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QuickStudy: Radio Frequency Identification (RFID)

By Bob Brewin
December 16, 2002 12:00 PM ET

Computerworld -

Listen to the Computerworld TechCast: RFID.

Australian sheep and haute couture from Prada might not seem to have much in common, but they do. Each is a valuable asset tracked by radio frequency identification (RFID) technology.

In the case of the sheep, a small plastic "smart tag" affixed to the animal's ear contains pertinent information about its bloodlines, date of birth and shot records.

The tag Milan, Italy-based Prada (officially known as I Pellettieri d'Italia SpA) uses on merchandise at its showcase Epicenter store in New York carries information about a garment's style, size, color and other details, including price.

The RFID tag in the sheep's ear contains a silicon chip to store data and a miniature antenna. The Prada tag and antenna, developed by Dallas-based Texas Instruments Inc., can be printed or etched on an electronic substrate, which is then embedded in a plastic or laminated paper garment tag.

Data from these tags is captured by a reader unit, which consists of an antenna and radio transmitter, attached to a stationary or handheld device. The reader emits radio waves, and when a tag comes within the range of the reader, the tag wakes up and starts sending data. The reader captures this bit stream, decodes it and sends it back over a network to a host processor.

RFID operates in a number of unlicensed frequency bands worldwide, with 125 KHz and 13.56 MHz the most common. The 13.56-MHz tags hold as much as 2,000 bits of data, or roughly 30 times the information of 125-KHz tags.

These systems have a relatively short range—inches to a few feet—but that's enough for inventory control or payment applications, such as Irving, Texas-based Exxon Mobil Corp.'s SpeedPass, which is already used by 6 million motorists. A gas-pump-based reader interrogates the key-fob SpeedPass (which contains a chip and an antenna) waved inches from the pump, obtains its identifier, passes that on via a Very Small Aperture Terminal (VSAT) network to a back-end system for credit approval and then turns on the pump—all in seconds.

Although the majority of RFID tags are write-once/read-only, others offer read/write capability and could, for example, allow origin and destination data embedded in a shipping container's tag to be rewritten if the container is rerouted. The data store on a 13.56-MHz tag is large enough to contain routing information for the shipping container and a detailed inventory of the products inside.



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