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16. NAVIGATION SENSORS
16-10
16.6 Switching of Sensor and Resulting Indication
When a sensor cannot be used because of some problem, the system automatically
switches the sensor. When this occurs the name of the newly selected sensor appears
in yellow.
16.7 Filter Status
The ECDIS incorporates a filter that receives raw sensor data, checks sensor integrity
and processes sensor data to produce a continuous estimate of ship’s position and
motion.
By default, the filter uses data from all available sensors for filtering and integrity mon-
itoring. The exception is heading data; only the selected heading device affects the
output of the filter, but other heading sensors (including magnetic compasses) are
used for integrity monitoring.
Sensors may be excluded manually or automatically. An excluded sensor participates
in neither integrity monitoring or filtering. The filter automatically excludes a sensor
from use if the sensor fails the first level of integrity check (for example, if a sudden
jump is detected). If the actual integrity check fails for some reason and the filter is able
to identify the faulty sensor, the faulty sensor is automatically excluded.
Sensor integrity is determined by: (1) monitoring the statistical accuracy of each sen-
sor independently and analyzing the input values and using the information of the type
of sensor, and (2) monitoring the difference between pairs of sensors. The result is
either [Passed] or [Failed]. When there is no other source to compare with, the result
is [Doubtful]. If there are multiple sources with which the sensor can be compared with,
the result is [Failed] if all the pairwise comparisons have failed, otherwise the result is
[Passed].
LOG
BT
Speed sensor
changed