a radar device at a fixed location that, upon receiving a radar pulse, transmits a reply pulse that enables the original sender to determine his or her position relative to the fixed location.
O.E. beacen "sign, portent, lighthouse," from W.Gmc. *bauknan (cf. O.Fris. baken, O.S. bokan, O.H.G. bouhhan); not found outside Germanic. Perhaps borrowed from L. bucina "a crooked horn or trumpet, signal horn." But more likely from PIE *bhau-, a variant of the base *bha- "to gleam, shine" (see