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| Radio Frequency Identification
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Introduction In hundreds of thousands of government and private sector facilites around the world, passive RFID technology is used to gain access to buildings and or areas within these facilities. The usual form factor is a card, about the thickness of 3 credit cards. Since then, a number of other technologies have also been developed, each with their own sets of advantages and disadvanteages. The early cards, or "tags" operated in the 125 Kz frequency. Later tags operated in the 13.56 MHz frequency, the 915 Mhz, and even 2.4 Ghz frequencies, and higher. Dataflo specializes in the 13.56 MHz (High frequency) and the 915 MHz (Ultra-High Frequency) RFID systems. The latter, 915 MHz is also known as the "EPC" (Electronic Product Code) tag, and is the technology now mandated for use in shipments to the US Department of Defense, Wal-Mart, Target and many other retailers. We are one of very few fully RFID Certified integration experts in all facets of an RFID deployment. The mandate most manufacturers and distributors are concerned with and the mandate to which most are attempting to comply is that of Wal-Mart, which requires the top 100 suppliers to Wal-Mart to tag all shipments to Wal-Mart with a Class 0 or Class 1 tag by January 1, 2005. Subsequently, ALL suppliers must be shipping tagged product by January 1, 2007. The tagging requirement is at both the case AND pallet levels. See Wal-Mart RFID Compliance. What's driving these mandates is the understanding that RFID is one of the most promising and anticipated technologies in recent years. Magazine articles, television shows, analyst papers and the like are frequently trumpeting the potential benefits to users of RFID. RFID can provide immediate and tangible benefits throughout the supply chain. Organizations who take the time to understand the technology's capabilities and limitations can increase their inventory visibility while streamlining their operations. How
it works An antenna or coil The antenna emits radio signals to activate the tag and read and write data to it. Antennas are the conduits between the tag and the transceiver, which controls the system's data acquisition and communication. Antennas are available in a variety of shapes and sizes; they can be built into a door frame to receive tag data from persons or things passing through the door, or built in a portal configuration to read pallets as they are loaded on a truck, or placed in line on a sortation system to read goods on the conveyor, or mounted on an interstate toll booth to monitor traffic passing by on a freeway, etc. The electromagnetic field produced by an antenna can be constantly present when multiple tags are expected continually. If constant interrogation is not required, the field can be activated by a sensor device. Often the antenna is packaged with the transceiver and decoder to become a reader (a.k.a. interrogator), which can be configured either as a handheld or a fixed-mount device. The reader emits radio waves in ranges of anywhere from one inch to 100 feet or more, depending upon its power output and the radio frequency used. When an RFID tag passes through the electromagnetic zone, it detects the reader's activation signal. The reader decodes the data encoded in the tag's integrated circuit (silicon chip) and the data is passed to the host computer for processing. RFID tags come in a wide variety of shapes and sizes. Animal tracking tags, inserted beneath the skin, can be as small as a pencil lead in diameter and one-half inch in length. Tags can be screw-shaped to identify trees or wooden items, or credit-card shaped for use in access applications. The anti-theft hard plastic tags attached to merchandise in stores are RFID tags. In addition, heavy-duty 5- by 4- by 2-inch rectangular transponders used to track intermodal containers or heavy machinery, trucks, and railroad cars for maintenance and tracking applications are RFID tags. RFID tags are categorized as either active or passive. Active RFID tags are powered by an internal battery and are typically read/write, i.e., tag data can be rewritten and/or modified. An active tag's memory size varies according to application requirements; some systems operate with up to 1MB of memory. In a typical read/write RFID work-in-process system, a tag might give a machine a set of instructions, and the machine would then report its performance to the tag. This encoded data would then become part of the tagged part's history. The battery-supplied power of an active tag generally gives it a longer read range. The trade off is greater size, greater cost, and a limited operational life (which may yield a maximum of 10 years, depending upon operating temperatures and battery type). Passive RFID tags operate without a separate external power source and obtain operating power generated from the reader. Passive tags are consequently much lighter than active tags, less expensive, and offer a virtually unlimited operational lifetime. The trade off is that they have shorter read ranges than active tags, smaller data capacity and require a higher-powered reader. Read-only tags are typically passive and are programmed with a unique set of data (usually 32 to 128 bits) that cannot