Velocity sensing apparatus

Claim 1

IN COMBINATION: AN EARTH MOVING APPARATUS HAVING TRACTIVE MEANS TO MOVE SAID APPARATUS AND HAVING A MOVABLE EARTH WORKING INSTRUMENTALITY TO ENGAGE AND TO WORK THE EARTH OVER WHICH THE APPARATUS MOVES; MEANS FOR SENSING THE VELOCITY OF SAID APPARATUS WITH RESPECT TO THE EARTH OVER WHICH IT MOVES HAVING TRANSMITTER MEANS AND RECEIVER MEANS MOUNTED UPON SAID EARTH MOVING APPARATUS, SAID TRANSMITTER MEANS INCLUDING MEANS DIRECTED DOWNWARDLY TOWARD THE EARTH TOWARD WHICH SAID APPARATUS IS MOVING AND PROVIDING A SIGNAL OF PREDETERMINED FREQUENCY WHICH IS DIRECTED TOWARD THE EARTH TOWARD WHICH SAID APPARATUS IS MOVING, SAID RECEIVER MEANS INCLUDING MEANS DIRECTED DOWNWARDLY TOWARD THE EARTH TOWARD WHICH SAID APPARATUS IS MOVING TO RECEIVE A REFLECTED SIGNAL OF VARYING FREQUENCY WHICH IS REFLECTED FROM THE EARTH TOWARD WHICH SAID APPARATUS IS MOVING, AND HAVING FURTHER MEANS CONNECTED TO SAID RECEIVER MEANS AND RESPONSIVE TO THE DIFFERENCE BETWEEN SAID SIGNAL OF PREDETERMINED FREQUENCY AND SAID REFLECTED SIGNAL OF VARYING FREQUENCY TO PROVIDE A FURTHER SIGNAL PROPORTIONAL TO THE VELOCITY OF SAID EARTH MOVING APPARATUS; AND MEANS CONTROLLED BY SAID FURTHER MEANS TO CONTROL THE POSITION OF SAID EARTH WORKING INSTRUMENTALITY.