A method for using a system for detecting a position of a second device in relation to a first device, - the system comprising an array of fields, fixed to the first device, the fields consisting of a plurality of first fields presenting a first physical characteristic, and a plurality of second fields presenting a second physical characteristic, which is different from the first physical characteristic, the first and second fields (4611, 4612) being arranged in an alternating manner along the array of fields, where the fields (4611, 4612) comprise an extended field, which has, compared to other fields (4611, 4612), a larger extension along the array of fields, and the system comprises a third sensor, fixed to the second device, - the system further comprising a first sensor and a second sensor, fixed to the second device, wherein the first and second sensors (4521, 4622) are arranged to move along the array of fields when the second device moves in relation to the first device, - the first and second sensors (4521, 4622) being adapted to detect the first physical characteristic or the second physical characteristic in dependence of the positions of the first and second sensors (4521, 4622) in relation to the fields (4611, 4612), the method comprising: - detecting, by means of the first sensor, and during a movement of the second device in relation to the first device, a transition from the first physical characteristic to the second physical characteristic, or vice versa, - detecting, substantially simultaneously to the transition detection, by means of the second sensor, either the first physical characteristic or the second physical characteristic, - and determining, based on the detected transition and the detected physical characteristic, the direction of movement of the second device in relation to the first device, characterized by - determining whether the transition detected by means of the first sensor, or a transition detected by means of the second sensor, is a transition from the first physical characteristic to the second physical characteristic, - determining whether a transition, detected by means of the third sensor, and substantially simultaneously to the transition detected by means of the first sensor or the second sensor, is a transition from the first physical characteristic to the second physical characteristic, - and determining, based on the determinations whether the transitions were transitions from the first physical characteristic to the second physical characteristic, whether the transitions occurred at opposite ends of the extended field. - the system comprising an array of fields, fixed to the first device, the fields consisting of a plurality of first fields presenting a first physical characteristic, and a plurality of second fields presenting a second physical characteristic, which is different from the first physical characteristic, the first and second fields (4611, 4612) being arranged in an alternating manner along the array of fields, where the fields (4611, 4612) comprise an extended field, which has, compared to other fields (4611, 4612), a larger extension along the array of fields, and the system comprises a third sensor, fixed to the second device, - the system further comprising a first sensor and a second sensor, fixed to the second device, wherein the first and second sensors (4521, 4622) are arranged to move along the array of fields when the second device moves in relation to the first device, - the first and second sensors (4521, 4622) being adapted to detect the first physical characteristic or the second physical characteristic in dependence of the positions of the first and second sensors (4521, 4622) in relation to the fields (4611, 4612), - detecting, by means of the first sensor, and during a movement of the second device in relation to the first device, a transition from the first physical characteristic to the second physical characteristic, or vice versa, - detecting, substantially simultaneously to the transition detection, by means of the second sensor, either the first physical characteristic or the second physical characteristic, - and determining, based on the detected transition and the detected physical characteristic, the direction of movement of the second device in relation to the first device, characterized by - determining whether the transition detected by means of the first sensor, or a transition detected by means of the second sensor, is a transition from the first physical characteristic to the second physical characteristic, - determining whether a transition, detected by means of the third sensor, and substantially simultaneously to the transition detected by means of the first sensor or the second sensor, is a transition from the first physical characteristic to the second physical characteristic, - and determining, based on the determinations whether the transitions were transitions from the first physical characteristic to the second physical characteristic, whether the transitions occurred at opposite ends of the extended field.