Achieving best possible accuracy

To get the best possible accuracy in the field, regardless of the GNSS receiver you are using, follow these best practices.

Use the antenna above head height

The GNSS receiver requires a clear and unobstructed view of the sky so that it can track the signals from GNSS satellites.

If you are using a Trimble GNSS receiver (rather than the one in your device), fit the receiver to a stand-alone pole or to a pole inside a backpack to elevate the antenna above head height so that it is not obstructed by your body or other nearby objects.

Set the correct antenna height in the software

To ensure that the software is recording accurate heights, enter the height in the Antenna height field in the TerraFlex Settings screen.

The Antenna height value is the distance from the ground to the bottom of the antenna at the height it is used to measure positions. This could be when it is mounted on a pole, in a backpack when you are wearing it, or attached to a Catalyst Handle fitted to your device.

Set your preferred Accuracy Display Value in the software

In the TerraFlex Settings screen, select whether the Horizontal or Vertical accuracy value is the primary value shown on the map and when filling out a form. Choose the value which is most appropriate for your workflow. If features require a certain vertical accuracy, for example, then choose Vertical to make capturing data that meets this requirement easier.

If you are not using a real-time correction source, change the Primary Display Value in the software

If you are using offline GNSS corrections as the primary correction source, in the TerraFlex Settings screen set the Primary Display Value field to After offline GNSS processing so that you can see the expected accuracy of the data you are capturing.

Carry the GNSS receiver upright

If you are capturing multiple points of interest, maintain good antenna orientation between points of interest by carrying the antenna upright, rather than at your side. If the receiver is fitted to a pole, this means keeping the pole close to vertical while carrying it. If you are using a Catalyst Handle, this means keeping the DA2 horizontal rather than carrying it sideways.

Pointing the antenna away from the sky while in use will reduce the number of satellites that can be tracked or may introduce poor/reflected GNSS signals into the position solution. This can lower GNSS performance, or interrupt positioning, which will slow you down and reduce your data quality.

Keep the antenna stable during measurement

The software will measure the exact position of the antenna. If you are attempting to map or survey a point on the ground, make sure that your pole is stable and remains as vertical as possible using a level bubble. If you are using a Catalyst Handle, try to keep the antenna as stable as possible during measurement.

Take care when working around trees and buildings

GNSS technology requires direct line-of-site to GNSS satellites for optimum performance. Trees and buildings obstruct and reflect GNSS satellite signals which can lower performance and introduce errors. The technology used and the design of Trimble GNSS receivers mitigate these challenges, but you should still take care when working with GNSS near trees and buildings.

Pay close attention to the precision estimate shown, and if necessary take more time in obstructed environments to allow the receiver to converge on a high-precision solution, before logging a point. If you notice that the precision estimated by the receiver increases significantly, try moving to a more open environment to allow the precision to recover, to an acceptable level.

If using a rangefinder for remote feature capture, set the laser height in the software

To accurately capture the height of features captured remotely, enter the height of the rangefinder in the Laser Height field in the TerraFlex Settings screen.

The Laser Height value is the distance from the ground to the bottom of the laser when it is mounted on the pole you are using. If you are not using a pole it is the distance from the ground to the bottom of the laser at the height at which the rangefinder is used (your eye height).