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D7.7: RFID, Profiling, and AmI

Basic operation of RFID systems*  Title:
 Transmission Frequencies and Related Effects


Types of RFID systems *

Since their conception, a plethora of RFID systems* have been developed. However, all of these systems are based on only a few basic operating procedures. The various operating methodologies can be derived from .


Essentially, the RFID system* can operate based on one of two basic protocols: Full (or half) duplex (FDX / HDX) or sequentially (SEQ). During FDX / HDX the transponder* sends its data when the RFID reader* is asking for it (and in the passive case, supplying power to it). SEQ however requires the reader* to briefly turn off, during which time the tag sends it data. 



Figure : A flow diagram representing the various basic combinations of RFID systems* possible


Typically, the data quantity a tag holds is in the region of a few bytes to a few kilobytes (sometimes referred to as n-bit). However, some tags only operate using 1 bit – that is the reader* can only tell if a tag is there or not, and nothing else. This is useful in applications such as shop security (Electronic Article Surveillance (EAS)) where you want an alarm to sound if a tag passes through the door regardless of what the tagged item is.


Some n-bit tags are programmable, that is the data that they contain can be changed by the ‘reader’*. Systems that have this functionality typically use Induction Coupling (IC) as their means of communicating between reader* and tag, and most IC systems utilise passive tags. Simpler programmable tags contain simple logic (also known as a state machine) which can control read/write access or to perform fairly complex sequences as well as hold ‘state variables’. More complex varieties use a microprocessor (uP) which allows some degree of complex operations to be performed, and is ultimately more flexible than the state machine solution. 



Basic operation of RFID systems*  fidis-wp7-del7.7.RFID_Profiling_AMI_02.sxw  Transmission Frequencies and Related Effects
Denis Royer 38 / 43