Garmin GPSMAP 295 - Manual (Page 100)

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What is WAAS?
The Wide Area Augmentation System (WAAS) is a system of geostationary satellites that support
the Global Positioning System (GPS) by offering improved position accuracy. WAAS satellites transmit
differential correction data that is applied, by your GPSMAP 295, to the range measurements from
each applicable GPS satellite in view. WAAS satellites also transmit information about the health and
integrity of each GPS satellite. The end result is an improved position accuracy, both horizontally (lat/
lon) and vertically (altitude).
When enabled on your GPSMAP 295, this feature searches for any WAAS satellite in view and
then receives differential data for correcting GPS satellite signals. WAAS satellites transmit on the same
frequency as GPS satellites and are displayed as additional satellites on the Satellite Status Page. The
GPSMAP 295 will display WAAS satellite numbers, beginning at 33 or above, on the Sky View and on
the Signal Strength Bars (see page 7). Once correction data is received from the WAAS satellite, a “D”
will appear in the signal strength bars of all satellites for which correction data is available.
In general, you should expect horizontal position accuracy to be around three meters (10ft) with
WAAS enabled and fifteen meters (49ft) with WAAS disabled. Of course, many variables will affect
your actual results, including the number of GPS satellites currently be received.
WAAS is still under development and additional satellites are being deployed. Currently, two
WAAS satellites provide coverage from Hawaii to the eastern U.S. To obtain the latest information on
the WAAS system, access the Federal Aviation Administration website (gps.faa.gov) for a comprehen-
sive description and links to detailed information.
Appendix B
WAAS
The WAAS feature is enabled/disabled from the Main Menu’s
‘SYSTEM’ file tab. See page 76 for step-by-step instructions.
With WAAS enabled, a “D” will appear on the signal
strength bar of each satellite for which correction data is
available. Note the EPE, or estimated position error, reading
in this example.