A basic RFID system consist of three components:

• An antenna or coil
• A transceiver (with decoder)
• A transponder (RF tag) electronically programmed with unique information

RFID hardware currently consists of two products, tags and readers.

Tags: An RFID tag is an electronic bar code. A tag is usually a chip attached to an antenna and housed in a plastic case. Originally, the chip's responsibility was to simply transmit a unique number in response to a reader's transmission. Today, tags contain memory and can retain a large amount of information about the product to which they are attached. Tags also can be programmed to have a life of their own. That is, they can announce their location when they have been moved, and provide information, such as temperature or pressure, from devices to which they are attached.

In the past, tags were big, expensive, and read very slowly. A trucker could have a tag the size of a hockey puck fastened to the bottom of his rig and when he parked at a gate, after a minute, the system would read and open the gate. There was no reason to produce small or quickly read devices. Today, a small and inexpensive RFID tag can sit on the dashboard of a vehicle and be read at 70 miles per hour on a toll road. Tags the size of four US quarters stacked together send information from the cones of Russian and American missiles. Some tags are paper-thin, the size of a US quarter, and can be read by the handful.

Readers: Readers are used to identify the location of assets in virtually real time. Readers can be as simple as a loop around a doorway to record tagged items arriving at or leaving the premises. When attached to an asset, a tag, upon motion or upon tampering, transmits at predefined intervals a unique identification code to a network of transceivers, or readers. These readers pass the message transmissions to the server software for decoding. The asset's movement is then graphically displayed in virtually real time and stored.

Common Applications

Transportation/Distribution

RFID systems are uniquely suited for use in the rigorous rail environment. Field programmable tags permit the full industry standard 12-character identification of each car by type, ownership and serial number. Tags are attached to the vehicle undercarriage; antennae are installed between or adjacent to the tracks, and readers or display devices are typically located within 40 to 100 feet in a wayside hut along with other control and communications equipment. A primary objective in rail applications is the improved fleet utilization that permits reductions in fleet size and/or deferral of investment in new equipment.

Commercial truckers are using RFID systems to monitor access and egress from terminal facilities. Combined with weigh-in-motion scales, the same systems can be used for transaction recording at refuse dumps, recycling plants, mines and similar operations, or for credit transactions at truck stops or service depots.

Industrial

In the plant environment, RF systems are ideally suited for the identification of high-unit-value products moving through a tough assembly process (e.g., automobile or agricultural equipment production where the product is cleaned, bathed, painted and baked). RF systems also offer the durability essential for permanent identification of captive product carriers such as:

• Tote boxes, containers, barrels, tubs, and pallets
• Tool carriers, monorail and power, and free conveyor trolleys; and
• Lift trucks, towline carts, automatic guided vehicles

Primary applications fall into two basic categories:

Direct product identification wherein the tag specifically identifies the item to which it is attached (e.g., by part number or serial number or, in the case of read/write systems, assembly or process instructions for the item).

Carrier identification where content is identified manually (or with a bar code reader) and fed to the control system along with the carrier's machine-readable RF "license plate number." Strategically deployed RF readers accomplish subsequent load tracking.

The automotive industry uses RFID systems to track vehicles through assembly, where tags must perform even after repeated subjection to temperatures of 150 to 200 C, painting, etc. A primary objective for use of the technology in this environment is verification of vehicle identity prior to execution of given assembly tasks. Although manufacturers sequentially track vehicles through assembly, undetected removal of a single vehicle from the line could be costly.

Because RFID tags need not be "seen" to be read, they can be buried within pallets, tote boxes, and other containers and provide solid performance for the life of the carrier. As an example, in a casting operation RF tags are attached to wire baskets which travel through a variety of degreasing, etching and cleaning tanks by means of an overhead power and free conveyor - not a job for optical or magnetic identification media.
In a manner similar to carrier identification, RF tags can be used for tool management. Miniature tags can be placed within tool heads of various types such as block or Cat V-flange, or even within items such as drill bits where individual bits can be read and selected by reader guided robot arms.

RFID systems are used for lift truck and guided vehicle identification in a number of installations. One approach buries tags at strategic locations throughout the facility and verifies vehicle location via on-board DC-powered readers. Other users station readers at the ends of warehouse aisles to monitor lift truck activity. Here, throughput rates permit multiplexing multiple antennae per reader.

Security and Access Control

The movement and use of valuable equipment and personnel resources can be monitored through RF tags attached to tools, computers, etc. or embedded in credit-card-size security badges. This type of monitoring also provides an extra measure of security for personnel working in high-risk areas in case of an emergency evacuation.

Animal Identification

Valuable breeding stock, laboratory animals involved in lengthy and expensive research projects, meat and dairy animals, wildlife, and even prized companion animals all present unique identification problems that can be solved by innovative applications of RFID technology.

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