What would be the best method for keeping tabs on such containers using radio frequency identification technologies?
The most common way to do this would be to outfit each container with an active RFID transponder set to broadcast every few seconds or minutes, depending on how often you want an update on each tagged container's location.
RFID readers would need to be set up around the perimeter of your distribution yard. As a tag "blinks"—or emits its unique serial number—that signal is picked up by the interrogators around the yard. Different systems use different techniques to calculate location, including triangulation or time differences of arrival (TDOA). The software pinpoints the tagged container on a map of the facility to within about 10 feet.
It is also possible to use passive tags with a shorter read range. One way to do this is to read tags on containers as they are offloaded from a ship, and then place them on specific vehicles that move them around the yard. The vehicles can be tracked with GPS or other technologies, in order to monitor each container's location.
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In discussions I've had with companies that have deployed an RFID-based real-time location system (RTLS) in their distribution yard, most say they achieved a return on their investment in approximately 12 to 18 months. Good luck with your project.
—Mark Roberti, Founder and Editor, RFID Journal