# Scenario: Doing Your Own Dead Reckoning

You might want to do your own dead reckoning or use velocity data in the ROV’s coordinate frame. You can do this by enabling the $DVPDL (position delta) output. **Take care to understand the different coordinate system used in the $DVPDL message.**

If you plan to operate using the $DVPDL message, take extra care mounting the sensor head and entering any mounting offsets into the DVL using the SET-SENSOR-ORIENATION command.

Since the compass aspect of the IMU is not used in this scenario, the upgraded IMU has no real benefit over the baseline IMU in this scenario. Consider this when configuring your system.


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