19. Navigation Sensors
19-10
Drift used by the system is shown in the Other page of the Sensors dialog box. In the example below, set and drift
have been entered manually since the Manual box is checked. Other text that may appear to show source of set and
drift are
(LOG): Log or dual-axis log
(POSN) Position sensor
(FILTER): Kalman filter
(MAN): Manual entry.
POSN
Manual
Drift
Selected
Drift
used
by
system
Calculator
SOG/COG used by the system
Speed (water speed) used by system
Heading used by system
kn
Not selected
Alert related to SOG, COG, speed, heading, ROT, drift and docking speed components
It is possible that the operator has not selected any speed or heading
sensors, or that the selected sensors do not have any valid values. This
kind of a situation is critical for the system, because it cannot even
perform dead reckoning. When no speed source is available, the system
generates the alert "401 No speed available". When no heading source is
available the system generates the alert " 402 No heading available".
The system may find that SOG and/or COG from the sensors are
unreliable, at which time it generates the alert "413 SOG&COG
unreliable". Note that the source of SOG and COG is not only speed and
course sensors, but the source can also be position-fixing equipment. For
more information about source priority for SOG/COG, see section 19.6
"Source of SOG, COG, Speed, Heading, ROT, Drift and Docking Speed
Components".
Verify and select valid sensors in the SPD/CRS and POSN pages of the
Sensors dialog box for SOG and COG used by the system. Check also
ROT alert limit in Count/ROT page.
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