SECTION II: Understanding Radio Frequency IDentification (RFID)

LOW FREQUENCY (LF) PASSIVE RFID


Transponders can either be read only (R/O) which are pre-programmed with a unique identification or they can be Read Write (R/W) for applications that require data to be stored in the transponder and can be updated dynamically. Another form of transponder is write once read many times (WORM). This will allow for an identification number to be written to the transponder once. The information is stored in the memory and it cannot be changed but the transponder can be read many times

Passive LF RFID has been utilized in several industries for many years. The most common frequencies used are 125 and 134.2 kHz.

One of the key features of LF RFID is that it is not as affected by surrounding metals. This makes it ideal for identifying metal items such as vehicles, equipment, tools and metal containers. The read range can vary from a few centimeters to a couple of meters depending on the size of the transponders and the reader being used.

Transponders come in various form factors, from glass, to wedge and disks of various sizes. Other form factors available are cards and cylindrical. These different form factors allow for the transponder to be embedded into most materials, except for metal.  Other form factors such as key tags can also be customized.

LF RFID also penetrates most materials, such as water and body tissue. The limitations are that if used in industrial environments, electric motors may interfere with the LF system.

Due to the size of the antenna required, the LF transponders are typically more expensive than high frequency transponders. This limits the frequency to applications where the transponders can be re-used.

The following are some of the benefits and limitations of LF RFID:

  • Penetrates most materials well including water and body tissue, which makes it ideal for animal identification
  • Tags can easily be embedded into any non-metallic items such as pallets, key tags, cards etc.
  • LF could be affected by electrical noise that may be generated by motors in an industrial environment
  • Relatively low data transfer rate (70ms for read command), the lower the frequency, the slower the communication
  • Transponders are more expensive
  • Most LF systems can only read one transponder at a time and does not support simultaneous read of multiple transponders
  • Read ranges are from a few centimeters to a couple of meters, depending on the size of the transponders
  • Frequency is used worldwide. There are no restrictions

Numerous access control systems are based on LF, contact-less cards or key tags for security. A read only card can be used simply as identification or a read-write card can be used to maintain access or security information.

The largest user for LF RFID is the automotive industry. Currently, most car immobilizer systems use an LF transponder embedded into a car key with a reader mounted in the ignition. Other applications are vehicle identification for highway and parking lot access.

In Canada, the success story of Esso and their Speedpass system clearly exemplifies how this technology is being used to broaden and heighten brand awareness as well as customer loyalty program. In this case, a TI (Texas Instruments) glass transponder is embedded into a key tag. To maintain a high level of security, all transponders are programmed with an encrypted number, which is validated as soon as the transponder is presented to the gas pump. Following the validation at the pump, communication is established with Esso’s accounting system.  At that point, Esso’s accounting system validates the customer’s account, prior to activating the gas pump. The customer will then be charged for all purchases and Esso will automatically update their customer loyalty program.

Numerous automotive manufactures use LF RFID for work-in-process. Being able to insert a transponder into a pallet or product gives the manufacturer the reliability required and also allows for the product to be identified and used throughout the manufacturing process.

LF is also used for animal identification, from endangered species, to pets and livestock. Currently, cattle are identified with a bar coded ear tag.  This form of identification is unreliable and is not robust enough for the environment. The Canadian Cattle Identification Agency (CCIA) is mandating that all cattle must be identified with an RFID ear tag. The standards being adopted are ISO 11784 & 11785, which have been in use in Europe for quite some time.

Continue reading…click here for Section III: HIGH FREQUENCY (HF) PASSIVE RFID

 


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