RFID System Frequently Asked Questions
RVB Systems Group can help you select the equipment for
your RFID system. An RFID system is just a reader and a tag
communicating over the air at a certain frequency - just like any other
type of radio communications. The readers, antennas, tags and
frequency make up the basics of an RFID system. We sell ready-to-use RFID kits as well as
individual components and media. Not sure which type of RFID system is
best for you??? CALL TODAY to discuss your project and let us
recommend the RFID equipment scanner that is best suited for your data
MOST COMMON RFID QUESTION
"From how far away can a typical RFID tag be read?"
The distance from which a tag can be read is called
its read range. Read range depends on a number of factors, including the
frequency of the radio waves uses for tag-reader communication, the size of the
tag antenna, the power output of the reader, and whether the tags have a battery
to broadcast a signal or gather energy from a reader and merely reflect a weak
signal back to the reader. Battery-powered tags typically have a read range of
300 feet (100 meters). These are the kinds of tags used in toll collection
systems. High-frequency tags, which are often used in smart cards, have a read
range of three feet or less. UHF tags-the kind used on pallets and cases of
goods in the supply chain-have a read range of 20 to 30 feet under ideal
conditions. If the tags are attached to products with water or metal, the
read range can be significantly less. If the size of the UHF antenna is reduced,
that will also dramatically reduce the read range. Increasing the power output
could increase the range, but most governments restrict the output of readers so
that they don't interfere with other RF devices, such as cordless phones.
RVB Systems Group is available for
on-site installation, training and system development involving any of these products.
Not sure which
scanner is best for
you??? CALL TODAY to discuss your project and let us
recommend the RFID equipment that is best suited for your data collection
RFID too expensive?
Need to track inventory or fixed assets using barcode technology?. Click
HERE to learn more about Track'Em, an Inventory and Fixed Asset
tracking application that can be used with any of the barcode scanners available
from RVB Systems Group.
1. What is automatic identification?
2. What is RFID?
3. How does an RFID system work?
4. Are there any health risks associated with RFID and radio waves?
5. Why is RFID better than using bar codes?
6. Will RFID replace bar codes?
7. Is RFID new?
8. If RFID has been around so long and is so great, why aren't
all companies using it?
9. Is the lack of standards what has prevented RFID from being
more widely used?
10. What is the difference between low-, high-, and ultra-high
11. How do I know which frequency is right for my application?
12. Do all countries use the same frequencies?
13. I've heard that RFID doesn’t work around metal and water.
14. What's the difference between passive and active tags?
15. What is an Electronic Product Code (EPC)?
16. How much information can the tag store?
17. What's the difference between read-only and read-write tags?
18. What is reader collision?
19. What is tag collision?
20. What is the read range for a typical RFID tag?
21. Are there any standards for RFID?
22. What are some of the most common applications for RFID?
23. I've heard RFID can be used with sensors. Is that true?
24. What are intelligent software agents and how do they fit into
25. What is "energy harvesting"?
26. Will RFID lead to massive layoffs of workers?
Important RFID Links
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, such as providing customer service. 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, and radio
frequency identification (RFID).
What is RFID?
Radio frequency identification, or RFID, is a generic term for
technologies that use radio waves to automatically identify people or
objects. There are several methods of identification, but the most
common is to store a serial number that identifies a person or object,
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 reflected back from the RFID tag into digital information
that can then be passed on to computers that can make use of it.
How does an RFID system work?
An RFID system consists of a tag, which is made up of a microchip
with an antenna, and an interrogator or reader with an antenna. The
reader sends out electromagnetic waves. The tag antenna is tuned to
receive these waves. A passive RFID tag draws power from field created
by the reader 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.
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
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.
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.
Is RFID new?
RFID is a proven technology that's been around since at least the
1970s. 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
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
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 – 20 cents
or more – which makes them impractical for identifying millions of
items that cost only a few dollars (see below).
What is the difference between low-, high-, and
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 - (LF - around 125 KHz), high- (HF - 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
LF (Low Frequency) reads at very close range, just beyond actual
HF (High Frequency) reads out to several inches to a foot.
UHF (Ultra High Frequency) reads several yards. In perfect
conditions, can read 30 to 40 feet.
