Hitachi Air Location unit uses WLAN for navigation

By Bernard Cole
iApplianceWeb
(12/05/03, 12:28:48 AM EDT)

Tokyo, Japan -- Hitachi Ltd. and Hitachi Cable Ltd. have jointly launched a new location detection system that uses the IEEE802.11b-based wireless LAN for location with an error range of 1-3 meters, compared with the global positioning system (GPS) which has an error range of about 10 meters.

The AirLocation system consists of a location detection server, a management server, more than five dedicated base stations, wireless LAN devices, and software designed for the system.

Most of the cost and system upgrade falls on the shoulders of the provider, with no upgrade or additional hardware purchases on the part of the users. They can can use ordinary personal computers or personal digital assistants (PDAs) that are compatible with the 802.11b standard as well as wireless LAN tags.

The system works by detecting the location of a wireless LAN device by sensing and measuring the slight difference of arrival times of radio waves that are transmitted from the wireless LAN device to multiple base stations, one master and the rest slaves.

To perform its location detection chores, the master base station transmits synchronized signals, which when received by the wireless LAN device responds to them by sending another transmision. The system measures the time required for the signals to reach each slave base station, and detects the location of the wireless LAN device by making triangular calculations based on the small differences in arrival time of the transmissions. When the system detects the location of more than one wireless LAN devices, each is identified by a unique IP address it has been assigned.

For more information on this system, go to www.hitachi.com. 

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