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Is RF signal harmful for human
beings and the environment?
No. The power levels used for any RFID applications
are well below the power levels that prove to have any
harmful effects. RFID uses the low-end of the electromagnetic
spectrum and is in compliance with the Federal Communications
Commission(FCC) regulation.
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Does
RF signal pass through walls?
RF signals easily pass through walls. Tags can also
be read through a variety of substances such as snow,
fog, ice, paint, grease, oil, etc. and other visually
and environmentally challenging conditions, where barcodes
or other optically read technologies would be useless.
The signal strength of RF falls off inversely to the distance
travelled and is further degrade by passing through walls
or reflecting off metal fixtures. |
How
does an Passive RFID system work?
The RFID system consists of an tag, which consists
of a microch ip with a coiled antenna, and an interrogator/reader
with an antenna. The reader emits electromagnetic waves
that form a magnetic field when they "couple"
with the antenna on the RFID tag. A passive RFID tag powers
the microchip’s circuits by drawing the power from
this magnetic field. The microchip 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
RFID better than using bar codes?
The two are different technologies which have some common
applications. The biggest distinguishing factor between
the two is bar codes are line-of-sight technology which
require the bar code to be oriented towards the scanner
for it to read.Radio frequency identification doesn’t
require line of sight. RFID tags can be read as long as
they are within range of a reader. Bar codes have several
other shortcomings as well. If a label is ripped, soiled
or falls off, there is no way to scan the item.Standard
bar codes can identify only the manufacturer and product,
they donot have a unique ID. The bar code on one medicine
bottle is the same as every other, making it highly impossible
to identify which one reaches its expiration date first.
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Will
RFID replace bar codes?
No. RFID and bar codes will have to coexist. |
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How much does an RFID tag cost?
The Passive tags cost a magnitude less than Active
tags. The Passive tags can cost as little as 30 cents
or even less if bought in bulk Active tags - those with
a battery - can cost far more. Some Active tags even
come with temperature or pressure sensors built in,
which cost more than $100.
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Does RFID
work around metal and water?
Radio waves cannot pass through metal,it bounces off
metal and are absorbed by water at higher frequencies.
This makes tracking metal products or those with high
water content difficult, but with a good system design
and engineering these problems can be easily overcomed.
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What is the difference between
passive, semi-passive and active tags?
Active RFID tags have a battery, which is used to
run the microchip's circuitry and to transmit a signal
to a reader. Passive tags have no battery. 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 /location
of high-value goods that need to be scanned over long
ranges, but they are costly, making them very expensive
to put on low-cost items. The read range for Passive
tags is less than ten feet. In case of Active tags the
read range is 100 feet or more. Passive tags are far
less expensive than active tags and require no maintenance.
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How much data can be stored in
a tag?
It depends on the vendor and the application, but
typically a tag would store around 2KB of data which
is good enough to store some basic information about
the item it is on.
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What is the difference between
read-only and read/write tags?
Microchips in RF tags can be read-write or read-only.
With read-write chips, information can be added to the
tag or write over existing information when the tag
is within range of a reader/interrogator. Since the
Read-write tags are expensive they are used only in
some specialized applications. Some read-only microchips
have information stored on them during the manufacturing
process. The information on such chips can never been
changed. With a EEPROM(electrically erasable programmable
read-only memory) the data can be overwritten using
a special electronic process.
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How does tag collision occur?
Tag collision occurs when more than one tag sends
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.
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What are the different read ranges
for a typical RFID tag?
The read range for a passive tag depends on a lot of
factors i.e 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, active tags are
used to boost read ranges to 300 feet or more.
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Are there any standards for RFID?
Yes. There are number of standards that define the various
aspects of operation of the RFID Technology.Some of
them are:The Auto-ID standard set up by Uniform Code
Council(UCC) and EAN International, and promoted by the
Auto-ID consortium.At present, the UCC standards offer
the most compatible technology for RFID systems, and
are the de-facto standards for all commercial implementations
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Is RF harmful for human beings and the environment?
