Acoustic position-determination system

摘要

The position of a mobile unit (12) within a detection zone is determined. An acoustic signal is emitted from the mobile unit and received along a first path (54). An echo of the signal is received after reflection from a surface (46) within said detection zone. The position of the mobile unit (12) within the detection zone is determined from the times of arrival of the signal and echo.

主权项

1. A method of determining the position of a mobile unit within a detection zone comprising:
emitting an acoustic signal from the mobile unit; receiving said acoustic signal along a first path from the mobile unit at a first transducer; receiving an echo of said acoustic signal after reflection from a surface within said detection zone at a second transducer; determining the time of arrival at the first transducer of the acoustic signal along said first path; determining the time of arrival of the echo at the second transducer; and determining the position of the mobile unit within the detection zone from said times of arrival, wherein the first transducer is optimised for the reception of the signal along the first path, and the second transducer is optimised for the reception of the echo, the second transducer being configured to have greater directional sensitivity than the first transducer, and being directed towards said surface.