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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
DVL A50 Supported
DVL A100 Planned, not available yet
DVL A125 Supported
DVL A250 Planned, not available yet

Water tracking requires a software version with water tracking support. See Software updates for update instructions. For DVL A100 and DVL A250, water tracking is planned but not available yet.

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.

TCP JSON API🔗

Water tracking is available in TCP JSON API json_v3.2 for supported models. Use the TCP JSON API configuration method for your model:

Enable water tracking by setting range_mode to wt:

{"command":"set_config","parameters":{"range_mode":"wt"}}

Set range_mode back to auto to return to automatic bottom tracking:

{"command":"set_config","parameters":{"range_mode":"auto"}}

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:

Serial API🔗

Water tracking is available in serial protocol >= 2.7.0 for supported models. Use the serial configuration method for your model:

Enable water tracking by setting range_mode to wt using the wcs command:

wcs,,,,,wt,

Set range_mode back to auto to return to automatic bottom tracking:

wcs,,,,,auto,

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: