Some embodiments of the invention relate to a mobile detection device for an evaluation of a distance value from the mobile detection device to an occluded AC-current carrying structure according to its emanated magnetic field, like a location of underground services. The mobile detection device may include multiple detection coils arranged with a spacing with respect to one another and an electronic signal evaluation unit for detecting the structure according to an electrical signal induced in the detection coils by the magnetic field and to evaluate the distance value according to a difference of the electrical signal in-between at least two of the detection coils.