Patent ID: 7905026

Claim:
A method of defining a compass direction by means of an electronic compass device comprising: measuring at least two field components of an external magnetic field, from which a set of data points is formed, which correspond to different orientations of the device relative to the external magnetic field, determining whether the set of data points corresponds to a measurement, in which the device has remained on the horizontal plane with a predefined accuracy, and if the set of data points corresponds to a measurement in which the device has remained on the horizontal plane with a predefined accuracy, defining a compass direction by using calibration made on the basis of said set of data points, wherein the calibration is made by calculating, on the basis of the data points, the center point of the circle defined by the data points and a new compass direction is defined on the basis of the center point, and wherein the defined center point is accepted as the new center point only if its distance from the previously defined center point is less than a predefined maximum distance.