Garmin GI 275 Pilot's Manual page 184

Hazard Avoidance
For example, if another aircraft can only receive 978 MHz UAT information, it cannot directly
'see' another aircraft sending only 1090 ES information aircraft unless an ADS-R ground station
in the vicinity rebroadcasts the 1090 ES data over the 978 MHz UAT frequency. This is also
true for an aircraft that can only receive 1090 ES data; it would need an ADS-R ground station
to 'see' another aircraft operating on the UAT frequency.
TIS-B (Traffic Information Service-Broadcast) provides a link between the secondary
surveillance radar (SSR)-based system ATC uses and the ADS-B-based system. When an ADS-B
Out capable aircraft is within the service volume of an FAA ADS-B ground station, the ground
station broadcasts a portion of the ATC radar data to the aircraft. This aircraft is then included
in the list of aircraft being provided TIS-B service and is then considered a "TIS-B participant."
TIS-B coverage is available when the aircraft is within ground station coverage, in SSR
coverage, and the other aircraft is also in SSR coverage, and is transmitting its altitude.
The ground station provides ATC radar information for other aircraft within ±3,500 feet and
15 NM of the participant, to include altitude, position, ground speed, and ground track. TIS-B
broadcasts occur once every three to thirteen seconds, depending on the characteristics of the
ground station providing the TIS-B service.
The symbols used to display ADS-B traffic are shown in the following table. Above or below
the traffic symbol is the traffic identifier, and altitude. A small up or down arrow next to the
traffic symbol indicates that traffic is climbing or descending at a rate of at least 500 feet per
minute.
Symbol
162
Traffic Advisory with directional information. Points in the direction of the
intruder aircraft track.
Traffic Advisory without directional information.
Target belongs to a group; when grouped, the most immediate threat is the
target displayed.
Traffic Advisory out of the selected display range with directional information.
Displayed at outer range ring at proper bearing.
Traffic Advisory out of the selected display range without directional information.
Displayed at outer range ring at proper bearing.
Proximity Advisory with directional information. Points in the direction of the
aircraft track.
Garmin GI 275 Pilot's Guide
Description
190-02246-01 Rev. A