WAAS is an acronym for Wide Area Augmentation
The term WAAS as it applies to Gps...what is
it,and precisely what does it mean for you?
You may have noticed WAAS on ads and boxes for Garmin
handheld and other makes of GPS units. The question is...precisely what is
a system of satellites and
ground stations that provide GPS signal corrections, giving you even
greater position accuracy.
Exactly how much greater?
Several industry professionals say anywhere from 4 to 5 times greater.
A new GPS with a WAAS capable receiver can easily provide you a
position accuracy of better than three meters (9 feet or less) 95 percent of the time.
Lets look at original system capabilities prior to WAAS GPS
Accuracy of the original GPS system, which was subject to
accuracy degradation under the government-imposed Selective Availability (SA) program.* 300 feet (100
Typical GPS position accuracy before WAAS, and SA was not induced 45 feet (15
Typical differential GPS (DGPS) position accuracy. 9 - 15 feet (3-5 meters) (The
differential GPS required additional equipment)
Today's normal WAAS position accuracy. 9 feet or less
Nice part is that you don't have to purchase any additional equipment or pay any
additional charges to use it. It is included in each Garmin hand held WASS enabled GPS.
Exactly what is WAAS?
The WAAS system is 20 or more ground reference stations positioned in the United States
that monitor GPS satellite data. There is one master station on each coast that collect this data from the
satellites and adjust the data to make a correction for satellite orbit, and weather and stellar conditions. This
data and correction is sent through two stationary satellites to your Garmin hand held GPS making position accuracy
within 3 meters for 95% of the time.
Who benefits from WAAS?
Any WAAS enabled GPS user in North America. This system is not in use on other continents,
but many countries are rushing to developing similar systems.
Does is work everywhere?
When buildings, trees or terrain obstruct the view of the horizon this may cause poor
signal reception from the satilites positioned over the equator. It works best on open water and unobsturcted land
areas, but this system is constantly updating with new techonolgy through Garmin handheld GPS systems. The
capability to recieve the WAAS correction data is improving with each new unit introduced.
*(Selective Availabilty was a program that
purposefully sent incorrect position data. When you thought that you were at your fishing spot on the Great lakes,
you could be as far as 300 feet off where your unit says you are. That is about 3/4 of a normal city block. It was
set up to dis-wade use of GPS systems for illegal purposes. This SA system was stopped under the Clinton
administration, but can be started again in the event of a national emergency)