What Is Waas; What Is Differential Gps - Garmin 3600 Application Manual

What is WAAS?

The Wide Area Augmentation System (WAAS) is an F.A.A. funded
project to improve the overall integrity of the GPS signal. It is a space-
based system that broadcasts integrity information and correction data
as determined by ground reference stations (see DGPS below). At
this time the system is still in the developmental stage with a goal of
providing reliable signals with an accuracy of 7 meters (21-22 ft.) both
horizontally and vertically 95% of the time. Current tests have shown
the actual accuracy to be on the order of 2-3 meters. For more informa-
tion, go to http://gps.faa.gov/Programs/WAAS/waas.htm.
What is Differential GPS (DGPS)?
The U.S. and Canadian governments (among others) have set up
Differential GPS (DGPS) stations to transmit correction signals. They are
operational in coastal areas and on many navigable river systems. The
DGPS system is available for use without fee.
In addition to compensating for errors in the position, these correc-
tions signals can also correct for deliberate degradation of the accuracy
of GPS by the U.S. Department of Defense under their Selective Avail-
ability (SA) program. Please refer to the U.S. Coast Guard' s web site:
http://www.navcen.uscg.gov/ for locations and the status of the differential
sites. Using DGPS requires additional equipment.
™
iQue 3600
Additional Information
Differential (D)
GPS
Status Indicator
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