Abstract: Objects in a cargo shipping container are detected by measuring vibration resonant frequency peaks of the container. The mass of an object on the floor of the container effects the vibration resonance of the container, enabling the object to be detected. A vibration source and a plurality of accelerometers are either attached to the steel structure of the container, or are disposed on a supporting structure, such as a cargo crane or lift, so that they contact the container. The vibration source causes the container to vibrate, and the accelerometers detect the vibration resonance of the container. A mismatch between a cargo manifest and an observed cargo, or detection of an object having relatively high mass, e.g., due to lead shielding, can justify a manual inspection. The process uses synchronous processing to achieve the sensitivity needed, is unobtrusive, and does not slow the flow of cargo through a facility.

Abstract: Objects in a cargo shipping container are detected by measuring vibration resonant frequency peaks of the container. The mass of an object on the floor of the container effects the vibration resonance of the container, enabling the object to be detected. A vibration source and a plurality of accelerometers are either attached to the steel structure of the container, or are disposed on a supporting structure, such as a cargo crane or lift, so that they contact the container. The vibration source causes the container to vibrate, and the accelerometers detect the vibration resonance of the container. A mismatch between a cargo manifest and an observed cargo, or detection of an object having relatively high mass, e.g., due to lead shielding, can justify a manual inspection. The process uses synchronous processing to achieve the sensitivity needed, is unobtrusive, and does not slow the flow of cargo through a facility.

Abstract: 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.