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Operator's Manual
GPS5 - RAIM Status Screen (for RAIM Enabled Models Only)
RAIM (Receiver Autonomous Integrity Monitoring) is an optional
feature that can be enabled in the MX420 CDU. The RAIM feature is
mandatory for IMO compliant vessels. It alerts the operator that a
condition may exists in the GPS positioning solution that reduces the
desired accuracy of the ship's position. This feature requires at least
five or more GPS satellites to operate properly, four satellites or less are
considered to be a caution or unsafe RAIM condition. If the statistical
RAIM error exceeds a selected limit (100 meters default) a "RAIM
Unsafe" or "RAIM Caution" alarm will be indicated in the MX CDU.
This means that the RAIM estimated position error is equal or greater
than the preset limit. The operator is advised to take extra precaution-
ary measures when using the navigation solution until the RAIM indi-
cator switches to "RAIM safe" condition. When less than 5 satellites
are receivable a "RAIM Caution" will be indicated.
The GPS5 screen shows the position Lat/Long, height of antenna,
HDOP, number of satellites used, the satellite ID number that may
cause the statistical error and its bias value. It also shows a table
containing the PRN numbers of satellites in use, their residual errors
and elevations. Below it is the RAIM Status indicator and time. The
RAIM icon is shown on the top-right corner of the display.
Position errors may be caused by unhealthy satellites, incorrect
pseudoranges, poor DGPS corrections and excessive atmospheric in-
terference. When the RAIM caution or RAIM unsafe alarm is on, the
GPS/DGPS accuracy may be degraded but still usable when navigat-
ing in open waters.
When the RAIM option is enabled an icon is posted on the top right
corner of all screens.
96
- means RAIM safe condition
- means RAIM Unsafe condition, position errors exceeded the
range limit specified under the CFG/GPS/Accuracy Rng.
GPS
Version 2.0
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