Method and a device for determining a direction in a magnetic field

An electronic device for determining the direction of a magnetic field, comprising:

• at least one electromagnetic sensor configured to produce signals representing measurements of at least three field components of the magnetic field, and the direction of the magnetic field;
• a memory;
• and
• a processing unit operably coupled to the memory and to the at least one sensor, the processing unit adapted:
• to form from each measurement a data point in a three-dimensional co-ordinate system,
• to calculate a common reference point for a number of data points produced by several measurements,
• to compare the co-ordinates of the calculated reference point with the value of the co-ordinates of at least one previous reference point,
• to calibrate on the basis of the comparison the location of the device relative to the reference point in the co-ordinate system, and
• to produce an indication of the direction of the magnetic field relative to the device with the aid of the reference point, wherein the data points are arranged to be formed on an essentially spherical surface, whereby the common reference point obtained by calculation is the centre point of the sphere, the processing unit being adapted to calculate the reference point by forming three line segments between selected data points, from which unit vectors are formed to three planes passing through the centre points of the segments, whereby the intersection point of the planes is the reference point.