Patent ID: 9151610
Filing Date: 2015-10-06
Classification: G01C,G01R

Abstract:
1. A method comprising: receiving a reading from a magnetometer of a mobile device; selecting a cluster from a plurality of clusters of bias offsets generated from previously-calibrated readings, wherein the selected cluster has a representative bias offset, a mean of magnitudes in the selected cluster, and a magnitude threshold; estimating an external magnetic field based on the reading and the representative bias offset for the selected cluster; determining whether a magnitude of the estimated external field is within a magnitude range defined by the mean magnitude and the mean magnitude plus the magnitude threshold; determining a gravitational vector; determining an inclination angle between the gravitational vector and the estimated magnetic field; determining whether the inclination angle is within an angle range defined by a mean inclination angle for the selected cluster and the mean angle plus an angle threshold; determining the magnitude of the estimated external field matches the magnitude range and the inclination angle matches the angle range; determining a first heading for the mobile device using the estimated external field; comparing the first heading with a second heading obtained from data provided by a location processor of the mobile device; and validating the first heading in response to the comparing, where the method is performed by one or more hardware processors.