| 摘要 |
The objective of the present invention is to provide proximity sensors employing impulse waves to detect the characteristics of objects lying inside the object of surveillance, such as a container, including their distance, the reflection strength from an object, the speed an object is moving, etc., as well as to provide a status surveillance system which detects, from the data from the proximity sensors, that the inside of the container remains unchanged. To achieve the foregoing objectives, the present invention adds proximity sensor functions to wireless communication nodes inside of the object of surveillance, such as inside of a container. Said proximity sensors output microimpulse waves from the wireless communication nodes, and said communication nodes receive the reflections of those waves from nearby objects. The wave reception sampling is performed based upon the bit signals of the clock for the microimpulse transmissions and the local clock, and the analysis of the received signals enables the highly precise measurement of the distance to an object using simple circuitry. It is then possible to detect an abnormal occurrence inside the object of surveillance by comparing the characteristic data obtained from the initial environment with that data obtained during the period of surveillance. Further, the proximity sensing function is able to detect the direction of any penetration.
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