Transponder

A aircraft [|transponder] is an electronic device that produces a response when it receives a radio frequency. Various modes exist from Mode 1 to 5 for military use, to [|Mode] A, B, [|C] and D and Mode S for civilian use. Basically it is used for finding a aircraft's altitude, Speed, [|location] and some what kind of plane it is. It is a small electronic circuit board [|box].