be modified. Read/Write tags can contain up 2KB of data and highter. Read-only tags most often operate as a license plate into a database, in the same way as linear barcodes reference a database containing modifiable product-specific information. The significant advantage of all types of RFID systems is the noncontact, non-line-of-sight nature of the technology. Tags can be read through a variety of substances such as snow, fog, ice, paint, crusted grime, and other visually and environmentally challenging conditions, where barcodes or other optically read technologies would be useless. RFID tags can also be read in challenging circumstances at remarkable speeds, in most cases responding in less than 100 milliseconds. The read/write capability of an active RFID system is also a significant advantage in interactive applications such as work-in-process or maintenance tracking. Though it is a costlier technology (compared with barcode), RFID has become indispensable for a wide range of automated data collection and identification applications that would not be possible otherwise. Developments in RFID technology continue to yield larger memory capacities, wider reading ranges, and faster processing. It is highly unlikely that the technology will ultimately replace the barcode — even with the inevitable reduction in the cost of raw materials coupled with economies of scale, the integrated circuit in an RF tag will never be as cost-effective as a barcode label. However, RFID will continue to grow in its established niches where barcode or other optical technologies are not effective. If some standards commonality is achieved - whereby RFID equipment from different manufacturers can be used interoperably - the market will very likely grow exponentially What
is EPC? The Electronic Product Code (EPC) is a unique number that identifies a specific item in the supply chain. The EPC is stored on a radio frequency identification (RFID) tag, which combines a silicon chip and an antenna. Once the EPC is retrieved from the tag, it can be associated with dynamic data such as from where an item originated or the date of its production. Much like a Global Trade Item Number (GTIN) or Vehicle Identification Number (VIN), the EPC is the key that unlocks the power of the information systems that are part of the EPCglobal Network. RFID Tags: Passive Passive RFID tags obtain power generated by the radio waves produced by the transceiver to send a response, they can be read/write, but have smaller memory than active tags. Read ranges are from 3 inches - 10M depending on the frequency selected. Costs, although dropping rapidly, are still from $1 - $10. Low Frequency (LF) RFID, which operates at 120-140KHz, is a mature technology that has been around for many years in industries that include agricultural animal tracking and security door access. Advantages of Low Frequency RFID technology include sturdy tags and superior insensitivity to read interference from liquids and metals. The main disadvantage is that the tags require long windings of copper wire in the manufacturing process which adversely affects both the RFID tag's size and cost of production. As a result, the LF RFID technology has a limited market and is being replaced by higher frequency RFID technologies in many newer applications. High Frequency (HF) RFID, operating at 13.56MHz, uses a similar technology to LF RFID but has notable advantages in terms tag cost, data size and form factors since it does not require long winding of copper wire in the tag manufacturing process. Available form factors range from flat inlet tags to environmentally robust tags similar to those used in LF RFID applications. Other advantages of the HF RFID technology are greatly increased data storage capacity and specific ISO standards for high security applications. The increased data storage capacity has lead to the creation of "mobile database" applications where data records are stored on RFID tag instead of a networked database. Security applications using the ISO 14443 RFID specification can use HF RFID tags to conduct the same financial transactions as smartcards, but without the mechanical wear and higher costs. The main limitation of HF RFID technology is the typical read range of three to six inches. Ultra High Frequency (UHF) RFID technology, operating at 915MHz, is specifically designed for retail and supply chain management. Data storage is typically limited to enough bytes for a UPC, EPC or SKU number. The main advantages of UHF RFID are the increased read range and high number of RFID tags that can be read in an operation. The technology used in UHF RFID technology is fairly new with many companies working to reduce the cost of both readers and tags. Wal-Mart has been one of the largest proponents of using UHF RFID to improve supply chain automation and reduce costs associated with tracking of retail supplies. The Electronic Product Code (EPC) specification was created with sponsorship from companies such as Wal-Mart to help standardize RFID use in supply chain management. Although HF RFID does have an EPC specification, Wal-Mart has stated that it will only accept UHF based RFID tags. Companies that are concerned with Wal-Mart RFID Compliance should only consider UHF based RFID solutions at this time.
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