Automatic Identification and Data Capture Techniques - An overview

The technologies used in the world of Automatic Identification and Data Capture (AIDC) are varied and often used in combinations to provide a broader base of information flow. This article attempts to summarize the technologies in common use today, and give the reader a basic understanding of the technology and its uses and limitations.

Bar Code - Perhaps the oldest of the AIDC technologies, bar code can be looked upon as the best known and probably most successful to date of the technologies. We are all familiar with the basic bar code on our box of cereal, or the jar of honey that we buy in the supermarket. This bar code is called UPC/EAN and is but one variation of over 250 bar codes that have been designed over time. Bar codes like this are referred to as linear bar codes as they are made up off a collection of bars and spaces side by side. Fortunately many of these bar codes have never gained broad acceptance and we usually only consider 10-12 linear bar codes. The most common examples in use today are: UPC/EAN, Code 128, Code 39, Code 93, and Interleaved 2 of 5. Typical data content capacity varies from 8 to 30 characters with some bar codes restricted to numerals only, and others using full alpha-numeric information. Standards for these bar codes are published by AIM and are currently in progress at ISO.

Linear bar codes are used in many applications where the use of a simple numeric or alpha-numeric code can provide the key to a database of "products". The most obvious limitation is the amount of data that can be stored in a linear bar code, though other problems can exist with the substrate that the bar code is printed on providing insufficient contrast or poor ink receptivity which can cause the quality of the bar code to be less than ideal.

Two Dimensional Bar Codes: A new growth area in the world of bar code is the two-dimensional versions. Several variations of 2D are available and as these do not all comprise bars and spaces the more accurate name of 2D symbologies is used. 2D symbologies provide a means of storing large amounts of data in a very small space. Whether you consider stacked symbologies (linear bar codes stacked on top of each other), matrix symbologies (comprising a matrix of light and dark elements, circles, squares, or hexagons), or packet symbologies (a collection of linear symbols "randomly" arranged on a page). Examples of the three types include PDF417, Code 49 Code 16K (stacked), Code One, MaxiCode, Data Matrix, Aztec Code, QR Code (matrix), and Super Code (packet). Standards for each of these symbologies are either available from AIM or are in progress. Several of these standards have also been submitted to ISO for standardization.

2D symbologies have a major advantage over linear bar codes, they can store vast amounts of data. Individual symbols can store as much as 7000 numeric only or 4200 alpha-numeric characters. Many of the symbologies also have the ability to use a device called structured append that allows messages to be split over multiple symbols, providing almost infinite storage space. The disadvantage of the 2D symbologies is that a special scanner is needed. Matrix symbologies need a vision based scanner to read the data, though some of the stacked symbologies can be read with a rastering laser scanner. Expect to see many new scanners with variations in technology in the next year or so.

Card Technologies - Magnetic Stripe: The first magnetic stripe cards were used in the early 1960s on transit tickets and in the 1970s for bank cards. Since then the use of magnetic stripes continues to grow. Credit cards were first issued in 1951, but it wasn't until the establishment of standards in 1970 that the magnetic stripe became a factor in the use of the cards. Whether the card is a credit card sized plastic card, a thin paper ticket or an airline boarding card, the uses for magnetic stripe technology have grown considerably. Today with an infra-structure that encompasses every store in the high street giving them an ability to read the information on the magnetic stripe, the technology is everywhere. Although some limitations exist in the amount of information that can be stored on the stripe and the security of the data, solutions to solve these problems exist from various vendors.

With the advent of new technologies many people have predicted the demise of the magnetic stripe. However, with the investment in the current infrastructure this is not likely to be any time soon. Magnetic stripe technology provides the ideal solution to many aspects of our life. It is very inexpensive and readily adaptable to many functions. The standardization of high coercivity for the financial markets has provided the industry with a new lease on life. This coupled with the advent of the security techniques now available means that many applications can expect to be using magnetic stripe technology for the next ten to twenty years. Standards for magnetic stripe technologies are available from ISO, where the focus is on the interchange environment, other standards are available from AIM.

