A DSP-Based Compensation System for Residual Field Suppression Within a Magnetically Shielded Cylinder

To achieve ultra-high sensitivity measurement of the optically-pumped magnetometer (OPM), the ambient magnetic field should be well suppressed to construct a near zero-field environment. In this paper, a DSP-based active compensation system has been developed to improve the shielding performance of the magnetically shielded cylinder (MSC). Meanwhile, we introduce the particle swarm optimization (PSO) algorithm to obtain the optimal PID gains. The experimental results show the PSO-PID method has better compensation performance than the classical PID method. In the time domain, the DC component and fluctuation of the residual field can be suppressed to 0 pT and 5.9 pT, respectively, which indicates the feasibility of our active compensation system.