Automatic Dependent Surveillance–Broadcast (ADS-B)

It is a modern technology and it is an Electronic surveillance system in which an aircraft determines its position through satellite navigation or other sensors and periodically broadcasts it, enabling it to be tracked. 

The information can be received by air traffic control (ATC) ground stations as a replacement for secondary surveillance radar, as no interrogation signal is required from ground.

It can also be received by other aircrafts to provide pilot with situational awareness and allow self-separation.




ADS-B is "automatic" in that it requires no pilot or external input. It is "dependent" in that it depends on data from the aircraft's navigation system.