PCF OFFSET
The
GPS
navigation system relies on
complex mathematical calculations
to determine your position based on satellite data and other factors. One
factor is the Earths
shape. Since
the Earth is not atrue
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 GPS 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.
at a location
that is accurately
longitude position that is .010
Using the Position Correction
unit read the same as the chart.
If
you move, the unit will con-
tinuously add the change to all
position displays.
This makes it
more
closely
match the datum
used by
the chart. Forthis rea-
son,you should be careful when
entering the PCF offset. This
offset is saved in memory. It
doesn't
change whenthe unit is
turned off. However, a Preset
does erase the PCF factor.
INTRODUCTION
The UltraNav II is a high quality, wide screen combination sonar and
differntial ready OPS receiver with performance that is
second
to none in
its class.
Using menu features and "soft-key" operation, the UltraNav II is
also one of the easiest-to-use products that
Eagle has ever built. The wide
"UltravisionTM"
screen shows the underwater world with high resolution
and detail. The display and keyboard are also lighted for
night operation.
Installing an optional ST-T speed/temperature sensor, gives digital boat
speed, surface water
temperature, and distance travelled
(log) displays.
Read this manual and take itwith
you
the firstfew times
you use
your
unit.
It makes a great
reference if
you need it.
MOUNTING
Install the UltraNav II in any convenient location, provided there is
clearance behind the
unitwhen it is tilted forthe best
viewing angle.
Holes
in the bracket base
allow wood screw orthrough-bolt mounting. You may
need to place
a
piece
of
plywood on the back of thin fiberglass panels
to
secure the
mounting hardware. Make certain there is
enough
room behind
the unit to attach the power and transducer cables.
The smallest hole that
will pass
one
power or transducer
plug is one inch.
Afterthe hole is
drilled, passthe
transducerconnector up throughthe
hole
first,
then pass
the
power
cable down through it.
After the cables have been
routed, fill the hole with a
good marine
sealing
compound. Offset
the bracket to cover the hole. Route the power cable
through the slot and break out one of the other slots in the bracket for the
transducer cable.
76 1
For example, suppose you are stopped
marked on a chart. Your unit shows a
degrees less than the one on the chart.
Factor (PCF)
Offset
feature,
you
make the
Position Correctq Factor
LAT OFFSET:
LOll OFFSET: N.:,C!PiJO1I1OC.
SLOT
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