What is WAAS?
The Wide Area Augmentation System (WAAS) is an
FAA-funded project to improve the overall integrity
of the GPS signal and increase position accuracy for
users in North America.
The system is made up of satellites and approximate-
ly twenty-five ground reference stations positioned
across the United States that monitor GPS satellite
data. Two master stations, located on either coast, col-
lect data from the reference stations and create a GPS
data correction message.
According to the FAA’s Web site, testing in Septem-
ber 2002 of WAAS confirmed an accuracy perfor-
mance of 1–2 meters horizontal and 2–3 meters verti-
cal throughout the majority of the continental United
States and portions of Alaska.
WAAS is just one service provider that adheres to the
MOPS (Minimum Operational Performance Standard)
for global Satellite Based Augmentation Systems
(SBAS). Eventually, there will be several services of
worldwide geostationary communication satellites and
ground reference stations.
All SBAS systems use the same receiver frequency;
therefore, any operational SBAS system should be
capable of providing your GPS unit with increased ac-
curacy at any location in the world.
Currently, enabling WAAS on your Garmin 76CS
Plus in regions that are not supported by ground sta-
tions may not improve accuracy, even when receiving
signals from an SBAS satellite. In fact it can degrade
the accuracy to less than that provided by GPS satel-
lites alone. For this reason, when you enable WAAS
on your Garmin GPS receiver, the receiver automati-
cally uses the method that achieves the best accuracy.
To enable WAAS, refer to page 6.
For more information, go to
http://gps.faa.gov/Programs/WAAS/waas.htm.
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