JPS6481093A - Vehicle flow rate measuring instrument - Google Patents

Abstract

PURPOSE:To exactly measure the degree of a traffic jam by laying a radio wave absorbing body on the road, radiating a radio wave from the upper part, and generating a pulse train of a car by receiving a reflection by an automobile. CONSTITUTION:When no automobile exists in a measuring point, a radio wave from an antenna 2 is absorbed by a radio wave absorbing body 4 on the road surface 3, and there is no reflected wave. On the contrary, when an automobile exists, the radio wave is reflected by the automobile, and received by the antenna. In order to utilize this theory, a radio wave from a transmission circuit 11 is sent to the antenna through a circulator 12, and also, the reflected wave is led to a reception circuit 13 through the circulator 12. A signal from the reception circuit 13 is shaped to a pulse train by a pulse shaping circuit 15 with a clock 14, it is identified by an identification circuit that no car exists when zero is continued, and a car exists when '1' is continued, and by counting a signal for showing that the car exists by a counting circuit 17, the degree of a traffic jam is calculated.