Patent ID: 6366216
Filing Date: 2002-04-02
Classification: G01S,G08B

Abstract:
A system for monitoring a position of movable objects, comprising:a plurality of movable objects, each of said movable objects equipped with a transponder; and a plurality of nodes arranged to communicate with said transponders, each of said nodes having a register of transponders and monitoring and communicating with those transponders listed in said register, each of said nodes sending a unique signal to each transponder in its respective register to which the transponders, respectively, reply with a response signal containing transponder identification, each of said nodes further including, means for detecting a speed at which each transponder is moving towards or away from said node; and means for delivering an alarm signal when movement of a monitored transponder towards or away from said node exceeds a predetermined value; said plurality of nodes communicating with each other such that, responsive to specified transponder movement, at least one of said plurality of nodes adds to its respective register a transponder previously monitored by another one of said plurality of nodes; and at least one of said plurality of nodes being mobile, said mobile node including GPS equipment which automatically monitors a current global position of said node, said mobile node monitoring transponders in its respective register in view of said current global position.