| 摘要 |
A system and method for determining the locations of freight containers in a freight yard is described. A remote unit that includes a GPS receiver is attached to the freight containers. The remote receivers have an independent power supply-a battery. Intermittently, either by a timer or by a motion detector, the remote receivers are operated. Duping operation, the remote receivers receive signals from the global positioning satellite system and at an allotted time, transmit the GPS data to a base station before shutting down to conserve power. The base station processes the GPS data to determine a position in the freight yard of each freight container. When a particular freight container or contents is desired, a database in the base station can be consulted and the contents and location of a particular freight container located. The freight yard is typically outside with a view of the GPS constellation, such as a rail yard. airport baggage area, ship yard, truck park, etc. An alternative is described for use where the freight yard is a warehouse and the satellite view is obstructed. The alternative uses pseudolite or repeaters to track freight containers within the warehouse.
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