NSR Marine NGR-1000, User Manual

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NGR-1000/NGR-3000 USER MANUAL
NGR-1000/NGR-3000 UM.E 20190331-04
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– the probability of false alarms >5 %, or
– the probability of not detecting an error condition >5 %.
Those conditions may occur if an insufficient number of satellites are available, for
example 4 or 5 with 2 satellites "close" together in azimuth and elevation, causing the
geometry to degrade to the point that the RAIM calculation becomes unreliable. Note
that the resulting accuracy based on 4 or 5 satellites in use may be within the selected
accuracy level, but the RAIM algorithm cannot verify it.
 Conditions for the "unsafe" state
The "unsafe" status will be used if the integrity calculation is performed with a
confidence level above 95 % for the selected accuracy level, and RAIM calculates the
probable position error exceeding the selected accuracy level. Note that also here a
robust geometry is required to reach this confidence level. The "unsafe" state can be
reached when satellite range errors degrade the navigation solution, causing the resulting
accuracy to be outside the selected accuracy level.
5.1.4.2 RAIM Level
RAIM level can be set between 10-100m.
Accuracy level is not of the indication of position accuracy while it is only the calculation
reference for RAIM.
5.1.5 Beacon/SBAS
The system will alarm if the condition of loss of differential signal occurs.