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Radio frequency identification (RFID)




Definition
Radio frequency identification (RFID) is a contactless form of automatic identification and data capture. Dating back to World War II, RFID transponders were used to identify friendly aircraft. The RFID system consists of a reader, transponder, and antenna utilizing several frequency ranges. Over 40 million RFID tags will be used in 1999 with sales projected to break the one billion-dollar mark before 2003 (Frost & Sullivan, 1997). Radio frequency identification is used in access control, asset control, and animal identification. The advantages of RFID are the capability for multiple reads, ability to be used in almost any environment, and the accuracy. The Automatic Identification Manufacturers, International Standards Organization, and the American National Standards Institute are currently developing standards.
Barcodes have been developed in the railroad business to keep track of the various cars. Out of this system of identification grew the U.P.C. (Universal Product Code) which is now used in almost all manufactured goods. UPC is used to store the manufacturer code as well as the product code in a form that can be easily read by various scanners - even from a distance. But there are limits to the use of barcodes. There must be a direct line of sight between the reader and the code. The barcode can be obscured, for example by paint. One only has read-access to the data, i.e., one cannot add new data without adding another label.
This is the point where a relatively new technology comes in: RFID (Radio Frequency IDentification). In RFID electronic chips are used to store data that can be broadcast via radio waves to the reader, eliminating the need for a direct line of sight and making it possible for "tags" to be placed anywhere on or in the product. One can even write to tags made of semiconductor chips, thus enabling updating of data. This write function introduces new capabilities, such as the updating of the manufacturing process of the attached item.
RFID first appeared in tracking and access applications during the 1980s. These wireless AIDC systems allow for non-contact reading and are effective in manufacturing and other hostile environments where bar code labels could not survive. RFID has established itself in livestock identification and automated vehicle identification (AVI) systems because of its ability to track moving objects.
To understand and appreciate the capabilities of RFID systems it is necessary to consider their constituent parts. It is also necessary to consider the data flow requirements that influence the choice of systems and the practicalities of communicating across the air interface. By considering the system components and their function within the data flow chain it is possible to grasp most of the important issues that influence the effective application of RFID.
The RFID reader is designed for fast and easy system integration without losing performance, functionality or security. The RFID reader consists of a real time processor, operating system, virtual portable memory, and transmitter/receiver unit in one small self-contained module that is easily installed in the ceiling or in any other convenient location.

Radio frequency identification (RFID)

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ABSTRACT

The main objective of this letter is to present the design of an efficient, real-time data archival system to a secure digital flash memory card via reconfigurable hardware. The data ac-cess from the SD(Secure Data) card is implemented completely using Verilog and hence, there is no use of any microcontroller or on-chip general purpose processors. And since the complete design is a single purpose system, no extra hardware is required. The design has four in-dependent modules for the required different operations on the SD memory card. These four modules are for single-block write, multiple-block write, single-block read, and multiple-block read operations. We show how the bidirectional access takes place correctly and the data integrity has been verified using cyclic redundancy code in both field-programmable gate array (FPGA) chip and the SDcard controller.

INTRODUCTION

Almost every product in the market has a barcode printed on it. Barcodes are machine-readable parallel bars that store binary information, revealing information about the product. Thus, it acts as the product fingerprint. As we go to the supermarket to buy things, the checkout person runs our selection over the scanner to scan the barcode, there is audible beep, and we are told how much money we owe.
But the days of barcode are numbered. The reason is that a technology called radiofrequency identification (RFID) is catching on.RFID tags are being used by corporations to track people and products in just about every industry. They transform everyday objects like cargo containers, car keys, and even clothes on the rack at a shopping mall into mini nodes on a network. Databases then record the location and status of these network nodes to determine product movements.
This technology can completely replace barcodes.

RFID TAGS

A tag is any device or label that identifies the host to which it is attached. It typically does not hinder the operation of the host or adversely affect its appearance.The word transponder is derived from the words transmitter and responder.The tag responds to a transmitted or communicated request for the data it carries.

