Credit-card-sized electronic transponders have been proposed for use in tracking cargo anywhere on Earth. A transponder would be carried on a cargo container, where it would act as a "smart tag." The transponder would store data on the cargo in the container and would respond to inquiries —whether local or remote — about the contents and location of the shipment. The transponder and the communication and data-processing systems with which it would interact would ensure accurate and up-to-the-minute tracking of cargo, whether the cargo was in a warehouse, train, truck, airplane, or ship. Tracking cargo in this way would eliminate the need for the voluminous paperwork now used to track cargo and would make it unnecessary to prematurely open cargo containers at transshipment points to ascertain their contents.

Figure 1. RAM Chips would be laid out in an area of about the same dimensions as those of the magnetic strip on a conventional credit card. The retainer unit would provide electric power (about 1 mW) to the transponder and would serve as an electrical interface between the transponder and the outside world. The retainer unit would be about the size of a hand calculator.

A transponder would contain a microprocessor and a strip of random-access memory (RAM) integrated-circuit chips that would store the information on the cargo and its location. For limited applications, the transponder itself would be self-contained, with all the required functions [i.e., encoding, Global Positioning System (GPS), battery] retained by it. For universal applications, the transponder would be held in a retainer unit (see Figure 1) mounted on a cargo container. The retainer unit would be the medium through which information would be transferred. The retainer unit would function somewhat in the manner of a credit-card reader, except that the reading would be done completely electronically; that is, there would be no moving magnetic reader head because the information would not be stored in magnetic strips as it is on credit cards. The retainer unit would include an infrared transceiver for local communication and a microwave transceiver for communication over longer distances (see Figure 2).

Figure 2. A Network of Satellites would link "smart" tags on transport vehicles over long distances to a central interrogation point. GPS satellites would send data to the tags about their current locations.

There are many ways of transferring information to the transponder. Information on the cargo could be transferred into the transponder RAM from a laser bar-code scanner wired to the retainer unit by a long, flexible cord like a telephone cord. Alternatively, the information could be transmitted from a remote bar-code reader analogous to devices now used in rental-car-return yards. A third alternative would be to enter the data manually via a keyboard.

Either the transponder or the retainer unit would include a GPS receiver, with GPS being integral with the transponder when used alone. Periodically (e.g., every 15 minutes) data on the latitude and longitude of the unit, as determined from GPS signals, would automatically be stored in the transponder RAM.

To retrieve information from the transponder at short range (about 100 m or less), an operator would aim an infrared interrogation "gun" at the retainer unit. From somewhat greater distances, information could be retrieved through infrared or microwave repeaters in the transport vehicle, at shipping depots, or at stations en route, for example. At still greater distances, satellite microwave links would be used. Thus, data on the contents, ownership, origin, destination, and location of a cargo container could be obtained at any time from anywhere.

When the cargo reached its destination, the transponder would be removed from the retainer and inserted into a reader on a personal computer to obtain a complete shipping record. The transponder could be then filed or reused for subsequent shipments.

This work was done by Philip I. Moynihan and Govind K. Deshpande of Caltech for NASA's Jet Propulsion Laboratory.

This invention is owned by NASA, and a patent application has been filed. Inquiries concerning nonexclusive or exclusive license for its commercial development should be addressed to

the Patent Counsel
NASA Resident Office - JPL; (818) 354-5179

Refer to NPO-19769.


NASA Tech Briefs Magazine

This article first appeared in the September, 1998 issue of NASA Tech Briefs Magazine.

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