Development Of Transient Electromagnetic Pulse Electric Field Measurement System Based On FPGA

Electromagnetic pulse electric field is a transient electromagnetic phenomenon.In time domain,the waveform has features that steep rising edge,narrow pulse width,and flat falling edge.And in frequency domain,the band-width is very wide.Because of strong electromagnetic pulse electric field,wide range,and its range from 100 volts per meter to tens of kilovolts per meter,it's difficulty to measure strength of the electric field.The weak signal is measured in strong electromagnetic environment.So the measurement equipment of strong anti-interference ability and large dynamic range is required.In addition,the steep rising edge is required less than 2.5ns in new standard.Then,the measurement equipment which includes high sampling rate and front-end probe of inducing electric field signal without distortion is required.So the rising edge of electromagnetic pulse electric field can be measured accurately.Third,because of the electromagnetic pulse signal is non-periodic,transient,wide frequency band signal,and its band-width is often up to hundreds of megahertz.So the measurement device of wide frequency band is required.In order to measure the transient electric field of electromagnetic pulse,a transient electric field of electromagnetic pulse measurement system based on FPGA is proposed and developed in this paper.The system contains probe device and software,which sampling rate of the system is as high as 1.5GSPS and can measure the electric field range is±50kV/m.Monopole antenna is used to induce and convert electrical signal to voltage signal.To ensure that the voltage signal can be converted to digit signal accurately by ADC,signal conditioning module is used to match impedance and convert the voltage signal to a range that ADC can receive.FPGA is used to receive and cache the digit signal into DDR2.After sampled done,the digit signal can be transferred into high speed SD Card.At last,the data of electric field can be transfered,copied,displaied,storaged,analyzed and processed.The main contents that the whole scheme of the system is analyzed,the main functions and technical indexes are listed,key components are selected,schematic diagram and PCB are designed,FPGA logic is designed and simulated,MCU program and computer system software are designed,et al are introduced detailedly in this paper.At last,the experiments results of the system probe and a wideband oscilloscope is compared.Experimental results show that the performance index of this electric field equipment which is used in the electric field measurement successfully is meeted the design requirements.