Scientific Generics Limited

Sagentia Limited

Nicolas Vasilopoulos

Michael Raymond Reynolds

David Bartlett

Paul Smith

Aled Wynne Jones

Daniel Reginald Ewart Timson

Andrew Michael Rhodes

Peter Duffet-Smith

Peter Duffett-Smith

Paul Joseph Bearpark

The present invention provides a tracking system in which a mobile tag having an unknown position, which tag is to be tracked in space over time, transmits a signal comprising a pair of tones at different frequencies. The transmitted signal is received at each of three receivers, each having a known location, where the phase of each of the tones within the signal is measured. The measured phases are passed to a processing unit which determines the position of the tag at the time of transmission of the signal on the basis of the difference between the measured phases of the two tones. The tracking system operates over a defined finite range to track the position of the mobile tag uniquely in space.

Tag tracking

A position determining system in which a mobile tag having an unknown position is tracked in space over time. In use, the mobile tag either transmits or receives signals including a pair of tones at different frequencies from a number of base stations having known locations. The phase of each of the received signals is then measured and the measured phases are then passed to a processing unit which determines the position of the tag at the time of the transmission of the signals on the basis of the difference between the measured phases of the two tones. In one embodiment, this system is combined with a conventional phase-based position measurement which is derived from phase measurements of similar tones transmitted between the mobile tag and different base stations.

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Harston, United Kingdom

Nicolas Vasilopoulos