Introduction
RFID is an area of
automatic identification that has quietly been gaining momentum in recent years
and is now being seen as a radical means of enhancing data handling processes,
complimentary in many ways to other data capture technologies such as bar coding.
Developments in RFID technology continue to yield larger memory capacities,
wider reading ranges, and faster processing. The object of any RFID system is
to carry data in suitable transponders, generally known as tags, and to
retrieve data, by machine-readable means, at a suitable time and place to
satisfy particular application needs. Data within a tag may provide
identification for an item in manufacture, goods in transit, a location, the
identity of a vehicle, an animal or individual.
Modulation
To transfer data efficiently via the air interface or space
that separates the two communicating components requires the data to be
superimposed upon a rhythmically varying (sinusoidal) field or carrier wave.
This process of superimposition is referred to as modulation, and various
schemes are available for this purposes, each having particular attributes that
favour their use. They are essentially based upon changing the value of one of
the primary features of an alternating sinusoidal source, its amplitude,
frequency or phase in accordance with the data carrying bit stream.
Rf Transponder
Programmers
Transponder programmers are the means by which data is
delivered to write once, read many (WORM) and read/write tags. Programming is
generally carried out off-line, at the beginning of a batch production run, for
example. For some systems re-programming may be carried out on-line,
particularly if it is being used as an interactive portable data file within a
production environment, for example. Data may need to be recorded during each
process. Removing the transponder at the end of each process to read the
previous process data, and to programme the new data, would naturally increase
process time and would detract substantially from the intended flexibility of the
application.
Carrier Frequencies
In wired communication systems the physical wiring
constraints allow communication links and networks to be effectively isolated
from each other. The approach that is generally adopted for radio frequency
communication channels is to separate on the basis of frequency allocation.
This requires, and is generally covered by government legislation, with
different parts of the electromagnetic spectrum being assigned to different
purposes.
Basic Features Of An
RFID Transponder
The transponder memory
may comprise read-only (ROM), random access (RAM) and non-volatile programmable
memory for data storage depending upon the type and sophistication of the
device. The ROM-based memory is used to accommodate security data and the transponder
operating system instructions which, in conjunction with the processor or
processing logic deals with the internal "house-keeping" functions
such as response delay timing, data flow control and power supply switching.
About
RFID is an area of automatic identification that has quietly
been gaining momentum in recent years and is now being seen as a radical means
of enhancing data handling processes, complimentary in many ways to other data
capture technologies such as bar-coding. The object of any RFID system is to
carry data in suitable transponders, generally known as tags, and to retrieve
data, by machine-readable means, at a suitable time and place.
Conclusion
In the near future, tags may become more than just
identifiers of objects in space- they might also monitor status, history, and
events, just as some boxes with fragile equipment now sport “excess G-force tags
that turn red when the box is dropped beyond a set distance. Electronic tags might well keep a
continuously updated history of sensed events over time.
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