# $DVPDL and $DVPDX: DVL Position and Angle Deltas Messages

The $DVPDL/X messages supply odometry data intended for use in user-supplied dead reckoning or in user-built position-hold functions. It is output at a variable rate between 5Hz and 20 Hz. The $DVPDX message is the same as a $DVPDL message with a few extra fields tacked onto the end.

The Position Deltas X, Y and Z are in the [vehicle coordinate frame](/c/tracker-650/coordinate-systems.md) as modified by the [SET-SENSOR-ORIENTATION](/c/tracker-650/communicating-with-the-tracker-650/commands-accepted-by-the-tracker-650/set-sensor-orientation.md) command. 

The Pitch and Roll data and the standoff datum are in the [sensor coordinate system](/c/tracker-650/coordinate-systems.md) and are not influenced by the SET-SENSOR-ORIENTATION command.

Format:

$DVPDL,tu,dtu,adr,adp,ady,pdx,pdy,pdz,c\*hh

$DVPDX,tu,dtu,adr,adp,ady,pdx,pdy,pdz,c,mode,pitch,roll,stdoff\*hh

Example:

```
$DVPDL,101234000,50000,0.001263,-0.019663,-0.745226,-0.000,0.001,-0.005,100*22
```

| **Field** | **Name**          | **DVL Notes**                                                                                                               |
| --------- | ----------------- | --------------------------------------------------------------------------------------------------------------------------- |
| tu        | Time uSec         | Time since system boot in microseconds                                                                                      |
| dtu       | Delta Time uSec   | Time since the last message, in microseconds                                                                                |
| adr       | Angle Delta Roll  | Angle delta from previous message, in radians. Always 0 for Tracker 650.                                                    |
| adp       | Angle Delta Pitch | Angle delta from previous message, in radians. Always 0 for Tracker 650.                                                    |
| ady       | Angle Delta Yaw   | Angle delta from previous message, in radians. Always 0 for Tracker 650.                                                    |
| pdx       | Position Delta X  | Position delta from previous message, in meters                                                                             |
| pdy       | Position Delta Y  | Position delta from previous message, in meters                                                                             |
| pdz       | Position Delta Z  | Position delta from previous message, in meters                                                                             |
| c         | Confidence        | 0..100, where 100 = maximum confidence, 0 = no confidence. If 0, assume all other fields after dtu are garbage.             |
| mode      | System Mode       | Used by Cerulean for diagnostic purposes                                                                                    |
| pitch     | Pitch             | Rotation of the sensor head around the Y axis, with respect to the target plane, in degrees. Parallel = 0. Right-hand rule. |
| roll      | Roll              | Rotation of the sensor head around the X axis, with respect to the target plane, in degrees. Parallel = 0. Right-hand rule. |
| stdoff    | Standoff          | Distance between sensor head and target plane along a normal to the target plane, in meters.                                |
| \*        | End of fields     |                                                                                                                             |
| hh        | Checksum          | NMEA standard                                                                                                               |


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.ceruleansonar.com/c/tracker-650/communicating-with-the-tracker-650/outgoing-message-formats-tracker-650-to-host/usddvpdl-and-usddvpdx-dvl-position-and-angle-deltas-messages.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.