Patent ID: 7155836
Filing Date: 2007-01-02
Classification: G01C

Abstract:
1. A method of using a magnetic field, comprising: measuring and storing magnetic field data indicating magnitudes of a magnetic field in different directions at each time by rotating sensors in different directions over a space, said magnetic field data forming one or more magnetic field trajectories; checking whether a disturbance of the magnetic field exists, using an amplitude and an offset of at least one of the magnetic field trajectories; determining a candidate location of a compass, moving the compass to the candidate location, measuring and storing the magnetic field data indicating the magnitudes of the magnetic field and checking whether the disturbance of the magnetic field exists, until it is determined that the disturbance of the magnetic field does not exist; and when it is determined that the disturbance of the magnetic field does not exist, calculating the compass by using the stored magnetic field data.