Garmin GPSMAP 172 Owner's Manual

Also see for GPSMAP 172: Installation instructions Specifications Quick reference

Contents

Highlight ‘WAAS Off’ and press ENTERto disable the WAAS capabilities.Main Menu:GPS TabWAAS CapabilityThe GPSMAP 172/172C is capable of receiving WAAS (Wide Area Augmentation System) satellitesignals. WAAS is an FAA (Federal Aviation Administration) funded project to improve the overall accu-racy and integrity of the GPS signal for aviation use, but land/sea based users may also benefit from thissystem. At this time, the system is still in the development stage and is not fully operational. There arecurrently two WAAS satellites that can be received in the U.S.A., one over the Atlantic Ocean and oneover the Pacific Ocean, in a geo-stationary orbit over the equator. Effective use of the WAAS satellitesignal may be limited by your geographic location in relation to those satellites, now in developmentalservice. WAAS satellite signal reception requires an absolute clear view of the sky and works best whenthere are no nearby obstructions such as buildings, mountains, etc. WAAS satellites are numbered 33or higher when viewing the sky view on your GPSMAP 172/172C. Initial reception of the WAAS signalmay take up to 15-20 minutes, then 1-2 minutes afterwards. When WAAS differential correction hasbeen received for GPS satellites (numbers 32 or below), a ‘D’ appears in the signal bar of the sky viewand ‘2D or 3D Differential’ appears in the receiver status. To learn more about the WAAS system, itssatellite positions and current state of development, visit the FAA web site (http://gps.faa.gov). SinceWAAS requires CPU resources of the GPSMAP 172/172C to search for and track the satellites, you maydisable the WAAS feature to improve unit performance if WAAS reception is not available in your area.To disable/enable WAAS capability:1. From the GPS tab, press MENU, then use the ARROW KEYPAD to highlight ‘WAAS Off’ or ‘WAASOn’ and press ENTER.Receiver Status and AccuracyReceiver status is indicated at the top field of the page, with the current Accuracy and Dilution OfPrecision (DOP) to the right of the sky view. Accuracy uses DOP and other factors to calculate horizon-tal position accuracy in feet or meters.Reference