Flatness Optimization Of Broadband Solar Radio Spectral Data In 35-40GHz

The sun,as the nearest star to the earth,provides energy to lives on the earth.However,solar eruptions can affect short wave communication,aerospace and so on.Therefore,observations and studies on solar activities are important.With the development of microelectronics technology,the performance of solar radio telescopes has been improved significantly.However,the amplitude-frequency inconsistencies of devices of the system may distort the output data and affect the data quality.This thesis presents data flatness optimization methods based on the 35-40 GHz broadband Solar Radio Observation System of Laboratory for ElectromAgnetic Detection of Institute of Space Sciences Shandong University.Millimeter wave solar radio data are important in diagnosing the solar magnetic field and studying the mechanism of solar eruption.Due to the influence of atmospheric absorption,turbulent and device processing technology,the flatness of the observation system is poor.And the observation system with poor flatness affects the data accuracy and the system calibration.Therefore,it is necessary to find the causes of the poor flatness of the system and the optimization methods of flatness.This thesis proposes four kinds of flatness optimization methods of millimeter wave solar radio signal by software processing,including background subtraction method,gain table compensation method,channel compensation method,and quantile-quantile plots compensation method.Firstly,the feasibility of applying the four flatness optimization methods to 35-40 GHz broadband solar radio observation system is verified by simulation.By comparing the mean value,standard deviation and coefficient of variation of the simulation results,the advantages and disadvantages of four flatness optimization methods are evaluated.According to the flatness before and after the data compensation,the analysis shows that the method of quantile-quantile plots compensation provides the most improvement of the data flatness,which is about 15.8 times higher than the flatness of original data.Then we apply the four methods to the dynamic spectrum correction.It is concluded that the quantile-quantile plots compensation method is the best one in data flatness of the 35-40 GHz broadband radio observation system.The display interface is designed to display the spectrum data real-time and result of flatness optimization.The interface is designed by the combination of Microsoft Foundation Classes(MFC)and TeeChart.The interface can receive,store,and display data,and the software can also display flux line chart,spectrum chart,and spectrum line chart simultaneously.Through the dynamic spectrum test,the four flatness optimization methods can improve the flatness of the system significantly.It is found that the quantile-quantile plots compensation method has the best optimization effect.In this thesis,data recorded during the partial solar eclipse on June 21st 2020 in Weihai Shandong have been processed using the quantile-quantile plots compensation method.The system flatness is improved from 12.5 dBm to 4 dBm.The application of compensation method of quantile-quantile plots can significantly improve the data flatness,achieving better effect of spectrum optimization.