Electronic methods to detect persons hidden within cargo containers

Physical security technologies have been unable to address most 'Trojan Horse' scenarios at vehicle portals which provide access through the perimeter of a secure area. Through visual searches of vehicle cargo containers are time consuming, involve a number of security personnel and are cursory at best. Vehicles entering or exiting a protected site provide and adversary with an easy pathway across secure boundaries. A method to detect the presence of persons hiding within a vehicle's enclosed cargo container has been developed by Lockheed Martin Energy Systems. The system measures vibrations coupled to the container and generated by the human heart. Each time the human heart beats, it generates a small but measurable shock wave. This shock wave is propagated though the body and transmitted to anything with which the body has contact. This wave is referred to as a ballistocardiogram and is the mechanical equivalent to an electrocardiogram. Sympathetic vibrations of the cargo container's surface can be collected using any of several detection methods. When initiated by the operator, analog signals are recorded for a specific interval of time and rate. At the end of the recording interval, the data are analysed using wavelet transform techniques and compared with a ballistocardiographic template. If the collected data are similar, the system informs the operator that there is a high degree of probability that a person is within the vehicle. The paper describes in depth the development of the system, and focuses on technologies being evaluated for future iterations of the system and applications other than the protection of perimeters