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Radio-frequency identification (RFID) is different than the other building wireless systems. It can't control anything, and it only identifies things. Its primary use is in asset management and security. RFID tags are incorporated into products or carried by people to identify and track their location using radio frequencies. RFID is deployed in retail, hospitals, airports, education, and other building uses.

Systems generally consist of RFID readers and tags. RFID tags are simply radio transponders. They are a small integrated circuit or computer chip which has a tiny radio antenna built in. In passive RFID systems the tag does not have its own power source, the tag absorbs energy from the system reader antenna, a process called coupling. The tag is programmed with a unique identification. When the tag is excited by and absorbs the radio waves of the reader antenna it sends out its unique ID which is picked up by the reader antenna.

Active RFID systems tags have their own power source and don't need to use the reader's antenna radio waves to power up and transmit their identity. Active tags have greater range, can store larger amounts of data, and are larger than passive tags.

RFID tags come in various sizes and shapes to address a variety of uses. The tag can be paper thin to fit inside a book. They also can be directly mounted onto equipment, embedded in wrist straps, attached to clothing, or worn on a belt.

Wireless tracking systems are only as good as their networks. RFID readers have an antenna attached to them. Essentially the reader interfaces or sits in between the wireless portion of the system (the antenna) and the head end or host system. The antenna attached to the reader sends radio signals out to activate tags. It listens for tags to communicate and once a tag responds, reads the data transmitted by the tag and sends it to the reader. Readers can have multiple antennas attached. The reader can decipher the signal and send the data to the host server.

RFID operates in several radio frequencies: 125 kHz or 134 kHz low- frequency systems, 13.56 MHz for high-frequency system, and 2 or 3 frequencies for ultra-high frequency systems.

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