A high performance active noise control system for magnetic fields.

We present a system for active noise control (ANC) of environmental magnetic fields based on a Filtered-x Least Mean Squares (FxLMS) algorithm. The system consists of a sensor that detects the ambient field noise and an error sensor that measures the signal of interest contaminated with the noise. These signals are fed to an adaptive algorithm that constructs a physical anti-noise signal cancelling the local magnetic field noise. The proposed system achieves a maximum of 35 dB root-mean-square (RMS) noise suppression in the DC-1 kHz band and 50 dB and 40 dB amplitude suppression of 50 Hz and 150 Hz AC line noise respectively for all three axial directions of the magnetic vector field.