Earth's magnetic field measurement device - uses excitation and monitoring coils with rotating magnetic arm for accurate direction finder

摘要

A rotating magnetised bar with ferromagnetic ends is held in pivots so that it can swing freely. The bar normally aligns itself with the earths magnetic field. A bipolar electric current pulse is passed through an excitation coil (EXC). Pulsing follows the routine, positive, off, negative, off, which is repeated. The bar moves to a new position under the influence of the electromagnetic field. Two coils (C1, C2) monitor the changing magnetic field created by the movement of the bar. The signals are processed and the direction of the earths magnetic field is displayed. ADVANTAGE - Good precision, small size.