rfid - Computer Definition
(Radio Frequency IDentification) A data collection technology that uses electronic tags for storing data. The tag, also known as an "electronic label," "transponder" or "code plate," is made up of an RFID chip attached to an antenna. Transmitting in the kilohertz, megahertz and gigahertz ranges, tags may be battery-powered or derive their power from the RF waves coming from the reader. Like bar codes, RFID tags identify items. However, unlike bar codes, which must be in close proximity and line of sight to the scanner for reading, RFID tags do not require line of sight and can be embedded within packages. Depending on the type of tag and application, they can be read at a varying range of distances. In addition, RFID-tagged cartons rolling on a conveyer belt can be read many times faster than bar-coded boxes. Serialization - A Major Factor RFID tags hold more data than bar codes, but a major differentiator is the unique serial number in the RFID's Electronic Product Code (EPC) because it allows tracking of individual items. While a UPC bar code might identify a 16 oz. bottle of mayonnaise, an EPC RFID tag could identify that single bottle. In this case, item level tracking could determine if the food had passed its expiration date. See bar code, UPC and EPC. Tracking livestock was one of the first uses of RFID, as well as vehicle and container tracking. RFID is also used to track people. In 2004, an amusement park in Denmark put RFID wrist bands on children, which could be quickly located by readers in the park if they were lost. RFID chips are even implanted into humans (see VeriChip). Libraries use RFID tags to quickly check out books and videos, and employees merely wave their RFID badges by a reader rather than insert them into a slot. For entrance ways manned with security guards, RFID tags can trigger calls to a database that puts pictures of the badge holders on screen by the time they approach the gate. To prevent theft, retail stores tag their merchandise with a tag similar to RFID, but without the chip (see EAS). Passive, Active and Semi Tags "Passive" tags have no power source but use the electromagnetic waves from the reader to energize the chip and transmit back (backscatter) their data. Passive tags can cost less than a quarter and be read up to approximately 10 feet from the reader's antenna. "Active" tags have a battery that can transmit up to 300 feet indoors and more than a thousand feet outdoors. Used for tracking trailers in yards and containers on the loading dock, active tags cost several dollars and may periodically transmit a signal for readers to pick up or may lie dormant until they sense the reader's signal. "Semi-passive" tags, also called "semi-active" tags, combine passive backscattering with a battery that allows the device to beep, blink or perform some operation. For example, a semi-passive tag on refrigerated cartons can include a sensor that, when interrogated, reports the temperature range during shipment.