一种SQUID传感器基线漂移和工频干扰联合抑制新方法

基于超导量子干涉器件的低频微弱磁场测量系统，在无磁屏蔽环境下工作时容易受到大地磁场和输电线路干扰，测量数据中混叠有严重的基线漂移和工频谐波干扰。为了提高微弱磁场信号检测性能，本文提出了一种基线漂移和工频干扰联合抑制新方法。该方法首先利用噪声辅助的多维经验模式分解部分重构信号，消除基线漂移带来的非平稳性影响。然后根据工频干扰的短时平稳特性，采用最小二乘法对工频干扰进行抑制。数值仿真和不同环境下实测数据处理结果表明，与自适应滤波方法相比，本文方法对于基线漂移和工频干扰具有更好的处理效果，满足系统在野外无磁屏蔽条件下的应用要求。 

A New Joint Suppression Method for Baseline Wandering and Power Line

In the absence of magnetic shielding room, the data measured with the low frequency magnetic measurement system using superconducting quantum interference device, could be easily interrupted by serious baseline wandering and harmonic power line interference, which are brought by the geomagnetic activity and the power line. In order to enhance the detection performance for weak magnetic signal, a new joint suppression method for baseline wandering and power line interference is proposed. In this proposed method, the signal is partially reconstructed with intrinsic mode functions decomposed by the noise assisted multivariate empirical mode decomposition. Consequently, the non-stationary effect brought by the baseline wandering could be eliminated. And then according to the short-time stationarity of the power line interference, the least square method is adopted for interference suppression. Numerical simulation and wild measured data processing results show that, compared with adaptive filter method, the proposed method achieves better performance for baseline wandering and power line interference, which indicates it is applicable to wild measurement without magnetic shielding room.