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Location system and method that achieves time synchronized network performance with nodes divided into separate networks

  • US 7,218,229 B2
  • Filed: 11/03/2004
  • Issued: 05/15/2007
  • Est. Priority Date: 11/07/2003
  • Status: Active Grant
First Claim
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1. A system for locating an object within a monitored environment comprising:

  • a plurality of receivers contained in the monitored environment and arranged in a plurality of loosely coupled networks such that receivers in each network are tightly coupled to each other allowing a timing signal that is received by receivers in the same network not to be received by receivers within the other loosely coupled network;

    a tag transmitter positioned within the monitored environment at a location for transmitting an RF signal to receivers within each network and operative as a reference network node and bridge between loosely coupled networks; and

    a processor operative with each receiver within each network for defining a network clock timing for each network such that each network has its own time reference independent from any other loosely coupled network, a global system time common for all networks, wherein said processor is operative to use the tag transmitter as a network bridge between the networks and track its relationship to the clock timing for each network for time synchronizing all receivers, wherein the processor is operative for conducting differentiation of time of arrival signals received from another tag transmitter to locate an object associated with the other tag transmitter.

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