Personal Navigation System: Garmin C330
Matthew Kimball – Retail Sales Trainer - Simulation Exercise
Garmin C330 FG (PANEL)v1.0
16 of 16
What
is
WAAS:
You've
heard
the
term
WAAS,
seen
it
on
packaging
and
ads
for
Garmin®
products,
and
maybe
even
know
it
stands
for
Wide
Area
Augmentation
System.
Okay,
so
what
the
heck
is
it?
Basically,
it's
a
system
of
satellites
and
ground
stations
that
provide
GPS
signal
corrections,
giving
you
even
better
position
accuracy.
How
much
better?
Try
an
average
of
up
to
five
times
better.
A
WAAS
‐
capable
receiver
can
give
you
a
position
accuracy
of
better
than
three
meters
95
percent
of
the
time.
And
you
don't
have
to
purchase
additional
receiving
equipment
or
pay
service
fees
to
utilize
WAAS.
The
origins
of
WAAS
The
Federal
Aviation
Administration
(FAA)
and
the
Department
of
Transportation
(DOT)
are
developing
the
WAAS
program
for
use
in
precision
flight
approaches.
Currently,
GPS
alone
does
not
meet
the
FAA's
navigation
requirements
for
accuracy,
integrity,
and
availability.
WAAS
corrects
for
GPS
signal
errors
caused
by
ionospheric
disturbances,
timing,
and
satellite
orbit
errors,
and
it
provides
vital
integrity
information
regarding
the
health
of
each
GPS
satellite.
How
it
Works
WAAS
consists
of
approximately
25
ground
reference
stations
positioned
across
the
United
States
that
monitor
GPS
satellite
data.
Two
master
stations,
located
on
either
coast,
collect
data
from
the
reference
stations
and
create
a
GPS
correction
message.
This
correction
accounts
for
GPS
satellite
orbit
and
clock
drift
plus
signal
delays
caused
by
the
atmosphere
and
ionosphere.
The
corrected
differential
message
is
then
broadcast
through
one
of
two
geostationary
satellites,
or
satellites
with
a
fixed
position
over
the
equator.
The
information
is
compatible
with
the
basic
GPS
signal
structure,
which
means
any
WAAS
‐
enabled
GPS
receiver
can
read
the
signal.
Who
benefits
from
WAAS?
Currently,
WAAS
satellite
coverage
is
only
available
in
North
America.
There
are
no
ground
reference
stations
in
South
America,
so
even
though
GPS
users
there
can
receive
WAAS,
the
signal
has
not
been
corrected
and
thus
would
not
improve
the
accuracy
of
their
unit.
For
some
users
in
the
U.S.,
the
position
of
the
satellites
over
the
equator
makes
it
difficult
to
receive
the
signals
when
trees
or
mountains
obstruct
the
view
of
the
horizon.
WAAS
signal
reception
is
ideal
for
open
land
and
marine
applications.
WAAS
provides
extended
coverage
both
inland
and
offshore
compared
to
the
land
‐
based
DGPS
(differential
GPS)
system.
Another
benefit
of
WAAS
is
that
it
does
not
require
additional
receiving
equipment,
while
DGPS
does.
It
just
keeps
getting
better
•
100
meters:
Accuracy
of
the
original
GPS
system,
which
was
subject
to
accuracy
degradation
under
the
government
‐
imposed
Selective
Availability
(SA)
program.
•
15
meters:
Typical
GPS
position
accuracy
without
SA.
•
3
‐
5
meters:
Typical
differential
GPS
(DGPS)
position
accuracy.
•
<
3
meters:
Typical
WAAS
position
accuracy.
http://www.garmin.com/aboutGPS/waas.html
