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Operational Range
The range of tags varies widely but for all types a general rule of
thumb is the greater the range required the more expensive the tag.
At a range of just a few millimetres, an RFID tag can be embedded
in objects for high-speed sorting and authentication, but for logisti-
cal purposes a range of up to one metre is often required. Other
applications for real time location can require read ranges of several
kilometres.
RFID Readers
Readers can differ considerably in complexity depending upon
the type of tags being supported. Functions performed by a reader may include quite
complex signal processing, parity error checking, data correction algorithms and sophisti-
cated polling techniques. An outstanding feature of readers is their anti-collision capabili-
ty, thus ensuring data integrity when several RFID tags are read simultaneously.
Generally all RFID readers share the same basic architecture:
- An antenna (a coil or wire in a housing with a driver board);
- Reader electronics consisting of a decoder, data converter,
and computer interface (RS 232, RS 422, RS 485, Ethernet);
- Power supply;
- Portable readers have the same basic architecture as other RFID-readers but their
elements are typically enclosed in a single hand-held unit. Portable readers often
draw power from their host.
RFID Tag Programmers (Writers)
Tag programmers are used to deliver data to R/W and WORM tags and the program-
ming itself is generally carried out off-line, though some systems are capable of re-pro-
gramming on-line. In such cases, the functions of the programmer are combined with
those of the reader these are often called `reader-writers'.The range over which the
programming can be achieved is generally less than the read range. Programmers are also
generally designed to handle only a single tag at a time, despite the capability for multi-
ple simultaneous reads.
Smart Label Printers
Smart label printers enable users to create smart labels on demand and encode them
with information of different kinds. Printers use label stock that incorporates blank
RFID integrated circuits sandwiched between the surface face and the adhesive layer.
The integrated circuit may be so tiny that it is invisible to the human eye.
Smart label printers function in traditional thermal mode when creating barcodes,
graphics or text.They also have RFID encoders and readers embedded. Before the label
is printed, the RFID data is encoded on the tag which is subsequently read to ensure
Smart Labels
and Smart Tags
77
Sensors (Gate reader) with
three antennas (Winterthur
library)
by courtesy info@bibliotheca-rfid.com