with the GNSS emulator, including tilt compensation, re-initialization, tracking resets, and SV subsets.

- While a job does not need to be open to simulate a device, you must open a job before you can use the GNSS emulator.

- To emulate a Trimble DA2 receiver, the controller must be connected to the internet. This allows the software to emulate using the DA2 with the Trimble Corrections Hub.

- The GNSS emulator function is not supported when using Trimble Access on a controller running Android.

To start the GNSS emulator

1. In Trimble Access, open the project and job you want to work in.

   The GNSS emulator function cannot be used with the default coordinate system, which is Scale 1.000. You must open a job that uses a fully defined a coordinate system, such as any coordinate system selected from the coordinate system library provided with the software.

2. Tap and select About / Support / GNSS emulator. The GNSS emulator form appears next to the map.

   The GNSS emulator item does not appear in the Support menu until you have opened a job.

   If you frequently use the GNSS emulator, tap and add it to your list of Favorite items. See Favorite screens and functions.

3. From the Receivers list, select the receiver type.

4. To be able to change the position of the rover using the GNSS joystick, select the GNSS joystick check box.

5. Configure the location of the base receiver. You can:

   - Enter coordinates that are appropriate for the coordinate system settings defined for the job.
   - Tap inside one of the coordinate fields and then use the Select tool on the map toolbar to select a position on the map. The coordinate fields are updated with the coordinates of the selected position.

6. Configure the starting location of the rover.

7. To see the extra buttons and features available if you are using augmented reality (AR) with a receiver that supports IMU tilt compensation, select the Show AR check box.

   The GNSS emulator function does not support emulating tilt functionality using the receiver. Enabling the Show AR check box enables additional controls in the software but it does not emulate inertial tilt or AR functionality. Viewing the AR controls may be useful in a classroom learning environment.

8. Tap Accept.

   The GNSS Emulator form closes and the emulator starts. The icons in the status bar indicate the software is connected to the GNSS receiver.

   The GNSS Emulator DOS window appears alongside the Trimble Access window. You must keep this window open while you are using the GNSS emulator.

   If you selected the GNSS joystick check box, the GNSS joystick pop‑up window also appears in Trimble Access.

To use the GNSS emulator

1. To start the GNSS RTK survey, do one of the following:

   - Tap a point on the map to select it and then tap Stakeout.
   - Tap and select Measure / RTK / Measure points or Measure codes.

2. Tap Accept to accept all of the default settings for the emulator receiver.

   The survey starts just like when Trimble Access is connected to a real receiver. The status line on the status bar updates, indicating the survey has started. In the map, the base position and the current rover location (indicated by the green cross) appear.

3. Measure a point or stake out the selected point.

4. To change the position of the rover, tap and hold on the map and select Move rover here, or use the GNSS joystick.

   If the GNSS joystick pop‑up window is not already shown, tap and hold on the map and select GNSS joystick.

   In the GNSS joystick pop‑up window, the current location of the rover is at the center of the position circle in the λ, ϕ tab.

   - To change the horizontal position of the rover, tap anywhere in the Position circle. For example, tap on the inner circle to move the rover 1 m in that direction.

     After a small delay, the map shows the new position of the rover.

   - To change the vertical position of the rover antenna, tap in the Height tile.
   - To reduce the scale used by the GNSS joystick by a factor of 10, for example from 1.0 m to 0.1 m, select the Fine check box. This change applies to both the Position and Height tiles.
   - To change the precision of the rover position, select the σ tab. The default option is Precise.
   - To change the amount of tilt of the pole, select the θ tab. Tap the eBubble softkey to open the eBubble to see the effect of changing the amount of tilt.
5. Continue measuring or staking out points as usual.
6. To end the survey, tap the receiver icon on the status bar and then tap End survey in the GNSS functions screen.
7. When prompted, choose whether to power down the receiver.
   - Tap Yes to disconnect from the simulated receiver and close the GNSS Emulator DOS window.
   - Tap No to keep the GNSS Emulator running and stay connected to the receiver (for example, if you want to start a new survey).