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How Can You Get Better Accuracy from GPS?
Satellite Based Augmentation Systems (SBAS) are additional resources
to use in improving accuracy. SBAS works similar to DGPS in that a correction is calculated and picked up by your receiver in addition to the regular
four satellites. However, in this case, the correction is being sent from an
additional new satellite, not from an Earth-bound station. An example of
a SBAS is called the Wide Area Augmentation System (WAAS), which was
developed by the Federal Aviation Administration (FAA) to obtain more
accurate position information for aircraft. WAAS has since spread to uses
beyond aircraft as a quick and easy method of improving overall GPS position accuracy.
WAAS operates through a series of base stations spread throughout the
United States that collect and monitor the signals sent by the GPS satellites.
These base stations calculate position correction information (similar to the
operation of DGPS) and transmit this correction to a geostationary WAAS
satellite. These WAAS satellites then broadcast this correction signal back
to Earth, and if your receiver can pick up this signal, it can use this correction information in its position calculation (Figure 4.10). WAAS reduces the
position error to 3 meters or less with its use. A drawback to WAAS is that
it will only function within the United States (including Alaska and Hawaii)
and nearby portions of North America (although WAAS base stations have
SBAS Satellite
Based Augmentation
System—a method
of using correction
information sent from
an additional satellite
in the GPS position
determination.
WAAS the Wide
Area Augmentation
System—a satellite
based augmentation
system that covers
the United States and
other portions of North
America.
FIGURE 4.10 The setup
and operation of the
WAAS system.
WAAS
master station
WAAS satellite
L1
L1
GPS satellites
WAAS ground
station
WAAS
reference station
How Can You Get Better Accuracy from GPS?
Satellite Based Augmentation Systems (SBAS) are additional resources
to use in improving accuracy. SBAS works similar to DGPS in that a correction is calculated and picked up by your receiver in addition to the regular
four satellites. However, in this case, the correction is being sent from an
additional new satellite, not from an Earth-bound station. An example of
a SBAS is called the Wide Area Augmentation System (WAAS), which was
developed by the Federal Aviation Administration (FAA) to obtain more
accurate position information for aircraft. WAAS has since spread to uses
beyond aircraft as a quick and easy method of improving overall GPS position accuracy.
WAAS operates through a series of base stations spread throughout the
United States that collect and monitor the signals sent by the GPS satellites.
These base stations calculate position correction information (similar to the
operation of DGPS) and transmit this correction to a geostationary WAAS
satellite. These WAAS satellites then broadcast this correction signal back
to Earth, and if your receiver can pick up this signal, it can use this correction information in its position calculation (Figure 4.10). WAAS reduces the
position error to 3 meters or less with its use. A drawback to WAAS is that
it will only function within the United States (including Alaska and Hawaii)
and nearby portions of North America (although WAAS base stations have
SBAS Satellite
Based Augmentation
System—a method
of using correction
information sent from
an additional satellite
in the GPS position
determination.
WAAS the Wide
Area Augmentation
System—a satellite
based augmentation
system that covers
the United States and
other portions of North
America.
FIGURE 4.10 The setup
and operation of the
WAAS system.
WAAS
master station
WAAS satellite
L1
L1
GPS satellites
WAAS ground
station
WAAS
reference station