Design And Implementation Of Modulation And Demodulation System For Satellite Communication Based On FPGA

As the core link of deep space exploration missions,Satellite communication technology is a necessary condition for successful completion of space flight missions.Therefore,it is necessary to study the modulation and demodulation technology and system model of satellite communications.The current satellite communication system has many types of equipment,so it is difficult to design a dedicated hardware circuit to realize the function of each modulation and demodulation algorithm,which not only increases the complexity of the modem hardware circuit,but also raises the threshold for adding new demodulation algorithms.Therefore,according to the design principles of software-defined functions,open modular structure,and enhancement of system hardware versatility in software-defined radio,a modem with hardware generalization,function softwareization,and software modularization is designed to solve the problem,corresponding to satellite communication.The research of wireless communication system and software-defined radio technology is of great significance.First of all,this article expounds the technical links in the satellite communication system.The main contents include: transmitter technology,receiver synchronization technology principles and conventional modulation and demodulation algorithms.The general model of modulation and demodulation based on software-defined radio is analyzed in detail,and the orthogonal modulation and demodulation algorithm of digital signals in software-defined radio is studied and derived.Secondly,a software platform for modulation and demodulation algorithms is designed.The transmitting part uses orthogonal modulation to realize the common MPSK and 16 QAM modulation methods to modulate the source signal;the receiving part uses down conversion,carrier synchronization and other technologies to synchronize and decode the received signal Bit output,and the correctness and feasibility of these commonly used modulation and demodulation algorithms are simulated by Matlab software.If other modulation and demodulation methods are needed later,only the corresponding modulation and demodulation algorithm module needs to be added to this system.Finally,the hardware platform of the signal receiving end was designed,whichused FPGA and ADS62P49 to complete the system hardware platform design,including FPGA selection,system clock circuit design,and configuration of AD and DA.Finally,save the data processed by the board demodulation module as a.dat file,and read the file through the playback software to display the demodulation results for analysis.