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Appendix C
WAAS Capability
The eTrex is capable of receiving WAAS (Wide Area Augmentation System) satellite
signals. WAAS is an FAA (Federal Aviation Administration) funded project to improve the
overall accuracy and integrity of the GPS signal for aviation use, but land/sea based users may
also benefit from this system. There are currently two WAAS satellites that can be received
in the U.S.A., one over the Atlantic Ocean and one over the Pacific Ocean, in a geo-station-
ary orbit over the equator. Effective use of the WAAS satellite signal may be limited by your
geographic location in relation to those satellites. WAAS is most effective for users in the
continental U.S. WAAS satellite signal reception requires an absolute clear view of the sky and
works best when there are no nearby obstructions such as buildings or mountains. WAAS
satellites are numbered 33 or higher when viewing the sky view on your eTrex. Initial recep-
tion of the WAAS signal may take up to 15–20 minutes, then 1–2 minutes afterwards. When
WAAS differential correction has been received for GPS satellites (numbers 32 or below), a
‘D’ appears in the signal bar of the Advanced Sky View. When enough satellites have received
WAAS differential correction, ‘DIFF’ appears below the ‘Ready to Navigate’ message.
To learn more about the WAAS system, its satellite positions and current state of develop
-
ment, visit the FAA Web site (
http://gps.faa.gov
).
Since WAAS requires CPU resources of the eTrex to search for and track the satellites,
you may disable the WAAS feature to improve unit performance if WAAS reception is not
available in your area.
To disable/enable WAAS capability:
1. From the MENU Page, highlight ‘SETUP’ and press ENTER. The SETUP Page appears.
2. Press the
UP or DOWN button to highlight ‘SYSTEM.’
3. Press the UP or DOWN button to highlight ‘GPS.’ Press ENTER. The Option List appears.
4. Press the
UP or DOWN button to highlight the desired GPS mode and press ENTER.
What is WAAS?