Activating a fuse

A fuse system for a projectile 30 for a ranged weapon, comprises a plurality of magnetic field sensors 20, 32 and a controller 22. Each sensor 20, 32 is arranged to provide a signal that changes in response to a relative change in position and/or orientation between the system and the Earth's magnetic field. Each sensor 20, 32 has a different alignment in terms of magnetic field sensitivity. The controller 22 is arranged to receive one or more signals from the plurality of magnetic field sensors 20, 32 and to activate a fuse 24 of the projectile 30 depending on the received one or more signals. The controller 22 is arranged to infer a particular change in location of the projectile 30 from the received one or more signals and is arranged to activate the fuse when the particular change equates to the projectile 30 being at a target location.