January 24, 2005
Radio Frequency IDentification - RFID
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We are all familiar the ubiquitous bar coding that appears on most products we purchase. The idea for bar code was described in a patent application titled "Classifying Apparatus and Method” filed by Norman Joseph Woodland and Bernard Silver in October 1949 and granted in 1952. Neither man made much money out of their idea but Woodland was awarded the 1992 National Medal of Technology by President Bush.
The first attempt at an industrial application of automatic identification was begun in the late 1950's by the Association of American Railroad. In 1967, the Association adopted an optical bar code. Car labeling and scanner installation began 1967. Unfortunately, the system simply did not work and was abandoned in the late 1970's.
The event that really got bar code into industrial applications occurred September 1, 1981 when the United States Department of Defense adopted the use of Code 39 for marking all products sold to the United States military. This system was called LOGMARS.
A series of meetings between Grocery Manufacturers of America (GMA) and the National Association of Food Chains lead to a decision in September 1969 to seek a standard "interindustry product code." The result of this meeting and four years of research was the Universal Product Code (U.P.C.). On June 26, 1974, a 10-pack of Wrigley's chewing gum became the first item to be scanned at a grocery checkout counter. The first UPC scanner was made by National Cash Register Co (now NCR).
The code is split into two halves of six digits each. The first one is always zero, except for products like meat and produce that have variable weight, and a few other special items. The next five are the manufacturer's code the next five are the product code: and the last is a check digit used to verify that the preceding digits have been scanned properly. Hidden cues in the structure of the code tell the scanner which end is which, so it can be scanned in any direction. Manufacturers register with the UCC to get an identifier code for their company, and then register each of their products. Thus each package that passes over a checkout stand has its own unique identification number.
The U.P.C. has allowed supermarkets to control their inventory more efficiently, provided a faster and more accurate check out for customers, and made gathering information for accurate and immediate marketing studies very simple. The uses of the U.P.C. have spread to all facets of the food and beverage industry, the government, the industrial/commercial industry and the transportation industry.
Perhaps it is not surprising to learn that the Europeans came up with a different system, namely the European Article Numbering system. The EAN association was formed in February 1977 and headquartered in Brussels. Membership was extended to companies from other continents and the name was changed to EAN International in 1992. Today EAN International has 101 Member Organizations representing 103 countries.
With the exception of the United States and Canada, retail products from around the world are marked with EAN-8 and EAN-13 symbols. To sell those products in the U.S. and Canada, manufacturers must re-label with a 12-digit U.P.C. symbol. This creates additional expense and time-to-market issues.
In 1997 the Uniform Code Council, Inc. (UCC) announced the '2005 Sunrise' initiative whereby all U.S. and Canadian companies must be capable of scanning and processing EAN-8 and EAN-13 symbols, in addition to 12-digit U.P.C. symbols, at point-of-sale by January 1, 2005.
We have all witnessed clerks at grocery stores and other places struggle (think carpal tunnel syndrome) to orient packages for the bar code reader. It would obviously be an improvement if the object itself could somehow assist in the process even at a distance. Also bar codes do not currently contain all the desired information. Enter Radio Frequency Identification (RFID).
An RFID system consists of an antenna, a transceiver and a tag (transponder - derived from TRANSmitter/resPONDER). The antenna emits radio signals to activate the tag and reads and writes data to it. Often the antenna is packaged with the transceiver and decoder to become a reader or interrogator. The RFID system is part of an automated data collection system that includes a host system or server that process and manages the data collected.
An RFID transponder is characterized among other things by its
Carrier frequency ranges can be grouped as low, medium and high. Low frequency (100-500kHz) devices are inexpensive and have low reading speed and a short to medium read range. Medium frequency (10-15MHz) devices are somewhat more expensive and have medium reading speed and a short to medium range. High frequency (UHF 850-950 MHz and Microwave 2.4-5.8 GHz) devices are expensive and have high reading speed and a long range. Also they require line of sight. A low frequency system would be used in applications like access control, inventory control and animal identification. Medium frequency systems would be used in applications like smart cards and access control. High frequency system
would be used in applications like highway toll collections and railroad car monitoring. Allowable frequency ranges are generally set by government agencies for different applications. The carrier frequency greatly determines the data transfer rate.
The range of an RFID system is determined by the power available at the reader and within the tag as well as by environmental conditions. In a space free of any obstructions or absorption mechanisms the strength of the field reduces in inverse proportion to the square of the distance. Reflections from obstacles and the ground can further reduce the strength.
The transponder memory may comprise read-only (ROM), random access (RAM) and non-volatile programmable memory for data storage depending upon the type and sophistication of the device. The ROM-based memory is used to accommodate security data and the transponder operating system instructions. The RAM-based memory is used to facilitate temporary data storage during transponder interrogation and response. The non-volatile programmable memory used to store the transponder data. Some tags can be programmed infield while attached to the item being identified or accompanied.
Tags are classified according to a scheme by the Auto-ID Center as
Passive tags are also constrained in their capacity to store data and the ability to perform well in electromagnetically noisy environments.
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-- Jack Horgan, EDACafe.com Contributing Editor.
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