Patent ID: 8237438

Claim:
A fundamental mode orthogonal fluxgate magnetometer comprising: a magnetic alloy sensing element; a current source to supply an excitation current to the sensing element, said excitation current including a DC component on which is superimposed a smaller, high frequency, AC xcitation current; a sensing coil wound over the sensing element for picking up a signal proportional to an applied magnetic field; an amplifier for amplifying the signal picked up by the sensing coil; a signal detector for detecting the amplified signal and producing an output voltage proportional to the applied magnetic field; an electronic circuit to null the magnetometer offset; a second coil wound over the sensing coil; and a compensating circuit including a coupling capacitor, an adjustable attenuator, and a switchable polarity reverser; wherein the compensating circuit takes a sample of the high frequency AC part of the excitation current and applies it to the second coil to create a field substantially equal and opposite to the magnetometer offset.