Radio frequency identification (RFID) technologies reader reach the chip’s antenna, the energy is con-are rapidly becoming a part of life. RFID tags receive verted by the antenna into electricity that can power or transmit data (usually a unique serial number) up the microchip in the tag (known as “parasitic over short distances when scanned by a reader. power”). The tag can then send back any informa-These tags have worked their way into robotics tion stored on the tag by reflecting the electromag-navigation, inventory tracking, access control, auto- netic waves (think of your access card at work). matic identification, payment systems, and dozens “Active tags” have their own power source and of other applications. Casinos are beginning to em- transmitter. The power source, usually a battery, bed RFID tags into their gambling chips in order to monitor gambling activity, detect counterfeit chips, and catch cheaters who try to surreptitiously add or Needless to say, we’ve seen remove chips from a wager. Needless to say, we’ve seen only the tip of the only the tip of the iceberg iceberg for the possibilities of RFID applications, deployments, and projects. The technologies are for the possibilities of RFID out there and they’re cheap enough for anyone to applications, deployments, start experimenting with. Now’s your chance to create that access-control-based pet feeder you’ve and projects. always wanted to make. Or maybe you can finally track your kids throughout the house.
In this article, I’ll briefly explain the concepts of is used to run the microchip’s circuitry and to
RFID technologies, introduce the Parallax RFID broadcast a signal to a reader. Since active tags
Reader Module, and show you how to put together a have their own transmitter, the reading distance
simple, portable RFID “scanner” so you can experi- is much longer than with passive tags. Active tags
ment with RFID and snoop around on your own to are typically larger and more expensive, and re-
discover any hidden or embedded RFID tags. quire occasional service. They’re commonly used
in automatic toll collection systems like Fas Trak
How RFID Works and E-ZPass. Within both passive and active tag (Material in this section is based on information types, there exist read-only, read/write, and cryp- provided by rfidjournal.com.) tographic variations.
There are two major types of RFID tag technolo- Just as you tune your radio to different frequencies gies. “Passive tags” do not contain their own power in order to hear different radio stations, RFID tags source or transmitter. When radio waves from the and readers have to be properly tuned in order to
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