Water tracking🔗
Water tracking is a mode where the DVL estimates velocity relative to the water column instead of the sea bottom. It can be useful when the DVL cannot get bottom lock, or when the movement of the water itself is relevant.
Supported models🔗
| Model | Water tracking | Available from software version |
|---|---|---|
| DVL A50 | Supported | 2.7.0 |
| DVL A100 | Supported | 3.4.0 |
| DVL A125 | Supported | 2.7.1 |
| DVL A250 | Supported | 3.3.0 |
Water tracking requires a software version with water tracking support. See Software updates for update instructions.
Water tracking works the same way on all models.
Mode of operation🔗
Water tracking uses acoustic reflections from the water column, approximately 1.5 m to 4.5 m below the DVL. It is intended for use when the distance to the bottom is more than 4.5 m.
When the bottom is within the normal bottom-tracking range of the DVL, water-tracking velocity estimates can be affected by bottom reflections. With fast currents the velocity estimate can become invalid, and with slow currents the estimate can be biased toward the bottom-relative velocity.
The maximum measurable velocity in water tracking mode is 7.5 m/s.
Update rate is 2 Hz.
Warning
Dead reckoning performance with water tracking is untested and can give large errors.
Web GUI🔗
The dashboard shows the active tracking mode. On supported software, the tracking mode can be selected from the configuration page.
The diagnostic page still shows spatial velocity, per-transducer velocity, and validity. In water tracking mode, the acoustic signal view shows signal strength and noise as separate time-based graphs.
Enable water tracking🔗
Water tracking is enabled by setting range_mode to wt. Select the interface you integrate with:
Available in TCP JSON API version json_v3.2 and up on DVL A50/A125, and json_v4.1 and up on DVL A100/A250. The commands and reports are identical on both model families; only the version numbering differs, because DVL A100/A250 have additional capabilities such as hardware triggering.
Use the TCP JSON API configuration method for your model:
Enable water tracking by setting range_mode to wt:
Set range_mode back to auto to return to automatic bottom tracking:
Water tracking does not introduce a separate report type. The DVL continues to use the normal velocity-and-transducer report, with the field "type" showing the active tracking mode. When water tracking is active, the report describes velocity relative to the water column rather than velocity relative to the bottom and the "type" will be "velocity_water".
See the TCP JSON API for your model for the report fields:
Available in serial protocol 2.7.0 and up on DVL A50/A125, and 3.1.0 and up on DVL A100/A250. The commands and reports are identical on both model families; only the version numbering differs, because DVL A100/A250 have additional capabilities such as hardware triggering.
Use the serial configuration method for your model:
Enable water tracking by setting range_mode to wt using the wcs command. The wcs command takes one more parameter on DVL A100/A250 than on DVL A50/A125, so the number of commas differs between the model families.
On DVL A50/A125:
On DVL A100/A250:
Set range_mode back to auto to return to automatic bottom tracking.
On DVL A50/A125:
On DVL A100/A250:
Water tracking introduces a serial report called wrs, which is similar to the wrz report but does not include altitude data. Use this data when water tracking is activated.
wrs,[vx],[vy],[vz],[valid],[fom],[covariance],[time_of_validity],[time_of_transmission],[time],[status]
See the serial protocol for your model for the report format:
wrs is used for two different reports on DVL A50/A125
On DVL A50/A125 the wrs prefix is used for both the time status response and the water tracking velocity report. Inspect the fields after the prefix to tell them apart: a water tracking velocity report begins with a decimal velocity (e.g. wrs,0.120,...), while a time status report begins with an integer epoch timestamp (e.g. wrs,1776409079,...).