Army Medical Center Looking to Boost Asset Awareness

The receivers use the ZigBee protocol to forward the first tag's ID number and signal strength, along with the time it was read and the ID of the transceiver that picked up its signal, to a bridge. According to Howe, there are generally two bridges installed on each floor of a facility. These bridges link, via an Ethernet cable, to a central Awarepoint server that calculates the location of all tagged assets and displays this information on a map of the facility. Any computer linked to the system's local area network (LAN) can access the map and employ Awarepoint's software to search for a specified type of asset. Howe says the software can provide the asset's location to an accuracy level of 1 to 3 meters. Awarepoint uses a proprietary algorithm to determine asset locations, based on the tags' RF signal strength.

The main advantage of Awarepoint's RTLS system over platforms using RFID tags operating on a Wi-Fi network, Howe claims, is that the Awarepoint access points plug directly into any available power outlet. With Wi-Fi systems, he notes, the installation of access points—in addition to those already installed in a Wi-Fi-powered facility—is required to provide the level of location accuracy generally desired by end users. Skilled labor must install the Wi-Fi access points, he says, and the wiring and mounting involved generate dust, resulting in the suspension of normal operations in the room in which the devices are being installed.

What's more, Howe says, because ZigBee devices transmit data at slower rates than Wi-Fi tags, Awarepoint tags are less power-hungry. According to the company, the battery in an Awarepoint tag can last for up to five years of daily use.

Awarepoint leases its system to end users. Thus, Howe explains, rather than purchasing the tags and interrogators, then paying for system installation and maintenance, customers pay a monthly fee of less than $10 per asset. He says the medical center selected his company from a group of seven service providers, many of which offer Wi-Fi based RFID asset-tracking systems.