The analysis of gradiometer signal in magnetic field measurement with fluxgate transducer

Abstract

Gradiometer techniques are generally employed to detect near sources of weak magnetic field, especially in biomagnetic measurements, but they are also effective in the detection of the magnetic signature of surface vessels and submarines. In this paper there is analyzed the recorded signal of a fluxgate gradiometer consisting of two coaxial transducers based on the rejection coefficient. There are also discussed error sources affecting the gradiometer signal. The object of analysis is the magnetic signature gradient of a ship model. The measurement setup consists of a shielded room surrounded by a triaxial Helmholtz coil, with magnetic field automatic compensation system. The measuring device is a triaxial fluxgate magnetometer picking up the values of the magnetic signature components for the ship model. Magnetic field measurements were processed by the time derivative gradiometer technique. Thus there is determined the spatial variation of the magnetic signature components and of the total field signature, on the three axes of the rectangular coordinate system.