Patent ID: 6317386
Filing Date: 2001-11-13
Classification: G01S

Abstract:
An ultrasonic location system for determining the positions and orientations of objects by measuring the times-of-flight of ultrasonic pulses emitted by transmitter units placed on the objects to be tracked, and detected by receiver units synchronised with the transmitter units and placed at known points around a room in which they are located, wherein transmitter unit address information to be transmitted using ultrasound is encoded so as to enable a plurality of transmitter units to be permitted to emit ultrasound pulses during a common timeslot, whereby to permit a corresponding plurality of different transmitter unit locations to be determined within that timeslot, at the beginning of each new timeslot, one of N available different ultrasonic encoding techniques is allocated to each of N different transmitter unit addresses selected by a central controller, and this allocation information is transmitted to enable each of the N selected transmitter units to determine which of the N encoding techniques is to be used by that transmitter unit during that particular timeslot.