Multilateration System (MLAT) for Aviation

INTRODUCE

MLAT ground stations receive replies from all transponder-equipped aircraft, including legacy radar and ADS-B avionics. And determine aircraft position based on the time difference of arrival (TDOA) of the replies.
While the Multilateration concept was originally developed for military air surveillance purposes, one of its earliest civil aviation applications was the monitoring of aircraft movements on the airport's surface.