| 摘要 |
PURPOSE:To provide a robust and highly accurate speedometer which does not have any moving parts by providing ultrasonic transmitting-receiving parts at an equal spacing in the moving direction integrally with a moving object and receiving the random noise included in the reflected waves from the ground during running. CONSTITUTION:The receiving signals having been transmitted and received by ultrasonic transmitters-receivers 31 thru 38, 31' thru 38' as a moving object 1 moves in the arrow direction have been modulated by the random noise owing to the undulations of the ground 2. The receiving signals from the receivers 31' thru 38' are applied to modulators 41 thru 48 to become modulated signals which are then sent out to an adder-subtractor 50, by which the output signal f0' is obtained and this becomes the signal wherein the specific frequency component (N+1/2)v/d has been intensified. Here, v denotes the speed of the moving object and N the receiving part serial numbers and if their spacing d is suitably selected, the signal f00=v/2d of N=0 may be intensified, thus the speed v may be known by measuring the frequency f00. The object 1 is installed to the body of an automobile and its speed may be known from the signal f0, thus the speed to the ground may be obtained at high accuracy and the robust speedometer obtained. |
