An electronic theft-preventing system, comprising: a first multi-axis magnetometer arranged in a first station at a first position and configured to output a first vector signal (vs0) representing movement of a first magnetic field vector; a second multi-axis magnetometer (102;104) arranged in a second station at a second position and configured to output a second vector signal (vs1;vs3) representing movement of a second magnetic field vector; wherein the second position is different from the first position; and a signal processor coupled to receive the first vector signal (vs0) and the second vector signal (vs1), and configured to: estimate a first multi-dimensional transformation (C1), which represents a difference between the first magnetic field vector and the second magnetic field vector; generate a first compensation signal (cs1) from a transformation of the first vector signal (vs0) in accordance with the first multi-dimensional transformation (C1); generate a compensated second vector signal (cvs1) from the second vector signal (vs1) and the first compensation signal (cs1); determine that a detector signal (D), which is responsive to the compensated second vector signal (cvs1), meets a predefined criterion; and in response to at least the determining that the detector signal meets the predefined criterion, raising or forgo raising a first alarm that warns about a possible theft-related event. a first multi-axis magnetometer arranged in a first station at a first position and configured to output a first vector signal (vs0) representing movement of a first magnetic field vector; a second multi-axis magnetometer (102;104) arranged in a second station at a second position and configured to output a second vector signal (vs1;vs3) representing movement of a second magnetic field vector; wherein the second position is different from the first position; and a signal processor coupled to receive the first vector signal (vs0) and the second vector signal (vs1), and configured to: estimate a first multi-dimensional transformation (C1), which represents a difference between the first magnetic field vector and the second magnetic field vector; generate a first compensation signal (cs1) from a transformation of the first vector signal (vs0) in accordance with the first multi-dimensional transformation (C1); generate a compensated second vector signal (cvs1) from the second vector signal (vs1) and the first compensation signal (cs1); determine that a detector signal (D), which is responsive to the compensated second vector signal (cvs1), meets a predefined criterion; and in response to at least the determining that the detector signal meets the predefined criterion, raising or forgo raising a first alarm that warns about a possible theft-related event. estimate a first multi-dimensional transformation (C1), which represents a difference between the first magnetic field vector and the second magnetic field vector; generate a first compensation signal (cs1) from a transformation of the first vector signal (vs0) in accordance with the first multi-dimensional transformation (C1); generate a compensated second vector signal (cvs1) from the second vector signal (vs1) and the first compensation signal (cs1); determine that a detector signal (D), which is responsive to the compensated second vector signal (cvs1), meets a predefined criterion; and in response to at least the determining that the detector signal meets the predefined criterion, raising or forgo raising a first alarm that warns about a possible theft-related event. <EOS>