US Patent 7053823 System and method for cargo protection

A method and system for the detection, notification and tracking of cargo theft proposes to install, inside cargo to be protected, a tracking device having communication and dead reckoning capabilities. As long as the tracking device senses that it is within a virtual fence generated by an access point, it lays dormant. When the tracking device senses that it is no longer within the virtual fence it activates the dead reckoning capabilities and communicates with a central server to supply dead reckoning data thereto. The central server processes this data and determines the current location of the cargo.