Patent attributes
A passive identification system for shipping containers. The shipping containers contain passive identification devices that are interrogated by separate on-board location trackers (OBLT) located in places where shipping containers are expected to pass in proximity to during the shipping and transport process. The OBLTs contain an active transmitter and GPS device. After the OBLT interrogates the passive identification device on a shipping container, the OBLT generates a geo-word comprised of the container identification, the GPS location of the OBLT, and a time stamp, and transmits the geo-word to a receiving station for tracking and/or security purposes. The receiving station has manifest information regarding the shipping containers stored in memory. In this manner, the receiving station can compare the geo-word to the expected shipping locations and expected times for the shipping container to determine if the shipping container is lost, misplaced, or off-schedule.