RADAR

RADAR (an acronym for RAdio Detection And Ranging) is a sensor system that uses electromagnetic rays to detect objects, identify them, and determine their velocity. RADAR was first introduced during the Second World War.

RADAR can operate in an active mode, generating pulses of radio waves, receiving echoes reflected from objects they strike, and analyzing the echoes to determine the characteristics of the objects that reflected the initial pulses.

RADAR can also operate in a passive mode, simply receiving radio waves from other sources and analyzing them.