Card Technologies - Smart Card: Smart cards are not new, the first patent was filed in France in 1974 and the first cards were used in France in 1982. The technology was rapidly accepted in Europe because the high cost of telecommunications made on-line verification of transactions very expensive. The smart card provided the mechanism to move that verification off line, reducing the cost without sacrificing any of the security. Smart cards are credit card-sized plastic cards that contain relatively large amounts of information in an imbedded micro-chip. There are several terms used to identify cards with integrated circuits embedded in them. The terms "chip card," "integrated circuit card", and "smart card" really all refer to the same thing.

There are two types of smart card. The first is really a "dumb" card in that it only contains memory. These cards are used to store information. Examples of this might include stored value cards where the memory stores a dollar value which the user can spend in a variety of transactions. Examples might be pay phone, retail, or vending machines. The second type of card is a true "smart" card where a microprocessor is embedded in the card along with memory. Now the card actually has the ability to make decisions about the data stored on the card. The card is not dependent on the unit to which it is attached to make the application work. A smart purse or multi-use card is possible with this technology.

As there is a microprocessor on the card, various methods can be used to prevent access to the information on the card to provide a secure environment. This security has been touted as the main reason that smart cards will replace other card technologies.

The microprocessor type smart card comes in two flavors - the contact version and the contactless version. Both types of card have the microprocessor embedded in the card however the contactless version does not have the gold plated contacts visible on the card. The contactless card uses a technology to pass data between the card and the reader without any physical contact being made. The advantage to this contactless system is there are no contacts to wear out, no chance of an electric shock coming through the contacts and destroying the integrated circuit, and the knowledge that the components are completely embedded in the plastic with no external connections. The disadvantage to this is that the card and reader are more sophisticated and hence are more expensive. The biggest disadvantage today with smart cards is the cost to create a smart card system. Individual card prices have fallen over the past few years but they are still high when compared with a magnetic stripe card. The biggest advantage is of course the amount of data that can be stored and the security that can be built into the card. Standards for the smart card technologies exist from ISO for both contact and contactless versions of the technology.

Card Technologies - Optical Card: Optical memory cards use a technology similar to the one used for music CDs or CD ROMs. A panel of the "gold colored" laser sensitive material is laminated in the card and is used to store the information.

The material is comprised of several layers that react when a laser light is directed at them. The laser burns a tiny hole (2.25 microns in diameter) in the material which can then be sensed by a low power laser during the read cycle. The presence or absence of the burn spot indicates a "one" or a "zero". Because the material is actually burned during the write cycle, the media is a write once read many (WORM) media and the data is non volatile (not lost when power is removed). The optical card can currently store between 4 and 6.6 MB of data which gives the ability to store graphical images such as photographs, logos, fingerprints, x-rays, etc.. Standards for optical cards can be obtained from ISO.

The major disadvantage with the optical card is the fact that it is a write once technology and so the amount of data storage available is used up with every piece of new data written. In some applications this can be considered an advantage because it maintains the complete history of changes made to the card.

Radio Frequency Identification (RFID): The hot technology in the AIDC arena is RFID. Although it has been available for a long time, it has only been available in proprietary formats from a variety of vendors. Work is at last progressing to provide standardized forms of RFID, with standardization work being done at ISO and AIM.

RFID provides a means of obtaining information on an item without making direct contact. Reading and writing distances can vary from a few millimetres to several metres depending on the technology variation used. The tags themselves come in a variety of form factors from credit card sized plastic cards, to tiny injectable glass transponders for tracking animals, to large "bricks" suitable for use on the side of containers on trains. The actual technology used to implement RFID varies depending on manufacturer and application, with frequencies used varying from 125kHz to 5.8GHz. There are many obstacles in the path of creating standards for RFID including the use of globally available frequencies. The work to remove some of these obstacles has started and the chance for global standards is now very real. Whether you are looking for a one-bit electronic article surveillance device or a multi-character inventory label, RFID has a solution that can provide a non-contact method for storing the information.

The biggest advantage is the non-contact aspect of the technology, with read distances to tens of metres available. This can also be a disadvantage where the reading of multiple tags can take place simultaneously can occur and special steps have to be implemented to assist with this.

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