| In recent decades,with the continuous development of science and technology,the improvement of the ways of lightning detection,human beings have a clearer understanding of the basic characteristics of thunder and lightning.As the saying goes,"spring thunder sound,the growth of all things".This sentence not only means the thunder and lightning will convert nitrogen from the air into nitrogen needed for the growth of all things,but also means thunder signals generated by lightning can stimulate seed growth.Because of the interference of complex environment in the course of thunder signal transmission,the existing complicated method of thunder signal denoising,this paper put forward a design method of the thunder signal generator based on singular value denoising algorithm,in order to the further study about the promoting effect of thunder signal on seeds.Firstly,this paper adopts singular value decomposition(SVD)method to decompose the thunder signal,and obtains a series of characteristic values with different sizes.Then,using the minimum description length(MDL)criterion to estimate the number of effective signal’s eigenvalues.Thereafter,separating the noise signal and reconstructing the thunder signal:in order to reduce the noise of thunder signal.The simulation results show that the singular value decomposition method is effective in reducing the noise of thunder signal.Secondly,the data communication between the host computer and the slave computer is realized.The paper uses the advanced application programming interface of Lab VIEW software to communicate with USB devices,sending the four groups of different seasons of noise signals to the FPGA development board of lower computer,and cahced in the synchronous dynamic random access memory(SDRAM).Then through the button A and button B on FPGA development board to control the read manner of digital signal stored in SDRAM,and converted the read digital thunder signal into analog thunder signal.Finally,through the power amplifier output these signals.In this paper,the signal generator can be divided into five functional modules:thunder signal denoising module,USB communication module,thunder signal cache module,data conversion module and power amplifier module.Thereinto,the thunder signal denoising module achieves the noise reduction function:the USB communication module transmits the thunder signal after denoising into lower computer FPGA development board;the thunder signal cache module stores the digital noise signal after denoising;the data conversion module converts the digital thunder signal into the analog signal;the power amplifier module controls the output power of the thunder signal.The experimental results show that the design of the signal generator based on singular value denoising algorithm is effective to reduce the noise of thunder signals in different seasons.And the utility model can effectively reduce the thunder signal,and realize the selectable output type,adjustable period and controllable power of thunder signals. |
