Garmin GPSMAP 580 Owner's Manual

Garmin GPSMAP 580 Owner's Manual Manual pdf 89 page image

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 ringson the Satellite Information Page. The outer ring represents the horizon,the inner ring represents 45° above the horizon, and the center representsdirectly overhead. When the unit is using a satellite for navigation, thesatellite number is highlighted on the location rings. The unit can showsatellite location with either North or your current heading at the top of thescreen.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. Ahollow gray bar means the unit is in the process of storing orbital data it isreceiving from the satellite signal. When the bar turns solid green, the unitis using the satellite signal for navigation. A “D” in or above the bar meansdifferential corrections (WAAS) are being applied to that satellite.Differential FieldDifferential receiver status is indicated in the lower-left field of theGPS tab and shows one of the following conditions:• None—no optional beacon receiver is attached or enabled inthe Interface sub tab on the Main menu—Setup tab or WAASis disabled.• Searching for WAAS—WAAS is enabled and the receiver issearching for WAAS signal.• Using WAAS—WAAS capability is enabled and the unit isreceiving WAAS corrections.What is WAAS?The Wide Area Augmentation System (WAAS) is an FAA-fundedproject to improve the overall integrity of the GPS signal andincrease position accuracy for users in North America.The system is made up of satellites and approximately 25 groundreference stations positioned across the United States that monitorGPS satellite data. Two master stations, located on either coast,collect data from the reference stations and create a GPS datacorrection message. According to the FAA’s Web site, testing inSeptember 2002 of WAAS confirmed an accuracy performanceof 1–2 meters horizontal and 2–3 meters vertical throughout theGPSMAP 580/585 Owner’s Manual 83Appendix