Radio-frequency (RF) tags, or simply “tags,” are small
electronics devices used for communications in a wide variety of
tagging, tracking, and locating (TTL) applications. The common feature
of all RF tags is the use of radio frequencies (kHz -> MHz -> GHz) over
the air as an information-transport layer.
Differing from traditional radios, RF tags typically do not convey
real-time voice communications. Fundamentally, the job of the RF tag is to provide some measure
of information back to another entity (the “interrogator”), be it a
locating signal, data (ID, sensor information, etc.), or a synthetic
radar echo. Unlike a radio, a tag is usually intended to be
“autonomous” (no human input required); however, many tags take command
and control instructions directly from a user or host.
Common Features of RF Tags
Tags may be as simple as a tiny RF switch providing a 1-bit “yes/no”
response, and they can be as complex as high-speed signal-processing
devices in a complex communications channel. Typically a Tag integrates the electronics,
antenna, and batteries in a single package. The list below includes many common features of RF tags. In some cases, one or more of these features is not included in
the tag, but rather as a “next-level assembly.” Arguably, integration of
more of these features creates a more useful tag!
Common Tag features include the following:
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RF transmitter, or transceiver
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Antenna(s)
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Internal battery and/or external power port
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Control and timekeeping electronics with embedded software
and hardware
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Internal sensors (temperature, movement, GPS, etc.)
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External data I/O ports
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Efficient mechanical and environmental packaging
The Tag-System Concept
An RF tag does not exist in a vacuum; instead, in a system sense, it
co-exists with the interrogation device and operates in a dynamic
environment. The tag must therefore be designed not only for the RF
communications channel, but its design must consider intended
operational procedures, the user community, environmental concerns, and
co-existence with other communications systems. A major design
factor can be procurement cost.
Sandia TTL expertise was born out of and has grown along with our long
history of building radar systems (http://www.sandia.gov/radar/). In
parallel with Sandia’s fuzing, SAR, and MTI radar development, Sandia’s RF tag technology has branched into every kind of radar,
communications, and monitoring application.
Sandia applies a system-centric approach to RF tag development
regardless of application. Indeed, some programs desire “black box”
designs, whereas some programs develop complete tag-interrogator
systems. In either case, Sandia attempts to understand the complete
tag-system concept to maximize utility and effectiveness. To solve
difficult problems, Sandia tag engineers, radar engineers, and system
analysts work together and share experiences and new ideas.
Interaction with the customer and user community is also critical. We
believe this interaction is vital in order to provide robust solutions
for our Nation’s TTL missions.
RF Tags vs. RFID
Commercial RFID (radio-frequency identification) tags are widely used in
toll/access applications and are now making headway into item tracking.
Sandia RF tags differ from these devices in several fundamental
ways. The table below describes the many differences between COTS RFID
and Sandia TTL applications.
|
Sandia TTL |
COTS RFID |
Operating range |
1m to >>1000 km |
1m to 100m |
Operating frequencies |
Any NTIA-approved band |
FCC ISM bands
(0.4, 0.9, 2.4, 5.8 GHz) |
Communications method |
ASK/OOK, FSK, PSK, QAM |
ASK/OOK |
Communications generator |
Active RF transmitter |
Passive RF backscatter |
Power supply |
Battery |
RF beam; battery |
Protocol |
Full or semi-custom; |
Published standards |
|
published standards |
|
Volume |
<1 cm3 to >100 cm3 |
<1 cm3 to 10 cm3 |
Though COTS RFID tags are not a primary focus at Sandia,
we have in-house expertise in this area. Several staff have worked in
the RFID area and have consulted on commercial and government RFID
ventures and evaluations.
Independent Organization
Sandia National Laboratories is a Federally-funded
research and development center (FFRDC). As such, one of our primary
missions is to develop critical technology for our Nation’s missions and
transition that technology into manufacturing or to an outside entity as
appropriate. Sandia works with numerous organizations, both government
and commercial, to advise and to develop solutions to many types of
tagging problems. Where the solution requires technologies that go
beyond what is currently available, Sandia can help design a solution
and transition that solution to a partner organization. We take pride in
the fact that government and leading commercial entities put their trust
in Sandia to deliver hardware for real-world applications.
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Contact:
To send feedback
or request information about the contents of Sandia National Laboratories'
RF Tags website, please contact:
Ken Plummer
RF Tags Website Owner
Sandia National Laboratories
Albuquerque, NM 87185-0529
(505) 844-5122 (Phone)
(505) 844-0858 (Fax)
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