Chip-size Passive RFID Tag Promises Long Range
Tagent's ultra-wideband (UWB) RFID system will be piloted in a medical laboratory, where it will track the locations of blood specimens in real time.
Feb 03, 2009—Silicon Valley startup company Tagent had developed an ultra-wideband (UWB) passive tag RFID system that will be piloted this summer at a California medical lab. The new system, according to Geoff Zawolkow, the company's VP of marketing and business development, will offer a locating capability and read range comparable to that of an active UWB tag, but in a form factor and price that would allow them to attach the tags to disposable labels.
The Talon system features the Talon Integrated RTLS Tag, a 2-millimeter (0.1-inch) passive RFID chip with a built-in antenna. The system also includes a specially designed RFID interrogator, as well as a network of power nodes that emit a 5.8 GHz RF signal that energizes the tags. The power nodes, deployed 2 meters (6.6 feet) apart from one another, can also be used to determine a chip's location.
The tag has 128 bits of read-only memory. According to Zawolkow, the tag came out of assembly this month, and Tagent has been testing it in-house. The tests, he says, have proven the technology works, and the company intends to begin a pilot at an unnamed California medical laboratory this summer, by embedding the tag on labels attached to blood tubes. In addition, he notes, several other similar pilots are scheduled to take place later this year, in other parts of the world. If the initial pilots go well, Tagent intends to begin selling the chips commercially by August or September.
Here's how the system works: A Tagent reader transmits a 2.4 GHz signal instructing a specific power node to emit its 5.8 GHz signal. The node transmission can be picked up by a tag up to 1 meter (3.3 feet) away, or the strength of the node's signal can be adjusted to a shorter range to further pinpoint the tag's location. Any tag within that node's transmission range then emits its own 6.7 GHz signal, which can be received by a Tagent reader up to 20 meters (65.6 feet) away.
Because the tag responded, following the instruction, to a specific power node, and because the system knows that power node's location, the system can also deduce that the tag is located within 1 meter (3.3 feet) of that power node. The reader is typically wired to the back-end server via an Ethernet cable. Web-based Tagent software links the RFID tag's ID number with the power node and its location, thereby identifying the tag's whereabouts based on that information. It then displays the location to within several meters (or less, if the node's power has been dialed down to provide greater RTLS accuracy), which represents the 2-meter-wide (6.6-foot-wide) spherical space circumscribed by the power node's RF signal. This provides a real-time location system, since the reader can instruct the nodes to pulse very frequently (every second, for instance).
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