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Series 188 000
RF Identification Tags, Badges and Reader/Writers

Operating Principles

RF/ID technology is based on bidirectional radio frequency communication between a base station consisting of a PC (or some other microprocessor system) equipped with a Read/Write unit, and an ID tag or badge attached to a person or object. The tag consists of an antenna, some control circuitry and memory in which ID information is stored. This memory may be Read-Only in which case the information is unalterable or Read/Write which means that information can be overwritten or added to memory at a later time by the user.

The Read/Write unit consists of an antenna and modulation/demodulation circuits which are controlled by the microprocessor system. When operating, the unit emits an electromagnetic field which extends over a certain volume about the base station. If an ID tag passes into this volume, this field activates the control circuitry of the tag. A dialog is then set up in which the tag identifies itself by sending the information contained in its memory to the base station. Upon receiving the information, the base station analyzes the data and takes appropriate action such as opening (or refusing to open) a door, debiting an account, or sending information back to the tag for storage in its memory. What this action is depends on the application.

One characteristic of RF/ID tags is the absence of an intrinsic power supply. Instead, energy is obtained from the electromagnetic field generated by the base station. In this case, the antenna in the tag also serves as the inductive coil for power generation. Tags of this sort are known as passive tags. Active tags which contain a source of energy, such as a battery, are also possible and are generally used where longer range and/or faster data exchange are required. The tradeoff, of course, is a shorter lifetime, higher cost and larger overall dimensions.




RF/ID systems offer a number of major advantages over current ID systems such as bar codes or magnetic cards. For example,

  • Hands-free operation. There is no need to insert the tag or badge into a reader as in the case of magnetic or smart cards. This is particularly advantageous in moving environments such as buses or trains. Operation is also faster as there is no wait time in front of a reader or machine.
  • Writeability. The write capability of tags are particularly advantageous for certain applications such as access control in security environments. By writing each accessed location into the tag’s memory, an audit trail of the person or object can be kept. Writeability also allows tags to be reused for different applications.
  • Security. The information contained in a tag may be protected through the use of passwords. This presents a much higher level of security than bar codes or magnetic cards
  • No need for intrinsic energy source. The absence of batteries or other intrinsic energy sources within passive tags allows for long lifetimes and ecological use.
  • Adaptability. Tags may be adapted to various environments, made in different sizes and shapes, encapsulated in different materials such as plastic, aluminum, etc.


RF ID tags are ideal for applications such as logistics tracking of objects, animals and even people. The secured read/write capability of CFG badges also makes it suitable for stored value applications such as

  • Parking, Toll Collection
  • Ticket collection, for example, ski lifts, club entry, swimming pools,
  • Industrial automatization
  • Security.

CFG RF/ID Components

CFG produces a complete line of RF tags, badges and reader/writers based on 125 KHz operation.