GeoLock

Trimble instruments provide Autolock® and GeoLock™ technology for locking onto and tracking remote moving targets. GeoLock technology is GNSS assisted Autolock. During a robotic survey, if the instrument loses lock to the target and GNSS positions are available from the controller or another connected device, you can use GeoLock technology to use the GNSS positions to help point the instrument to the target.

When lock to a prism is lost, GeoLock turns to your GNSS location before using Autolock to lock back onto the prism. GeoLock uses the best available GNSS location. This could be an autonomous position or an RTK position from a GNSS receiver, or an autonomous position from your controller if that is all that is available.

NOTE – When using a controller with internal GNSS, a connected GNSS receiver is always used in preference to the internal GNSS.

Enable GeoLock from the Target controls screen or the Instrument Functions screen. If the total station is set up in terms of the defined projection and datum, then GeoLock is ready as soon as the station setup is complete. When GeoLock is ready, the message GeoLock ready appears in the status bar, and the target icon displays a satellite icon above the prism . For more information on enabling GeoLock, see Enabling Autolock, GeoLock, FineLock or Long Range FineLock.

NOTE – With GeoLock enabled when storing a point, the Lock type will be shown as Autolock in Review job under the Target lock details group box.

If you have a fully defined coordinate system, then an accurate relationship between the GNSS positions and local positions already exists using the coordinate system definition. The software assumes that the total station is set up in terms of the defined projection and datum, and GeoLock is ready as soon as the station setup is complete. If the total station is not setup in terms of the defined projection and datum, Trimble Access will automatically refine and update the relationship after you complete a station setup to ensure GeoLock works well.

If you do not have a defined coordinate system, you must resolve the relationship between GNSS positions and local positions before GeoLock is ready. Once a station setup is complete, the Trimble Access software uses the positions from the GNSS receiver and the angles tracked by the robotic instrument to determine the relationship between the two positioning systems. GeoLock computes the relationship independently of the job's coordinate system settings.

To determine the relationship, make sure that the GNSS receiver has a clear view of the sky and then, with the instrument locked to the prism, move the pole around the instrument until the relationship between the GNSS positions and local positions is resolved. A minimum of five positions at least five meters apart and at least ten meters from the instrument are required. It is best to have the instrument in TRK mode while resolving the relationship. If the geometry and GNSS positional accuracy is poor, you need more than five positions to resolve the relationship. Poor GNSS positional accuracy may result in an inaccurate relationship being computed.

TIP – If you are using a scale factor only projection

  • and you are going into a bad GNSS environment for an extended period of time, tap pause to pause GeoLock and stop new positions being added into the GNSS solution. Tap play to resume GeoLock and start adding points into the GNSS solution again.

  • and GeoLock has good data, it can detect bad data and exclude it from its computations. However, if there are more bad positions than good positions, it is difficult for GeoLock to detect and exclude bad positions. Too much bad data in the computations may prevent GeoLock from becoming ready. If this occurs, move to a better GNSS environment and then tap Reset to delete the GeoLock solution. Repeat the process of resolving the relationship between GNSS positions and local positions for GeoLock to be ready again.

NOTE –  

  • To view the GNSS status, tap GNSS on the Target controls screen. Alternatively, from the GNSS status screen, tap and hold on the target icon.
  • If you perform a calibration or change the coordinate system settings, the existing relationship between the GNSS positions and local positions is lost and must be recomputed.

If GeoLock is ready and when snap to target is enabled, the instrument typically snaps to the target immediately if there is a target within the Autolock view area. If the instrument does not snap immediately, it performs the chosen automatic behavior to assist with locking on to the target. See Target control settings for more information on when lock is lost.

When using GeoLock with a Trimble receiver and a GNSS survey has been started, a cross indicates the position of the GNSS receiver. When using any other receiver or a Trimble receiver without a survey started and a GNSS position is available, a satellite icon appears in the map. If a GNSS position is available and GeoLock is ready, a black satellite icon appears . If a GNSS position is available and GeoLock is not ready, a red satellite icon appears .

To turn to the GNSS position in a conventional survey, make sure that there is nothing selected in the map and then tap and hold briefly in the map. From the menu that appears, select Turn to GNSS to turn the instrument horizontally to the GNSS position.

TIP – A better GeoLock solution can be computed if the instrument is in TRK mode and locked to the target at the beginning of a survey while moving around for 10-20 seconds when more than 10m from the instrument.