Detector for ferromagnetic objects in homogeneous field - uses three colinear field detectors to determine range and size of object

摘要

The apparatus detects ferromagnetic bodies by using the earth's magnetic field. A probe (1) contains three field detectors lying in the same direction (A, B, C) which form two differential pairs (A, B and B, C). The pair signals are processed by the magnetometers (13, 14) and compared with each other (HYB-HYC and HYA-HYB). This values is used to determine the distance of the body from the probe, its magnetic moment and hence its size, and the absolute values of the interference fields at each detector. Small surface objects can thus be eliminated from the search.