Development Of 0.5-6GHz Solar Radio Telescope And Spectrogram Processing

Solar radio bursts,such as coronal mass ejections and solar flares,hurl massive amounts of high-energy particles into space.When these high-energy particles pass near the Earth,they will threaten the normal operation of satellite communication,aerospace,power network and other equipment.Therefore,it is of great significance to conduct all-weather and high-precision observation of solar activities.At the same time,in-depth study of solar radio burst data is an indispensable method to explain the physical theory of solar activity and the radiation mechanism.Especially in the microwave band,violent solar activity occurs frequently,which is an important frequency band for obtaining fine burst structure.There are many solar radio observation systems in microwave band around the world,which can obtain solar radio burst data.However,most of the current observation systems are backward in the configuration of analog receivers,and the digital receivers have low time and frequency resolution,which cannot meet the urgent needs of the field of radio astronomy to observe the fine fiber structure of solar radio bursts.In order to meet the needs of solar physics research,a solar radio observation system with high time and high frequency resolution covering 0.5-6GHz band is planned to be built at Chesham Radio Observation Station of Shandong University.This thesis mainly designs and implements the antenna,analog receiver and upper computer software of the 0.5-6GHz solar radio observation system.In the aspect of real-time prediction of radio bursts and data storage of solar radio observation system,in order to reduce the amount of observed data,a real-time detection algorithm of solar radio bursts based on digital filtering is designed and implemented in the upper computer software.According to whether solar radio bursts occur,the system time resolution is dynamically adjusted to reduce the amount of data stored.At the same time,according to the specific requirements of the research group for high security of solar radio spectrogram storage and network transmission,a sub-window was opened in the upper computer software,and combined with the chaotic system and the Deoxyribonucleic acid(DNA)dynamic coding theory,spectrogram encryption software was designed and implemented.The main research contents of this thesis are as follows:(1)The overall structure of the 0.5-6GHz solar radio observation system is designed and constructed.Combined with the specific needs of the research group for scientific research and the actual test results of the electromagnetic environment at Chashan Station,a solar radio observation system covering 0.5-6GHz is determined to be developed.At the same time,according to the calculation results of solar radiation flow in microwave band and considering the electromagnetic interference of observation station,the specific architecture of receiving antenna,analog receiver and digital receiver is designed.(2)A multifunctional upper computer software platform is developed.The upper computer software was realized based on Tee chart control and Microsoft Foundation Classes(MFC),with PCIe communication,data acquisition,data storage,real-time data graphical display,scene control and other functions.At the same time,it is equipped with the solar radio burst real-time detection module to dynamically adjust the time resolution of the digital receiver.This function effectively ensures that the spectrum data storage is greatly reduced when the observation system obtains the fine structure of solar radio bursts,and the long-term and stable operation of the observation system is realized.(3)A solar radio spectrogram encryption system is developed in the upper computer software.This encryption system uses two new variable parameter chaotic systems,combines SHA-256 algorithm and DNA dynamic coding to scramble,diffuse,and synchronously random scramble spectrograms to realize secure encryption.Performance analysis proves that the encryption system has a large key space,which can effectively resist differential attacks,statistical attacks and other conventional attack methods,and meet the requirements of high security and high reconstruction quality of solar radio spectrogram storage and network transmission.(4)The overall performance of the 0.5-6GHz solar radio observation system was tested,and the expected goal of stable and long-term operation at Chashan Radio observation Station was achieved.Before the formal operation,the basic performance indexes of analog receiver,digital receiver and upper computer are tested in detail.At last,the whole system is debugged at Chashan radio observation station,and the normal observation of the system has been realized.The 0.5-6GHz solar radio observation system has been observed normally for several months since its completion.The system can receive left/right linearly polarized solar radiation signals in real time,the linearity is up to 0.9999,the frequency resolution is 3 MHz,the time resolution is 0.26 ms,and the dynamic range is up to 60 dB.According to the theoretical index analysis and the sensitivity test results of the system,it is proved that the system can realize the scientific goal of real-time observation of the fine structure of the solar radio bursts,and meet the high-resolution requirement of the spectrogram with radio burst data in the scientific research of radio astronomy.