06512478 is referenced by 394 patents.

An extensible short-range tracking system is disclosed. The tracking system disclosed is a multi-level tracking system. At the first level is an RF tag, which is a transmit-only unit that transmits information including minimally an identification number. The transmission from the RF tags are sporadic with timing depending upon the application at implementation. Generally, the transmission timing comprises a transmission, which is repeated periodically at random times. Transmissions from the RF tags are received in a series of relays. The relays may calculate the position of the tags by knowing the position of the relays and the time difference of arrival of the signals from the RF tags by several relays or may pass the information needed to calculate position to a base station. Alternately, the RF tags may generate position information and transmit that information along with the RF tag identifier to the relays. The relays, which may be networked among themselves, then relay the information from the tags to a base station unit. The base station unit may be part of various applications such as a fire control system in a military application or an inventory system in an industrial application.

Title
Location position system for relay assisted tracking
Application Number
9/513982
Publication Number
6512478 (B1)
Application Date
February 26, 2000
Publication Date
January 28, 2003
Inventor
Charles Chien
Newbury Park
CA, US
Agent
Foley & Lardner
US
Assignee
Rockwell Technologies
CA, US
IPC
H04B 7/185
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