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Getting Started
Power-Off. To turn the unit off, press the ON/OFF key again. When the ON/
OFF key is pressed while the unit is on, the unit begins a countdown from 5
to 0 seconds. This countdown is displayed on the screen.
When the counter reaches 0 the
unit turns off. The countdown can
be interrupted and the unit re-
turned to normal operation before
0 seconds by pressing any key ex-
cept LIGHT or ON/OFF. You can
also turn the unit off immediately
by pressing ON/OFF a second time.
Initialization
Initialization means telling the unit where it is, and if necessary, collecting an
almanac.
To initialize, you must know your location within 300 miles (482.7 km). You
should also know your altitude as accurately as possible and the correct date.
If you do not know your position, consult an atlas or chart.
Although you can obtain a position fix without entering an initial position,
the unit obtains the first position fix in 55 seconds or less (after locating the
first satellite) if a correct initial position was entered. It is also possible to
operate without having entered an altitude, but this will affect the accuracy
of the position fixes, especially in 2D operation.
Regardless of which mode you plan to use, an altitude should be entered.
When operating in 2D, this altitude will be used to calculate all position fixes;
an inaccurate altitude will affect the accuracy of the computed fixes. When
operating in 3D, the initial altitude will be used as the basis for further
calculations; an inaccurate initial altitude will have a small effect on subse-
quent position fixes. An altitude must be entered when automatic operation
is selected because the unit will switch between 2D operation and 3D
operation. You should also enter the date, and if possible the time, although
the date is the critical input.
You must know your position within 300 miles (482.7 km) to initialize
manually. If you do not know your position, you can press AUX 9 or POS to
self-initialize. (This also requires that you are outside and have a clear view
of the sky.)
This procedure requires between 15 and 30 minutes to
complete. Self-initialization is discussed later in this chapter.
2-8
**WARNING**
POWER OFF IN
5 SECONDS
ProMARK X
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