Portable Weak Magnetic Signal Detection System Based on Lock-in Amplifier

The accurate detection of the weak magnetic signal has important applications in many fields, and lock-in amplifiers are often used in them. However, commercial lockin amplifiers are expensive and bulky, and are not suitable for use in field environments such as the magnetic exploration. In this paper, a weak magnetic signal detection system is designed based on a portable lock-in amplifier, which is used to solve the problem. The system takes the portable lock-in amplifier circuit as its core, and contains a fluxgate sensor. Combined with A/D acquisition and LabVIEW, the system achieves the real-time display of measurement data on the laptop. Experimental results show that the correlation coefficient of input and output of the system is up to 0.998 under the noise environment. The system achieves the effective measurement of the amplitude of the weak alternating magnetic field signal when the interference magnetic fields are complex. The detection system has the characteristics of high resolution, good linearity and portability, and has good potential for field applications.