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Time Domain Enhances Its UWB Location System

The company's PLUS 2.0 system, which uses active ultra-wide band RFID tags, costs less but comes with increased performance and scalability, more options and better management tools.
By Beth Bacheldor
Jun 25, 2008Real-time location systems (RTLS) provider Time Domain Corp. has upgraded its ultra-wide band (UWB) system for tracking assets and people to include new features that boost performance and precision and make it easier to implement and manage the system. The Huntsville, Ala., vendor has also redesigned the reader to cut its manufacturing costs and ultimately reduce the cost of its system.

PLUS 2.0 advances Time Domain's PLUS platform, first announced in December 2007. "Our initial version, 1.0, had a baseline set of features. But we learned a lot from our beta customers about what they'd like to see in PLUS, and we've rolled all of that into this release," says Greg Clawson, VP of sales and marketing at Time Domain. This [PLUS 2.0] represents the first real commercially ready version of our system."

Time Domain's PLUS platform consists of active UWB RFID tags, interrogators, ceiling-tile antennas, synchronization distribution panels and software. UWB tags emit a series of extremely short signals (billionths of a second or shorter), with each signal spanning a wide band of frequencies between 3.1 to 10.6 GHz. The pulsed signals act much like sonar waves, enabling the system to determine distance by measuring how long it takes a pulse to travel from one point (such as a tag) to another (such as an interrogator), and using time distance of arrival (TDOA) technology to calculate location.

PLUS 2.0 includes an updated interrogator (that's backwards-compatible with PLUS 1.0) that has more accurate reading capability—about a 10 to 15 percent increase in read ranges over the first version of PLUS—according to Clawson. The updated device has enhanced fault-tolerance capabilities that help the customer determine if and when the RFID system isn't operating properly. These include the ability of the reader to monitor the detection of corrupt packets of tag data, which can be used to assess the amount of RF interference in its environment; the ability of the reader to provide a reboot notification to alert when a power failure has occurred or some other error condition, and the ability of the system to provide reader and tag timeout warnings if the reader or tag haven't been heard from in a preset amount of time. In addition, the reader can now store calibration constants, making it easier for customers to use and reboot their RTLS in the event of a power outage.

"We made the readers so that they can store calibration constants that are used in the initial setup of the RTLS. TDOA technology requires calibration at the initial setup; basically you lay out readers in a known grid and then place [reference] tags in those grids. The system reads the tags, and you input the tag locations as well, and then the readers tune themselves for optimal performance," Clawson explains. "But most technologies have to have some reference tags left out in field and require calibrations on a regular basis, either because of poor levels of performance or because there may be a loss of power. We've eliminated that."

Now if there is a power outage or some other problem, such as a hardware failure or reader replacement, each reader within the RTLS can tell the back-end PLUS software its initial calibration points. "That means you can get the system up and running quickly and be sure it will operate as it did before the power went down," Clawson says.

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