Noise correlation in fundamental mode orthogonal fluxgate

One of the key issues to reduce noise in a flux gate is the knowledge of how the noise is originated within the sensor. In this paper we measured the noise of an orthogonal flux gate operated in the fundamental mode in narrow regions of the magnetic wire used as a core, and we show how the correlation between the noise measured in two different sections drops when the distance between the sections is increased. This indicates that the noise is originated locally in the magnetic wire and then spread thought the wire due to its high permeability. This was confirmed by the measurement with a longer wire that yields higher correlation than those observed with shorter ones. Therefore, uncorrelated noise generated in sections of the wire far enough can be compensated. Finally, we show how the noise from two different wires is totally uncorrelated even if excited by the same current source, confirming that the noise is originated within the magnetic core. Such results can be used to design sensors with lower noise.