| This subject mainly relies on the "Spaceborne Radio Plasma Detection System",a major scientific research instrument development project of the National Natural Science Foundation of China,according to the target parameters indicated in the system design index,this thesis puts forward the preliminary design idea of the off-line data processing software system of the system,that is,the data processing system "Spaceborne Plasma 3D Imaging system" presented in this thesis.The detection parameters of the system in active mode include Plasma Density,Distance,Doppler,Echo Arrival Angle and so on.The research content and results of this thesis mainly include three aspects:First,according to the signal data processing process of the principle prototype of "Spaceborne Radio Plasma Detection System" developed by the project,this thesis presents a three-dimensional space-time distribution model of plasma density,namely "Space Plasma Three-Dimensional Imaging System".The data processing system is based on modular structure,and the preliminary design mainly includes three software modules.They are ranging module(output distance-density distribution information),direction finding module(output azimuth information),and velocity measurement module(output Doppler frequency shift and drift velocity information).The modular design reduces the complexity of the program,simplifies the debugging and maintenance of the system program,and supports the addition of other functional modules in the later stage of the project.Secondly,an algorithm model of plasma parameter extraction is presented in this thesis.As the current detection system cannot directly carry out spaceborne detection,it can only be tested by a principle prototype on the ground,so in the part of plasma parameter extraction,the eclectic algorithm is verified by the data of ionosphere detected by vertical sounding instrument.The proposed algorithm can extract the corresponding plasma information and invert the electron density profile,which proves the feasibility of the algorithm model.Finally,this thesis proposes an incoming wave direction finding and location method based on three-channel receiver and omni-directional antenna on moving vehicle.In the case of only considering the amplitude information of the received signal,the direction-finding method of three-dimensional spatial amplitude ratio is studied.A preliminary direction-finding experiment is carried out by using the Universal Software Radio Peripheral(USRP-LW B210),and a set of direction-finding simulation and experimental data processing system is built independently to verify and evaluate the feasibility of the direction-finding method based on this method. |
