05119104 is referenced by 506 patents and cites 5 patents.

A radiolocation system for multipath environments, such as for tracking objects in a semiconductor fabrication facility (FIGS. 1a-1b), includes an array of receivers (20) distributed within the tracking area, coupled to a system processor (40) over a LAN. A TAG transmitter (30) located with each object transmits, at selected intervals, spread spectrum TAG transmissions including at least a unique TAG ID. In a high resolution embodiment, object location is accomplished by time-of-arrival (TOA) differentiation, with each receiver (FIG. 2b) including a TOA trigger circuit (64) for triggering on arrival of a TAG transmission, and a time base latching circuit (65) for latching the TOA count from an 800 MHz time base counter. In a low resolution embodiment, each receiver of the array is assigned a specific location-area, and receives TAG transmissions almost exclusively from TAGs located in that area, thereby eliminating the need for any time-of-arrival circuitry.

Title
Location system adapted for use in multipath environments
Application Number
7/518802
Publication Number
5119104
Application Date
May 4, 1990
Publication Date
June 2, 1992
Inventor
Alan C Heller
3918 Forest Creek, San Antonio (Bexar County), 78230
TX, US
Agent
Baker & Botts
IPC
H04L 27/30
G01S 3/02
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