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Frequently Asked Questions
What Is automatic
identification?
What is RFID?
How does an RFID
system work?
Is there any
health risks associated with RFID and
radio waves?
Why is RFID better
than using bar codes?
Will RFID replace
bar codes?
Is RFID new?
If RFID has been
around so long and is so great, why
aren’t all companies using it?
Is the lack of
standards the only thing that has
prevented RFID from being more widely
used?
How much do RFID
tags costs?
What is the
difference between low-, high-, and
ultra-high frequencies?
How do I know
which frequency is right for my
application?
Do all countries
use the same frequencies?
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?
What’s the
difference between passive and active
tags?
How much
information can the tag store?
What’s the
difference between read-only and
read/write tags?
What is reader
collision?
What is tag
collision?
What is the read
range for a typical RFID tag?
Are there any
standards for RFID?
Who are the
leading RFID vendors?
What are some of
the most common applications for RFID?
I’ve heard RFID
can be used with sensors. Is that true?
What are
intelligent software agents and how do
they fit into RFID?
What is "energy
harvesting"?
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.
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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.
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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.
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Is 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.
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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.
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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.
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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).
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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to Top
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.
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.
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.
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