MEANS FOR DETERMINING DISTANCE BETWEEN TWO POINTS

摘要

A means for determining the distance between two spaced points, such as ground surface and a tip of a ground working tool of an agricultural machine, comprising transmitting and receiving means (13, 15) adapted for positioning at a location remote from the two points, and means (27) for generating a first timing signal equal to the time a pulse emitted by the transmitting means (13) takes to be reflected from one of said two points and received by the receiving means (15). There is provided a means (25) for generating a reference timing signal representative of the time the pulse would take to be reflected from the other of said two points and received. A gate means (29) is provided for deriving a differential timing signal equal to the time difference between the first timing signal and the reference timing signal. The differential timing signal is converted by a converting means (37, 39, 41) into an output signal representative of the spacing between the first and second points. ing between the first and second points.) for generating a first