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RFID technology can be applied to many business processes, namely asset management
and tracking, logistics, product identification and tracking, personnel tracking,
access control, document management and so on. This technology is also used in quality
control processes, product authentication and even operational productivity.
Low-frequency (30 KHz to 500 KHz) systems have short reading ranges and lower system
costs. They are most commonly used in security access, asset tracking, and animal
identification applications. High (HF)and Ultra High Frequency (UHF) (850 MHz to
950 MHz and 2.4 GHz to 2.5 GHz respectively) systems, offering long read ranges
(greater than 30 metres) and high reading speeds, are used for such applications
as railroad car tracking and automated toll collection.
The significant advantage of all types of RFID systems is the non-contact, non-line-of-sight
nature of the technology. Tags can be read through a variety of substances such
as snow, fog, ice, paint, crusted grime, and other visually and environmentally
challenging conditions, where barcodes or other optically read technologies would
be useless.
RFID tags can also be read in challenging circumstances at remarkable speeds, in
most cases responding in less than 100 milliseconds. The read/write capability of
an active RFID system is also a significant advantage in interactive applications
such as work-in-process or maintenance tracking. Though it is a costlier technology
(compared with barcode), RFID has become indispensable for a wide range of automated
data collection and identification applications that otherwise, would not be possible.
An RFID system consists of three components: a tag, a reader, and a database.
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Types of tags
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RFID tags are produced in various configurations depending on their functionality.
Following is a list of the functionality associated with each class of tag.
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Class |
Attributes |
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Class 0 |
Read only passive ID tags |
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Class I |
Write once passive ID tags |
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Class II |
Passive tags with added functionality, eg memory or encryption |
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Class III |
Semi – passive |
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Class IV |
Active tags – communicate with readers and other tags on the same frequency band. |
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Class V |
Essentially readers can power class I,II, and III as well as communicating with
Class IV and with each other |
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A tag consists of a microchip, and an antenna imbedded in a substrate (usually paper
or plastic). Every tag is uniquely identified and is either passive, semi passive
or active.
Passive Tags
Passive tags are composed of an integrated electronic microchip and an antenna coil
that includes basic modulation circuitry and a non-volatile memory.
The tag is energized by a time-varying electromagnetic radio frequency waves that
are transmitted by the reader. The information contained on the tag is transmitted
back to the reader through the same radio waves.
The unique identity of the tag is decoded by the reader and passed to a host. Tag
manufacture can be customised to suit to the application for which its intended.
Anatomy of a passive label
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Active Tags
Active tags are powered by an internal battery and are typically read/write, i.e.,
tag data can be rewritten and/or modified. An active tag’s memory size varies according
to application requirements; some systems operate with up to 1MB of memory. In a
typical read/write RFID work-in-process system, a tag might give a machine a set
of instructions, and the machine would then report its performance to the tag.
This encoded data would then become part of the tagged part’s history. The battery-supplied
power of an active tag generally gives it a longer read range. The trade off is
greater size, greater cost, and a limited operational life (which may yield a maximum
of 10 years, depending upon operating temperatures and battery type).
Readers
Readers are the communication core of RFID systems they can both read and write
to compatible tags.
Readers come in many different configurations and can be hand held or fixed depending
on the required function. Most of them have the following integrated components:
Antenna, Transceiver, Microprocessor, Memory, Communications Interface, Power source
and Controller.
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Radio Frequency Ranges
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RFID systems are also distinguished by their frequency ranges as detailed in the
following table.
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Band |
Frequency Range |
Frequency Used |
Tag type |
Read Range |
Application
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Low(LF) |
30 – 300 KHz |
125 or 134 Khz |
Passive |
15 - 90 cm |
Animal ID, Security Personnel Tracking |
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High (HF) |
3 – 30 Mhz |
13.56 Mhz |
Passive |
15cm – 1.2 m |
Item tracking Document Tracking |
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Ultra High (UHF) |
300 Mhz – 1 GHz |
866 - 950 MHz |
Active and Passive |
3 to 6 m |
Product tracking, Logistics |
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Micro Wave (MW) |
1GHz up
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2.5 or 5.8 Ghz |
Passive and Semi Passive |
30 m |
Railroad container tracking, Tolls, E-tag |
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