# To start an RTX survey

1. Start the survey using the RTK survey style you configured for RTX. See Configuring an RTX survey.

   When data from the RTX correction service is being received via:

   - RTX (SV signals), the radio icon changes to an RTX icon , and RTX appears on the status line.
   - RTX (internet), the GNSS internet source icon appears.

2. Wait for convergence.

   Typical convergence times depend on the region you are working in and the GNSS receiver you are using:

   - If the GNSS receiver has Trimble ProPoint technology, in most cases you should experience convergence in 1-3 minutes in RTX fast regions and 3-10 minutes globally.

   - If the GNSS receiver does not have Trimble ProPoint technology, convergence will typically take 5-10 minutes in RTX fast regions and less than 15-30 minutes globally.

   For more information on convergence times, see RTX correction service.

   When the message Convergence has been gained appears, you can begin surveying

   To view the RTX status screen, in an RTX (SV) survey, tap . In an RTX (internet) survey, tap RTX status in the Instrument menu.

3. If you are using a receiver with IMU tilt compensation, align the IMU.

4. Measure or stake out points.

- Although the RTX rover solution may have converged, it may not yet meet the precision tolerances for point measurement. You may need to remain at a point longer to meet the precision tolerances specified, as the RTX rover solution should converge more when the rover is in static mode. Precisions for surveys using the Trimble Centerpoint RTX service are very sensitive to environmental conditions such as multipath, ionosphere scintillation, and particularly tropospheric conditions and tree canopy.
- To change the precision level at which convergence is acceptable, clear the Auto tolerance check box in the Rover options screen and enter the values that you want to use.

To compute an RTX‑RTK offset

Take great care to avoid changing the offset already in a job to a less precise offset, as this action may cause the precision of the points stored in the job to no longer meet the precision tolerances applied when the points were measured. See RTX‑RTK offsets.

1. Tap and select Measure. Tap RTX‑RTK offset.
2. In the RTK point field, select a point. This must be a point measured using RTK.

3. In the RTX point field, select or measure an RTX point. This must be a point measured using the CenterPoint RTX correction service.

   The offset is computed immediately when the two point fields are completed.

4. Review the results of the offset computation. If acceptable, tap Store to commit the offset to the job.

   The precision of the offset and therefore the precision of the RTX points reduced into the RTK reference frame depends on the precision of the measured RTK and RTX points used to compute that offset. You must use the most precise point measurements possible to compute the offset.

To remove an RTX‑RTK offset, view the offset in the RTX‑RTK offset screen and then tap None. Tap Yes to confirm. The value of the offset is changed to zero.

To view RTX status

To view the RTX status screen, in an RTX (SV) survey, tap . In an RTX (internet) survey, tap RTX status in the Instrument menu.

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.

In an RTX survey, the Reset button on the satellite plot/list screen resets SV tracking as well as RTX convergence. The Reset button on the RTX status screen resets the RTX convergence but not the satellite tracking.