The Research Of Optical-Frequency Lightning Detection Technology

The lightning is one of the most dangerous nature disaster, we wish to do anything for early warning and protection to decrease the loss. If the energy of lightning can be made useful, a great of benefit can be acquired. No mater what we can do for the lightning, detecting and locating lightning effectively is the first thing need to be considered before we prevent the damage or use the lightning energy. The optical-frequency signal of the lightning is an important part, which includes a lot of information of the lightning itself. If we can detect the optical-frequency of lightning effectively, the optical characteristics and the process of the lightning can be acquired, even the electronic characteristics can be acquired when return stroke current and the radiated electromagnetic field are considered together, which is a effective way for realizing the Very Low Frequency(VLF)/Low Frequency(LF) or Very High Frequency(VHF) lightning detecting system. The two key technologies in the article, the lightning locating technology and the lightning detecting technology, have been studied deeply and been simulated. Based on the results, a optical-frequency lightning detecting system has been developed. The main contents and the creative results are below:(1) The reasons for lightning occurs have been analyzed and been classified. The whole discharge process and the characteristics of lightning have been studied deeply. And the lightning detecting technology is investigated based on the study.(2) The bottom return-stroke models when the lightning occurs, and the whole return-stroke engineering models for the total lignhning tunnel, have been built mathematically. Based on these, a modified return-stroke model is mentioned, and all the return-stroke engineering models are fixed by the new model. The detailed 2-dimension or 3-dimension stimulation has been taken for both models, and the results are compared. The tunnel bottom current model for the cloud-field flash, which is the most dangerous for humans, are stimulated and analyzed in frequency. From the spectrogram, the frequency of the more concentrated energy for the lightning current is found and can be used for deeper research about the return-stroke current.(3) The deep and meticulous study about the lightning locating technology based on the ground in China has been carried, and the error of the locating technologies based on the VLF/LF and the VHF is analyzed. Based on these, optical-frequency lightning locating technology is mentioned. The satellites locating technology, which is under the beginning development process, is been studied in the article, too. Take the example of time difference based on optical-frequency on the grounds, the lightning locating system is designed totally, and the system configuration is modeled and stimulated.(4) The hardware wave filter detecting technology, which is most taken currently, has been studied deeply and the results with noise of the lightning signal are stimulated. Base on this, the wavelet transform detecting technology and the new random resonance technology are applied in the lightning signal detection, and these two technologies can overcome some of the shortcomings of the hardware filter detecting technology. The stimulation results of the two technologies are compared, analyzed and prove the validity for lightning detecting under different environments.(5) The configuration of optical-frequency lightning detecting system is presented in the article. And the detailed hardware and software solutions of different function modules are introduced and the results shows the system works well.