The concept of ADS-B (Automatic Dependent Surveillance-Broadcast) is defined by ICAO as "a surveillance application that provides the transmission of information such as position, track and ground speed, etc., that any ground/air user may need, via a broadcast mode data line at certain intervals".
In the ADS-B concept, there are 3 (three) data transmission methods called VDL Mode 4, UAT and 1090 MHz Extended Squitter. It is an application that transmits in all directions.
In accordance with the legal regulations applied in Europe and the USA, ADS-B transponders are present in almost all aircraft that carry out commercial flights today.
ADS-B position reports transmitted from aircraft can be received and processed by ADS-B receivers on the ground or in space, or by other aircraft in the air.