A Novel Motion Noise Suppression Method for SQUID Sensor Based on VME

The low-frequency magnetic field measurement system of superconducting quantum interference device (SQUID) contains not only the transmitted signal, but also a variety of noise components. The sensor motion noise has the characteristics of low frequency, large amplitude, aperiodic and so on, which is one of the main noise sources of low-frequency magnetic field measurement system. Based on the variational mode decomposition (VMD), a motion noise reduction method based on variational mode extraction (VME) is proposed in this paper. In this new VME method, a new criterion is proposed: the residual signal extracted from a specific mode should have no energy or less energy at the central frequency of the mode. In this paper, VME can solve the problem of demotion noise of SQUID by regarding the motion noise signal as the mode of center frequency approximately zero. The components extracted from VME are used to fit the motion noise of the sensor, and the motion noise is removed from the measured electromagnetic signal. Compared with several traditional methods, the results show that the VME method has the advantages of small computation, fast convergence speed, and can remove the motion noise of the sensor SQUID more accurately.