ULTRASONIC WAVE WATCHING DEVICE OF MOVING OBJECT DETECTING TYPE

摘要

This invention provides an ultrasonic wave watching device for detecting a moving object wherein an ultrasonic wave signal generated by an oscillator is transmitted from a transmitter, reflected signals from a stationary object and moving object are received by a receiver and the variation with time of the phase difference between these received signals and the transmitted signal is detected to determine the presence and moving direction of the moving object.