The present application relates to a system for determining an orientation of a first device relative to a user. The system comprises a first device including a first orientation measuring unit arranged to measure an orientation of the first device relative to the earth, a second device arranged to be worn by the user on a body part, the second device including a second orientation measuring unit arranged to measure an orientation of the second device relative to the earth. The system also comprises a processing unit arranged to calculate an orientation of the first device relative to the second device by comparing the measured orientation of the first device relative to the earth with the measured orientation of the second device relative to the earth.
