User Guide

ACCURACY
within .1 mile ala recalled
waypoint
if the arrival alarm's
setting
is .1 mile.
You
mayhave
heardtalesof
extraordinaryaccuracyfrom
GPS receivers. The
DOD
requires accuracyof
1 Oto 15
metersfromthesatellitesystem. However,
onlythe military getsthis precision.
The
waythe military keeps
us and other
unauthorized
peoplefrom usingthe
more
precise system
is
coding.
In other
words,thedatacomingfromthesateiiitesisencrypted.
Civilian aPS receivers
use"C/ACode."
It'saccuracyisintentionallyworsethanthemilitary's"P
Code."
Inthis
manner,
civilian usersworldwidecan
benefitfromexcellentpositionfixes.
Meanwhile,
the
militarykeepsthe
most accurate
system awayfrom potential
enemies.
Theoretically,
C/A code can
give
accurate
position
fixes
up
to 15
meters. This is more than
adequate
for most
people.
However
(as
of this
writing),
the
military
isn't satisfied with C/A's
potential
accuracy
inthe hands of theworid.
So,
Ws
degrading
itfurtherwith "Selective
Availabili
t'
orSA. This is
small,
random errors
intentionallyaddedto
the
system
so
youraccuracywill
typicallybe
within 100 meters. Of
course,
accuracy
also
depends
on the
angle
of the satellite abovethe
horizon, signal-to-noise ratio,
the
numberofsatellitestrackedatonetime
(the
morethe
better),
andotherfactors.
The smallest
ranges
on
the
plotter may
not be usable if the SA is
high.
The
present
position symbol
can move off thescreen even
whileyou're sitting
still.
Don't let this
discourage you,
however. GPS
by
nature has much faster
updates
than other
systems (such
as
Loran),
and
typically
is much easier
to use.
Accuracy,
even with SA on is still betterthan most other
navigation
systems.
You've
purchased
one of the finest
navigation
instruments on
the market
today.
We
hope you'll enjoy
it for
many years
to come.
The Lowrance LGC-1 GPS Module
This GPS receiver is
currently
used in all Lowrance GPS receivers. It's
small,
rugged,
and fast. The five channel
design
lets it track all satellites
in view and
acquire up
to five satellites at one time. It sends
position
information to the GlobalNav II once
every
second.
By incorporating
Rockwell's GPS receiver
technology
with Lowrance's state-of-the-art
design
and
manufacturing capabilities,
Lowrance
brings
to the consumer
the most advanced line of GPS marine
navigation systems
available in the
world.
WRANE
it
The alarm is
adjustable
from .01 to 9.9 miles.
XTE ALARM
The XTE
(cross
track
error)
alarm sounds a tone when
your
cross track
error is
greater
man the alarms
setting. unanging
tne XI h alarm also
changes
the XTE
range
on the
steering
screen. The alarm is
adjustable
from 0.0 to 9.9 miles.
ANCHOR ALARM
The anchoralarm sounds atone when the
present position
moves
outside
a
preset
radius.
Forexample,
if
you
setthe
anchoralarmto
.1
nautical mile
(600 feet),
then the alarm will sound if
you
move more than 600 feet from
the location where
you
setthe alarm.
It's
adjustable
from
0.01 to 9.9 miles.
CHANGING GPS SE11'INGS
Forthefastestacquisition
of
satellites,
the GlobalNav
II
mustbe initialized
when it's turned on for the
first time. This is described at the
beginning
of
the GPS section in this manual.
However,
if
you
need to
change only
one
of the
parameters (such
as
time),
use the menu features in the "CHANGE
SETUP" menu. To do
this, press
the MENU
key,
then
press
the
key
next
to the
"Change
GPS
Settings"
label.
Finally, press
the
key
next to the "Set
Lat, Lon, Alt, Time,
Date" label. The screen shown below
appears.
Using
the menus on this menu
pages, you
can
changethe
Initial
Position,
Time, Date,
or Altitude without
affecting any
other initialization
setting.
All
of these menus work
identically
to the ones described in the initialization
section atthe
beginning
of the GPS section.
Afteryou
make
achange,
the
unit returns to the OPS or
plotter
screen.
You
may
need to re-initialize
__________
the unit if
you
move a
long
distance
(over
100
miles)
with
the unit off. In
this
example you
would need to enter a new ini-
tial
position
to
help
the
GlobalNav II find the correct
satellites
quicker.
10
39
N 36'O1.042'
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