# Inertial Measurement Unit (IMU) The DVL has two options for the Inertial Measurement Unit. The baseline IMU supplied with the system is reasonably priced, but it requires you to manage its calibration, a tedious and sometimes annoying process. We offer an upgraded IMU as an option. It does a reasonable job of managing its own calibration, but you need to check to be sure it is ready for use each time before deploying the ROV. The actual dead reckoning performance of the DVL with either IMU is similar, assuming you have properly calibrated the baseline unit. The upgraded IMU is substantially more expensive. Only read and follow the calibration instructions for the IMU you are using. Mix-and-match will just lead to confusion and frustration. If you want the simplest setup with the least hassle from the IMU, we recommend upgrading the IMU. The upgraded IMU has a much simpler (almost non-existent) calibration process that is easy to do without seeing the calibration state. Additionally, if your ROV is too big to physically manipulate easily during calibration, consider the upgraded IMU. --- # 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/dvl-75/inertial-measurement-unit-imu.md?ask= ``` 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.