USE OF ULTRASOUND FOR MONITORING SECURITY OF SHIPPING CONTAINERS

摘要

Ultrasound is used to detect either or both the opening of a door of a shipping container or a change in the contents of a shipping container. Ultrasound signals transmitted from one or more ultrasonic transducers configured to be mounted within an interior of a shipping container travel through the interior and are reflected by a reflector, e.g., a corner reflector. The reflected ultrasound is received by an ultrasonic receiver, which produces an output signal corresponding to the received ultrasound signal. If the ultrasonic transducer or the reflector is mounted on the door, the time of flight of the ultrasound signal can be used to determine the distance that the ultrasound signal travels. Opening the door changes this distance, which can be detected. Similarly, changes in ultrasound reflected from contents in the shipping container can be detected and used to detect changes in the contents, which may be caused by terrorist activity.