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WAAS New GARMIN Products to Support WAAS
Using select GARMIN GPS products with WAAS capable receivers, users can now realize position accuracies better than 9 feet, 95% typical. WAAS corrections do not require the purchase of additional equipment and there are no service charges. Additionally, WAAS signal corrections are transmitted using microwave frequencies that are not affected by electrical noise from thunderstorms. The origins of WAAS The Federal Aviation Administration (FAA) and the Department of Transportation are developing the WAAS program for use in precision 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 ionospheric disturbances, timing and satellite orbit errors and provides vital integrity information regarding the health of each GPS satellite. Although WAAS has not yet been approved for aviation, the system is available for civilian use, such as for boaters and recreational GPS users. How it Works WAAS consists of approximately 25 ground reference stations positioned across the United States that monitor GPS satellite data. Two master stations, located on either coast, collect data from the reference stations and create a GPS correction message. This correction accounts for GPS satellite orbit and clock drift plus signal delays caused by the atmosphere and ionosphere. The corrected differential message is then broadcast through one of two geostationary satellites, or satellites with a fixed position over the equator. The information is compatible with the basic GPS signal structure, which means any WAAS-enabled GPS receiver can read the signal. Who benefits from WAAS? 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 ideal 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. WAAS-enabled products:
WAAS
support also includes the following: GPSMAP188 Sounder, GPSMAP 238
Sounder, RINO 110/120, GPS V, GPS 16 Sensor, GPS 17-N Sensor and
GPSMAP 76S. |
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The
Wide Area Augmentation System (WAAS) provides differential GPS corrections
through a system of ground stations and several geosyncronous satellites.
The program is being developed to support the Federal Aviation Administration
and the Department of Transportation for precision approaches.
- combines a basemap of North and South America, with a barometric
altimeter and electronic compass. The compass provides bearing
information while you're standing still and the altimeter
determines your precise altitude. 
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Last up date: 02/16/02 |
