Kongsberg Simrad ST90, Reference Manual

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MRU (Motion Reference Unit) page
Use the
MRU
(Motion Reference Unit) page to insert the physical location of the motion
reference sensor (MRU) with reference to the vessel coordinate system.
Description
The ST90 system is provided with a built-in motion sensor to provide electronic stabilization
of the sonar beams. It is placed inside the Motor Control Unit. The motion sensor measures
the roll and pitch movements of the vessel.
Note
If you want to use the built-in motion sensor, you do not need to enter any offset values.
If the hull unit has been installed with the Motor Control Unit pointing straight aft, you do
not need to enter any rotation values. If the unit faces in any other direction you must
compensate for this by typing the relevant value for
Rotation Around Z
.
For improved operational accuracy, an external motion reference unit (MRU) can be used.
offsets
The offset values specify the physical location of the motion reference unit relative to
the reference point (origin). The relevant offset values can normally be taken from
the vessel drawings.
Rotation
The values for rotation around the X, Y and Z axis are used to compensate for any
misalignments made during the physical installation of the motion reference unit.
Such misalignments occur if the sensor is not placed in parallel with the vessel’s
horizontal and/or vertical planes. We strongly recommend that you install your motion
reference unit so that all rotation angles can be set to 0 (zero).
The required accuracy of the offset and rotation angles depends on the accuracy requirements
for the echo data.
Tip
The motion sensor offset values are not important for sonar operation. Correct values for
motion sensor rotation are important for roll and pitch compensation.
Simrad ST90 Reference Manual