The invention relates to a system for measuring the direction of the geomagnetic field (a) in the proximity of a magnetic jamming device with a magnetic field direction which can be varied. Said system is characterized in that it comprises at least two magnetic field measuring devices, each measuring all three vector components of the total magnetic field (b), that said devices have a fixed position, not variable in time (c), in relation to each other and to the jamming device, and that the measurements can be retrieved in a time-synchronous manner and evaluated on the basis of (d), where P(c) describes the geometric position of the magnetic field measuring devices in relation to each other and to the jamming device.