# Bridging data outages using xFill

Trimble xFill® technology leverages a worldwide network of Trimble reference stations to bridge communication outages via satellite‑delivered correction data.

Select the xFill check box in the Rover options screen of the survey style to continue surveying during base data outages for up to 5 minutes. Note that the xFill solution precision will degrade over time. Trimble Access continues storing RTK vectors and all points are measured relative to the same RTK coordinate system.

To use this option, your GNSS receiver must support xFill. xFill is not available if you have selected OmniSTAR as the fallback option in the Satellite differential field.

xFill is only available for areas covered by the RTX broadcast satellite. For more information go to positioningservices.trimble.com.

xFill-RTX

When using a receiver that has a subscription to the Trimble Centerpoint RTX correction service, select the xFill option to use xFill‑RTX and continue surveying during base data outages indefinitely. When the xFill precision estimates have increased to the level of the RTX precision estimates, the receiver transitions from an RTK‑based xFill position solution to using an RTX position solution called xFill‑RTX. The xFill‑RTX position solution suffers no continuing degradation of precision over time. The XFill‑RTX solution is brought into terms with the RTK base station by the rover receiver.

When measuring a point in xFill, the precision estimates continue to increase, and cannot converge until xFill‑RTX positioning begins. During xFill the best position is the single measurement at the beginning of the occupation. For this reason, any point measured when using xFill technology prior to the transition to xFill‑RTX will become acceptable after 1 second. The Occupation time and Number of measurements settings in Options are overridden by the 1 second rule during xFill mode.

If you are using xFill‑RTX and have a CenterPoint RTX subscription based on hourly blocks purchased for the service, an "End RTX tracking to stop subscription timer?" message appears when you end the survey. Select Yes to disable the RTX SV tracking in the receiver. When you start a new survey using the RTX service, you will need to wait for the RTX solution to re‑converge before you can use xFill‑RTX. If you wish to start another survey in a relatively short period of time after ending the current survey, and you don't want to wait for the RTX solution to re‑converge, select No. Selecting No means your RTX subscription will continue to use time even though you are not in a survey, but the next survey will start with a converged solution if RTX and GNSS tracking is maintained between surveys.

xFill status

If xFill is not ready, the icon in the status bar is . When xFill is ready the xFill ready field shows Yes in the Rover data link screen and the status bar icon changes to . If you lose RTK corrections, xFill takes over and the status bar icon changes to . Regaining RTK base data reception causes a switch back to RTK and the status bar icon returns to .

Once RTX has converged the xFill‑RTX ready field shows Yes in the Rover data link screen. When the receiver transitions to xFill‑RTX positioning, the status bar icon changes to .

To view the RTX status screen, in an RTX (SV) survey, tap . The RTX status screen shows the current Correction satellite name. To select a different satellite, tap Options and then select the required satellite from the list. You can change the correction satellite at any time; changing the correction satellite does not require restarting the survey. Alternatively, select Custom and then enter the frequency and bit rate to use. Changes you make to the settings are used the next time you start a survey.