WO1998028634B1 - Detection system for determining positional and other information about objects - Google Patents

Abstract

A system for tracking the position of each of a plurality of labelled objects in a specified environment by determining the transit time of ultrasound signals transmitted from a transmitter on each labelled object, to a plurality of ultrasound receivers positioned at fixed points in or around the specified environment, and computing therefrom the distance of the transmitter from the receivers. The ultrasound transmissions are initiated by radio signals from a master transmitter and each of the objects includes a radio receiver adapted to respond to the radio transmissions to initiate a burst of ultrasound. In order to allow the system to adapt to different numbers of transponder-transmitters and differing demands for service (e.g. frequency of position determination per transponder-transmitter), a coordinating control system is provided for determining the order in which the object mounted transponder-transmitters are to be triggered by the radio transmissions, in response to updatable information relating to the objects and related service demands.

Claims

89AMENDED CLAIMS[received by the International Bureau on 7 August 1998 (07.08.98); original claim 1 amended; remaining claims unchanged (1 page)]

1. A system which enables the position of each of a plurality of labelled objects in a specified environment to be determined by determining the transit time of slowly propagating energy transmitted from a transmitter on each labelled object to a plurality of receivers positioned at fixed points in or around the specified environment, and computing therefrom the actual distance of the transmitter from the receivers, wherein the transmission of the slowly propagating energy is initiated by a burst of high speed propagating energy from a master transmitter located so as to cause transmitted bursts of such high speed energy to enter the said environment, the transmitter on the object being controlled by a receiver adapted to respond to an appropriately encoded burst of such high speed energy, each said burst being encoded so as only to be responded to by one of the object mounted receivers (each transmitter/receiver combination being referred to as a transponder) , to thereby initiate a burst of slowly propagating energy therefrom, wherein the burst originating transponder location is identifiable from the encoding of the transmission which triggers it and the burst is of just sufficient duration to provide a response at the receivers and in order to allow the system to adapt to different numbers of transponders and different demands for service (for example frequency of position determination) , a coordinating control system is provided for determining the order in which the object mounted transmitters are to be triggered by the encoded transmissions from the master transmitter, in response to updatable information relating to. the service demands of the transmitter and/or transponders and/or objects.

2. A system as claimed in claim 1, in which each of the said plurality of receivers is adapted also to be responsive to each said burst of high speed energy so as to identify the beginning