Kongsberg EM 122, Руководство по установке

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EM 122
Figure 42 Reference points
Reference points must be established on the vessel at selected positions. These are
needed during measurements of the sensor positions. Visual markings at these positions
should be prepared and noted on the vessel drawings with XYZ coordinates in the vessel
coordinate system.
Sensor location and alignment
Motion sensor
The system motion sensor is to provide the multibeam echo sounder with the angular
orientation of the vessel coordinate system with respect to the gravity vector i.e. roll
and pitch (usually the motion sensor also provides heave and sometimes heading). The
motion sensor must thus know how it is oriented physically with respect to the vessel
coordinate system. The motion sensor installation manual should be followed with
respect to how this is to be achieved. If the sensor has input fields for how it is mounted,
and the measurement of its orientation is feasible with an acceptable accuracy and effort,
it is recommended that this done at the same time as the orientation measurements of
the transducers is done. The final accuracy of the alignment of the sensor should in any
case be evaluated and confirmed by examining the sensor measurement values when the
vessel is in drydock with a known and accurately determined orientation. A calibration
survey should afterwards be performed at sea to confirm correct performance.
The motion sensor must have a specified accuracy in roll and pitch of 0.02º or better. Any
orientation measurements should be performed to this accuracy, as must the evaluation
of the measurement data of the sensor. (Note that the most critical parameter is roll and
a pitch accuracy of 0.05º is acceptable.)
The motion sensor must be aligned with the vessel centre line to an accuracy of 0.1º to
avoid that crosscoupling between roll and pitch measurements degrades the accuracy.
The motion sensor should normally be mounted on the centre line of the vessel, either
close of the multibeam transducers or close to the vessel's CG (Centre of Gravity).
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