Garmin GDL 88 User Guide - Page 13

2.1 ADS-B - Broadcast (ADS-B) ADS-B is the automatic broadcast of position reports by aircraft, surface vehicles, and transmitters on fixed objects. These broadcasts contain much more data than just a simple position report, they include: identity (Flight ID, Call Sign, Tail Number, ICAO registration number, etc), ground track, ground speed, pressure altitude, indications of multitude capabilities, and emergency status. This list of data is non-inclusive of other data fields and bits used for various other functions. Figure 2-3 ADS-B Operation - FAA Illustration Garmin display units have the capability to show the status of the ground station services being received. Examples for the GTN and GNS products are shown below. See the display device Pilot Guide for the symbology used on that display. Unit Symbol Description GNS Within coverage of a TIS-B ground station when connected to a GDL 88. GNS Not within coverage of a TIS-B ground station when connected to a GDL 88. GNS GDL 88 does not have a valid track or heading and cannot place ADS targets on the display. GTN Within coverage of a TIS-B ground station when connected to a GDL 88. GTN Not within coverage of a TIS-B ground station when connected to a GDL 88 Table 2-1 Map TIS-B Availability Symbols 190-01122-03 Rev. A GDL 88 ADS-B Transceiver Pilot's Guide 2-3