Garmin GPSMAP 3205 Owner's Manual

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Garmin GPSMAP 3205 Owner's Manual Manual pdf 106 page image

GPSMAP 3205 Owner’s ManualaPPendIX > satellIte InforMatIon and what Is waas/egnos?Satellite InformationSatellite Sky View45°90°Outer ring -the horizonInner ring- 45°above the horizonCenter dot - 90°above the horizonSatellite LocationThe location of each available satellite is shown over two location rings onthe Satellite Information Page. The outer ring represents the horizon, theinner ring represents 45° above the horizon, and the center represents directlyoverhead. When the unit is using a satellite for navigation, the satellite number ishighlighted on the location rings. The unit can be set to display satellite locationwith North or your current track at the top of the display.Satellite Strength Indicator BarsThe Satellite Strength Indicator Bars show the strength of the signal beingreceived, and the status of the signal. The bars are either shaded or filled. Thehollow gray bar means the GPS is in the process of storing orbital data it isreceiving from the satellite signal. When the bar turns solid green, the GPSis using the satellite signal for navigation. A “D” in or above the bar meansdifferential corrections (WAAS or DGPS) are being applied to that satellite.Date, Time, and Current LocationThe GPS gets date and time information from the satellite’s on-board atomicclock. When the GPS receiver has achieved a 2D or 3D GPS location, the currentlocation is shown in the selected location format.What is WAAS/EGNOS?The Wide Area Augmentation System (WAAS) is an FAA funded service toimprove the overall integrity of the GPS signal for users in North America. InEurope, WAAS is referred to as EGNOS.The system is made up of satellites and approximately 25 ground referencestations positioned across the United States that monitor GPS satellite data. Twomaster stations, located on either coast, collect data from the reference stationsand create a GPS data correction message.According to the FAA’s Web site, testing of WAAS in September 2002 confirmedan accuracy performance of 1–2 meters horizontal and 2–3 meters verticalthroughout the majority of the continental United States and portions of Alaska.WAAS is just one service provider that adheres to the MOPS (MinimumOperational Performance Standard) for global Satellite Based AugmentationSystems (SBAS). Eventually there will be several services of worldwidegeostationary communication satellites that broadcast integrity information anddifferential correction data as transmitted by ground reference stations.All SBAS systems use the same receiver frequency; therefore any operationalSBAS system should be capable of providing your GPS unit with increasedaccuracy at any location in the world.Currently, enabling WAAS on your GPSMAP 3205 in regions that are notsupported by ground stations, may not improve accuracy, even when receivingsignals from an SBAS satellite. In fact it can degrade the accuracy to less thanthat provided by GPS satellites alone. For this reason, when you enable WAASon your Garmin GPS receiver, the receiver automatically uses the method thatachieves the best accuracy.For more information, go to gps.faa.gov.