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
Do all countries use the same low-, high and ultra-high frequencies?
Most countries have assigned the 125 kHz or 134 kHz area of the
radio spectrum for low-frequency systems, and 13.56 MHz is used around
the world for high-frequency systems. But UHF RFID systems have only
been around since the mid-1990s and countries have not agreed on a
single area of the UHF spectrum for RFID. Europe uses 868 MHz for UHF
and the U.S. uses 915 MHz. Until recently, Japan did not allow any use
of the UHF spectrum for RFID, but it is looking to open up the 960MHz
area for RFID. Many other devices use the UHF spectrum, so it will take
years for all governments to agree on a single UHF band 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
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 ultra-high
frequencies. That makes tracking metal products or those with high water
content problematic, but good system design and engineering can overcome
this shortcoming. Low- and high-frequency tags work better on products
with water and metal. In fact, there are applications in which
low-frequency RFID tags are actually embedded in metal auto parts to
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.
Companies are focusing on passive UHF tags, which cost under a 50 cents
today in volumes of 1 million tags or more. Their read range isn't as
far -- typically less than 20 feet vs. 100 feet or more for active tags
-- but they are far less expensive than active tags and can be disposed
of with the product packaging.
What is an Electronic Product Code?
EPC stands for "electronic product code", and it
is an emerging RF identification standard to identify a case or individual
package in the retail space.
The Electronic Product Code (EPC) is a new product numbering standard
under development by the Uniform Code Council (UCC) that can be used to
identify a variety of items using radio frequency identification (RFID)
technology. The 96-bit EPC code links to an online database, providing a
secure way of sharing product-specific information along the supply chain.
Like other RFID solutions, the EPC's ability to be read without a
line-of-sight offers users significant timesavings. This is further
enhanced by the ability to update information automatically to the EPC's
online database -- identifying where and when a case or pallet of goods
arrived, for example -- in supply chain logistics applications.
The EPC technology, in conjunction with the expanding production of
RFID capable printers/encoders,
has the potential to revolutionize the supply chain by providing more
accurate information about product movement, stock rotation, inventory
levels and other management information. It also would be a significant
tool for product recalls and theft prevention.
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. Companies are now looking at using
a simple "license plate" tag that contains only a 96-bit
serial number. The simple tags are cheaper to manufacture and are more
useful for applications where the tag will be disposed of with the
What's the difference between read-only and read-write tags?
Microchips in RFID 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 usually have a serial number that can't be
written over. Additional blocks of data can be used to store additional
information about the items the tag is attached to. Some read-only
microchips have information stored on them during the manufacturing
process. The information on such chips can never been changed. Other
tags can have a serial number written to it once and then that
information can't be overwritten later.
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.
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.
What is the read range for a typical RFID tag?
The read range of passive tags (tags without batteries) 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.
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 International Organization for
Standardization (ISO) is working on standards for tracking goods in the
supply chain using high-frequency tags (ISO 18000-3) and ultra-high
frequency tags (ISO 18000-6). EPCglobal, a joint venture set up to
commercialize Electronic Product Code technologies, has its own
standards process, which was used to create bar code standards.
EPCglobal intends to submit EPC protocols to ISO so that they can become
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, reusable
containers, high value tools and other assets, and parts moving to a
manufacturing production line. RFID is also used for security (including
controlling access to buildings and networks) and payment systems that
let customers pay for items without using cash.
I've heard RFID can be used with sensors. Is that true?
Yes. Some companies are combining RFID tags with sensors that detect
and record temperature, movement, even radiation. 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.
Will RFID lead to massive layoffs of workers?
RFID technology is a labor-saving technology so it's likely that some
workers will laid off. That's because fewer workers will be needed to
scan bar codes. But the transition from bar codes to RFID could take a
decade or more, so it is unlikely that RFID will lead to wide-scale
displacement of workers. The technology will likely create new jobs,
just as Internet technologies creating new jobs, from Web developers to
warehouse workers managing inventory for online stores such as
Amazon.com. The jobs that will be affected by RFID are those that
involve scanning bar codes. Most of those jobs also have other
components, such as moving products or restocking shelves. Those jobs
will not go away because of RFID.