Sensor Calibration
Example of color change in magnetometer output when the magnetometer passes over a metal object. The intensity of the color increases (more red or purple) when a large metal object is within minimal distance.​
USBL System Calibration
The USBL System Calibration supports hydrophone, GPS and reference offsets. The purpose of this type of USBL System Calibration is to confirm that no biases are caused by the system's bearing information and that the speed of sound (scale factor) used in position calculations is correct.
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It is usually considered acceptable to use calibration results to remove any minor residual errors such as a bearing error of less than 1 or 2 degrees and speed of sound error within 1% or so. If large errors are found then the instillation of the USBL and its support equipment should be reviewed and necessary corrections made.
Multibeam Sensor Calibration
The Multibeam sensor calibration finds the angular offsets with respect to the navigation sensors, for example the Vertical Reference Unit, Motion Reference Unit and the Gyro Compass and Time Latency.
3 Axis Magnetometer Calibration
The 3 Axis Magnetometer Calibration corrects the raw magnetometer output for magnetic and permanent soft iron influences. The corrections for each axis are the bias, the scaling factors and non-orthogonal axis angular biases.
This image shows a Mag survey layered on gray shaded sonar data of a steel wreck. The inserted image of uncalibrated data shows a greatly reduced detection range and Mag output dependency on heading.
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