Kongsberg Simrad ST90, Reference Manual

Page: 226 / 690

224
442704/A
Adjusting the built-in motion sensor offset
The information from a motion reference unit (MRU) (normally heave, roll and pitch
information) is imported into the ST90 system to increase the accuracy of the echo data. 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.
Prerequisites
Illustration:
A
Bow
B This is the alignment angle: (±180°)
C
0° transducer mark
D
0° motion sensor reference
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.
Context
As a general recommendation, the hull unit shall be oriented with the hoisting motor
pointing aft. If this orientation makes it difficult to access electrical connections, the hull
unit may be rotated during its installation to the most suitable direction. The 0° reference
for the built-in sensor is always related to the gantry. If the hoist/lower motor
does not
point aft (on or parallel to the vessel’s centre line) the built-in motion sensor offset must
be defined. Independent of the hull unit orientation, the offset of the built-in motion sensor
is always defined as:
The angle measured from the bow to the motion sensor’s 0° reference.
On the
MRU
page, define the offset as rotation around Z .
Simrad ST90 Reference Manual