In view of the weakness of induction current and the serious electromagnetic interference in the electric field instrument at home and abroad

we designed a new type of differential sensor with dual stator structure. Two current signals were sensed by the sensor and they were converted to voltage signals by passing through the I/V converter

and the common mode interference and the power frequency interference were eliminated by subtracting the instrument and the50 Hz power frequency notch filter. The synchronous signals were obtained by using photoelectric switch sensors

and a phase sensitive detector was used to process the signal to obtain a direct current voltage proportional to the field strength.The experimental results show that the resolution of the system is 10 V/m and linearity is less than 1% in the range of simulated field strength of-50～50 kV/m. The actual measurement results show that the differential double stator structure and the reducer can effectively eliminate the common mode interference

the 50 Hz trap filters can eliminate the power frequency interference

and the high precision amplifier can improve the measuring accuracy of electric field instrument.The system can measure the intensity of the atmospheric electric field in real time and show the curve of the field intensity of the atmosphere

which can provide a necessary basis for lightning monitoring and early warning.