Abstract: A position tracking system comprises a transmitter at a first location for producing a signal and an array of plural ultrasonic transducers at a second location arranged in a grid pattern at a plurality of respective discrete locations. The plural ultrasonic transducers are responsive to the signal to produce plural reactive signals corresponding to the signal as received at respective ones of the plural ultrasonic transducers. A computer is responsive to the reactive signals from the plural ultrasonic transducers for continuously determining the position of the array. The ultrasonic transducers are physically separated.The ultrasonic transducers and spatial light modulators share a common backplane.

Abstract: An ultrasonic tracking system embodying the invention has an array of plural ultrasonic detectors at discrete locations, the plural detectors being responsive to an ultrasonic signal of frequency f emanating from a single remote transmitter to produce respective plural electronic signals corresponding to the ultrasonic signal as received at respective ones of the plural detectors, and a processor for determining from the plural electronic signals a direction of travel of the ultrasonic signal relative to the array of ultrasonic detectors. In order to provide range, a phase shift key encoder connected to the transmitter encodes every N cycles of the ultrasonic signal with one of a succession of encoder counts, while a phase shift key decoder coupled to receive an electronic signal from one of the plural detectors produces a new decoder count every N cycles of the electronic signal that are decodable.