What
Is Automatic Identification?
Automatic identification, or auto ID for short, is the broad term given
to a host of technologies that are used to help machines identify objects.
Auto identification is often coupled with automatic data capture. That
is, companies want to identify items, capture information about them and
somehow get the data into a computer without having employees type it
in. The aim of most auto-ID systems is to increase efficiency, reduce
data entry errors, and free up staff to perform more value-added functions.
There are a host of technologies that fall under the auto-ID umbrella.
These include bar codes, smart cards, voice recognition, some biometric
technologies (retinal scans, for instance), optical character recognition,
radio frequency identification (RFID) and others. Back
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What is RFID?
Radio frequency identification, or RFID, is a generic term for technologies
that use radio waves to automatically identify individual items. There
are several methods of identifying objects using RFID, but the most common
is to store a serial number that identifies a product, and perhaps other
information, on a microchip that is attached to an antenna (the chip and
the antenna together are called an RFID transponder or an RFID tag). The
antenna enables the chip to transmit the identification information to
a reader. The reader converts the radio waves returned from the RFID tag
into a form that can then be passed on to computers that can make use
of it. Back to Top
How does an RFID
system work?
The system consists of a tag, which is made up of a microchip with a coiled
antenna, and an interrogator or reader with an antenna. The reader sends
out electromagnetic waves that form a magnetic field when they "couple"
with the antenna on the RFID tag. A passive RFID tag draws power from
this magnetic field and uses it to power the microchip’s circuits.
The chip then modulates the waves that the tag sends back to the reader
and the reader converts the new waves into digital data. Back
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Are there any
health risks associated with RFID and radio waves?
RFID uses the low-end of the electromagnetic spectrum. The waves coming
from readers are no more dangerous than the waves coming to your car radio.
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Why is RFID better
than using bar codes?
RFID is not necessarily "better" than bar codes. The two are
different technologies and have different applications, which sometimes
overlap. The big difference between the two is bar codes are line-of-sight
technology. That is, a scanner has to "see" the bar code to
read it, which means people usually have to orient the bar code towards
a scanner for it to be read. Radio frequency identification, by contrast,
doesn’t require line of sight. RFID tags can be read as long as
they are within range of a reader. Bar codes have other shortcomings as
well. If a label is ripped, soiled or falls off, there is no way to scan
the item. And standard bar codes identify only the manufacturer and product,
not the unique item. The bar code on one milk carton is the same as every
other, making it impossible to identify which one might pass its expiration
date first. Back to Top
Will RFID replace
bar codes?
Probably not. Bar codes are inexpensive and effective for certain tasks.
It is likely that RFID and bar codes will coexist for many years. Back
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Is RFID new?
RFID is a proven technology that's been around since the Second World
War. Up to now, it's been too expensive and too limited to be practical
for many commercial applications. But if tags can be made cheaply enough,
they can solve many of the problems associated with bar codes. Radio waves
travel through most non-metallic materials, so they can be embedded in
packaging or encased in protective plastic for weather-proofing and greater
durability. And tags have microchips that can store a unique serial number
for every product manufactured around the world. Back
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If RFID has been
around so long and is so great, why aren’t all companies using it?
Many companies have invested in RFID systems to get the advantages they
offer. These investments are usually made in closed-loop systems –
that is, when a company is tracking goods that never leave its own control.
That’s because all existing RFID systems use proprietary technology,
which means that if company A puts an RFID tag on a product, it can’t
be read by Company B unless they both use the same RFID system from the
same vendor. But most companies don’t have closed-loop systems,
and many of the benefits of tracking items come from tracking them as
they move from one company to another and even one country to another.
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Is the lack
of standards the only thing that has prevented RFID from being more widely
used?
Another problem is cost. RFID readers typically cost $1,000 or more. Companies
would need thousands of readers to cover all their factories, warehouses
and stores. RFID tags are also fairly expensive – 50 cents or more
– which makes them impractical for identifying millions of items
that cost only a few dollars (see below). Back
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How much do RFID
tags costs?
They can cost as little as 30 cents or as much as $50 depending on the
type of tag and the application. Generally speaking, finished smart labels
that can be applied top products typically cost 50 cents or more. Active
tags – those with a battery – can cost far more. And if you
bundle in a sophisticated sensor, the cost can rise to more than $100.
Back to Top
What is
the difference between low-, high-, and ultra-high frequencies?
Just as your radio tunes in to different frequency to hear different channels,
RFID tags and readers have to be tuned to the same frequency to communicate.
RFID systems use many different frequencies, but generally the most common
are low- (around 125 KHz), high- (13.56 MHz) and ultra-high frequency,
or UHF (850-900 MHz). Microwave (2.45 GHz) is also used in some applications.
Radio waves behave differently at different frequency, so you have to
choose the right frequency for the right application. Back
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How do
I know which frequency is right for my application?
Different frequencies have different characteristics that make them more
useful for different applications. For instance, low-frequency tags are
cheaper than ultra high frequency (UHF) tags, use less power and are better
able to penetrate non-metallic substances. They are ideal for scanning
objects with high-water content, such as fruit, at close range. UHF frequencies
typically offer better range and can transfer data faster. But they use
more power and are less likely to pass through materials. And because
they tend to be more "directed," they require a clear path between
the tag and reader. UHF tags might be better for scanning boxes of goods
as they pass through a bay door into a warehouse. It is probably best
to work with a consultant, integrator or vendor that can help you choose
the right frequency for your application. Back
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Do all countries
use the same frequencies?
