1.10 SBAS (Satellite Based Augmentation Systems)
SBAS
(Satellite
Based
Augmentation
System)
is
an
augmentation
technology
for
GPS,
which
calculates
GPS
toring
Stations)
on
the
ground
and
uses
geostationary
satellites
(GEOs)
to
broadcast
GPS
integrity
and
correction
data
to
GPS
users.
The
correction
data
is
n
therefore
there
is
no
additional
receiver
required
to
integrity
and
correction
data
with
RIMS
(Ranging
and
Integrity
Moni
tra smitted
on
the
GPS
L1
frequency
(1575.42
MHz),
and
make
use
of
the
correction-
and
integrity
data.
Ionosphere
GPS
Satellites
SB
Solar
activity
Influences
signal
propagation
delay
AS
Satellites
(e.g. WAAS, EGNOS), geostationary
orbit
g
(e.g.
charged
particle
storms)
Additional Contents:
Ranging
Signal
(like
a GPS SV)
Contents:
Ephemeris
corrections
Clock
corrections
Ionosphere
corrections
Integrity
info
(SV
use
/
d
e
info)
Ranging
and
Integrity
Monitorin
Stations
(RIMS)
at
known
locations
Uplink
Stations
Master
Control
Centers
RIMS
RIMS
ANTAR
GPS
receiv
IS
®
er
on't
us
RIMS
RIMS
Contents:
Signal
Propagation
delays
Orbit
deviations
ck
errors
heric
conditions
Integrity
information
R
(Operational
Readiness
Review)
in
Q2/2005.
Full
operation
of
EGNOS
is
planned
•
MSAS
(Multi-Functional
Satellite
Augmentation
System)
for
Asia
is
in
development
stage
and
is
sending
test
data.
MSAS
initial
Operating
Capability
(IOC)
is
expected
early
2007.
Other
systems
are
planned
for
Canada
(CSAS),
India
(GAGAN),
Africa
(EGNOS)
and
South
America.
SBAS
support
allows
the
ANTARIS
®
4
Technology
to
take
full
benefit
of
the
augmentation
systems
that
are
available
(WAAS,
EGNOS),
the
test
beds
(NSTB,
ESTB)
and
future
systems
that
are
planned
(such
as
MSAS)
for
non-avionics
applications.
With
SBAS
enabled
the
user
benefits
of
additional
satellites
for
ranging
(navigation).
The
ANTARIS
®
4
Technology
uses
the
available
SBAS
Satellites
for
navigation
just
like
GPS
satellites,
if
the
SBAS
satellites
offer
this
service.
To
improve
position
accuracy
SBAS
uses
different
types
of
correction
data:
•
Fast Corrections
account
for
short-term
disturbances
in
GPS
signals
(due
to
clock
problems,
etc).
•
Long-term corrections
cancel
effects
due
to
slow
GPS
clock
problems,
broadcast
orbit
errors
etc.
fects
due
to
Ionosphere
activity
SV
Clo
Ionosp
Figure 26: SBAS-Principle
There
are
several
compatible
SBAS
systems
available
or
in
development
all
around
the
world:
•
WAAS
(Wide
Area
Augmentation
System)
for
Northern
America
is
in
operation
since
2003.
•
EGNOS
(European
Geostationary
Navigation
Overlay
Service)
is
in
test
mode
ESTB
(EGNOS
satellite
test
bed).
EGNOS
has
passed
the
OR
for
2007.
•
Ionosphere corrections
cancel
ef
GPS
Modules
-
System
Integration
Manual
(SIM)
(incl.
Reference
Design)
GPS
Fundamentals
GPS.G4-MS4-05007-A1
Page 31