CLASSIFICATION OF TAGS

On the basis of the presence of battery, tags can be classified into active or passive tags.
Active tags are powered by an internal battery and are generally read/write devices. They contain a cell having a high power to weight ratio and are capable of operating over a temperature range of -50 to +70 degree Celsius. Active tags have a finite life time. A suitable cell coupled to suitable low power circuitry can ensure functionality of ten or more years depending on operating temperatures, read/write cycles and usage. They have greater size and increased cost compared to passive tags.
Passive tags operate without an internal battery source, deriving the power to operate from the field generated by the reader. They are hence lighter than active tags and have greater life time. They have shorter read ranges compared to active tags. They are also constrained in their ability to store data and perform well in electromagnetically noisy environments.
RFID tags can also be classified on the basis of coupling into inductively and capacitively coupled tags.
Inductively coupled RFID tags consist of the silicon microprocessor which vary in size depending on their purpose and metal coil which is made of copper or aluminumwire that is wound into a circular pattern on the transponder. This coil acts as the tagâ„¢s antenna. The tag transmits signal to the reader with the read distance determined by the size of the coil antenna. It also consists of an encapsulating material of glass or polymer that wraps around the chip and coil. Inductively coupled RFID tags are powered by the magnetic field generated by the reader .The tagâ„¢s antenna picks up the magnetic energy and the tag communicates with the reader. The tag then modulates the magnetic field in order to retrieve and transmit data back to the reader. Data which is transmitted back to the reader is directed to the host computer. These tags are expensive due to the silicon, the coil antenna and the process that is needed to wind the coil around the surface of the tag.

READER/INTERROGATOR

The reader/interrogators can differ considerably in complexity depending on the type of tags being supported and functions to be fulfilled. The overall function is to provide the means of communicating with the tag and facilitating data transfer. Functions performed by readers include signal conditioning, parity error checking and correction. Once the signal from a transponder has been correctly received and decoded, algorithms can be applied to decide whether the signal is a repeat transmission and may then instruct the transponder to stop transmitting. This is known as Command Response Protocol and is used to circumvent the problem ofreading multiple tags in a short span of time. Using interrogators in this way is also referred to as Hands Down Polling. A more secure, but slower tag polling technique is called Hands Up Polling which involves the interrogator looking for tags with specific identities and interrogating them, in turn. A further approach uses multiple readers, multiplexed into one interrogator but results in cost increase.

RFID SYSTEM

An RFID system consists of RFID tags ,a means of reading or interrogating the tags and a means of communicating the data to a host computer or information management system. The system will also include a facility for entering or programming data into tags, if it is not done at the source by the manufacturer. There may also be present antennas for communication between the ag and the reader.
The reader sends out a radio frequency wave to the tag and the tag broadcasts back its stored data to the reader. The system has two antennas, one for the tag and the other on the reader. The data collected from the tag can either be sent directly to a host computer through standard interfaces or it can be stored in a portable reader and later updated to the computer for data processing. The automatic reading and direct use of tag data is called data.

IMMOBILIZER SYSTEM

Immobilizers are the security systems in automobiles. The latest generation of RFID transponders called crypto transponders can be used as the chief part of immobilizers.
Key-based immobilizer systems consist of four main components. The core of the system is the transponder, a batteryless device which is available in various form factors and with different functionalities. For operation, the transponder has to be supplied with energy from an external source. The transceiver generates a high frequency magnetic field which is radiated by an antenna coil. The energy activates the transponder and it sends a data stream in form of a modulated RF signal. This signal is demodulated by the transceiver and then passed to the controller for data processing. Different physical principles for RFID systems have been established on the market. Concerning the transmission of energy, two different systems can be distinguished.
Full Duplex Systems. The energy for the transponder and the data signal generated by the transponder are transmitted at the same time.

CONCLUSION

RFID tags will soon be tracking millions of consumer products worldwide. Manufacturers will know the exact location of each product they make from the time it is made until it is used and tossed in the recycle bin or trash can. The crypto transponders will be well suited for future generation vehicle entry systems.
The RFID tagging will take off when the cost of the tags drops to one percent of the cost of the product it is applied to, and that date is somewhere near.
2005 is the date that researchers say when radio frequency tagging becomes viable and until then, we must wait and see.