| At present,domestic and foreign lightning warning methods mainly include a warning algorithm that incorporates meteorological parameters and an integrated detection system that based on the atmospheric electric field data incorporates radar,satellite,or lightning positioning data.Based on this,this paper developed a single station integrated electromagnetic acoustic signal early warning system,and added the lightning magnetic field detection module and sound detection module(for detecting thunder)on the basis of the ordinary atmospheric electric field instrument.Based on the different detection distances of electro-acoustic magnetic signals and the single station of magnetic field module,the approximate distance and azimuth between the thunderstorm cloud and the measuring station can be obtained.The magnetic signal is used to judge the electric field signal and the sound signal.The main results of this article are as follows:(1)Design of electric field detection module: This module is mainly used to process the signal received by the electric field sensor.It includes charge amplifier,voltage amplifier,phase-sensitive detection circuit,filter circuit and voltage follower.According to the structure of the electric field meter,the full-wave rectifying circuit is designed by combining the square wave of the same frequency and same phase with the induction electric field signal generated by the photoelectric gate and the signal pair of the four-channel analog switch.The final output is a dc voltage signal proportional to the amplitude of the induced electric field and with the same polarity.The detection range of the electric field module is 20 km.The parallel plate electrode method was used to calibrate the atmospheric electric field instrument.The calibration curve of the atmospheric electric field instrument has high linearity and the consistency is also ideal.It can obtain more accurate detection results in practical detection applications.(2)Design of sound detection module: This module is mainly used to process the signal received by the sound sensor.It includes preamplifier and power amplifier.For the microphone input audio circuit,use a MOSFET to design the preamplifier.The power amplifier circuit can well filter and amplify the input signal,and remove the DC signal and clutter under the condition that the input signal is not distorted.Finally,the processed signal is output through the voltage follower.The detection range is 10 km and the receiving frequency band is 600hz-30 khz.(3)Design of magnetic field detection module: This module is mainly used to process the signal received by the magnetic antenna.It includes I/V conversion circuit,voltage amplifier circuit and filter circuit.The magnetic antenna sensor’s induction signal was converted into a voltage signal by an I/V conversion circuit while amplifying it,and a filter circuit designed to meet the cutoff frequency of the sampling law.The magnetic antenna calibration system was used to calibrate the magnetic antenna,and the frequency response curve of the magnetic antenna was obtained.By observing the frequency response curve,the 3d B bandwidth of the magnetic antenna is 25 k Hz ～ 680 k Hz,and the stability is good.The detection range can reach 40 km.(4)Early warning system parameters and schemes: The specific technical performance of the device,the design requirements of the acquisition terminal,and a detailed warning plan are given.The warning plan proposes a method for correcting the electric field detection signal using sound signals and magnetic field signals. |
