> For the complete documentation index, see [llms.txt](https://docs.ceruleansonar.com/c/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.ceruleansonar.com/c/dvl-75/inertial-measurement-unit-imu/baseline-imu-calibration-for-each-mission-or-each-time-power-is-applied.md).

# Baseline IMU Calibration for Each Mission or Each Time Power is Applied

Once the initial calibration is complete and stored in flash memory, on subsequent boot-ups only a few simple maneuvers should be needed for the IMU to recognize the saved calibration is still valid and begin outputting data. These maneuvers are typically as simple as smoothly turning the ROV upside-down and then right-side up once or twice.

If you can at least see the heading output, a great final check is to point the ROV (or the bow direction on the DVL head) north and make sure the heading output goes to zero degrees. If it does not, you may need to let the system sit for a few minutes, then rotate the ROV around the Z axis a few times until it does.

If you re-mount the unit without both invalidating the old calibration data and then completing an initial calibration, on subsequent boot-ups it may take quite a few maneuvers to complete calibration. It may be worse than starting the initial calibration from scratch since the IMU may have to “undo” old calibration coefficients before converging on the new


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