Kongsberg Simrad CS90, Справочное руководство

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antennas, echo sounder and sonar transducers, motion reference units, etc.) are referenced to
the origin. In most cases, the location of the vessel’s "official" origin has been defined by
the designer or shipyard. This origin is normally identified with a physical marking, and
also shown on the vessel drawings.
Frequently used locations are:
• Aft immediately over the rudder (frame 0)
• Vessel’s centre of gravity
• The physical location of the motion sensor
Coordinate system alternative origins
If necessary, other origin locations may be defined for specific products or purposes. One
example is the
Navigation Reference Point that is frequently used. Whenever a vessel
is surveyed to establish accurate offset information, the surveyor may also establish an
alternative origin location. Whenever relevant, any such alternative locations must be
defined using offset values to the "official" origin established by the designer or shipyard. A
commonly used alternative origin is the physical location of the vessel’s motion sensor.
Defining the physical location of each sensor
By means of the vessel coordinate system, the physical location of every sensor can be
defined using three numerical values for X, Y and Z. These values must define the vertical
and horizontal distances from a single reference point; the origin. The physical location of
the motion reference unit (MRU) is often the most important sensor to define. For many
systems, the vessel heading is also a critical measurement.
In this example, a second reference
point has been established. It
is defined with three positive
offset values for X, Y and Z. All
values are positive because the
new reference point is in front of
and below the origin, and on the
starboard side.
The accuracy of the three
numerical values for X, Y and Z defines the accuracy of the sensor data. If you require a
high accuracy, for example for underwater positioning, underwater mapping or scientific
measurements, you must have each sensor positioned using professional land surveying. For
such use, a good alignment survey is critical for high quality results. Surveys are normally
done by qualified and trained surveyors using proven survey equipment and methods.
Simrad CS90 Reference Manual