| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a radio wave firing source detection sensor for determining whether a radio wave has arrived from a self-lane or the other lane and an automatic charge collection system and a road side unit using this sensor. <P>SOLUTION: This radio wave firing source detection sensor installed in a preliminarily set lane, and configured to receive a response signal from a response unit carried by a traveling body as a first reception beam, and connected to a road side unit which communicates with the response unit includes: an antenna part; a direction specification part; and an identification determination part. The antenna part is configured to receive the response signal as a second reception beam whose beam width is wider than that of the first reception beam. The direction specification part is configured to measure the signal strength of the response signal, and to specify a direction of arrival. The identification determination part is configured to determine whether or not the response signal has arrived from the lane, and the signal strength exceeds a preliminarily set threshold based on the signal strength and the direction of arrival, and to determine that the response signal is valid when the result of determination is positive, and to transmit the result of determination to the road side unit. <P>COPYRIGHT: (C)2012,JPO&INPIT |
