Kongsberg cJoy OT, Руководство оператора

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Operating procedures
• A prediction test detects sudden jumps or large systematic deviations in the measured
position. The limit for the prediction test is a function of the estimated position in
the Vessel Model and the actual measurement accuracy.
If the results of the variance and prediction tests suggest that the position measurements
from the reference system are not accurate, then the measurements are not used.
The characteristics of the position-reference system (when active) are shown on the
Position-reference System view (see
Position-reference System view on page 34).
Freeze test
If the position-reference system has an internal error causing the same measurements
to be continuously sent to the Vessel Model, the system could, if no precautions were
taken, mistake the data for good and stable measurements.
The freeze test rejects repeated measurements and the system treats repeated
reports of the same position from the position-reference system with caution. The
position-reference system is monitored and its input rejected if the variation in its
position measurements is less than a predefined limit over a given time period. In such a
situation, the following alarm message is displayed:
Reference position frozen
You should disable the position-reference system.
Note
By configuration, the freeze test is usually disabled for GPS position-reference systems
due to the resolution in the data from this particular type of position-reference system.
Variance, weight and the Variance test
The system calculates a variance for the position-reference system when it is in use. It
then assigns a weighting factor to the position-reference system, based on its calculated
variance. The higher the system's variance, the lower its weighting factor. However,
with only one position-reference system, the assigned weighting factor will be either
“one” (maximum) when the position-reference system has an “online” status or zero
when it has any other status.
The following warning message is displayed if the variance of the position-reference
system exceeds a system-set limit:
Reference high noise
The position-reference system is not rejected in this event.
The variance test detects if the variance in the measured values exceeds the reject limit.
The variance reject limit is based on the expected variance of the position-reference
system. The following warning message is displayed when the position-reference system
is rejected due to too high variance:
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