No. Europe uses 868 MHz for UHF and the U.S. uses 915 MHz. Japan currently
does not allow any use of the UHF spectrum for RFID. Government’s
also regulate the power of the readers to limit interference with other
devices. Some groups, such as the Global Commerce Initiative, are trying
to encourage governments to agree on frequencies and output. Tag and reader
makers are also trying to develop systems that can work at more than one
frequency, to get around the problem. Back
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I’ve heard
that RFID doesn’t work around metal and water. Does that mean I
can’t use it to track cans or liquid products?
No. Radio waves bounce off metal and are absorbed by water at higher frequencies.
That makes tracking metal products or those with high water content problematic,
but good system design and engineering can overcome this shortcoming.
In fact, there are applications in which RFID tags are actually embedded
in metal auto parts to track them. Back
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What’s
the difference between passive and active tags?
Active RFID tags have a battery, which is used to run the microchip's
circuitry and to broadcast a signal to a reader (the way a cell phone
transmits signals to a base station). Passive tags have no battery. Instead,
they draw power from the reader, which sends out electromagnetic waves
that induce a current in the tag's antenna. Semi-passive tags use a battery
to run the chip's circuitry, but communicate by drawing power from the
reader. Active and semi-passive tags are useful for tracking high-value
goods that need to be scanned over long ranges, such as railway cars on
a track, but they cost a dollar or more, making them too expensive to
put on low-cost items. The Auto-ID Center is focusing on passive tags,
which cost under a dollar today. Their read range isn't as far - less
than ten feet vs. 100 feet or more for active tags - but they are far
less expensive than active tags and require no maintenance. Back
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How much information
can the tag store?
It depends on the vendor and the application, but typically a tag would
carry no more than 2KB of data – enough to store some basic information
about the item it is on. Back
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What’s
the difference between read-only and read/write tags?
Chips in RF tags can be read-write or read-only. With read-write chips,
you can add information to the tag or write over existing information
when the tag is within range of a reader, or interrogator. Read-write
tags are useful in some specialized applications, but since they are more
expensive than read-only chips, they are impractical for tracking inexpensive
items. Some read-only microchips have information stored on them during
the manufacturing process. The information on such chips can never been
changed. A more flexible option is to use something called electrically
erasable programmable read-only memory, or EEPROM. With EEPROM, the data
can be overwritten using a special electronic process. Back
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What
is reader collision?
One problem encountered with RFID is the signal from one reader can interfere
with the signal from another where coverage overlaps. This is called reader
collision. One way to avoid the problem is to use a technique called time
division multiple access, or TDMA. In simple terms, the readers are instructed
to read at different times, rather than both trying to read at the same
time. This ensures that they don't interfere with each other. But it means
any RFID tag in an area where two readers overlap will be read twice.
So the system has to be set up so that if one reader reads a tag another
reader does not read it again. Back
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What is
tag collision?
Another problem readers have is reading a lot of chips in the same field.
Tag collision occurs when more than one chip reflects back a signal at
the same time, confusing the reader. Different vendors have developed
different systems for having the tags respond to the reader one at a time.
Since they can be read in milliseconds, it appears that all the tags are
being read simultaneously. Back
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What is the
read range for a typical RFID tag?
The read range of passive tags depends on many factors: the frequency
of operation, the power of the reader, interference from metal objects
or other RF devices. In general, low-frequency tags are read from a foot
or less. High frequency tags are read from about three feet and UHF tags
are read from 10 to 20 feet. Where longer ranges are needed, such as for
tracking railway cars, active tags use batteries to boost read ranges
to 300 feet or more. Back
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Are there
any standards for RFID?
Yes. International standards have been adopted for some very specific
applications, such as tracking animals. Many other standards initiatives
are under way. The most interesting efforts involve GTag, which is promoted
by EAN and UCC as a way to communicate with UHF tags; ISO 18000-6, which
is an international effort that forms the foundation for the GTag standard;
and the Auto-ID Center’s electronic product code. The EPC and the
technology surrounding it is not a standard in any formal way, but the
Auto-ID Center hopes that it will be widely adopted and become the de
facto standard. Back to Top
Who are the
leading RFID vendors?
There are many different RFID vendors with different areas of expertise.
We have compiled a director of vendors around the world. Click on Find
a Vendor in the left-hand navigation bar to locate the type of vendor
you are looking for. Back
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What are
some of the most common applications for RFID?
RFID is used for everything from tracking cows and pets to triggering
equipment down oil wells. It may sound trite, but the applications are
limited only by people’s imagination. The most common applications
are tracking goods in the supply chain, tracking assets, tracking parts
moving to a manufacturing production line, security (including controlling
access to buildings and networks) and paymant systems that let customers
pay for items without using cash. Back
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I’ve heard
RFID can be used with sensors. Is that true?
Yes. Some companies are combining RFID tags with radiation sensors. One
day, the same tags used to track items moving through the supply chain
may also alert staff if they are not stored at the right temperature,
if meat has gone bad, or even if someone has injected a biological agent
into food. Back to Top
What are intelligent
software agents and how do they fit into RFID?
Software agents are basically autonomous applications that automate decision
making by establishing a set of rules. For instance, if X happens, do
Y. They are important to RFID because humans will be overwhelmed by the
amount of data coming from RFID tags and the speed at which it comes (real-time
in many cases). So agents will likely be used to automate routine decisions
and alert employees when a situation requires their attention. SAP and
a company called BiosGroup are working on an automated replenishment system
in which software agents would make decisions when trends indicate a product
will be out of stock. Back
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What is "energy
harvesting"?
Most passive RFID tags simply reflect back waves from the reader. Energy
harvesting is a technique in which energy from the reader is gathered
by the tagged, stored momentarily and transmitted back at a different
frequency. This method may improve the performance of passive RFID tags
dramatically.Back to Top
