Multibeam Sonar Theory of Operation

Detection Processing and Range Calculations Multibeam Sonar Theory of Operation
The effect of rotation about each of these directions is illustrated in Figure Chapter 4 - -14. The
degree of rotation is measured as an angle.
Figure Chapter 4 - -14: Roll, Pitch, and Yaw Angles
Between time slices, the ship moves in each of these six different ways: surge, sway, and heave
of its center of mass, and roll, pitch, and yaw about its center of mass. In other words, the ship has
six degrees of freedom to its motion. The SEA BEAM 2100 accepts input from two
measurement systems that constantly monitor all six degrees of freedom:
• The Navigation instrument records the position of the ship (latitude, longitude, and heading at
time of ping) associated with surge, sway, and yaw motions.
• The Vertical Reference Unit (VRU) records roll, pitch, and heave information.
Of these instrument readings, the roll and pitch values from the VRU are necessary for per-timeslice
processing. The VRU, however, does not make measurements with the frequency of the
time slices. Obtaining unique and accurate values that correspond to the times of the time slices
requires linear interpolations from the two nearest VRU measurements.
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