Magellan GPS Navigation -
Magellan Explorist XL Road -
Magellan Explorist XL Off Road -

Garmin Running Watches

Garmin Forerunner 101 -
Garmin Forerunner 201 -
Garmin Forerunner 301 -
Garmin Foretrex 101 -
Garmin Foretrex 201 -
WAAS - Wide Area Augmentation System

Garmin GPS Navigation

Garmin QUEST -
Garmin eTrex -
Garmin Geko 201 -
GPS Links -
GPS Movies -

You might also be interested in the Timex Bodylink T5F011 and Timex Bodylink GPS running watches.

GPS Vehicle Tracking
Trackstick II -
Super Trackstick -
LandAirSea Tracking Key -

 

What is WAAS (Wide Area Augmentation System) ?

Mabe you have heard the term WAAS or seen it on packaging and ads for Garmin GPS navigation products, and maybe you even know that it stands for Wide Area Augmentation System.  Okay, so what the heck does that mean?  Basically, it is a system of satellites and ground stations that provide GPS signal corrections to yield a better position accuracy.  How much better?  How about an average of five times better!?  A WAAS capable receiver can give you a position accuracy of better than three meters 95 percent of the time.  And you don't have to purchase additional receiving equipment or pay service fees to utilize WAAS.

The Federal Aviation Administration (FAA) and the Department of Transportation (DOT) are developing the WAAS program for use in precision air flight approaches.  Currently, GPS alone does not meet the FAA's navigation requirements for accuracy, integrity, and availability.  WAAS corrects for GPS signal errors caused by disturbances in the upper atmosphere (ionosphere), timing, and satellite orbit errors, and it provides vital integrity information regarding the health of each GPS satellite.

WAAS consists of about 25 ground stations positioned across the United States that monitor GPS satellite data.  Two master stations located on the east and west coasts collect data from the reference stations and create a GPS correction message.  This correction accounts for GPS satellite orbit, clock drift, and signal delays caused by the atmosphere and ionosphere.  The corrected differential message is broadcast to one of two geostationary satellites (satellites with a fixed position over the equator).  The information is compatible with the basic GPS signal structure, which means that any WAAS enabled GPS receiver can read and interpret the signal.

Currently, WAAS satellite coverage is only available in North America.  There are no ground reference stations in South America, so even though GPS users there can receive WAAS, the signal has not been corrected and thus would not improve the accuracy of their unit.  For some users in the U.S., the position of the satellites over the equator makes it difficult to receive the signals when trees or mountains obstruct the view of the horizon.  WAAS signal reception is best suited for open land and marine applications.  WAAS provides extended coverage both inland and offshore compared to the land based DGPS (differential GPS) system.  Another benefit of WAAS is that it does not require additional receiving equipment, while DGPS does.

Other governments are developing similar satellite-based differential systems.  In Asia, it's the Japanese Multi-Functional Satellite Augmentation System (MSAS), while Europe has the Euro Geostationary Navigation Overlay Service (EGNOS).  Eventually, GPS users around the world will have access to precise position data using these and other compatible systems.

The Evolution of GPS Accuracy:

  • 100 meters: Accuracy of the original GPS system, which was subject to accuracy degradation under the government imposed Selective Availability (SA) program.

  • 15 meters: Typical GPS position accuracy without SA.

  • 3-5 meters: Typical differential GPS (DGPS) position accuracy.

  • Less than 3 meters: Typical WAAS position accuracy.

List of Garmin WAAS enabled products:

Apollo CNX80

garmin etrex gpsThe famous Garmin eTrex Legend !!
eTrex Legend C
eTrex Venture
eTrex Vista
eTrex Vista C

Foretrex 101
Foretrex 201
Geko 201
Geko 301
GPS V
GPS 15H and GPS 15L
GPS 16
GPS 17N
GPS 18
GPS 18 OEM
GPS 72
GPS 76
GPS 152
GPSMAP 76
GPSMAP 76C
GPSMAP 76S
GPSMAP 76CS
GPSMAP 162
GPSMAP 172C
GPSMAP 178C
GPSMAP 168 Sounder
GPSMAP 176
GPSMAP 176C
GPSMAP 182
GPSMAP 188 Sounder
GPSMAP 196
GPSMAP 232
GPSMAP 238 Sounder
GPSMAP 276C
GPSMAP 295
GPSMAP 296
GPSMAP 60C
GPSMAP 60CS
GPSMAP 2006
GPSMAP 2010
GPSMAP 3006C
GPSMAP 3010C
iQue 3600
Quest
Rino 110
Rino 120
Rino 130
StreetPilot 2610
StreetPilot 2620
StreetPilot 2650
StreetPilot 2660