Patent ID: 8669847

Claim:
A method for determining the position of a tag by detecting directions of at least two fibers arranged in the tag intended to be attached to an item for identification of said item, said fibers having an impedance for high frequency electromagnetic waves, which impedance is dependent on a magnetic field at said fiber, comprising: generating a modulation magnetic field having an amplitude modulated magnetic component with a first modulation frequency; generating a bias magnetic field for counterbalancing any constant magnetic fields parallel to the direction of the fiber; directing electromagnetic waves towards the fiber; receiving electromagnetic waves from the fiber, which are modulated by said first modulation frequency; determining that said received electromagnetic waves are modulated by a second frequency, which is the double of said first modulation frequency, upon application of said bias magnetic field in a specific angular direction; and calculating the angular position of the fiber from said angular direction of the bias magnetic field and said modulated magnetic component, arranging at least three index fibers and at least two identity fibers, whereby the mutual angles between the index fibers are known; calculating the angles between the index fibers; comparing the calculated angles with the known mutual angles; calculating an inclination of the tag based on the calculated angles and the known angles.