Apple Inc.
Target Localization Using AC Magnetic Fields

Abstract:

A device operates in pairing mode, indoor navigation mode or search mode. For each mode, a magnetic sensor in the device senses one or more alternating current (AC) magnetic fields emitted by one or more transmitters in a three-dimensional (3D) space, and uses the one or more AC magnetic fields to determine a position of the device relative to the one or more transmitters or another device. In pairing mode, relative position vectors computed from two or more AC magnetic fields allows the device to choose the closest transmitter for pairing. In indoor navigation mode, multiple detections of AC magnetic fields emitted by multiple transmitters assist a user in navigating an indoor space. In search mode, a companion device and a lost device each sense an AC magnetic field from a transmitter, and the AC magnetic fields are used to determine a relative position vector from the companion device to the lost device.