Surface
Mounting
-
Without Access
PCF OFFSET
If
you
don't have access to the back side of the
mounting
surface,
use
the "cleats"
supplied
with the AccuNav II.
(Note:
This is
assuming you
can "snake" the module's
cable to a location that is accessable. A hole
will still need to
be drilled in the
mounting
surface for the
cable.) Using
the
gasket
as a
template,
mark and drill the 17mm
(11/16")
hole for the
cable. Attach the cable
to the module and
drop
the other end of the
cable
through
the
gasket
and down the hole. Place the module on the
gasket.
Slide
the "cleats" onto each end of the module and
(using
the
cleats as
templates)
mark four holes for 5 mm
(#10) mounting
screws.
Drill
the
holes,
then
replace
the cleats on the module and fasten them to
the
mounting
surface with 5 mm
(#10)
screws. Route the cable to the
AccuNav II.
The GPS
navigation system
relies on
complex
mathematical calculations
to determine
your position
based on satellite data and other factors. One
factor is the Earth's
shape.
Since
the Earth
is
not
a
true
sphere,
variations
in the calculations have to be made to accommodate deviations. To make
matters more
complex,
not
everyone
uses the same data to determine
what the deviations are. The size and
shape
of the
ellipsoids
that are
used
to
approximate
the earth's surface are
improved
often. This can lead to
errors if
your navigation
device uses one
ellipsoid,
while
your
chart uses
a different one. The term used for these
ellipsoids
is
"Datum."
To reduce the errorfactor between
datum,
this unit
gives you
the
capability
to move or "offset" the
position
shown on the
display
to
match the one on
the
chart.
The unit will add this
offset to all
position displays
at all times.
Remember,
the UPS error is
very dynamic
and the PCF
offset should
never be used in an
attempt
to cancel the error. In
general
terms this
feature should
only
be used if
your map
indicates what the
possible
error
is. This feature should
always
be reset to zero
(0)
when finished with that
chart.
For
example, suppose you
are
stopped
at a location that is
accurately
marked on a chart. Your unit shows a
longitude position
that is .010
degrees
less than the one on the chart.
Using
the
Positipn
Correction
Factor
(PCF)
Offset
feature,
you
make the unit read the same as the
chart.
If
you move,
the unit will
continuously
add the
change
to all
position
displays.
This makes it more
closely
match the datum used
by
the
chart.
For this
reason,
you
should be careful when
entering
the PCF offset. This
offset is saved in
memory.
It doesn't
change
when the unit is turned off.
However,
a Preset does erase the PCF factor.
To set the PCF
factor,
first
press
the MENU
key,
then
press
the
key
next
to the "CHANGE GPS SET-
Position Correct
ioid
TINGS" label. Now
press
the
Factor
key
next to the "ADJUST FCF
______________
OFFSET" label. The screen
______________
shown below
appears.
Now
press
the
key adjacent
to
the
"CHANGE
OFFSET" label
to enterthe correction factorfor
your
location. The screen
shown at the
top
of the next
page appears. Remember,
this
'CLEAT"
MARK AND
DRILL FOUR
PLACES
GPS
GASKET
CABLE
LAT OFFSET:
LON OFFSET:
IIJ.tAUJ.UJ.U
E 0°OO.000'
4
41
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