Abstract: A method for tracking performance of player including determining global direction of magnetic field at first court and computing first court specific data; providing rotation for rotating apparatus about spin axis via player, wherein rotating apparatus comprising XYZ-magnetic field sensor; measuring plurality of magnetic field values as function of time when rotating apparatus is rotating about spin axis; computing magnetic field component of magnetic field in direction of local body co-ordinate of spin axis of rotating apparatus; determining direction of spin axis using computed magnetic field component of magnetic field and determined global direction of magnetic field; determining player specific data comprising angle of spin axis with respect to horizontal ground plane and angle of shot direction with respect to horizontal component of spin axis; and calibrating and storing first court specific data and player specific data to track performance of player at first court.

Abstract: A method for determining a direction of a spin axis of a rotating apparatus which includes an XYZ-magnetic field sensor. The method includes determining a global direction of a magnetic field; rotating the rotating apparatus around the spin axis, measuring at least one magnetic field value as a function of time with the XYZ-magnetic field sensor when the rotating apparatus is rotating about the spin axis, computing a magnetic field component of the magnetic field in a direction of a local body co-ordinate of the spin axis of the rotating apparatus from the measured at least one magnetic field value and determining a direction of the spin axis using the computed magnetic field component of the magnetic field and the determined global direction of the magnetic field.

Abstract: A method for determining a direction of a spin axis of a rotating apparatus which includes an XYZ-magnetic field sensor. The method includes determining a global direction of a magnetic field; rotating the rotating apparatus around the spin axis, measuring at least one magnetic field value as a function of time with the XYZ-magnetic field sensor when the rotating apparatus is rotating about the spin axis, computing a magnetic field component of the magnetic field in a direction of a local body co-ordinate of the spin axis of the rotating apparatus from the measured at least one magnetic field value and determining a direction of the spin axis using the computed magnetic field component of the magnetic field and the determined global direction of the magnetic field.