See also:
|
RFID Readers
The types of devices used to read RFID tags have expanded in the last few years as RFID
technology has gained in popularity. Older
RFID readers have been expensive and limited
in capabilities, but now the buyer has a
number of choices:
- "Agile readers" can read tags from
several different frequency groups, and may
have multiple options for transmitting the
data off the reader to a system for processing.
- "Dumb" readers do only simple reading,
while "intelligent" readers may
do some local storing and processing of the
tag data.
- "Reader collision avoidance" algorithms.
"Reader collision" occurs when
too many readers are in close proximity and
interfere with each other. Most reader manufacturers
have devised timing algorithms to deal with
collisions, but it may still a problem in
older or low-cost readers.
Some more innovative methods
for reading
tags include:
- Cellphone readers - an add-on to certain
cellphones which capture the RFID data into
the phone for later uploading. These use
the phone's display for feedback and interaction.
The advantage here is that the omnipresent
cellular network becomes the transmission
link, allowing RFID tags to be read almost
anywhere there is phone service.
- PCMCIA-based readers for laptops and handhelds
- these readers use the portable's
power
to provide the electromagnetic
energy necessary
to read the tags. An added
benefit is that
the reading application resides
on the portable,
eliminating the need to transmit
it elsewhere
for processing.
Whichever type and capability reader you
choose, the primary consideration is that
it is compatible with the tags you want to
read. Tags operate on specific frequencies,
and ISO, the standards body, has specifications
defined for different standards and applications
of tags. Tag frequencies are in three major
groups:
- Low frequency: 125 kHz and 134 kHz frequencies
- Medium frequency: popular 13.56 MHz tags
based on the ISO15693 and ISO14443 standards.
- Medium frequency: 26.957 to 27.283 MHz, used
for special applications
- UHF (ultra high): 433 MHz, 868 - 870 (Europe
only,) and 902 - 928 MHz
Many companies are working to produce readers
compliant with the ISO 14443A and ISO 14443B
standards for proximity tags (used, for instance,
in medical identification cards).
|
|
|
