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,
barcode can be looked upon as the best known and probably most successful to
date of the technologies. We are all familiar with the basic barcode on our box
of cereal, or the jar of honey that we buy in the supermarket. This barcode is
called UPC/EAN and is but one variation of over 250 barcodes that have been
designed over time. Barcodes like this are referred to as linear barcodes as
they are made up off a collection of bars and spaces side by side. Fortunately
many of these barcodes have never gained broad acceptance and we usually only
consider 10-12 linear barcodes. 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 barcodes restricted to
numerals only, and others using full alpha-numeric information. Standards for
these barcodes are published by AIM and are currently in progress at ISO.
Linear barcodes 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 barcode, though other problems can exist with the
substrate that the barcode is printed on providing insufficient contrast or poor
ink receptivity which can cause the quality of the barcode to be less than
ideal.
2D barcodes: A new growth area in the world of barcode 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
barcodes 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 barcodes, 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. More
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. More
