NorthStar Navigation GM1708 961XD - Manual (Page 39)

SECTION TWO - Installation
961 INSTALLATION MANUAL Revision A Page 29
Figure 21: Advisory message
If chart CDs for your geographical area have been installed onto the 961’s
hard drive, and after the unit acquires GPS signals, you’ll see your vessel
symbol centered on the CHART screen at your present position. Until the
961 acquires GPS signals, the small position-fix circle will be located at
the last known position.
If there aren’t any charts covering your geographic location installed on
the hard drive, the 961 displays a plotter grid instead of a chart.
For new units
only
When you first turn your 961 on, you’ll see your present vessel position
at the center of the chart, represented as a small circle. A 961 that
recently has been used either at or near that same position will usually be
ready to navigate within several minutes.
If the 961 doesn’t acquire GPS signals soon enough, however, your last
position fix (from the last time the unit ran) will be represented by a small
position-fix circle; you’ll see an alarm message in the upper portion of the
CHART screen, and you’ll hear the GPS alarm beep. This sequence often
occurs when a 961 is used for the first time in a new location hundreds of
miles from where it was last used, and means you’re being notified that
the 961 is searching for the necessary satellites. This take should take two
to five minutes to acquire, after which the 961 is ready to navigate.
GPS signals The 961 uses a high-performance GPS receiver as its primary source of
position data. Calculated directly from the received satellite data are your
present position in lat/lon coordinates, time of day and date,
speed-over-ground (SOG) and course-over-ground (COG), and an esti-
mate of the 961’s accuracy.