Kongsberg Simrad ST90, Reference Manual

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Inserting the installation parameters for the motion reference
unit (MRU)
The physical location of the motion reference unit (MRU) relative to the transducer is
required to allow the ST90 system to adjust for roll and pitch as accurately as possible.
This task is only applicable is you are using an external motion reference unit on your
ST90 system.
Prerequisites
The ST90 system has been set up with its hardware units connected as specified in the
Installation Manual .
• The ST90 system is turned on and operates normally.
• The ST90 system is in Normal mode, but
TX Power
is set to Off to prevent transmissions.
• The vessel is berthed or at sea.
• Neither tools nor instruments are required.
The relevant offset values can normally be taken from the vessel drawings.
Context
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
Maintenance procedures